CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to U.S. Provisional Application No. 63/412,393, filed on Oct. 1, 2022, the entire contents of which is incorporated herein by reference.
BACKGROUND 1. Field The present disclosure relates generally to mechanical inertial igniters and electrical impulse switches, and more particularly to compact and reliable mechanical inertial igniters and electrical impulse switches for reserve batteries such as thermal batteries and the like with prescribed accidental acceleration protection are which are activated by prescribed acceleration profiles defined in terms of the acceleration level and its duration, such as by gun firing acceleration with a prescribed level and duration.
2. Prior Art Reserve batteries of the electrochemical type are well known in the art for a variety of uses where storage time before use is extremely long. Reserve batteries are in use in applications such as batteries for gun-fired munitions including guided and smart, mortars, fusing mines, missiles, rockets and many other military and commercial applications. The electrochemical reserve-type batteries can in general be divided into two different basic types.
The first type includes the so-called thermal batteries, which are to operate at high temperatures. Unlike liquid reserve batteries, in thermal batteries the electrolyte is already in the cells and therefore does not require a release and distribution mechanism such as spinning. The electrolyte is dry, solid and non-conductive, thereby leaving the battery in a non-operational and inert condition. These batteries incorporate pyrotechnic heat sources to melt the electrolyte just prior to use in order to make them electrically conductive and thereby making the battery active. The most common internal pyrotechnic is a blend of Fe and KClO4. Thermal batteries utilize a molten salt to serve as the electrolyte upon activation. The electrolytes are usually mixtures of alkali-halide salts and are used with the Li(Si)/FeS2 or Li(Si)/CoS2 couples. Some batteries also employ anodes of Li(Al) in place of the Li(Si) anodes. Insulation and internal heat sinks are used to maintain the electrolyte in its molten and conductive condition during the time of use.
Thermal batteries have long been used in munitions and other similar applications to provide a relatively large amount of power during a relatively short period of time, mainly during the munitions flight. Thermal batteries have high power density and can provide a large amount of power as long as the electrolyte of the thermal battery stays liquid, thereby conductive. The process of manufacturing thermal batteries is highly labor intensive and requires relatively expensive facilities. Fabrication usually involves costly batch processes, including pressing electrodes and electrolytes into rigid wafers, and assembling batteries by hand. The batteries are encased in a hermetically sealed metal container that is usually cylindrical in shape.
The second type includes the so-called liquid reserve batteries in which the electrodes are fully assembled for cooperation, but the liquid electrolyte is held in reserve in a separate container until the batteries are desired to be activated. In these types of batteries, by keeping the electrolyte separated from the battery cell, the shelf life of the batteries is essentially unlimited. The battery is activated by transferring the electrolyte from its container to the battery electrode compartment.
A typical liquid reserve battery is kept inert during storage by keeping the aqueous electrolyte separate in a glass or metal ampoule or in a separate compartment inside the battery case. The electrolyte compartment may also be separated from the electrode compartment by a membrane or the like. Prior to use, the battery is activated by breaking the ampoule or puncturing the membrane allowing the electrolyte to flood the electrodes. The breaking of the ampoule or the puncturing of the membrane is achieved either mechanically using certain mechanisms usually activated by the firing setback acceleration or by the initiation of certain pyrotechnic material. In these batteries, the projectile spin or a wicking action is generally used to transport the electrolyte into the battery cells.
Reserve batteries are inactive and inert when manufactured and become active and begin to produce power only when they are activated. Reserve batteries have the advantage of very long shelf life of up to 20 years that is required for munitions applications.
Thermal batteries generally use some type of initiation device (igniter) to provide a controlled pyrotechnic reaction to produce output gas, flame or hot particles to ignite the heating elements of the thermal battery. There are currently two distinct classes of igniters that are available for use in thermal batteries. The first class of igniter operates based on electrical energy. Such electrical igniters, however, require electrical energy, thereby requiring an onboard battery or other power sources with related shelf life and/or complexity and volume requirements to operate and initiate the thermal battery. The second class of igniters, commonly called “inertial igniters,” operate based on the firing acceleration. The inertial igniters do not require onboard batteries for their operation and are thereby often used in munitions applications such as in gun-fired munitions and mortars.
Inertial igniters are also used to activate liquid reserve batteries through the rupture of the electrolyte storage container or membrane separating it from the battery core. The inertial igniter mechanisms may also be used to directly rupture the electrolyte storage container or membrane.
Inertial igniters used in munitions must be capable of activating only when subjected to the prescribed setback acceleration levels and durations and not when subjected to any of the so-called no-fire conditions such as accidental drops or transportation vibration or the like. This means that safety in terms of prevention of accidental ignition is one of the main concerns in inertial igniters.
In recent years, new improved chemistries and manufacturing processes have been developed that promise the development of lower cost and higher performance thermal and liquid reserve batteries that could be produced in various shapes and sizes, including their small and miniaturized versions. Such developments have accelerated the need for inertial igniters for a wide range of munitions applications.
In some munitions and the like applications, the prescribed firing acceleration level may be lower than the level of accidental accelerations that the munition may experience. In certain applications, the duration of the latter acceleration may be lower than the prescribed firing acceleration duration and sometimes even longer. The inertial igniters must therefore be capable of satisfying both such scenarios. The wide range of prescribed firing acceleration levels and durations as well as the wide range of accidental acceleration levels and durations that must be considered make the configuration of inertial igniters challenging and unique configurations must usually be developed for each different munition application.
Inertial igniters used in munitions must be capable of activating only when subjected to the prescribed setback acceleration levels and durations and not when subjected to any of the so-called no-fire conditions such as accidental drops or transportation vibration or the like. This means that safety in terms of prevention of accidental ignition is one of the main concerns in inertial igniters.
Mechanical inertial igniters have been developed for many munitions applications in which the munitions are subjected to relatively high firing setback accelerations of generally over 1,000 Gs with long enough duration that provides enough time for the inertial igniter to activate the igniter pyrotechnic material, which may consist of a primer or an appropriate pyrotechnic material that is directly applied to the inertial igniter as described in previous art.
In some munition applications, the firing acceleration is high and long enough to allow a striker mass to be accelerated to high enough velocity so that it would gain enough kinetic energy to initiate the igniter primer or other provided pyrotechnic material.
In some munition applications, however, the setback acceleration duration is not long enough or the required inertial igniter size and/or volume does not allow the use of a large enough striker mass to achieve the required kinetic energy for percussion primer or other pyrotechnic material. In such applications, the inertial igniter must be provided with preloaded springs to accelerate the provided striker mass to the required velocity so that upon impact, it would reliably initiate the provided inertial igniter percussion primer or other pyrotechnic material of the device.
Inertia-based igniters can provide two basic functions. The first function is to provide the capability to differentiate the aforementioned accidental events such as drops over hard surfaces or transportation vibration or the like, i.e., all no-fire events, from the prescribed firing acceleration level and its duration, i.e., the so-called all-fire condition. In inertial igniters, this function is performed by keeping the device striker fixed to the device structure during all aforementioned no-fire events until the prescribed firing acceleration event, i.e., the firing acceleration level and duration, is detected. At which time, the device striker is released. The second function of an inertia-based igniter is to provide the means of accelerating the device striker to the kinetic energy level that is needed to initiate the device pyrotechnic material as the striker (hammer element) strikes an “anvil” over which the pyrotechnic material is provided. In general, the striker is provided with a relatively sharp point which strikes the pyrotechnic material covering a raised surface over the anvil, thereby allowing a relatively thin pyrotechnic layer to be pinched to achieve a reliable ignition mechanism. In many applications, percussion primers are directly mounted on the anvil side of the device and the required initiation pin is machined or attached to the striker to impact and initiate the primer. In either configuration, exit holes are provided on the inertial igniter to allow the reserve battery activating flames and sparks to exit.
Two basic methods are currently available for accelerating the device striker to the aforementioned needed velocity (kinetic energy) level. The first method is based on allowing the setback acceleration to accelerate the striker mass following its release. This method requires the setback acceleration to have long enough duration to allow for the time that it takes for the striker mass to be released and for the striker mass to be accelerated to the required velocity before percussion primer or pyrotechnic material impact. As a result, this method is applicable to larger caliber and mortar munitions in which the setback acceleration duration is relatively long and in the order of several milliseconds, sometimes even longer than 10-15 milliseconds. This method is also suitable for impact induced initiations in which the impact induced decelerations have relatively long duration.
The second method relies on potential energy stored in a spring (elastic) element, which is then released upon the detection of the prescribed all-fire conditions. This method is suitable for use in munitions that are subjected to very short setback accelerations, such as those of the order of 1-2 milliseconds or when the setback acceleration level is low and space constraints does now allow the use of relatively large striker mass or where the height limitations of the available space for the inertial igniter does not provide enough travel distance for the inertial igniter striker to gain the required velocity and thereby kinetic energy to initiate the pyrotechnic material.
Inertia-based igniters must therefore comprise two components so that together they provide the aforementioned mechanical safety, the capability to differentiate the prescribed all-fire condition from all aforementioned no-fire conditions and to provide the required striking action to achieve ignition of the provided percussion primer or pyrotechnic element. The function of the safety system is to keep the striker element in a relatively fixed position until the prescribed all-fire condition (or the prescribed impact induced deceleration event) is detected, at which time the striker element is to be released, allowing it to accelerate toward its target under the influence of the remaining portion of the setback acceleration or the potential energy stored in its spring (elastic) element of the device. The ignition itself may take place as a result of striker impact, or simply contact or proximity. For example, the striker may be akin to a firing pin and the target akin to a standard percussion cap primer. Alternately, the striker-target pair may bring together one or more chemical compounds whose combination with or without impact will set off a reaction resulting in the desired ignition.
A schematic of a cross-section of a conventional thermal battery and inertial igniter assembly is shown in FIG. 1. In thermal battery applications, the inertial igniter 10 (as assembled in a housing) may be positioned above (in the direction of the acceleration) the thermal battery housing 11 as shown in FIG. 1. Upon ignition, the igniter initiates the thermal battery pyrotechnics positioned inside the thermal battery through a provided access 12. The total volume that the thermal battery assembly 16 occupies within munitions is determined by the diameter 17 of the thermal battery housing 11 (assuming it is cylindrical) and the total height 15 of the thermal battery assembly 16. The volume of the thermal battery for a given battery diameter 17 is generally determined by the amount of energy that it has to produce over the required period of time. For a given thermal battery height 14, the height 13 of the inertial igniter 10 would therefore determine the total height 15 of the thermal battery assembly 16. To reduce the total space that the thermal battery assembly 16 occupies within a munitions housing, it is therefore important to reduce the height of the inertial igniter 10. This is particularly important for small thermal batteries since in such cases and with currently available inertial igniter, the height of the inertial igniter portion 13 is a significant portion of the thermal battery height 15.
A configuration of an inertial igniter for satisfying the safety (no initiation) requirement when dropped from heights of up to 7 feet (up to 2,000 G impact deceleration with a duration of up to 0.5 msec) is described below using one such embodiment disclosed in the prior art. An isometric cross-sectional view of this embodiment 200 of the inertia igniter is shown in FIG. 2. The full isometric view of the inertial igniter 200 is shown in FIG. 3. The inertial igniter 200 is constructed with igniter body 201, consisting of a base 202 and at least three posts 203. The base 202 and the at least three posts 203, can be integral but may be constructed as separate pieces and joined together, for example by welding or press fitting or other methods commonly used in the art. The base of the housing 202 is also provided with at least one opening 204 (with a corresponding opening in the thermal battery 12 in FIG. 1) to allow the ignited sparks and fire to exit the inertial igniter into the thermal battery positioned under the inertial igniter 200 upon initiation of the inertial igniter pyrotechnics 204, FIG. 2, or percussion cap primer when used in place of the pyrotechnics as disclosed therein.
A striker mass 205 is shown in its locked position in FIG. 2. The striker mass 205 is provided with vertical surfaces 206 that are used to engage the corresponding (inner) surfaces of the posts 203 and serve as guides to allow the striker mass 205 to ride down along the length of the posts 203 without rotation with an essentially pure up and down translational motion. The vertical surfaces 206 may be recessed to engage the inner three surfaces of the properly shaped posts 203.
In its illustrated position in FIGS. 2 and 3, the striker mass 205 is locked in its axial position to the posts 203 by at least one setback locking ball 207. The setback locking ball 207 locks the striker mass 205 to the posts 203 of the inertial igniter body 201 through the holes 208 provided in the posts 203 and a concave portion such as a dimple (or groove) 209 on the striker mass 205 as shown in FIG. 2. A setback spring 210, which can be in compression, is also provided around but close to the posts 203 as shown in FIGS. 2 and 3. In the configuration shown in FIG. 2, the locking balls 207 are prevented from moving away from their aforementioned locking position by the collar 211. The collar 211 can be provided with partial guide 212 (“pocket”), which are open on the top as indicated by numeral 213. The guides 213 may be provided only at the locations of the locking balls 207 as shown in FIGS. 2 and 3, or may be provided as an internal surface over the entire inner surface of the collar 211 (not shown). The advantage of providing local guides 212 is that it would result in a significantly larger surface contact between the collar 211 and the outer surfaces of the posts 203, thereby allowing for smoother movement of the collar 211 up and down along the length of the posts 203. In addition, they would prevent the collar 211 from rotating relative to the inertial igniter body 201 and makes the collar stronger and more massive. The advantage of providing a continuous inner recess guiding surface for the locking balls 207 is that it would require fewer machining processes during the collar manufacture.
The collar 211 can ride up and down the posts 203 as can be seen in FIGS. 2 and 3, but is biased to stay in its upper most position as shown in FIGS. 2 and 3 by the setback spring 210. The guides 212 are provided with bottom ends 214, so that when the inertial igniter is assembled as shown in FIGS. 2 and 3, the setback spring 210 which is biased (preloaded) to push the collar 211 upward away from the igniter base 201, would hold the collar 211 in its uppermost position against the locking balls 207. As a result, the assembled inertial igniter 200 stays in its assembled state and would not require a top cap to prevent the collar 211 from being pushed up and allowing the locking balls 207 from moving out and releasing the striker mass 205.
In this embodiment, a one-part pyrotechnics compound 215 (such as lead styphnate or some other similar compounds) is used as shown in FIG. 2. The surfaces to which the pyrotechnic compound 215 is attached can be roughened and/or provided with surface cuts, recesses, or the like and/or treated chemically as commonly done in the art (not shown) to ensure secure attachment of the pyrotechnics material to the applied surfaces. The use of one-part pyrotechnics compound makes the manufacturing and assembly process much simpler and thereby leads to lower inertial igniter cost. The striker mass can be provided with a relatively sharp tip 216 and the igniter base surface 202 is provided with a protruding tip 217 which is covered with the pyrotechnics compound 215, such that as the striker mass is released during an all-fire event and is accelerated down, impact occurs mostly between the surfaces of the tips 216 and 217, thereby pinching the pyrotechnics compound 215, thereby providing the means to obtain a reliable initiation of the pyrotechnics compound 215.
Alternatively, instead of using the pyrotechnics compound 215, FIG. 2, a percussion cap primer can be used. An appropriately shaped striker tip can be provided at the tip 216 of the striker mass 205 (not shown) to facilitate initiation upon impact.
An operation of the embodiment 200 of the inertial igniter of FIGS. 2 and 3 is now described. In case of any non-trivial acceleration in the axial direction 218 which can cause the collar 211 to overcome the resisting force of the setback spring 210 will initiate and sustain some downward motion of the collar 211. The force due to the acceleration on the striker mass 205 is supported at the dimples 209 by the locking balls 207 which are constrained inside the holes 208 in the posts 203. If the acceleration is applied over long enough time in the axial direction 218, the collar 211 will translate down along the axis of the assembly until the setback locking balls 205 are no longer constrained to engage the striker mass 205 to the posts 203. If the event acceleration and its time duration is not sufficient to provide this motion (i.e., if the acceleration level and its duration are less than the predetermined threshold), the collar 211 will return to its start (top) position under the force of the setback spring 210 once the event has ceased.
Assuming that the acceleration time profile was at or above the specified “all-fire” profile, the collar 211 will have translated down past the locking balls 207, allowing the striker mass 205 to accelerate down towards the base 202. In such a situation, since the locking balls 207 are no longer constrained by the collar 211, the downward force that the striker mass 205 has been exerting on the locking balls 207 will force the locking balls 207 to move outward in the radial direction. Once the locking balls 207 are out of the way of the dimples 209, the downward motion of the striker mass 205 is no longer impeded. As a result, the striker mass 205 accelerates downward, causing the tip 216 of the striker mass 205 to strike the pyrotechnic compound 215 on the surface of the protrusion 217 with the requisite energy to initiate ignition.
In the embodiment 200 of the inertial igniter shown in FIGS. 2 and 3, the setback spring 210 is of a helical wave spring type fabricated with rectangular cross-sectional wires (such as the ones manufactured by Smalley Steel Ring Company of Lake Zurich, Illinois). This is in contrast with the helical springs with circular wire cross-sections used in other available inertial igniters. The use of the aforementioned rectangular cross-section wave springs or the like has the following significant advantages over helical springs that are constructed with wires with circular cross-sections. Firstly, and most importantly, as the spring is compressed and nears its “solid” length, the flat surfaces of the rectangular cross-section wires come in contact, thereby generating minimal lateral forces that would otherwise tend to force one coil to move laterally relative to the other coils as is usually the case when the wires are circular in cross-section. Lateral movement of the coils can, in general, interfere with the proper operation of the inertial igniter since it could, for example, jam a coil to the outer housing of the inertial igniter (not shown in FIGS. 2 and 3), which is usually desired to house the igniter 200 or the like with minimal clearance to minimize the total volume of the inertial igniter. In addition, the laterally moving coils could also jam against the posts 203 thereby further interfering with the proper operation of the inertial igniter. The use of the wave springs with rectangular cross-section would therefore significantly increase the reliability of the inertial igniter and also significantly increase the repeatability of the initiation for a specified all-fire condition.
In the embodiment 200 of FIGS. 2 and 3, following ignition of the pyrotechnics compound 215, the generated flames and sparks are configured to exit downward through the opening 204 to initiate the thermal battery below. Alternatively, if the thermal battery is positioned above the inertial igniter 200, the opening 204 can be eliminated and the striker mass could be provided with at least one opening (not shown) to guide the ignition flame and sparks up through the striker mass 205 to allow the pyrotechnic materials (or the like) of a thermal battery (or the like) positioned above the inertial igniter 200 (not shown) to be initiated.
Alternatively, side ports may be provided to allow the flame to exit from the side of the igniter to initiate the pyrotechnic materials (or the like) of a thermal battery or the like that is positioned around the body of the inertial igniter. Other alternatives known in the art may also be used.
In FIGS. 2 and 3, the inertial igniter embodiment 200 is shown without any outside housing. In many applications, as shown in the schematics of FIG. 4a (4b), the inertial igniter 240 (250) is placed securely inside the thermal battery 241 (251), either on the top (FIG. 4a) or bottom (FIG. 4b) of the thermal battery housing 242 (252). This is particularly the case for relatively small thermal batteries. In such thermal battery configurations, since the inertial igniter 240 (250) is inside the hermetically sealed thermal battery 241 (251), there is no need for a separate housing to be provided for the inertial igniter itself. In this assembly configuration, the thermal battery housing 242 (252) is provided with a separate compartment 243 (253) for the inertial igniter. The inertial igniter compartment 243 (253) can be formed by a member 244 (254) which is fixed to the inner surface of the thermal battery housing 242 (253), for example, by welding, brazing or very strong adhesives or the like. The separating member 244 (254) is provided with an opening 245 (255) to allow the generated flame and sparks following the initiation of the inertial igniter 240 (250) to enter the thermal battery compartment 246 (256) to activate the thermal battery 241 (251). The separating member 244 (254) and its attachment to the internal surface of the thermal battery housing 242 (252) must be strong enough to withstand the forces generated by the firing acceleration.
It is appreciated by those skilled in the art that by varying the mass of the striker 205, the mass of the collar 211, the spring rate of the setback spring 210, the distance that the collar 211 has to travel downward to release the locking balls 207 and thereby release the striker mass 205, and the distance between the tip 216 of the striker mass 205 and the pyrotechnic compound 215 (and the tip of the protrusion 217), the designer of the disclosed inertial igniter 200 can try to match the all-fire and no-fire impulse level requirements for various applications as well as the safety (delay or dwell action) protection against accidental dropping of the inertial igniter and/or the munitions or the like within which it is assembled.
Briefly, the safety system parameters, i.e., the mass of the collar 211, the spring rate of the setback spring 210 and the dwell stroke (the distance that the collar 210 must travel downward to release the locking balls 207 and thereby release the striker mass 205) must be tuned to provide the required actuation performance characteristics. Similarly, to provide the requisite impact energy, the mass of the striker 205 and the aforementioned separation distance between the tip 216 of the striker mass and the pyrotechnic compound 215 (and the tip of the protrusion 217) must work together to provide the specified impact energy to initiate the pyrotechnic compound when subjected to the remaining portion of the prescribed initiation acceleration profile after the safety system has been actuated.
The significant shortcomings of the prior art inertial igniters are related to their limitations for use in munitions with relatively low setback acceleration levels, for example, for munitions with setback acceleration levels of below around 300-500 Gs, or where the duration of the setback acceleration is very short, for example around 1 millisecond, and when the available space limits the height of the inertial igniter, for example to around 5-10 mm, or when more than one of the indicated limitations are present.
In addition, due to the unavoidable friction related forces, the difference between the no-fire impulse due to the acceleration level and duration acting on the striker mass release mechanism and the all-fire impulse due to the setback acceleration level and its duration acting on the striker mass release mechanism must be large enough to ensure the very high reliability that is required for the proper operation of the inertial igniters. In most munitions, operational reliability requirement of sometimes over 99.9 percent at 95 percent confidence level is very common and in certain cases must be even higher. In munitions in which the difference between no-fire and all-fire impulsive forces acting on the striker mass release mechanism is relatively small, the friction forces between the relevant moving parts of the inertial igniter must therefore be minimized.
It is also appreciated that such inertial igniters must be very compact to occupy minimal space in reserve batteries and initiation trains.
It is also highly desirable to have inertial igniters that would not initiate when subjected to accelerations that are significantly larger in magnitude and even in duration.
It is also appreciated by those skilled in the art that currently available G-switches of different type that are used for opening or closing an electrical circuit are configured to perform this function when they are subjected to a prescribed acceleration level without accounting for the duration of the acceleration level. As such, they suffer from the shortcoming of being activated accidentally, e.g., when the object in which they are used is subjected to short duration shock loading such as could be experienced when dropped on a hard surface as was previously described for the case of inertial igniter used in munitions.
When used in applications such as in munitions, it is highly desirable for G-switches to be capable to differentiate the aforementioned accidental and short duration shock (acceleration) events such as those experienced by dropping on hard surfaces, i.e., all no-fire conditions, from relatively longer duration firing setback (shock) accelerations, i.e., all-fire condition. Such G-switches should activate when firing setback (all-fire) acceleration and its duration results in an impulse level threshold corresponding to the all-fire event has been reached, i.e., they must operate as an “impulse switch”. This requirement necessitates the employment of safety mechanisms like those used in the inertial igniter embodiments, which can allow the switch activation only when the firing setback acceleration level and duration thresholds have been reached. The safety mechanism can be thought of as a mechanical delay mechanism, after which a separate electrical switch mechanism is actuated or released to provide the means of opening or closing at least one electrical circuit.
Such impulse switches with the aforementioned integrated safety mechanisms are highly desirable to be very small in size so that they could be readily used on electronic circuit boards of different products such as munitions or the like.
It is also highly desirable to have impulse switches that would not activate when subjected to accelerations that are significantly larger in magnitude and even in duration.
SUMMARY A need therefore exists for methods to configuration mechanical inertial igniters for munitions applications and the like in which the setback acceleration levels and/or duration are low; and/or due to space limitations, the size and particularly the height of the inertial igniter must be very low, for example, in the range of 5-10 mm; and/or the no-fire and all-fire acceleration levels are too close to each other; and that the inertial igniter is required to be highly reliable, for example, have better than 99.9 percent reliability with 95 percent confidence level.
A need also exists for mechanical inertial igniters that are developed based on the above methods and that can satisfy the safety requirement of munitions, i.e., the no-fire conditions, such as accidental drops and transportation vibration and other similar events.
A need therefore exists for novel miniature mechanical inertial igniters for thermal reserve batteries and liquid reserve batteries and other current and under development reserve batteries used in gun-fired munitions, mortars, rochets and missiles and the like, particularly for small thermal and other reserve batteries that could be used in fuzing and other similar applications, that are safe (i.e., satisfy the munitions no-fire conditions), are small in size, particularly in height, to minimize the size of the thermal battery, and that can be used in applications in which the setback acceleration level is relatively low (for example, 300-500 Gs) and/or the setback acceleration duration is short (for example, in the order of 1-2 milliseconds).
Such innovative inertial igniters are highly desired to be scalable to thermal batteries of various sizes, in particular to miniaturized inertial igniters for small size thermal batteries. Such inertial igniters are generally also required not to initiate if dropped from heights of up to 5-7 feet onto a concrete floor, which can result in impact induced inertial igniter decelerations of up to of 2000 G that may last up to 0.5 msec. The inertial igniters are also generally required to withstand high firing accelerations, for example up to 20-50,000 Gs (i.e., not to damage the thermal battery); and should be able to be configured to ignite at specified acceleration levels when subjected to such accelerations for a specified amount of time to match the firing acceleration.
To ensure safety and reliability, inertial igniters should not initiate during acceleration events which may occur during manufacture, assembly, handling, transport, accidental drops, etc. Additionally, once under the influence of an acceleration profile particular to the intended firing of ordinance from a gun, the device should initiate with high reliability. It is also conceivable that the igniter will experience incidental low but long-duration accelerations, whether accidental or as part of normal handling, which must be guarded against initiation. Again, the impulse given to the inertial igniter will have a great disparity with that given by the initiation acceleration profile because the magnitude of the incidental long-duration acceleration will be quite low.
In addition, the inertial igniters used in munitions are generally required to have a shelf life of better than 20 years and could generally be stored at temperatures of sometimes in the range of ˜65 to 165 degrees F. The inertial igniter configurations must also consider the manufacturing costs and simplicity in the configurations to make them cost effective for munitions applications.
Accordingly, methods are provided that can be used to configuration fully mechanical inertial igniters that can satisfy the prescribed no-fire requirements while satisfying relatively low all-fire firing setback acceleration level requirement and/or short all-fire firing setback acceleration duration requirement. The methods rely on potential energy stored in a spring (elastic) element, which is then released upon the detection of the prescribed all-fire conditions. These methods are particularly suitable for use in munitions that are subjected to very short setback accelerations, such as those of the order of 1-2 milliseconds or when the setback acceleration level is low and space constraints does now allow the use of relatively large striker mass or where the height limitations of the available space for the inertial igniter does not provide enough travel distance for the inertial igniter striker to gain the required velocity and thereby kinetic energy to initiate the pyrotechnic material.
Also provided are fully mechanical igniters that are configured based on the above methods that can satisfy the prescribed no-fire requirements while satisfying relatively low all-fire firing setback acceleration level requirements and/or short all-fire firing setback acceleration duration requirement. The inertial igniters rely on potential energy stored in a spring (elastic) element, which is then released upon the detection of the prescribed all-fire conditions. Such inertial igniters are particularly suitable for use in munitions that are subjected to very short setback accelerations, such as those of the order of 1-2 milliseconds or when the setback acceleration level is low and space constraints does now allow the use of relatively large striker mass or where the height limitations of the available space for the inertial igniter does not provide enough travel distance for the inertial igniter striker to gain the required velocity and thereby kinetic energy to initiate the pyrotechnic material.
A need also exists for methods to configure inertial igniters that would not activate when subjected to accelerations that are significantly larger in magnitude than the peak munition firing acceleration with durations that may also be relatively long.
Accordingly, methods are provided that can be used to configuration fully mechanical inertial igniters that would not activate when subjected to accelerations that are significantly larger in magnitude than the peak munition firing acceleration with durations that may also be relatively long.
Also provided are fully mechanical igniters that are configured based on the above methods that would not activate when subjected to accelerations that are significantly larger in magnitude than the peak munition firing acceleration with durations that may also be relatively long.
Those skilled in the art will appreciate that the inertial igniters disclosed herein may provide one or more of the following advantages over prior art inertial igniters:
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- provide inertial igniters that are safe and can differentiate no-fire conditions from all-fire conditions based on the prescribed all-fire setback acceleration level (target impact acceleration level when used for target impact activation) and its prescribed duration;
- provide inertial igniters that can be activated by very short duration setback accelerations (target impact acceleration level when used for target impact activation) of the order on 1-2 milliseconds or less;
- provide inertial igniters that are very short in height to minimize the space that is occupied by the inertial igniter in the reserve battery and other locations that they are used, which is made possible by separating the striker mass release mechanism from the mechanism that accelerates the striker element, i.e., the use of potential energy stored in the device elastic element (preloaded spring element);
- provide inertial igniters that allow the use of standard off-the-shelf percussion cap primers or commonly used one part or two-part pyrotechnic components;
- provide inertial igniters that would not activate when subjected to accelerations that are significantly larger in magnitude than the peak munition firing acceleration with durations that may also be relatively long;
- provide inertial igniters that can be sealed to simplify storage and to increase shelf life.
Accordingly, an inertial igniter is provided. The inertial igniter comprising: a striker mass movable towards one of a percussion cap or pyrotechnic material; a member for releasing the striker mass releasing element upon an acceleration time and magnitude greater than a prescribed threshold; a striker mass release element for releasing the striker mass to strike the percussion cap or pyrotechnic material.
Accordingly, an inertial igniter is provided. The inertial igniter comprising: a striker mass movable towards one of a percussion cap or pyrotechnic material; a member for releasing the striker mass releasing element upon an acceleration time and magnitude greater than a prescribed threshold; a striker mass release element for releasing the striker mass to strike the percussion cap or pyrotechnic material.
The inertial igniter further comprises an elastic element (such as a torsion spring) that is preloaded to provide the required amount of potential energy to accelerate the striker mass upon release to the required velocity to achieve reliable percussion cap or pyrotechnic material initiation upon impact.
The member for releasing the striker mass release element can further comprise a biasing member for biasing the element to demand higher all-fire release acceleration level.
The member for releasing the striker mass release element may be rotationally moveable to minimize the effects of friction on the operation of the inertial igniter.
The inertial igniter striker mass and the release element may be rotationally movable to minimize the effects of friction on the operation of the inertial igniter.
The member for releasing the striker mass release element can be configured to be returnable from the path of releasing the striker mass releasing element when the acceleration duration and magnitude (all-fire condition) threshold is not reached.
The inertial igniter may be provided with members that prevent the release of the striker mass by inhibiting the movement of the member for releasing the striker mass release element when the inertial igniter is subjected to no-fire accelerations with magnitudes that are significantly higher than the activation (all-fire) acceleration magnitude and even longer than the activation acceleration duration threshold (hereinafter referred to as “very high accelerations”.
The inertial igniter may be configured with members that prevent the release of the striker mass by inhibiting the movement of the member for releasing the striker mass release element when inertial igniter is subjected to “very high accelerations” that either reset following the to “very high accelerations” event or prevent future activation of the inertial igniter.
The inertial igniter can also be provided with a safety pin that prevents its activation for the purpose of safety during transportation and assembly in the reserve battery or the like.
Also provided is a method for initiating a thermal battery. The method comprising: releasing a striker mass upon an acceleration duration and magnitude greater than a prescribed threshold; and transferring potential energy stored in an elastic element (spring element) to the striker mass to gain enough kinetic energy to strike and initiate the provided percussion cap or pyrotechnic material.
The method can further comprise returning the striker mass release element to its original (zero acceleration condition) position when the acceleration duration and magnitude (all-fire condition) threshold is not reached.
The method can further comprise preventing the striker mass release in the event of a “very high accelerations” event.
It is appreciated by those skilled in the art that the disclosed inertial igniter mechanisms may also be used to construct electrical impulse switches, which are activated like the so-called electrical G switches but with the added time delays to account for the activation shock level duration requirement, i.e., similar to the disclosed inertial igniters to activate when a prescribed shock loading (acceleration) level is experienced for a prescribed length of time (duration). The electrical “impulse switches” may be configured as normally open or closed and with or without latching mechanisms. Such impulse switch embodiments that combine such safety mechanisms with electrical switching mechanisms are described herein together with alternative methods of their construction.
Also disclosed are inertial igniters with the capability to open or close an electrical switch, which can then be used by the user to determine the activation status of the inertial igniter as assembled in the reserve battery or the like. This capability may also be used for all-fire event detection in munitions or the like.
A need therefore exists for novel miniature impulse switches for use in munitions or the like that can differentiate accidental short duration shock loading (so-called no-fire events for munitions) from generally high but longer duration, i.e., high impulse threshold levels, that correspond to all-fire conditions in gun fired munitions or the like. Such impulse switches must be very small in size and volume to make them suitable for being integrated into electronic circuit boards or the like. They must also be readily scalable to different all-fire and no-fire conditions for different munitions or other similar applications. Such impulse switches must be safe and should be able to be configured to activate at prescribed acceleration levels when subjected to such accelerations for a specified amount of time to match the firing acceleration experienced in a gun barrel as compared to high G accelerations experienced during accidental falls or other similar events which last over very short periods of time, for example accelerations of the order of 1000 Gs when applied for 5 msec as experienced in a gun as compared to 2000 G acceleration levels experienced during accidental fall over a concrete floor but which may last only 0.5 msec. Reliability is also of much concern since most munitions are required to have a shelf life of up to 20 years and could generally be stored at temperatures of sometimes in the range of −65 to 165 degrees F. This requirement is usually satisfied best if the device is in a sealed compartment. The impulse switch must also consider the manufacturing costs and simplicity of configuration to make it cost effective for munitions applications.
Those skilled in the art will appreciate that the compact impulse-based mechanical impulse switches disclosed herein may provide one or more of the following advantages over prior art mechanical G-switches:
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- provide impulse-based G-switches that are small in both height and volume, thereby making them suitable for mounting directly on electronic circuit boards and the like;
- provide impulse-based switches that differentiate all-fire conditions from all no-fire conditions, even those no-fire conditions that result in higher levels of shock but short duration, thereby eliminating the possibility of accidental activation;
- provide impulse switches that are modular in configuration and can therefore be readily customized to different no-fire and all-fire requirements;
- provide impulse switches that do not operate when subjected to the aforementioned “very high acceleration” events;
- provide impulse switches that may be normally open or normally closed and that are modular in configuration and can be readily customized for opening or closing or their combination of at least one electric circuit.
Accordingly, impulse-based impulse switches with modular configuration for use in electrical or electronic circuitry are provided that activate upon a prescribed acceleration profile threshold. In most munition applications, the acceleration profile is usually defined in terms of firing setback acceleration and its duration.
BRIEF DESCRIPTION OF THE DRAWINGS These and other features, aspects, and advantages of the apparatus will become better understood with regard to the following description, appended claims, and accompanying drawings where:
FIG. 1 illustrates a schematic of a cross-section of a thermal battery and inertial igniter assembly of the prior art.
FIG. 2 illustrates a schematic of a cross-section of an inertial igniter for thermal battery described in the prior art.
FIG. 3 illustrates a schematic of the isometric drawing of the inertial igniter for thermal battery of FIG. 2.
FIG. 4a illustrates a schematic of a cross-section of a thermal battery of the prior art with an inertial igniter positioned on the top portion of the thermal battery and in which the ignition generated flame to be directed downwards into the thermal battery compartment.
FIG. 4b illustrates a schematic of a cross-section of a thermal battery of the prior art with an inertial igniter positioned on the bottom portion of the thermal battery and in which the ignition generated flame to be directed upwards into the thermal battery compartment.
FIG. 5 illustrates the schematic of the side view of the first inertial igniter embodiment o with linearly sliding movement of its components.
FIG. 5A illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 5 after it is subjected to the prescribed activation acceleration as the tip of the sliding release mass disengages the rotary release link element of the inertial igniter.
FIG. 5B illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 5 after it is subjected to the prescribed activation acceleration and the rotary release link element has rotated in the counterclockwise direction and has released the sliding member of the inertial igniter.
FIG. 5C illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 5 as the sliding member has been accelerated towards the percussion primer of the inertial igniter and its sharp end is about to strike the percussion primer to initiate it.
FIG. 6 illustrates the schematic of the side view of the second inertial igniter embodiment with rotary movement of its components.
FIG. 6A illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 6 after it is subjected to the prescribed activation acceleration as the tip of the release mass link disengages the rotary release link element of the inertial igniter.
FIG. 6B illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 6 after it is subjected to the prescribed activation acceleration and the rotary release link element has rotated in the counterclockwise direction and has released the striker mass of the inertial igniter.
FIG. 6C illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 6 as the striker mass is rotationally accelerated in the counterclockwise direction towards the percussion primer of the inertial igniter and its sharp tip is about to strike the percussion primer to initiate it.
FIG. 7 illustrates the schematic of the side view of the modified inertial igniter embodiment of FIG. 5 for activation for prescribed acceleration magnitude and duration in the opposite direction.
FIG. 7A illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 7 after it is subjected to the prescribed activation acceleration as the tip of the sliding release mass disengages the rotary release link element of the inertial igniter.
FIG. 7B illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 7 after it is subjected to the prescribed activation acceleration and the rotary release link element has rotated in the counterclockwise direction and has released the sliding member of the inertial igniter.
FIG. 7C illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 7 as the sliding member has been accelerated towards the percussion primer of the inertial igniter and its sharp end is about to strike the percussion primer to initiate it.
FIG. 8 illustrates the schematic of the side view of the modified inertial igniter embodiment of FIG. 5 for flame and spark exit in the direction of the prescribed activation acceleration.
FIG. 8A illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 8 after it is subjected to the prescribed activation acceleration as the tip of the sliding release mass disengages the rotary release link element of the inertial igniter.
FIG. 8B illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 8 after it is subjected to the prescribed activation acceleration and the rotary release link element has rotated in the counterclockwise direction and has released the sliding member of the inertial igniter.
FIG. 8C illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 8 as the sliding member has been accelerated towards the percussion primer of the inertial igniter and its sharp end is about to strike the percussion primer to initiate it.
FIG. 9 illustrates the schematic of the side view of the modified inertial igniter embodiment of FIG. 8 for flame and spark exit in the opposite direction of the prescribed activation acceleration.
FIG. 9A illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 9 after it is subjected to the prescribed activation acceleration as the tip of the sliding release mass disengages the rotary release link element of the inertial igniter.
FIG. 9B illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 9 after it is subjected to the prescribed activation acceleration and the rotary release link element has rotated in the counterclockwise direction and has released the sliding member of the inertial igniter.
FIG. 9C illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 9 as the sliding member has been accelerated towards the percussion primer of the inertial igniter and its sharp end is about to strike the percussion primer to initiate it.
FIG. 10 illustrates the schematic of the side view of the modified inertial igniter embodiment of FIG. 6 for activation by prescribed acceleration magnitude and duration in the opposite direction of that of the inertial igniter embodiment of FIG. 6.
FIG. 10A illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 10 after it is subjected to the prescribed activation acceleration as the tip of the release mass link disengages the rotary release link element of the inertial igniter.
FIG. 10B illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 10 after it is subjected to the prescribed activation acceleration and the rotary release link element has rotated in the counterclockwise direction and has released the striker mass of the inertial igniter.
FIG. 10C illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 10 as the striker mass is rotationally accelerated in the counterclockwise direction towards the percussion primer of the inertial igniter and its sharp tip is about to strike the percussion primer to initiate it.
FIG. 11 illustrates the schematic of the side view of the modified inertial igniter embodiment of FIG. 10 for activation by prescribed acceleration magnitude and duration and the flame exit in the direction opposite to the direction of prescribed acceleration.
FIG. 11A illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 11 after it is subjected to the prescribed activation acceleration as the tip of the release mass link disengages the rotary release link element of the inertial igniter.
FIG. 11B illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 11 after it is subjected to the prescribed activation acceleration and the rotary release link element has rotated in the counterclockwise direction and has released the striker mass of the inertial igniter.
FIG. 11C illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 11 as the striker mass is rotationally accelerated in the counterclockwise direction towards the percussion primer of the inertial igniter and its sharp tip is about to strike the percussion primer to initiate it.
FIG. 12 illustrates the schematic of the side view of the modified inertial igniter embodiment of FIG. 11 for activation by prescribed acceleration magnitude and duration in the direction opposite to the direction of prescribed acceleration.
FIG. 12A illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 12 after it is subjected to the prescribed activation acceleration as the tip of the release mass link disengages the rotary release link element of the inertial igniter.
FIG. 12B illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 12 after it is subjected to the prescribed activation acceleration and the rotary release link element has rotated in the counterclockwise direction and has released the striker mass of the inertial igniter.
FIG. 12C illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 12 as the striker mass is rotationally accelerated in the counterclockwise direction towards the percussion primer of the inertial igniter and its sharp tip is about to strike the percussion primer to initiate it.
FIG. 13 illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 5 in its pre-activation configuration and with the added mechanism for preventing activation of the inertial igniter when subjected to accidental “very high acceleration” events.
FIG. 14 illustrates the blow-up view “A” of the side view of the inertial igniter embodiment of FIG. 13 showing the details of the added mechanism for preventing activation of the inertial igniter when subjected to accidental “very high acceleration” events.
FIG. 15 illustrates the blow-up view “A” of the side view of the inertial igniter embodiment of FIG. 14 after the inertial igniter is subjected to a “very high acceleration” and its activation is being prevented.
FIG. 16 illustrates the blow-up view “A” of the side view of the inertial igniter embodiment 13 showing another example of the added mechanism for preventing activation of the inertial igniter when subjected to accidental “very high acceleration” events.
FIG. 17 illustrates the blow-up view “A” of the side view of the inertial igniter embodiment of FIG. 16 after the inertial igniter is subjected to a “very high acceleration” and its activation is being prevented.
FIG. 18A illustrates the blow-up view “B” of the “very high acceleration” event inertial igniter activation prevention mechanism of FIG. 14 with the added no-return mechanism in its normal state.
FIG. 18B illustrates the blow-up view “B” of the “very high acceleration” event inertial igniter activation prevention mechanism of FIG. 14 following a “very high acceleration” event and the action of the added no-return mechanism in preventing return to the normal state of FIG. 18A.
FIG. 19A illustrates the blow-up view “C” of the “very high acceleration” event inertial igniter activation prevention mechanism of FIG. 16 with the added no-return mechanism in its normal state.
FIG. 19B illustrates the blow-up view “C” of the “very high acceleration” event inertial igniter activation prevention mechanism of FIG. 16 following a “very high acceleration” event and the action of the added no-return mechanism in preventing return to the normal state of FIG. 19A.
FIG. 20 illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 6 in its pre-activation configuration and with the added mechanism for preventing activation of the inertial igniter when subjected to accidental “very high acceleration” events.
FIG. 21A illustrates the blow-up view “D” of the side view of the inertial igniter embodiment of FIG. 20 showing the details of the added mechanism for preventing activation of the inertial igniter when subjected to accidental “very high acceleration” events.
FIG. 21B illustrates the blow-up view “D” of the side view of the inertial igniter embodiment of FIG. 20 following a “very high acceleration” event and the action of the added no-return mechanism in preventing return to the normal state of FIG. 20A.
FIG. 22 illustrates the schematic of the side view of the inertial igniter embodiment of FIG. 11 in its pre-activation configuration and with the added mechanism for preventing activation of the inertial igniter when subjected to accidental “very high acceleration” events.
FIG. 23A illustrates the blow-up view “E” of the side view of the inertial igniter embodiment of FIG. 22 showing the details of the added mechanism for preventing activation of the inertial igniter when subjected to accidental “very high acceleration” events.
FIG. 23B illustrates the blow-up view “E” of the side view of the inertial igniter embodiment of FIG. 22 following a “very high acceleration” event and the action of the added mechanism in preventing activation of the inertial igniter.
FIG. 24A illustrates the blow-up view “E” of the “very high acceleration” event inertial igniter activation prevention mechanism of FIG. 22 with the added no-return mechanism in its normal state.
FIG. 24B illustrates the blow-up view “E” of the “very high acceleration” event inertial igniter activation prevention mechanism of FIG. 22 following a “very high acceleration” event and the action of the added no-return mechanism in preventing return to the normal state of FIG. 24A.
FIG. 25 illustrates the schematic of the top view of the third inertial igniter embodiment with all rotary elements mounted on a single shaft to achieve a high level of inertial igniter compactness.
FIG. 25A illustrates the cross-sectional view A-A of the inertial igniter embodiment of FIG. 25.
FIG. 25B illustrates the cross-sectional view B-B of the inertial igniter embodiment of FIG. 25.
FIG. 25C illustrates the view “C” of the inertial igniter embodiment of FIG. 25.
FIG. 25D illustrates the cross-sectional view A-A of the inertial igniter embodiment of FIG. 25 following its activation.
FIG. 26A illustrates the cross-sectional view A-A of the inertial igniter embodiment of FIG. 25 with repositioned percussion primer for flame and spark exit perpendicular to the direction of activation acceleration.
FIG. 26B illustrates the cross-sectional view of FIG. 26A following the inertial igniter activation.
FIG. 27A illustrates the view “C” of the modified inertial igniter embodiment of FIG. 25 to achieve ignition flame and spark exit in the same direction as the activation acceleration.
FIG. 27B illustrates the cross-sectional view B-B of the modified inertial igniter embodiment of FIG. 25 to achieve ignition flame and spark exit in the same direction as the activation acceleration.
FIG. 28A illustrates the view “C” of the top view of the inertial igniter embodiment of FIG. 25 showing the details of the added mechanism for preventing activation of the inertial igniter when subjected to accidental “very high acceleration” events.
FIG. 28B illustrates the view “C” of the top view of the inertial igniter embodiment of FIG. 25 following a “very high acceleration” event and the action of the added mechanism in preventing inertial igniter activation.
FIG. 29A illustrates the view “C” of the top view of the inertial igniter embodiment of FIG. 25 with the “very high acceleration” event inertial igniter activation prevention mechanism of FIG. 28A and the added no-return mechanism in its normal state.
FIG. 29B illustrates the view “C” of the top view of the inertial igniter embodiment of FIG. 25 with the “very high acceleration” event inertial igniter activation prevention mechanism and the no-return mechanism of FIG. 29A following a “very high acceleration” event and the action of the added no-return mechanism in rendering the inertial igniter non-functional.
FIG. 30A illustrates an alternative configuration of the mechanism “very high acceleration” event inertial igniter activation prevention mechanism for the inertial igniter embodiment of FIG. 25 in its pre-activation configuration.
FIG. 30B illustrates the alternative “very high acceleration” event inertial igniter activation prevention mechanism of FIG. 30A in its actuated configuration in response to a “very high acceleration” event.
FIG. 31A illustrates the schematic of the cross-sectional view A-A of the inertial igniter embodiment of FIG. 25 that is converted to a normally open electrical impulse switch for closing electrical circuits when subjected to a prescribed activation acceleration level and duration threshold in its non-activated state.
FIG. 31B illustrates the schematic of the cross-sectional view A-A of the inertial igniter embodiment of FIG. 25 that is converted to a normally open electrical impulse switch for closing electrical circuits of FIG. 31A when subjected to a prescribed activation acceleration level and duration threshold in its activated state.
FIG. 32A illustrates the schematic of the cross-sectional view A-A of the inertial igniter embodiment of FIG. 25 that is converted to a normally closed electrical impulse switch for opening electrical circuits when subjected to a prescribed activation acceleration level and duration threshold in its non-activated state.
FIG. 32B illustrates the schematic of the cross-sectional view A-A of the inertial igniter embodiment of FIG. 25 that is converted to a normally closed electrical impulse switch for opening electrical circuits of FIG. 31A when subjected to a prescribed activation acceleration level and duration threshold in its activated state.
DETAILED DESCRIPTION The methods to configure the inertial igniters are herein described through the following examples of their application.
The schematic of the side view of the first inertial igniter embodiment 300 is shown in FIG. 5. The inertial igniter is shown to be configured with mostly sliding joints, which makes it significantly easier to demonstrate an exemplary method of the present inertial igniters. It is noted that in the schematic of FIG. 5, the inertial igniter 300 is illustrated in its pre-activation configuration.
The inertial igniter embodiment 300 is constructed with an igniter structure 301 (i.e., base or housing), the inertial igniter component attachment points of which are shown in FIG. 5, and which would take the required shape to fit the intended munition or the like space. The inertial igniter is provided with a sliding member 302, which is free to slide inside the guide 303 provided in the structure 301 of the inertial igniter. The slider member is provided with a section 304, which may be conical in shape as shown in the schematic of FIG. 5. The section 304 may be integral to the sliding member 302 or may be a separate part that is fixedly attached to the sliding member 302 or is held against a provided step (not shown) on the slider member. A preloaded compression spring 305 is then provided over the sliding member 302, with one end of it resting against the surface 306 of the guide 303 on the structure 301 of the inertial igniter and on the other end against the back of the section 304 as shown in the schematic of FIG. 5. In its pre-activation configuration of FIG. 5, the compressive spring 305 is held in its preloaded state by the tip 310 of the rotary release link element 311, which is engaging the section 304 of the sliding member 302 as can be seen in FIG. 5. The rotary release link element 311 is in turn prevented from counterclockwise rotation and releasing the sliding member as is described later by the tip 312 of the sliding release mass 313.
In the inertial igniter embodiment 300 of FIG. 5, the rotary release link element 311 is attached to the inertial igniter structure 301 by the rotary joint 314 via the support 315. In the pre-activation configuration of the inertial igniter embodiment 300 shown in FIG. 5, the rotary release link element 311 is biased to its positioning by the section 304 of the sliding member 302, which tends to rotate it in the counterclockwise direction as viewed in FIG. 5 by applying a force to its tip 310 due to the preloaded compressive spring 305, and the engaging tip 312 of the sliding release mass 313 preventing its counterclockwise rotation. It is also appreciated that in general there is no need for the provided preloaded compressive spring 316 to bias it to its pre-activation positioning of FIG. 5, but the spring 316 may be provided to increase the speed with which the inertial igniter is activated following detection of the prescribed acceleration magnitude and duration (all-fire condition in munitions) as is described later.
The sliding release mass 313 is free to displace inside the guide 318 in parallel with the direction of the prescribed activation acceleration, as indicated by the arrow 317. The upward displacement of the sliding release mass 313 is limited by the stop 319. The preloaded compressive spring 320, one end of which is attached to the inertial igniter structure 301 and the other end to the sliding release mass 313 is used to bias the sliding release mass stop 319 against the structure 301 and in the configuration shown in FIG. 5.
The inertial igniter embodiment 300 of FIG. 5 would then operate as follows. When the device to which the inertial igniter is attached is accelerated in the direction of the arrow 317, if the applied acceleration magnitude and duration (i.e., acceleration profile) satisfies the prescribed acceleration level and duration thresholds, then the dynamic force due to the applied acceleration acting on the mass of the sliding release mass 313 would overcome the preloading of the compressive spring 320 and displace the sliding release mass 313 downward enough for its tip 312 to disengage the end 311a of the rotary release link element 311 as shown in the schematic of FIG. 5A.
In general, the mass of the sliding release mass 313, the distance that it has to displace downward to disengage the rotary release link element 311, the preloading level of the compressive spring 320 and its rate are selected such that if the prescribed activation acceleration level and duration thresholds are not reached, the rotary release link element 311 is not released, thereby the inertial igniter is not activated as described below.
Then once the sliding release mass 313 has disengaged the rotary release link element 311, the sliding member 302 is free to be accelerated to the left by the force of the preloaded compressive spring 305 and the rotary release link element 311 is rotated out of the path of the section 304 of the sliding member 302 by forcing it to rotate in the counterclockwise direction together with the force of the preloaded compressive spring 316 if it is provided as shown in the schematic of FIG. 5B. The sliding member is then accelerated to the left until its provided sharp tip 307 strikes the percussion primer 308, which is mounted firmly in the structure 301 of the inertial igniter as shown in the schematic of FIG. 5C. The mass and stiffness of the slide member and the preloading level of the spring 305 are selected such that it has gained enough kinetic energy before the tip 307 strikes the percussion primer 308 (or other proper pyrotechnic material) for its reliable initiation. The generated ignition flame and sparks would then exit the inertial igniter housing through the provided opening 309.
It is appreciated that if the acceleration in the direction of the arrow 317 is less than the prescribed acceleration threshold or if its duration is less than the prescribed duration threshold, the preloaded compressive spring 320 is configured to limit downward displacement of the sliding release mass 313 and prevent it from disengaging the rotary release link element 311.
The schematic of the side view of the second inertial igniter embodiment 330 is shown in FIG. 6. The inertial igniter is shown to be configured with moving components that undergo rotary motions, which allows further miniaturization of the inertial igniters and significantly reduces the effects of friction, thereby making the operation of the inertial igniter more reliable, particularly for applications in which the activation (all-fire in munition) and no-activation (no-fire accidental acceleration events in munitions) acceleration magnitudes are relatively close to each other. It is noted that in the schematic of FIG. 6, the inertial igniter 330 is illustrated in its pre-activation configuration
The inertial igniter embodiment 330 is constructed with an igniter structure 321 (i.e., base or housing), the inertial igniter component attachment points of which are shown in FIG. 6, and which would take the required shape to fit the intended munition or the like space. The inertial igniter is provided with a rotary striker mass 322, which is attached to the inertial igniter structure 321 by the rotary joint 323 via the support member 324. The rotary striker mass 322 is shaped, such as shown in the schematic of FIG. 6, to provide a room for the sharp tip 325 and the slanted surface 326.
In its pre-activation configuration of FIG. 6, the slanted surface 326 is biased to rests against the surface 331 of the tip of the striker mass release link 327, which is attached to the inertial igniter structure 321 by the rotary joint 328 via the support member 329. In the pre-activation configuration of the inertial igniter shown in FIG. 6, the striker mass release link 327 is prevented from counterclockwise rotation by the tip 332 of the release mass link 333, which is in engagement with the member 334, which can be integral to the striker mass release link 327. The engaging surface of the member 334 may be curved as shown in FIG. 6, for example with a radius matching or close to the radius defined by the contact point of the engaging tip 332 of the release mass link 333 to facilitate the rotation of the link 333 as described later during the inertial igniter activation.
In the pre-activation configuration of the inertial igniter embodiment 330 of FIG. 6, the rotary striker mass 322 is biased by the preloaded torsion spring 336 to keep its slanted surface 326 firmly against the tip 331 of the striker mass release link 327. The rotary striker mass may also be provided by a stop member 335 to limit clockwise rotation of the striker mass release link 327. The preloaded torsion spring 336 is attached on one end to the support 324 of the rotary joint 323 and to the rotary striker mass 322 on the other end 337. The striker mass release link 327 may also be provided with the preloaded compressive spring 338, which is attached to the inertial igniter structure 321 on one end and to the link 327 on the other end as can be seen in FIG. 6 for the purpose of assisting in its clockwise rotation during the inertial igniter activation as is described later.
The release mass link 333, FIG. 6, is also attached to the structure 321 of the inertial igniter by the rotary joint 339 via the support member 340. The release mass link 333 may also be provided with a mass member 341 to provide the link 33 with enough inertia to properly respond to the activation acceleration in the direction of the arrow 343 as the operation of the inertial igniter embodiment 330 is later described. The release mass link 333 is also provided with a preloaded compressive spring 342, which is attached on one end to the structure 321 of the inertial igniter embodiment 330 and to the release mass link 333 on the other end. The preloaded compressive spring 342 is used to bias the release mass link 333 against the provided stop 344 on the structure 321 of the inertial igniter and in the pre-activation, configuration shown in the schematic of FIG. 6.
The inertial igniter embodiment 330 of FIG. 6 would then operate as follows. When the device to which the inertial igniter is attached is accelerated in the direction of the arrow 343, if the applied acceleration magnitude and duration satisfies the prescribed acceleration level and duration thresholds, then the dynamic force due to the applied acceleration acting on the center of mass of the release mass link 333 and the mass member 341 would overcome the preloading of the compressive spring 342 and rotate it in the clockwise direction enough for its tip 332 to disengage striker mass release link 327 and its member 334 as shown in the schematic of FIG. 6A.
In general, the effective mass of the release mass link 333 and the mass member 341, the amount of clockwise rotation that the release mass link 333 has to undergo to disengage the striker mass release link 327, and the preloading level of the compressive spring 342 and its rate are selected such that if the prescribed activation acceleration level and duration thresholds are not reached, the striker mass release link 327 is not released, thereby the inertial igniter is not activated as described below.
Then once the release mass link 333 has disengaged the striker mass release link 327, i.e., the tip 332 of the release mass link 333 has disengaged the contacting surface of the member 334, the rotary striker mass 322 is free to be rotationally accelerated in the counterclockwise direction by the preloaded torsion spring 336 and the striker mass release link 327 is rotated in the counterclockwise direction and out of the path of the rotary striker mass 322 by forcing it to rotate in the counterclockwise direction by the slanted surface 326 of the rotary striker mass 322 together with the force of the preloaded compressive spring 338, if it is provided, as shown in the schematic of FIG. 6B.
The rotary striker mass 322 would then continue to be rotationally accelerated in the counterclockwise direction until its provided sharp tip 325 strikes the percussion primer 345, which is mounted firmly in the structure 321 of the inertial igniter as shown in the schematic of FIG. 6C. The mass and stiffness of the rotary striker mass 322 and the preloading level of the torsion spring 326 and its rate are selected such that the rotary striker mass would gain enough kinetic energy before the sharp tip 325 strikes the percussion primer 345 (or other proper pyrotechnic material) for its reliable initiation. The ignition flame and sparks would then exit the provided opening 346 in the structure of the inertial ignite housing 321.
It is appreciated that if the acceleration in the direction of the arrow 343 is less than the prescribed acceleration threshold or if its duration is less than the prescribed duration threshold, the preloaded compressive spring 342 is configured to limit clockwise rotation of the release mass link 333 and prevent it from disengaging the striker mass release link 327.
In certain applications, the direction of the applied activation acceleration is in the opposite direction than is indicated by the arrow 317 in FIG. 5 for the inertial igniter embodiment 300. To accommodate such applications, the following modifications can be made to the configuration of the inertial igniter embodiment 300 as shown in FIG. 7 and indicated as the inertial igniter embodiment 350.
The inertial igniter embodiment 350 construction is identical to that of the embodiment 300, except that its rotary release link element 351 (311 in FIG. 5) and the sliding release mass 347 (313 in FIG. 5) are positioned on the opposite side of the sliding member 302 as can be seen in the schematic of FIG. 7. Similarly, the inertial igniter component attachment points and geometry would be selected to fit the intended munition or the like space. Also similarly, in its pre-activation configuration of FIG. 7, the compressive spring 305 is held in its preloaded state by the tip 348 (310 in FIG. 5) of the rotary release link element 351, which is engaging the section 304 of the sliding member 302 as can be seen in FIG. 7. The rotary release link element 351 is in turn prevented from clockwise rotation and releasing the sliding member 302 as is described later by the tip 349 (312 in FIG. 5) of the sliding release mass 313.
In the inertial igniter embodiment 350 of FIG. 7, the rotary release link element 351 is also attached to the inertial igniter structure 301 by the rotary joint 352 via the support 353. In the pre-activation configuration of the inertial igniter embodiment 350 shown in FIG. 7, the rotary release link element 351 is biased to its positioning by the section 304 of the sliding member 302, which tends to rotate it in the clockwise direction as viewed in FIG. 7 by applying a force to its tip 348 due to the preloaded compressive spring 305, and the engaging tip 349 of the sliding release mass 347 preventing its clockwise rotation. It is also appreciated that in general there is no need for the provided preloaded compressive spring 354 (316 in FIG. 5) to bias it to its pre-activation positioning of FIG. 7, but the spring 354 may be provided to increase the speed with which the inertial igniter is activated following detection of the prescribed acceleration magnitude and duration (all-fire condition in munitions) as is described later.
The sliding release mass 347 is also free to displace inside the guide 355 (318 in FIG. 5) in parallel with the direction of the prescribed activation acceleration, as indicated by the arrow 356. The downward displacement of the sliding release mass 347 is limited by the stop 357 (319 in FIG. 5). The preloaded compressive spring 358 (320 in FIG. 5), one end of which is attached to the inertial igniter structure 301 and the other end to the stop 357 of the sliding release mass 357 is used to bias the sliding release mass 347 against the structure 301 and in the configuration shown in FIG. 7.
The inertial igniter embodiment 350 of FIG. 7 would then operate as follows. When the device to which the inertial igniter is attached is accelerated in the direction of the arrow 356, if the applied acceleration magnitude and duration satisfies the prescribed acceleration level and duration thresholds, then the dynamic force due to the applied acceleration acting on the mass of the sliding release mass 347 would overcome the preloading of the compressive spring 358 and displaces the sliding release mass 347 upward enough for its tip 349 to disengage the rotary release link element 351 as shown in the schematic of FIG. 7A.
In general, the mass of the sliding release mass 347, the distance that it has to displace downward to disengage the rotary release link element 351, the preloading level of the compressive spring 358 and its rate are selected such that if the prescribed activation acceleration level and duration thresholds are not reached, the rotary release link element 347 is not released, thereby the inertial igniter is not activated as described below.
Then once the sliding release mass 347 has disengaged the rotary release link element 351, the sliding member 302 is free to be accelerated to the left by the force of the preloaded compressive spring 305 and the rotary release link element 351 is rotated in the clockwise direction as viewed in the schematic of FIG. 7A and out of the path of the section 304 of the sliding member 302. This is done by the force applied by section 304 together with the force of the preloaded compressive spring 354 (if provided) to rotate the rotary release link element 351 in the clockwise direction as shown in the schematic of FIG. 7B. The sliding member is then accelerated to the left until its provided sharp tip 307 strikes the percussion primer 308, which is mounted firmly in the structure 301 of the inertial igniter as shown in the schematic of FIG. 7C. The mass and stiffness of the slide member and the preloading level of the spring 305 and its rate are selected such that it has gained enough kinetic energy before the tip 307 strikes the percussion primer 308 (or other proper pyrotechnic material) for its reliable initiation. The generated ignition flame and sparks would then exit the inertial igniter housing through the provided opening 309.
It is appreciated that if the acceleration in the direction of the arrow 356 is less than the prescribed acceleration threshold or if its duration is less than the prescribed duration threshold, the preloaded compressive spring 358 is configured to limit upward displacement of the sliding release mass 347 and prevent it from disengaging the rotary release link element 351.
It is appreciated that in the inertial igniter embodiments 5 and 7, the direction of the flame and spark exit following the initiation of the provided percussion primer (or other pyrotechnic material) is perpendicular to the direction of the activation (firing in munitions) accelerations shown by the arrows 317 and 356, respectively. However, in certain applications, the direction of the flame and spark exit is required to be in the direction or opposite to the direction of firing acceleration. To accommodate such applications, the following modifications can be made to the configuration of the inertial igniter embodiment 300 of FIG. 5.
The schematic of the side view of the modified inertial igniter embodiment 300 of FIG. 5 to direct ignition flame and spark exit to be directed in the direction of the activation acceleration is shown in FIG. 8 and indicated as the embodiment 360. The inertial igniter is shown to be configured with components that are either identical to those of the inertial igniter embodiment 300 or function similarly. It is noted that in the schematic of FIG. 8, the inertial igniter 360 is illustrated in its pre-activation configuration.
The inertial igniter embodiment 360 is similarly constructed with an igniter structure 362 (301 in FIG. 5), the inertial igniter component attachment points of which are shown in FIG. 8, and which would take the required shape to fit the intended munition or the like device space. The inertial igniter is provided with a sliding member 359 (302 in FIG. 5), which is free to slide inside the guide 361 (303 in FIG. 5) provided in the structure 362 of the inertial igniter. The slider member 359 is provided with a section 363 (304 in FIG. 5), which may be conical in shape as shown in the schematic of FIG. 8. The section 363 may be integral to the sliding member 359 or may be a separate part that is fixedly attached to the sliding member or is held against a provided step (not shown) on the slider member. A preloaded compression spring 364 (305 in FIG. 5) is then provided over the sliding member 359, with one end of it resting against the surface 365 (306 in FIG. 5) of the guide 361 on the structure 362 of the inertial igniter and on the other end against the back of the section 363 as shown in the schematic of FIG. 8. In its pre-activation configuration of FIG. 8, the compressive spring 364 is held in its preloaded state by the tip 366 of the rotary release link element 367 (modified 311 of FIG. 5), which is engaging the section 363 of the sliding member 359 as can be seen in FIG. 8. The rotary release link element 367 is in turn prevented from clockwise rotation and releasing the sliding member 359 as is described later by the tip 368 (312 in FIG. 5) of the sliding release mass 369 (313 in FIG. 5).
In the inertial igniter embodiment 360 of FIG. 8, the rotary release link element 367 is attached to the inertial igniter structure 362 by the rotary joint 370 via the support 371. In the pre-activation configuration of the inertial igniter embodiment 360 shown in FIG. 8, the rotary release link element 367 is biased to its positioning by the section 363 of the sliding member 359, which tends to rotate it in the clockwise direction as viewed in FIG. 8 by applying a force to its tip 366 due to the preloaded compressive spring 364, and the engaging tip 368 of the sliding release mass 369 preventing its clockwise rotation. It is also appreciated that in general, there is no need for the provided preloaded compressive spring 372 (316 in FIG. 5) to bias it to its pre-activation positioning and against the tip 368 of the sliding release mass 369, but the spring 372 may be provided to increase the speed with which the inertial igniter is activated following detection of the prescribed acceleration magnitude and duration (all-fire condition in munitions) as is described later.
The sliding release mass 369 is free to displace inside the guide 373 (318 in FIG. 5) in parallel with the direction of the prescribed activation acceleration, as indicated by the arrow 374. The downward displacement of the sliding release mass 369 is limited by the stop 375. The preloaded compressive spring 376 (320 in FIG. 5), one end of which is attached to the inertial igniter structure 362 and the other end to the stop 375 is used to bias the sliding release mass stop 369 against the structure 362 and in the configuration shown in FIG. 8.
The inertial igniter embodiment 360 of FIG. 8 would then operate as follows. When the device to which the inertial igniter is attached is accelerated in the direction of the arrow 374, if the applied acceleration magnitude and duration satisfies the prescribed acceleration level and duration thresholds, then the dynamic force due to the applied acceleration acting on the total inertia of the sliding release mass 369 would overcome the preloading of the compressive spring 376 and displaces the sliding release mass 369 upward enough for its tip 368 to disengage the rotary release link element 367 as shown in the schematic of FIG. 8A.
In general, the mass of the sliding release mass 369, the distance that it has to displace upward to disengage the rotary release link element 367, the preloading level of the compressive spring 376 and its rate are selected such that if the prescribed activation acceleration level and duration thresholds are not reached, the rotary release link element 367 is not released, thereby the inertial igniter is not activated as described below.
Then once the sliding release mass 369 has disengaged the rotary release link element 367, the sliding member 359 is free to be accelerated downward by the force of the preloaded compressive spring 364 and the rotary release link element 367 is rotated out of the path of the section 363 of the sliding member 369 by forcing it to rotate in the clockwise direction together with the force of the preloaded compressive spring 372 if it is provided as shown in the schematic of FIG. 8B. The sliding member is then accelerated downward until its provided sharp tip 379 strikes the percussion primer 377, which is mounted firmly in the structure 362 of the inertial igniter as shown in the schematic of FIG. 8C. The mass and stiffness of the slide member and the preloading level of the spring 364 are selected such that it has gained enough kinetic energy before the tip 379 strikes the percussion primer 377 (or other proper pyrotechnic material) for its reliable initiation.
It is appreciated that if the acceleration in the direction of the arrow 374 is less than the prescribed acceleration threshold or if its duration is less than the prescribed duration threshold, the preloaded compressive spring 376 is configured to limit upward displacement of the sliding release mass 369 and prevent it from disengaging the rotary release link element 367.
In certain applications, the direction of the applied activation acceleration is in the opposite direction than is indicated by the arrow 374 in FIG. 8 for the inertial igniter embodiment 360. To accommodate such applications, the following modifications can be made to the configuration of the inertial igniter embodiment 360 as shown in FIG. 8 and indicated as the inertial igniter embodiment 390 as shown in the schematic of FIG. 9.
The inertial igniter embodiment 380 construction is identical to that of the embodiment 360, except that its rotary release link element 382 (367 in FIG. 8) and the sliding release mass 383 (369 in FIG. 8) are positioned below the sliding member 359 as can be seen in the schematic of FIG. 9. Similarly, the inertial igniter component attachment points and geometry would be selected to fit the intended munition or the like space. Also similarly, in its pre-activation configuration of FIG. 9, the compressive spring 364 is held in its preloaded state by the tip 384 (366 in FIG. 8) of the rotary release link element 382, which is engaging the section 363 of the sliding member 359 as can be seen in FIG. 9. The rotary release link element 382 is in turn prevented from clockwise rotation and releasing the sliding member 359 as is described later by the tip 385 (368 in FIG. 8) of the sliding release mass 383.
In the inertial igniter embodiment 380 of FIG. 9, the rotary release link element 382 is also attached to the inertial igniter structure 362 by the rotary joint 386 via the support 387. In the pre-activation configuration of the inertial igniter embodiment 380 shown in FIG. 9, the rotary release link element 382 is biased to its positioning by the section 363 of the sliding member 359, which tends to rotate it in the clockwise direction as viewed in FIG. 9 by applying a force to its tip 384 due to the preloaded compressive spring 364, and the engaging tip 385 of the sliding release mass 383 preventing its clockwise rotation. It is also appreciated that in general there is no need for the provided preloaded in tension spring 389 to bias it to its pre-activation positioning of FIG. 9, but the spring 389 may be provided to increase the speed with which the inertial igniter is activated following detection of the prescribed acceleration magnitude and duration (all-fire condition in munitions) as is described later.
The sliding release mass 383 is also free to displace inside the guide 390 in parallel with the direction of the prescribed activation acceleration, as indicated by the arrow 381. The downward displacement of the sliding release mass 383 is limited by the stop 391. The preloaded compressive spring 388, one end of which is attached to the inertial igniter structure 362 and the other end to the stop 391 of the sliding release mass 383 is used to bias the sliding release mass 383 against the structure 362 and in the configuration shown in FIG. 9.
The inertial igniter embodiment 380 of FIG. 9 would then operate as follows. When the device to which the inertial igniter is attached is accelerated in the direction of the arrow 381, if the applied acceleration magnitude and duration satisfies the prescribed acceleration level and duration thresholds, then the dynamic force due to the applied acceleration acting on the effective mass of the sliding release mass 383 would overcome the preloading of the compressive spring 388 and displaces the sliding release mass 383 downward enough for its tip 385 to disengage the rotary release link element 382 as shown in the schematic of FIG. 9A.
In general, the effective mass of the sliding release mass 383, the distance that it has to displace downward to disengage the rotary release link element 382, the preloading level of the compressive spring 388 and its rate are selected such that if the prescribed activation acceleration level and duration thresholds are not reached, the rotary release link element 382 is not released, thereby the inertial igniter is not activated as described below.
Then once the sliding release mass 383 has disengaged the rotary release link element 382, the sliding member 359 is free to be accelerated downward by the force of the preloaded compressive spring 364 and the rotary release link element 382 is rotated in the clockwise direction as viewed in the schematic of FIG. 9A and out of the path of the section 363 of the sliding member 359. This is done by the force applied by section 363 together with the force of the preloaded in tension spring 389 (if provided) to rotate the rotary release link element 382 in the clockwise direction as shown in the schematic of FIG. 9B. The sliding member 359 is then accelerated downward until its provided sharp tip 379 strikes the percussion primer 377, which is mounted firmly in the structure 362 of the inertial igniter as shown in the schematic of FIG. 9C. The mass and stiffness of the slide member 359 and the preloading level of the spring 364 and its rate are selected such that it has gained enough kinetic energy before the tip 379 strikes the percussion primer 308 (or other proper pyrotechnic material) for its reliable initiation. The generated ignition flame and sparks would then exit the inertial igniter housing through the provided exit opening 378.
In certain applications, the direction of the applied activation acceleration is in the opposite direction than is indicated by the arrow 343 in FIG. 6 for the inertial igniter embodiment 330. To accommodate such applications, the following modifications can be made to the configuration of the inertial igniter embodiment 330 as shown in FIG. 10 and indicated as the inertial igniter embodiment 350. As indicated, the applied activation acceleration for this embodiment is in the direction of the arrow 392.
The inertial igniter embodiment 395 of FIG. 10 construction is identical to that of the embodiment 330 of FIG. 6, except that its release mass link 333 has the stop 393 (344 in FIG. 6) positioned in its opposite side as shown in FIG. 10 to prevent its clockwise rotation from its pre-activation position of FIG. 10. The preloaded compressive spring 394 (342 in FIG. 6) is also positioned in the opposite side as can be seen in FIG. 10 to bias the release mass link 333 against the stop 393. The mass member 396 (341 in FIG. 6) may also need to be moved as shown in FIG. 10 if it is in the way of the spring 394. The preloaded compression spring is similarly attached to the structure 321 of the inertial igniter on one end and to the release mass link 333 on the other end. Similarly, the inertial igniter component attachment points and geometry would be selected to fit the intended munition or the like space.
The inertial igniter embodiment 395 of FIG. 10 would then operate as follows. When the device to which the inertial igniter is attached is accelerated in the direction of the arrow 392, if the applied acceleration magnitude and duration satisfies the prescribed acceleration level and duration thresholds, then the dynamic force due to the applied acceleration acting on the center of mass of the release mass link 333 and the mass member 396 would overcome the preloading of the compressive spring 394 and rotate it in the counterclockwise direction enough for its tip 332 to disengage striker mass release link 327 and its member 334 as shown in the schematic of FIG. 6A.
In general, the effective mass of the release mass link 333 and the mass member 396, the amount of counterclockwise rotation that the release mass link 333 has to undergo to disengage the striker mass release link 327, and the preloading level of the compressive spring 394 and its rate are selected such that if the prescribed activation acceleration level and duration thresholds are not reached, the striker mass release link 327 is not release, thereby the inertial igniter is not activated as described below.
Then once the release mass link 333 has disengaged the striker mass release link 327, i.e., the tip 332 of the release mass link 333 has disengaged the contacting surface of the member 334, the rotary striker mass 322 is free to be rotationally accelerated in the counterclockwise direction by the preloaded torsion spring 336 and the striker mass release link 327 is rotated in the counterclockwise direction and out of the path of the rotary striker mass 322 by forcing it to rotate in the counterclockwise direction by the slanted surface 326 of the rotary striker mass 322 together with the force of the preloaded compressive spring 338, if it is provided, as shown in the schematic of FIG. 6B.
The rotary striker mass 322 would then continue to be rotationally accelerated in the counterclockwise direction until its provided sharp tip 325 strikes the percussion primer 345, which is mounted firmly in the structure 321 of the inertial igniter as shown in the schematic of FIG. 6C. The mass and stiffness of the rotary striker mass 322 and the preloading level of the torsion spring 326 and its rate are selected such that the rotary striker mass would gain enough kinetic energy before the sharp tip 325 strikes the percussion primer 345 (or other proper pyrotechnic material) for its reliable initiation. The ignition flame and sparks would then exit the provided opening 346 in the structure of the inertial ignite housing 321.
It is appreciated that if the acceleration in the direction of the arrow 392 is less than the prescribed acceleration threshold or if its duration is less than the prescribed duration threshold, the preloaded compressive spring 394 is configured to limit counterclockwise rotation of the release mass link 333 and prevent it from disengaging the striker mass release link 327.
It is appreciated that in the inertial igniter embodiments 6 and 10, the direction of the flame and spark exit following the initiation of the provided percussion primer (or other pyrotechnic material) is perpendicular to the direction of the activation (firing in munitions) accelerations shown by the arrows 343 and 392, respectively. However, in certain applications, the direction of the flame and spark exit is required to be in the direction or opposite to the direction of firing acceleration. To accommodate such applications, the following modifications can be made to the configuration of the inertial igniter embodiment 330 and 395 of FIGS. 6 and 10, respectively. The schematic of the modified inertial igniter embodiment 395 of FIG. 10 is shown in FIG. 11 and indicated as the inertial igniter embodiment 400.
The inertial igniter embodiment 400 of FIG. 11 construction is identical to that of the embodiment 395 of FIG. 10, except that the geometry of the rotary striker mass 401 (322 in FIG. 10) around the sharp tip 402 (325 in FIG. 10) is modified to allow for its larger clockwise rotation before striking the provided percussion cap 403 (345 in FIG. 10). The percussion cap 403 is also repositioned to direct the opening 404 for ignition flame and spark exit in the opposite direction to the activation acceleration, i.e., the direction of the arrow 392.
The rotary striker mass 401 (322 in FIG. 10) is similarly attached to the inertial igniter structure 321 by a rotary joint 405 (323 in FIG. 10) via the support member 406 (324 in FIG. 10). In its pre-activation configuration of FIG. 11, the slanted surface 407 (326 in FIG. 10) is biased to rests against the surface 331 of the tip of the striker mass release link 327. Similar to the inertial igniter embodiment 395 of FIG. 10, the striker mass release link 327 is prevented from counterclockwise rotation by the tip 332 of the release mass link 333, which is engagement with the member 334, which is usually integral to the striker mass release link 327. The engaging surface of the member 334 may also be similarly curved as shown in FIG. 11, for example with a radius matching or close to the radius defined by the contact point of the engaging tip 332 of the release mass link 333 to facilitate the rotation of the link 333 as described later during the inertial igniter activation.
In the pre-activation configuration of the inertial igniter embodiment 400 of FIG. 11, the rotary striker mass 401 is similarly biased by the preloaded torsion spring 409 (336 in FIG. 10) to keep its slanted surface 407 firmly against the tip 331 of the striker mass release link 327. The rotary striker mass 401 may also be provided by a stop member 408 (335 in FIG. 10) to limit clockwise rotation of the striker mass release link 327. The preloaded torsion spring 409 is attached on one end to the support 406 (324 in FIG. 10) of the rotary joint 405 (323 in FIG. 10) and to the rotary striker mass 401 on the other end 410 (337 in FIG. 10).
The inertial igniter embodiment 400 of FIG. 11 would then operate as follows. When the device to which the inertial igniter is attached is accelerated in the direction of the arrow 392, if the applied acceleration magnitude and duration satisfies the prescribed acceleration level and duration thresholds, then the dynamic force due to the applied acceleration acting on the center of mass of the release mass link 333 and the mass member 396 would overcome the preloading of the compressive spring 394 and rotate it in the counterclockwise direction enough for its tip 332 to disengage striker mass release link 327 and its member 334 as shown in the schematic of FIG. 11A.
In general, the effective mass of the release mass link 333 and the mass member 396, the amount of clockwise rotation that the release mass link 333 has to undergo to disengage the striker mass release link 327, and the preloading level of the compressive spring 394 and its rate are selected such that if the prescribed activation acceleration level and duration thresholds are not reached, the striker mass release link 327 is not release, thereby the inertial igniter is not activated as described below.
Then once the release mass link 333 has disengaged the striker mass release link 327, i.e., the tip 332 of the release mass link 333 has disengaged the contacting surface of the member 334, the rotary striker mass 401 is free to be rotationally accelerated in the counterclockwise direction by the preloaded torsion spring 409 and the striker mass release link 327 is rotated in the counterclockwise direction and out of the path of the rotary striker mass 401 by being forced to rotate in the counterclockwise direction by the slanted surface 407 of the rotary striker mass 401 together with the force of the preloaded compressive spring 338, if it is provided, as shown in the schematic of FIG. 11B.
The rotary striker mass 401 would then continue to be rotationally accelerated in the counterclockwise direction until its provided sharp tip 402 strikes the percussion primer 403, which is mounted firmly in the structure 321 of the inertial igniter as shown in the schematic of FIG. 11C. The mass and stiffness of the rotary striker mass 401 and the preloading level of the torsion spring 409 and its rate are selected such that the rotary striker mass would gain enough kinetic energy before the sharp tip 402 strikes the percussion primer 403 (or other proper pyrotechnic material) for its reliable initiation. The ignition flame and sparks would then exit the provided opening 404 in the structure of the inertial ignite housing 321.
It is appreciated that if the acceleration in the direction of the arrow 392 is less than the prescribed acceleration threshold or if its duration is less than the prescribed duration threshold, the preloaded compressive spring 394 is configured to limit clockwise rotation of the release mass link 333 and prevent it from disengaging the striker mass release link 327.
It is appreciated that in the inertial igniter embodiment 400 of FIG. 11, the direction of the activation acceleration indicated by the arrow 392 is downward. However, in certain applications, the direction of the activation acceleration is in the opposite direction while the direction of the flame and spark exit stays in the same direction as in the embodiment of FIG. 11. To accommodate such applications, the following modifications can be made to the configuration of the inertial igniter embodiment 400. The schematic of the modified inertial igniter embodiment 400 of FIG. 11 is shown in FIG. 12 and indicated as the inertial igniter embodiment 415.
The inertial igniter embodiment 415 of FIG. 12 construction is identical to that of the embodiment 400 of FIG. 11, except for the positioning of its release mass link 333 stop 413 (393 in FIG. 11) and the preloaded compressive spring 412 (394 in FIG. 11). In this inertial igniter embodiment, the stop 412 is positioned as shown in FIG. 12 to allow the preloaded compressive spring 412 to bias the release mass link against the stop and only allow its clockwise rotation from its pre-activation positioning shown in FIG. 12. The mass member 414 (396 in FIG. 11) may also be repositioned to provide space for spring 412 attachment if needed. The preloaded compressive spring 412 is similarly attached to the inertial igniter structure 321 on one end and to the release mass link on the other end.
The inertial igniter embodiment 415 of FIG. 12 would then operate as follows. When the device to which the inertial igniter is attached is accelerated in the direction of the arrow 411, if the applied acceleration magnitude and duration satisfies the prescribed acceleration level and duration thresholds, then the dynamic force due to the applied acceleration acting on the center of mass of the release mass link 333 and the mass member 414 would overcome the preloading of the compressive spring 412 and rotate it in the counterclockwise direction enough for its tip 332 to disengage striker mass release link 327 and its member 334 as shown in the schematic of FIG. 12A.
In general, the effective mass of the release mass link 333 and the mass member 414, the amount of clockwise rotation that the release mass link 333 has to undergo to disengage the striker mass release link 327, and the preloading level of the compressive spring 412 and its rate are selected such that if the prescribed activation acceleration level and duration thresholds are not reached, the striker mass release link 327 is not release, thereby the inertial igniter is not activated as described below.
Then once the release mass link 333 has disengaged the striker mass release link 327, i.e., the tip 332 of the release mass link 333 has disengaged the contacting surface of the member 334, the rotary striker mass 401 is free to be rotationally accelerated in the counterclockwise direction by the preloaded torsion spring 409 and the striker mass release link 327 is rotated in the counterclockwise direction and out of the path of the rotary striker mass 401 by being forced to rotate in the counterclockwise direction by the slanted surface 407 of the rotary striker mass 401 together with the force of the preloaded compressive spring 338, if it is provided, as shown in the schematic of FIG. 12B.
The rotary striker mass 401 would then continue to be rotationally accelerated in the counterclockwise direction until its provided sharp tip 402 strikes the percussion primer 403, which is mounted firmly in the structure 321 of the inertial igniter as shown in the schematic of FIG. 11C. The mass and stiffness of the rotary striker mass 401 and the preloading level of the torsion spring 409 and its rate are selected such that the rotary striker mass would gain enough kinetic energy before the sharp tip 402 strikes the percussion primer 403 (or other proper pyrotechnic material) for its reliable initiation. The ignition flame and sparks would then exit the provided opening 404 in the structure of the inertial ignite housing 321.
It is appreciated that if the acceleration in the direction of the arrow 411 is less than the prescribed acceleration threshold or if its duration is less than the prescribed duration threshold, the preloaded compressive spring 412 is configured to limit clockwise rotation of the release mass link 333 and prevent it from disengaging the striker mass release link 327.
In certain applications, the device in which an inertial igniter is mounted may be subjected to accidental accelerations that are significantly higher than the prescribed activation acceleration threshold and durations that may also be longer than the prescribed activation duration threshold. Such accidental accelerations, i.e., referred to as the “very high accelerations”, may be experienced by a device when it is dropped from high heights, for example duration mounting on or loading in a high structure or platform or during impact with hard surfaces or the like. In certain applications, the prescribed activation acceleration magnitude may be in tens of G range, while the device could be subjected to accidental accelerations that could be several thousand G in magnitude.
The disclosed inertial igniter embodiments may be provided with the means of preventing activation when the device in which they are mounted is subjected to such accidental “very high acceleration” events. A method of configuring such means of “very high acceleration” accidental event prevention is described below by its application to the inertial ignite embodiment 300 of FIG. 5. The schematic of the side view of the modified inertial igniter embodiment is shown in FIG. 13 and is indicated as the embodiment 420.
FIG. 14 illustrates the blow-up view “A” of the side view of the inertial igniter embodiment 420 of FIG. 13 showing the details of the added mechanism for preventing activation of the inertial igniter when subjected to accidental “very high acceleration” events. As can be seen in FIGS. 13 and 14, the added mechanism consists of the “L” shaped blocking link 416, which is attached to the inertial igniter structure 301 by the rotary joint 419 via the support 421.
It is appreciated that the blow-up view of FIG. 14 illustrates the pre-activation state of the inertial igniter embodiment 420 of FIG. 13. In this pre-activation state of the inertial igniter, the “L” shaped blocking link 416 is biased against the stop 422 by the preloaded compressive spring 417, which presses the tip 423 of the “L” shaped blocking link 416 against the stop 422. The stops 421 and 418 are provided on the inertial igniter structure 301.
As can be seen in the blow-up view of FIG. 14, in the pre-activation state of the inertial igniter embodiment 420, FIG. 13, the tip 424 of the “L” shaped blocking link 416 is positioned such that it would clear the path of downward motion of the sliding release mass stop 319 member of the sliding release mass 313. The tip 424 of the “L” shaped blocking link 416 is, however, positioned very close to the sliding release mass stop 319 so that with a relatively small counterclockwise rotation of the “L” shaped blocking link, the tip 424 is moved in the path of downward displacement of the sliding release mass stop 319.
The inertial igniter embodiment 420 of FIG. 13 would then operate as follows. When the device to which the inertial ignite is attached is accelerated in the direction of the arrow 317, as was previously described for the inertial igniter embodiment 300 of FIG. 5, if the applied acceleration magnitude and duration satisfies the prescribed acceleration level and duration thresholds, then the dynamic force due to the applied acceleration acting on the mass of the sliding release mass 313 would overcome the preloading of the compressive spring 320 and displaces the sliding release mass 313 downward enough for its tip 312 to disengage the rotary release link element 311 as shown in the schematic of FIG. 5A. In meantime, the applied acceleration would also apply a dynamic force at the center of mass of the “L” shaped blocking link 416, which is located on the left side of the rotary joint 419, FIG. 14, thereby applying a dynamic torque to the link 416 that would tend to rotate it in the counterclockwise direction. However, the preloading level of the compressive spring 417 is selected so that the indicated dynamic torque would not overcome the opposing torque due to the preloading force of the compressive spring 417 as long as the applied acceleration in the direction of the arrow 317, FIG. 13, does not exceed the prescribed acceleration level threshold. As a result, the “L” shaped blocking link 416 would not rotate in the counterclockwise direction and its tip 424 would not block downward motion of the sliding release mass 313 and the inertial igniter is activated as was described for the inertial igniter embodiment 300 of FIG. 5.
However, if the magnitude of the applied acceleration in the direction of the arrow 317, FIG. 13, is larger than that of the prescribed acceleration threshold, the preloading level and rate of the compressive spring 417 is selected not to overcome the larger dynamic counterclockwise torque applied to the “L” shaped blocking link 416, thereby allowing the “L” shaped blocking link to begin to rotate in the counterclockwise direction. It is appreciated that by positioning the tip 424 of the “L” shaped blocking link 416 very close to the path of downward displacement of the sliding release mass stop 319 member of the sliding release mass 313, a relatively small counterclockwise rotation of the “L” shaped blocking link 416 would position its tip 424 in the path of downward displacement of the sliding release mass stop 319, thereby preventing the sliding release mass 313 from displacing downward enough for its tip 312 to disengage the rotary release link element 311, thereby preventing the inertial igniter embodiment 420 of FIG. 13 from being activated.
This configuration of the “L” shaped blocking link 416 of the inertial igniter embodiment 420 of FIG. 13 and the positioning of the tip 424 of the “L” shaped blocking link 416 in the path of downward displacement of the sliding release mass stop 319 in the blow-up view “A” of FIG. 14 is shown in FIG. 15.
As can be seen in FIGS. 13 and 14, the stop 418 is provided to limit counterclockwise rotation of the “L” shaped blocking link 416, so that it would not disengage the sliding release mass stop 319 member of the sliding release mass 313 following application of an acceleration in the direction of the arrow 317 that is larger in magnitude than the magnitude of the prescribed activation acceleration, i.e., when the inertial igniter embodiment 420 of FIG. 13 is subjected to a “very high acceleration” event.
It is appreciated by those skilled in the art that once the inertial igniter 420 of FIG. 13 is subjected to an acceleration in the direction of the arrow 317 with a magnitude that is greater than that of the prescribed activation acceleration magnitude, the “L” shaped blocking link 416 would begin to rotate in the counterclockwise direction, FIG. 15, casing the tip 424 of the “L” shaped blocking link 416 to be positioned in the path of downward displacement of the sliding release mass 313, thereby as was previously described, preventing the tip 312 of the sliding release mass 313 from disengaging the rotary release link element 311, thereby preventing the inertial igniter embodiment 420 of FIG. 13 from being activated. It is noted that the action of the counterclockwise rotated “L” shaped blocking link 416 in blocking downward displacement of the sliding release mass 313 continues as long as the applied acceleration is greater in magnitude than the prescribed activation acceleration magnitude.
It is also appreciated by those skilled in the art that for the proper activation when the applied acceleration in the direction of the arrow 317 reached the prescribed threshold level and has the prescribed duration, the sliding release mass 313 must slide down enough to release the rotary release link element 311, during which time the preloaded compressive spring 417 prevents counterclockwise rotation of the “L” shaped blocking link 416. This means that once the applied acceleration in the direction of the arrow 317 is larger in magnitude, it would cause the sliding release mass 313 to displace downward faster than the center of mass of the “L” shaped blocking link 416, thereby leftward displacement of its tip 424. However, since the tip 424 of the “L” shaped blocking link 416 is positioned very close to the path of downward displacement of the stop member 319 of the sliding release mass 313, as long as the vertical distance between the tip 424 and the stop member 319 is large enough, the tip 424 of the “L” shaped blocking link 416 would always be positioned to block downward displacement of the sliding release mass 313, thereby activation of the inertial igniter embodiment 420 of FIG. 13, even if the applied “very high acceleration” event lasts longer than the prescribed activation duration threshold of the inertial igniter.
It is also appreciated by those skilled in the art that higher the magnitude of the applied acceleration in the direction of the arrow 317, smaller will be the ratio between the velocity downward displacement of the sliding release mass 313 and the leftward displacement of the tip 424 of the “L” shaped blocking link 416. This means that as long as a inertial igniter embodiment 420 of FIG. 13 and its “very high acceleration” event activation prevention mechanism are configured such that before the stop member 319 of the sliding release mass 313 has cleared the tip 424 of the “L” shaped blocking link 416 the “L” shaped blocking link 416 has rotated in the counterclockwise direction enough to position its tip 424 in the downward path of the stop member 319 displacement, the inertial igniter embodiment 420 of FIG. 13 would not be activated when subjected to “very high acceleration” events.
It is also appreciated by those skilled in the art that the parameters that the inertial igniter designer can select to achieve the above “very high acceleration” event activation include the effective mass of the sliding release mass 313 and the distance that it has to travel downward to release the rotary release link element 311; the center of mass and mass of the “L” shaped blocking link 416 and its geometry, i.e., the relationship between its counterclockwise rotation and leftward displacement of its tip 424; and the preloading levels and rates of the compressive springs 320 and 417.
It is also appreciated by those skilled in the art that various other mechanical mechanisms may be used to perform the function of the mechanism provided in the inertial igniter embodiment 420 of FIG. 13 to prevent inertial igniter activation when it is subjected to a “very high acceleration” event in its activation direction, that is the function of the “L” shaped blocking link 416 and it other related components. For example, the “L” shaped blocking link 416 may be replaced by a sliding member that would similarly slide into the path of downward displacement of the sliding release mass 313 motion. Another example of such “very high acceleration” event activation prevention mechanism is illustrated in the schematic of FIG. 16 and is hereinafter referred to as the “sliding activation prevention mechanism”.
It is appreciated that the blow-up view of FIG. 16 illustrates the pre-activation state of the inertial igniter embodiment 420 of FIG. 13 with the provided “sliding activation prevention mechanism”.
As can be seen in FIG. 16, the “sliding activation prevention mechanism” consists of usually equal length links 425 and 426, which are connected at the rotary joint 427. The link 425 is then attached to the inertial igniter structure 301 by the rotary joint 428 via the support 429 and the link 426 is attached to the sliding member 430 by the rotary joint 431. The sliding member 430 is free to slide in the provided guide 432, which is provided in the inertial igniter structure 301. A mass member 433 is attached to the rotary joint 427 and is biased against the stop 434 that is provided on the inertial igniter structure 301 by the preloaded compressive spring 435. A stop 436 is also provided on the inertial igniter structure 301 to limit downward displacement of the mass member 433.
As can be seen in the blow-up view of FIG. 16, in the pre-activation state of the inertial igniter embodiment 420, FIG. 13, the tip 437 of the sliding member 430 is positioned such that it would clear the path of downward motion of the sliding release mass stop 319 member of the sliding release mass 313. The tip 437 of the sliding member 430 is, however, positioned very close to the sliding release mass stop 319 so that with a relatively small leftward displacement of the sliding member 430, the tip 437 is moved in the path of downward displacement of the sliding release mass stop 319.
The inertial igniter embodiment 420 of FIG. 13 would then operate as follows. When the device to which the inertial ignite is attached is accelerated in the direction of the arrow 317, as was previously described for the inertial igniter embodiment 300 of FIG. 5, if the applied acceleration magnitude and duration satisfies the prescribed acceleration level and duration thresholds, then the dynamic force due to the applied acceleration acting on the mass of the sliding release mass 313 would overcome the preloading of the compressive spring 320 and displaces the sliding release mass 313 downward enough for its tip 312 to disengage the rotary release link element 311 as shown in the schematic of FIG. 5A. In meantime, the applied acceleration would also apply a dynamic force to the mass member 433, FIG. 16, that would tend to displace the mass member 433 and its connecting rotary joint 427 downward. However, the preloading level of the compressive spring 435 is selected so that the indicated dynamic force would not overcome the opposing preloading force of the compressive spring 435 as long as the applied acceleration in the direction of the arrow 317, FIG. 13, does not exceed the prescribed acceleration level threshold. In which case, the mass member 433 is not displaced downward and therefore the tip 437 of the sliding member 430 would not displace leftward as described later to block downward motion of the sliding release mass 313. As a result, the inertial igniter is activated as was described for the inertial igniter embodiment 300 of FIG. 5.
However, if the magnitude of the acceleration in the direction of the arrow 317, FIG. 13, is larger than the prescribed activation acceleration level threshold, the preloading level and rate of the compressive spring 435 are selected such that the mass member 433 is then allowed to be displaced downward towards the stop 436. Then downward displacement of the mass member 433 and thereby the joint 427 of the links 425 and 426 would cause the joint 431 of the link 426 to be displaced leftward, thereby displacing the sliding member 430 leftward and position its tip 437 in the path of downward displacement of the sliding release mass stop 319, thereby preventing the sliding release mass 313 from displacing downward enough for its tip 312 to disengage the rotary release link element 311, thereby preventing the inertial igniter embodiment 420 of FIG. 13 from being activated when the inertial igniter embodiment 420 of FIG. 13 is subjected to a “very high acceleration” event.
This configuration of the “sliding activation prevention mechanism” of FIG. 16 in the inertial igniter embodiment 420 of FIG. 13 and the positioning of the tip 437 of the sliding member 430 in the path of downward displacement of the sliding release mass stop 319 in the blow-up view “A” of FIG. 16 is shown in FIG. 17.
As can be seen in FIG. 16, the stop 436 is provided to limit downward displacement of the mass member 430, so that it would not withdraw the tip 437 of the sliding member 430 by allowing the joint 427 to pass the point at which the links 425 and 426 are collinear.
It is appreciated by those skilled in the art that once the inertial igniter 420 of FIG. 13 is subjected to an acceleration in the direction of the arrow 317 with a magnitude that is greater than that of the prescribed activation acceleration magnitude, the “sliding activation prevention mechanism” causes the tip 437 of the sliding member 430 to be positioned in the path of downward displacement of the sliding release mass 313, thereby as was previously described, preventing the tip 312 of the sliding release mass 313 from disengaging the rotary release link element 311, thereby preventing the inertial igniter embodiment 420 of FIG. 13 from being activated. It is noted that the action of the “sliding activation prevention mechanism” in blocking downward displacement of the sliding release mass 313 continues as long as the applied acceleration is greater in magnitude than the prescribed activation acceleration magnitude.
In the mechanisms of FIGS. 14 and 16 for preventing inertial igniter embodiment 300 of FIG. 5 from being activated when it is subjected to a “very high acceleration” event, the inertial igniter returns to its pre-activation configuration once the “very high acceleration” event has ceased, i.e., the “L” shaped blocking link 416 would return to its initial positioning of FIG. 14 and the sliding member would return to its initial positioning of FIG. 16, thereby clearing the path of the sliding release mass stop 319. The inertial igniter embodiment 300 can then be activated when subjected to the prescribed acceleration level threshold in the direction of the arrow 317 for the duration threshold.
In some applications, once an inertial igniter has been subjected to a “very high acceleration” event, the inertial igniter is required to become non-functional, i.e., not be capable of being initiated even by the application of the prescribed activation acceleration level and duration thresholds. In general, there are several methods of adding features to any of the disclosed embodiments to prevent inertial igniter activation following a “very high acceleration” event. For example, for the inertial igniters with the “very high acceleration” event activation prevention mechanisms of FIGS. 14 and 16, these methods include the provision of the means of preventing the deployed “L” shaped blocking link 416 and the sliding member 437, FIGS. 15 and 17, respectively, from returning to their pre-deployment positionings of FIGS. 14 and 16, respectively. Such means for the “very high acceleration” event activation prevention mechanisms of FIGS. 14 and 16 are shown in the blow-up views “B” and “C” (shown with dashed lines) of FIGS. 14 and 16, respectively, which are shown in FIGS. 18A-18B and FIGS. 19A and 19B, respectively.
FIG. 18A illustrates the blow-up view “B” of the “very high acceleration” event inertial igniter activation prevention mechanism of FIG. 14 with the added no-return mechanism in its normal state. As it was previously described, if the device in which the inertial igniter 420 of FIG. 13 is subjected to a “very high acceleration” event, the “L” shaped blocking link 416 is rotated in the counterclockwise direction, blocking the downward displacement of the sliding release mass 313, FIG. 15, thereby preventing the inertial igniter to be activated. Then once the “very high acceleration” event has ceased, the “L” shaped blocking link 416 and the sliding release mass 313 would return to their normal state of FIG. 14. The added mechanism shown in FIGS. 18A and 18B is configured to prevent the inertial igniter activation mechanism of the inertial igniter shown in FIG. 14 from returning to its normal state, i.e., the state before the “very high acceleration event.
As can be seen in FIG. 18A, which illustrates the mechanism positioning in the normal state of the inertial igniter embodiment 420 of FIG. 13, the added mechanism consists of a sliding member 439 which is free to slide up and down as viewed in the schematic of FIG. 18A in the guide 440. In the normal state of FIG. 18A, the sliding member 439 is biased against the top surface 443 of the “L” shaped blocking link 416 by the preloaded compressive spring 441. The preloaded compressive spring 441 is attached to the sliding member 439 on one end and to the structure 301 of the inertial igniter on the other end.
The inertial igniter embodiment 420 of FIG. 13 that is provided with the above-described mechanism of FIG. 18A would then operate as follows when subjected to a “very high acceleration” event. When the inertial igniter embodiment 420 is subjected to a “very high acceleration” event, the “L” shaped blocking link 416 is forced to rotate in the counterclockwise direction as was previously described and block downward displacement of the sliding release mass stop 319 and thereby the sliding release mass 313, preventing the inertial igniter from being activated, FIGS. 15 and 18B. Then as the “L” shaped blocking link 416 is rotated in the counterclockwise direction, the sliding member 439 slides passed the top surface 443 of the “L” shaped blocking link 416 and comes into contact with the surface 442 of the “L” shaped blocking link 416 as can be seen in the schematic of FIG. 18B. Now after the “very high acceleration” event has ceased, even though the preloaded compressive spring 417 would tend to rotate the “L” shaped blocking link 416 in the clockwise direction and back to its normal positioning of FIG. 18A, but the sliding member 439 prevent the rotation and the path of downward displacement of the sliding release mass stop 319 and thereby the sliding release mass 313 remains blocked. As a result, the inertial igniter embodiment 420 of FIG. 13 can no longer be activated even if it is subjected to the prescribed activation acceleration level and duration thresholds.
In the meantime, the preloaded compressive spring 320 would force the sliding release mass 313 to return to its normal positioning of FIG. 13.
FIG. 19A illustrates the blow-up view “C” of the “very high acceleration” event inertial igniter activation prevention mechanism of FIG. 16 (provided on the inertial igniter embodiment 300 of FIG. 5) with the added no-return mechanism in its normal state. As it was previously described, if the device to which the inertial igniter 300 of FIG. 5 with the added mechanisms shown in FIG. 19A is attached is accelerated in the direction of the arrow 317, FIG. 5, as was previously described, if the applied acceleration magnitude and duration satisfies the prescribed acceleration level and duration thresholds, then the dynamic force due to the applied acceleration acting on the mass of the sliding release mass 313 would overcome the preloading of the compressive spring 320 and displaces the sliding release mass 313 downward enough for its tip 312 to disengage the rotary release link element 311 as shown in the schematic of FIG. 5A. In meantime, the applied acceleration would also apply a dynamic force to the mass member 433, FIG. 16, that would tend to displace the mass member 433 and its connecting rotary joint 427 downward. However, the preloading level of the compressive spring 435 is selected so that the indicated dynamic force would not overcome the opposing preloading force of the compressive spring 435 as long as the applied acceleration in the direction of the arrow 317, FIG. 5, does not exceed the prescribed acceleration level threshold. In which case, the mass member 433 is not displaced downward and therefore the tip 437 of the sliding member 430 would not displace leftward as described later to block downward motion of the sliding release mass 313. As a result, the inertial igniter is activated as was described for the inertial igniter embodiment 300 of FIG. 5.
However, if the magnitude of the acceleration in the direction of the arrow 317, FIG. 5, is larger than the prescribed activation acceleration level threshold, the preloading level and rate of the compressive spring 435, FIG. 19A, are selected such that the mass member 433 is then allowed to be displaced downward towards the stop 436. Then downward displacement of the mass member 433 and thereby the joint 427 of the links 425 and 426 would cause the joint 431 of the link 426 to be displaced leftward, thereby displacing the sliding member 430 leftward and position its tip 437 in the path of downward displacement of the sliding release mass stop 319, thereby preventing the sliding release mass 313 from displacing downward enough for its tip 312 to disengage the rotary release link element 311, thereby preventing the inertial igniter embodiment 300 of FIG. 5 from being activated when the inertial igniter embodiment 300 of FIG. 5 is subjected to a “very high acceleration” event.
Now when the inertial igniter embodiment 300 of FIG. 5 is also provided with the “no-return mechanism” of FIG. 19A, the inertial igniter is prevented from activation following a “very high acceleration” event as described below.
As can be seen in the blow-up view of FIG. 19A, the added “no-return mechanism” consists of the sliding member 444, which is free to slide in the guide 445 provided in the structure 301 of the inertial igniter embodiment 300 of FIG. 5. In the normal state of the inertial igniter, the sliding member 444 is biased to stay in contact with the side surface 447 of the mass member 433 by the preloaded compressive spring 446. The preloaded compressive spring 446 is connected to the sliding member 444 on one end and to the inertial igniter structure 301 on the other end.
The inertial igniter embodiment 300 of FIG. 5 that is provided with the above-described mechanism of FIG. 19A would then operate as follows when subjected to a “very high acceleration” event. When the inertial igniter embodiment 300 is subjected to a “very high acceleration” event, the preloading level and rate of the compressive spring 435 are selected as was previously described to allow the mass member 433 to be displaced downward and cause the sliding member 430 to be displaced leftward and position its tip 437 in the path of downward displacement of the sliding release mass stop 319, thereby preventing the sliding release mass 313 from displacing downward enough for its tip 312 to disengage the rotary release link element 311, thereby preventing the inertial igniter embodiment 300 of FIG. 5 from being activated.
In the meantime, as the mass member 433 displaced downward, the tip 450 of the sliding member 444 slides over the surfaces 447 of the mass member 433, FIG. 19A, and at some point, clears the surface 447 and is pushed over the top surface 449 of the mass member 433 by the preloaded compressive spring 446 as can be seen in the schematic of FIG. 19B.
Now after the “very high acceleration” event has ceased, even though the preloaded compressive spring 435 would tend to displace the mass member 433 upward against the stop 434, but the sliding member 444 prevents its upward displacement, and the tip 437 of the sliding member 430 remains positioned in the path of downward displacement of the sliding release mass stop 319 as shown in FIG. 19B. As a result, the inertial igniter embodiment 300 of FIG. 5 can no longer be activated even if it is subjected to the prescribed activation acceleration level and duration thresholds.
In the meantime, the preloaded compressive spring 320 would force the sliding release mass 313 to return to its normal positioning of FIG. 5.
In general, it is highly desirable to provide a “safety pin” that would prevent an inertial igniter activation prior to assembly due to accidental drops or impacting forces or the like. A method of providing such safety pins is to provide a partial or a through hole through the inertial igniter housing and passing a pin through the hole that would interfere with the displaced or rotated of one of the members of the inertial igniter mechanism that is needed in order for the inertial igniter to be activated, i.e., prevent the motion of the striker mass release mechanism of the inertial igniter to be and thereby preventing the striker mass release. It is appreciated that such safety pins may be positioned in many locations, depending on the availability of space in the inertial igniter assembly. Examples of such safety pin positioning in the inertial igniter embodiments are provided below.
For the inertial igniter embodiment 300 of FIG. 5, a safety pin 451 shown in the schematic of FIG. 5A may be provided that is passed through a hole in the structure 301 (which includes the inertial igniter housing—not shown) of the inertial igniter. As a result, the rotary release link element 311 is prevented from being rotated in the counterclockwise direction even if it is disengaged from the sliding release mass 313 due to any acceleration event in any direction. As a result, the inertial igniter embodiment 300 of FIG. 5 is protected from accidental activation as long as its safety pin 451 is in place. It is appreciated that identically positioned safety pins in the inertial igniter embodiment 420 of FIG. 13 would similarly protect its accidental activation.
It is appreciated by those skilled in the art the following positioning of safety pins would similarly prevent activation of the indicated inertial igniter embodiments when they are subjected to accidental acceleration events. A possible positioning of a safety pin 451 in the inertial igniter embodiment 350 is shown in the schematic of FIG. 7. A possible positioning of a safety pin 452 in the inertial igniter embodiment 360 is shown in the schematic of FIG. 8. A possible positioning of a safety pin 453 in the inertial igniter embodiment 380 is shown in the schematic of FIG. 9. A possible positioning of a safety pin 454 in the inertial igniter embodiment 330 is shown in the schematic of FIG. 6. A possible positioning of a safety pin 455 in the inertial igniter embodiment 395 is shown in the schematic of FIG. 10. A possible positioning of a safety pin 456 in the inertial igniter embodiment 400 is shown in the schematic of FIG. 11. A possible positioning of a safety pin 457 in the inertial igniter embodiment 415 is shown in the schematic of FIG. 12.
The above-described method of proving the means of preventing activation of the inertial igniter embodiment 300 of FIG. 5 when the inertial igniter is subjected to a “very high acceleration” event in the direction of the activation acceleration, may also be applied to the inertial igniter embodiment 330 of FIG. 6, with and without the possibility of returning to normal state following a “very high acceleration” event, as described below.
The schematic of the side view of the modified inertial igniter embodiment 330 of FIG. 6 is shown in FIG. 20 and is indicated as the embodiment 460. In FIG. 21A, the blow-up view “D” of the side view of the inertial igniter embodiment 460, which is shown by the dashed lines, showing the details of the added mechanism for preventing activation of the inertial igniter when subjected to accidental “very high acceleration” events is illustrated.
In the inertial igniter embodiment 460 of FIG. 20, all components of the inertial igniter embodiment 330 are used without any modification and indicated by the same numerals except for the release mass link 333, in which the link length is extended from its rotary joint 339 attachment point end, FIG. 6, as shown in FIG. 20 and indicated with the numeral 458. The modified release mass link 458 is still attached to the structure 321 of the inertial igniter by a rotary joint 459 (339 in FIG. 6).
As can be seen in FIGS. 20 and 21A, the added mechanism consists of a mass member 461, which is free to displace parallel to the direction of the activation acceleration, shown by the arrow 464, in the guide 462 provided in the structure 321 of the inertial igniter 460 of FIG. 20. The links 464 and 465, which are attached together by the rotary joint 466, are then attached to the mass member 461 by the link 464 by the rotary joint 467, and to the structure 321 of the inertial igniter by the rotary joint 468, via the support 469. A preloaded tensile spring 463 is also provided, which is attached to the mass member 461 on one end and to the structure 321 of the inertial igniter on the other end. A sliding member 470, which is free to displace in the guide 471 in the structure 321 of the inertial igniter, is then attached to the rotary joint 466 as shown in the schematic of FIG. 21A. The guide 471 is configured to be wide enough relative to the width of the sliding member 470 to accommodate downward displacement of the joint 466 as the mass member 461 is displaced downward. In the normal configuration of FIGS. 20 and 21A, the preloading level of the tensile spring 436 is selected so that the tip 472 of the sliding member 470 would clear the end 473 of the release mass link 458 as it would rotate in the clockwise direction during the process of the inertial igniter embodiment 460 activation described later. A stop 475 is also provided as can be seen in the blow-up view of FIG. 21A to bias the link 465 against the stop by the preloaded tensile spring 463, thereby positioning the tip 472 of the sliding member 470 close, but clear of the end 473 of the release mass link 458.
It is appreciated that the blow-up view of FIG. 21A illustrates the pre-activation state of the inertial igniter embodiment 460 of FIG. 20. In this pre-activation state of the inertial igniter, the tip 472 of the sliding link 470 is positioned such that it would clear the path of clockwise rotation of the release mass link 458. The tip 472 of the sliding link 470 is, however, positioned very close to the end 473 of the release mass link 458 so that with a relatively small downward displacement of the mass member 461, the tip 472 is moved in the path of clockwise rotation of the end 473 of the release mass link 458, thereby preventing activation of the inertial igniter embodiment 460 as was previously described for the inertial igniter embodiment 330 of FIG. 6.
The inertial igniter embodiment 460 of FIG. 20 would then operate as follows. When the device to which the inertial ignite is attached is accelerated in the direction of the arrow 474, as was previously described for the inertial igniter embodiment 330 of FIG. 6, if the applied acceleration magnitude and duration satisfies the prescribed acceleration level and duration thresholds, then the dynamic force due to the applied acceleration acting on the effective center of mass of the release mass link 458 would overcome the preloading of the compressive spring 342 and rotates it in the clockwise direction enough for its tip 332 to disengage striker mass release link 327 and its member 334 as shown in the schematic of FIG. 6A for the inertial igniter embodiment 330 of FIG. 6. In meantime, the applied acceleration would also apply a dynamic force at the center of mass of the mass member 461, FIG. 21A, which would tend to displace it downward. However, the preloading level of the tensile spring 463 is selected so that the indicated dynamic force would not overcome the opposing preloading force of the tensile spring 463 as long as the applied acceleration in the direction of the arrow 474, FIG. 20, does not exceed the prescribed activation acceleration level threshold. As a result, the sliding link 470 would not displace to the right as viewed in FIG. 20, and its tip 472 would not block clockwise rotation of the release mass link 458 and the inertial igniter is activated as was described for the inertial igniter embodiment 330 of FIG. 6.
In general, the effective mass of the release mass link 458 (333 in FIG. 6) and the mass member 341, the amount of clockwise rotation that the release mass link 458 has to undergo to disengage the striker mass release link 327, and the preloading level of the compressive spring 342 and its rate are selected such that if the prescribed activation acceleration level and duration thresholds are not reached, the striker mass release link 327 is not released, thereby the inertial igniter is not activated as described below and returns to its normal (pre-activation) configuration.
It is appreciated that if the acceleration in the direction of the arrow 474 is less than the prescribed acceleration threshold or if its duration is less than the prescribed duration threshold, the preloaded compressive spring 342 is configured to limit clockwise rotation of the release mass link 458 and prevent it from disengaging the striker mass release link 327.
However, if the magnitude of the applied acceleration in the direction of the arrow 474, FIG. 20, is larger than that of the prescribed activation acceleration threshold, the preloading level and rate of the compressive spring 463 is selected not to overcome the larger dynamic force that is applied to the mass member 461, thereby allowing the mass member 461 to begin to displace downward. Then as the mass member 461 is displaced downward, the link 465 (464) is forced to rotate in the clockwise (counterclockwise) direction, thereby displacing the joint 466 and thereby the sliding link 470 to the right a significantly larger distance. The tip 472 of the sliding link 470 is thereby displaced to the right and positioned in the path of rotation of the end 473 of the release mass link 458 as shown in FIG. 21B. It is appreciated that by positioning the tip 472 of the sliding link 470 very close to the path of rotation of the end 473 of the release mass link 458, a relatively small downward displacement of the mass member 461 would position the tip 472 in the path of clockwise rotation of the release mass link 458 as shown in FIG. 21B, thereby preventing the release mass link to rotate enough in the clockwise direction for its tip 332 to disengage the striker mass release link 327 and its member 334 as shown in the schematic of FIG. 6A for the inertial igniter embodiment 330 of FIG. 6. The inertial igniter embodiment 460 of FIG. 20 is thereby prevented from being activated.
It is appreciated that smaller the angle between the links 464 and 465 with the vertical direction, the larger would be the displacement of the sliding link 470 relative to the downward displacement of the mass member 461.
It is appreciated by those skilled in the art that the added “very high acceleration” event activation mechanism of FIG. 20 may also be similarly added to the inertial igniter embodiment 415 of FIG. 12 to prevent its activation when subjected to a “very high acceleration” event.
It is also appreciated by those skilled in the art that the added “very high acceleration” event activation mechanism of FIG. 20 may also be similarly added to the inertial igniter embodiments 395 and 400 of FIGS. 10 and 11, respectively, with the minor modification as shown in FIG. 22 for the inertial igniter embodiment 11 and indicated as the inertial igniter embodiment 480.
The schematic of the side view of the modified inertial igniter embodiment 400 of FIG. 11 is shown in FIG. 22 with the added “very high acceleration” event activation mechanism and is indicated as the embodiment 480. In FIG. 23A, the blow-up view “E” of the side view of the inertial igniter embodiment 480, which is shown by the dashed lines, showing the details of the added mechanism for preventing activation of the inertial igniter when subjected to accidental “very high acceleration” events.
In the inertial igniter embodiment 480 of FIG. 22, all components of the inertial igniter embodiment 400 of FIG. 11 are used without any modification and indicated by the same numerals except for the release mass link 333, in which the link length is extended from its rotary joint 339 attachment point end, FIG. 11, as shown in FIG. 22 and indicated with the numeral 476. The modified release mass link 476 is still attached to the structure 321 of the inertial igniter by a rotary joint 477 (339 in FIG. 11).
As can be seen in FIGS. 22 and 23A, the added mechanism consists of a mass member 478, which is free to displace parallel to the direction of the activation acceleration, shown by the arrow 479, in the guide 481 provided in the structure 321 of the inertial igniter 480, FIG. 22. The links 482 and 483, which are attached together by the rotary joint 484, are then attached to the mass member 478 by the link 482 by the rotary joint 485, and to the structure 321 of the inertial igniter by the rotary joint 486, via the support 487. A preloaded tensile spring 488 is also provided, which is attached to the mass member 478 on one end and to the structure 321 of the inertial igniter on the other end. A sliding member 489, which is free to displace in the guide 491 in the structure 321 of the inertial igniter, is then attached to the rotary joint 484 as shown in the schematic of FIGS. 22 and 23A. The guide 491 is configured to be wide enough relative to the width of the sliding member 489 to accommodate upward displacement of the joint 484 as the mass member 478 is displaced upward. In the normal configuration of FIGS. 22 and 23A, the preloading level of the tensile spring 478 is selected so that the tip 492 of the sliding member 489 would clear the end 493 of the release mass link 476 as it would rotate in the counterclockwise direction during the process of the inertial igniter embodiment 480 activation described later. A stop 494 is also provided as can be seen in the blow-up view of FIG. 23A to bias the link 483 against the stop by the preloaded tensile spring 488, thereby positioning the tip 492 of the sliding member 489 close, but clear of the end 493 of the release mass link 476.
It is appreciated that the blow-up view of FIG. 23A illustrates the pre-activation state of the inertial igniter embodiment 480 of FIG. 22. In this pre-activation state of the inertial igniter, the tip 492 of the sliding link 489 is positioned such that it would clear the path of counterclockwise rotation of the release mass link 476. The tip 492 of the sliding link 489 is, however, positioned very close to the end 493 of the release mass link 476 so that with a relatively small upward displacement of the mass member 478, the tip 492 is moved in the path of counterclockwise rotation of the end 493 of the release mass link 476, thereby preventing activation of the inertial igniter embodiment 480 as was previously described for the inertial igniter embodiment 400 of FIG. 11.
The inertial igniter embodiment 480 of FIG. 22 would then operate as follows. When the device to which the inertial ignite is attached is accelerated in the direction of the arrow 479, as was previously described for the inertial igniter embodiment 400 of FIG. 11, if the applied acceleration magnitude and duration satisfies the prescribed acceleration level and duration thresholds, then the dynamic force due to the applied acceleration acting on the effective center of mass of the release mass link 476 would overcome the preloading of the compressive spring 394 and rotates it in the counterclockwise direction enough for its tip 332 to disengage striker mass release link 327 and its member 334 as shown in the schematic of FIG. 11A for the inertial igniter embodiment 400 of FIG. 11. In meantime, the applied acceleration would also apply a dynamic force at the center of mass of the mass member 478, FIG. 23A, which would tend to displace it downward. However, the preloading level of the tensile spring 488 is selected so that the indicated dynamic force would not overcome the opposing preloading force of the tensile spring 488 as long as the applied acceleration in the direction of the arrow 479, FIG. 22, does not exceed the prescribed activation acceleration level threshold. As a result, the sliding link 489 would not displace to the right as viewed in FIGS. 22 and 23A, and its tip 492 would not block counterclockwise rotation of the release mass link 476 and the inertial igniter is activated as was described for the inertial igniter embodiment 400 of FIG. 11.
In general, the effective mass of the release mass link 476 and the mass member 396 and its center of mass, the amount of counterclockwise rotation that the release mass link has to undergo to disengage the striker mass release link 327, and the preloading level of the compressive spring 394 and its rate are selected such that if the prescribed activation acceleration level and duration thresholds are not reached, the striker mass release link 327 is not released, thereby the inertial igniter is not activated as described below and returns to its normal (pre-activation) configuration.
It is appreciated that if the acceleration in the direction of the arrow 479 is less than the prescribed acceleration threshold or if its duration is less than the prescribed duration threshold, FIG. 22, the preloaded compressive spring 394 is configured to limit counterclockwise rotation of the release mass link 476 and prevent it from disengaging the striker mass release link 327.
However, if the magnitude of the applied acceleration in the direction of the arrow 479, FIG. 22, is larger than that of the prescribed activation acceleration threshold, the preloading level and rate of the compressive spring 488 is selected not to overcome the larger dynamic force that is applied to the mass member 478, thereby allowing the mass member 478 to begin to displace upward. Then as the mass member 478 is displaced upward, the link 482 (483) is forced to rotate in the clockwise (counterclockwise) direction, thereby displacing the joint 484 and thereby the sliding link 489 to the right a significantly larger distance. The tip 492 of the sliding link 489 is thereby displaced to the right and positioned in the path of counterclockwise rotation of the end 493 of the release mass link 476 as shown in FIG. 23B.
It is appreciated that by positioning the tip 492 of the sliding link 489 very close to the path of rotation of the end 493 of the release mass link 476, a relatively small upward displacement of the mass member 478 would position the tip 492 in the path of counterclockwise rotation of the release mass link 476 as shown in FIG. 23B, thereby preventing the release mass link to rotate enough in the counterclockwise direction for its tip 332 to disengage the striker mass release link 327 and its member 334 as shown in the schematic of FIG. 11A for the inertial igniter embodiment 400 of FIG. 11. The inertial igniter embodiment 480 of FIG. 22 is thereby prevented from being activated.
It is appreciated that smaller the angle between the links 482 and 483 with the vertical direction as viewed in FIG. 23A, the larger would be the displacement of the sliding link 489 relative to the upward displacement of the mass member 478.
It is also appreciated by those skilled in the art that the added “very high acceleration” event activation mechanism of FIG. 22 may also be similarly added to the inertial igniter embodiment 495 of FIG. 10 to prevent its activation when subjected to a “very high acceleration” event.
As it was previously indicated, in some applications, once an inertial igniter has been subjected to a “very high acceleration” event, the inertial igniter is required to become non-functional, i.e., not be capable of being initiated even by the application of the prescribed activation acceleration level and duration thresholds. The method of preventing inertial igniter activation following a “very high acceleration” event used for the inertial igniter embodiments 420 of FIG. 13 shown in the schematics of FIGS. 18A-18B and 19A-19B may similarly be applied to the inertial igniter embodiments 460 and 480 of FIGS. 20 and 22, respectively. Such means for the “very high acceleration” event activation prevention mechanisms of FIG. 22 is shown in the schematic of FIG. 24A, which illustrates the blow-up view “E” of FIG. 23A with the added mechanism.
It is appreciated by those skilled in the art that the same post “very high acceleration” event activation prevention mechanism may be readily applied to the inertial igniter embodiment 460 of FIG. 20.
FIG. 24A illustrates the blow-up view “E” of the “very high acceleration” event inertial igniter activation prevention mechanism of FIG. 22 with the added no-return mechanism in its normal state. As it was previously described, if the device in which the inertial igniter 480 of FIG. 22 is subjected to a “very high acceleration” event, sliding member 489 is displaced to the right as viewed in the schematic of FIG. 22, thereby positioning the tip 492 of the sliding member 489 in the path of counterclockwise rotation of the end 493 of the release mass link 476, thereby preventing the inertial igniter to be activated. Then once the “very high acceleration” event has ceased, the sliding member 489 would return to its normal state of FIG. 22. The added mechanism shown in FIGS. 24A and 24B is added to the inertial igniter activation prevention mechanism shown in FIGS. 22 and 23A-23B and is configured to prevent the inertial igniter activation mechanism to return to its normal state, i.e., the state before the “very high acceleration” event.
As can be seen in FIG. 24A, which illustrates the mechanism positioning in the normal state of the inertial igniter embodiment 480 of FIG. 22, the added mechanism consists of a sliding member 490, which is free to slide in the guide 495 provided in the structure 321 of the inertial igniter embodiment 480 of FIG. 22. In the normal state of FIG. 24A, the sliding member 490 is biased against the surface 496 of the mass member 478 by the preloaded compressive spring 497. The preloaded compressive spring 497 is attached to the sliding member 490 on one end and to the structure 321 of the inertial igniter on the other end.
The inertial igniter embodiment 480 of FIG. 22 that is provided with the above-described mechanism of FIG. 24A would then operate as follows when subjected to a “very high acceleration” event, i.e., an acceleration in the direction of the arrow 479 that is larger in magnitude than the prescribed activation acceleration threshold.
When the inertial igniter embodiment 480 of FIG. 22 that is provided with the mechanism shown in the blow-up view of FIG. 24A is subjected to an acceleration in the direction of the arrow 479, if the applied acceleration magnitude and duration satisfies the prescribed activation acceleration level and duration thresholds, then the dynamic force due to the applied acceleration acting on the effective center of mass of the release mass link 476 would overcome the preloading of the compressive spring 394 and rotates it in the counterclockwise direction enough for its tip 332 to disengage striker mass release link 327 and its member 334 as shown in the schematic of FIG. 11A for the inertial igniter embodiment 400 of FIG. 11. In meantime, the applied acceleration would also apply a dynamic force at the center of mass of the mass member 478, FIG. 24A, which would tend to displace it downward. However, the preloading level of the tensile spring 488 is selected so that the indicated dynamic force would not overcome the opposing preloading force of the tensile spring 488 as long as the applied acceleration in the direction of the arrow 479, FIG. 22, does not exceed the prescribed activation acceleration level threshold. As a result, the sliding link 489 would not displace to the right as viewed in FIGS. 22 and 24A, and its tip 492 would not block counterclockwise rotation of the release mass link 476 and the inertial igniter is activated as was described for the inertial igniter embodiment 400 of FIG. 11.
In general, the effective mass of the release mass link 476 and the mass member 396 and its center of mass, the amount of counterclockwise rotation that the release mass link has to undergo to disengage the striker mass release link 327, and the preloading level of the compressive spring 394 and its rate are selected such that if the prescribed activation acceleration level and duration thresholds are not reached, the striker mass release link 327 is not released, thereby the inertial igniter is not activated as described below and returns to its normal (pre-activation) configuration.
It is appreciated that if the acceleration in the direction of the arrow 479 is less than the prescribed acceleration threshold or if its duration is less than the prescribed duration threshold, FIG. 22, the preloaded compressive spring 394 is configured to limit counterclockwise rotation of the release mass link 476 and prevent it from disengaging the striker mass release link 327.
However, if the magnitude of the applied acceleration in the direction of the arrow 479, FIG. 22, is larger than that of the prescribed activation acceleration threshold, the preloading level and rate of the compressive spring 488 is selected not to overcome the larger dynamic force that is applied to the mass member 478, thereby allowing the mass member 478 to begin to displace upward. Then as the mass member 478 is displaced upward, the link 482 (483) is forced to rotate in the clockwise (counterclockwise) direction, thereby displacing the joint 484 and thereby the sliding link 489 to the right a significantly larger distance. The tip 492 of the sliding link 489 is thereby displaced to the right and positioned in the path of counterclockwise rotation of the end 493 of the release mass link 476 as shown in FIG. 24B.
It is appreciated that by positioning the tip 492 of the sliding link 489 very close to the path of rotation of the end 493 of the release mass link 476, a relatively small upward displacement of the mass member 478 would position the tip 492 in the path of counterclockwise rotation of the release mass link 476 as shown in FIG. 24B, thereby preventing the release mass link to rotate enough in the counterclockwise direction for its tip 332 to disengage the striker mass release link 327 and its member 334 as shown in the schematic of FIG. 11A for the inertial igniter embodiment 400 of FIG. 11. The inertial igniter embodiment 480 of FIG. 22 is thereby prevented from being activated.
In the meantime, when the inertial igniter embodiment 480 of FIG. 22 is provided with the “no-return mechanism” of FIG. 24A, the inertial igniter is prevented from activation following a “very high acceleration” event as described below.
As the mass member 478 is displaced upward, the tip 498 of the sliding member 490 slides over the surfaces 496 of the mass member 478, FIG. 24A, and at some point, clears the bottom surface 499 of the mass member and is pushed under the mass member 478 by the preloaded compressive spring 497 as can be seen in the schematic of FIG. 24B.
Now after the “very high acceleration” event has ceased, even though the preloaded compressive spring 488 would tend to displace the mass member 478 downward and bias the link 483 against the stop 494, but the sliding member 490 prevents its downward displacement, and the tip 492 of the sliding member 489 remains positioned in the path of clockwise rotation of the end 493 of the release mass link 476 as can be seen in FIG. 24B. As a result, the inertial igniter embodiment 480 of FIG. 22 can no longer be activated even if it is subjected to the prescribed activation acceleration level and duration thresholds.
It is appreciated that smaller the angle between the links 482 and 483 with the vertical direction as viewed in FIG. 24A, the larger would be the displacement of the sliding link 489 relative to the upward displacement of the mass member 478.
It is also appreciated by those skilled in the art that the added “very high acceleration” event activation mechanism of FIG. 22 may also be similarly added to the inertial igniter embodiment 415 of FIG. 12 to prevent its activation when subjected to a “very high acceleration” event.
In many munition applications, it is highly desired for the inertial igniter to be as compact as possible to minimize the occupied space and maximize the space available for other components of the munition. FIG. 25 illustrates the schematic of the top view of the third inertial igniter embodiment 500 in which all its moving components are mounted on a single shaft to achieve a high level of inertial igniter compactness. The inertial igniter also has a relatively few components and is configured for ease of manufacture and assembly.
In addition, the inertial igniter embodiment 500 is configured to operate based on the previously described method of separating activation mechanism that is configured to respond to the prescribed activation acceleration and duration threshold, from the ignition mechanism, which uses a striker element that is accelerated to the required kinetic energy to initiate a provided percussion primer or pyrotechnic material upon impact.
The inertial igniter embodiment 500 of FIG. 25 is constructed with an inertial igniter structure 501 (i.e., base or housing), which is shown as ground where need to be shown and which would take the required shape to fit the intended munition or the like space. The inertial igniter is provided with a rotary striker mass 502, which is mounted on the shaft 503 by a bearing 506 as shown in the cross-sectional view A-A of FIG. 25A. It is noted that the cross-sectional view A-A is intended to show the cross-sectioning plane shown by the dashed line, which passes through the percussion primer 525. The bearing 560 may be a ball bearing and prevent translation of the rotary striker mass 502 along the shaft 503, or may alternatively be a sleeve bearing or the striker mass hole accommodating the shaft 503 may be provided with enough clearance to allow its free while providing a step (not shown) or sleeve on the torsion spring 504 side of the shaft 503 to prevent the striker mass 502 from sliding to the right as viewed in the schematic of FIG. 25. It is appreciated that a ball bearing or the like can be used when rotational friction between the rotary striker mass 502 and the shaft 503 needs to be reduced. The rotary striker mass 502 is shaped as can be seen in FIGS. 25 and 25A to accommodate the sharp tip 505. The rotary striker mass 502 is also provided with a “step member” 507, the function of which is described below.
The inertial igniter is also provided with a with a preloaded torsion spring 504, which is attached on one end 508 to the inertial igniter structure 501 and on the other end to the rotary striker mass 502. The torsion spring 504 is preloaded in the clockwise direction as viewed in FIG. 25A, so that once the rotary striker mass 502 is released as is described later, it would apply a torque to the rotary striker mass 502 to accelerate it rotationally in the counterclockwise direction. In normal condition shown in FIGS. 25 and 25A, the rotary striker mass 502 is prevented from rotating in the counterclockwise direction by the stop member 509, which is provided on the striker mass release member 510 as described below.
FIG. 25B shows the cross-sectional view B-B of FIG. 25, showing the geometry of the striker mass release member 510. As can be seen in FIG. 25B, the striker mass release member 510 is mounted on the shaft 503 by a sleeve bearing 511, which allows it to freely displace along the length of the shaft 503. The striker mass release member 510 provided with a step member 509, which in the normal state of the inertial igniter shown in FIGS. 25 and 25B is in contact with the step member 507. In this configuration of the inertial igniter 500, the contacting surface of the step member 507 is biased against the contacting surface of the step member 509 by the preloaded torsion spring 504, and the striker mass release member 510 is prevented from clockwise rotation as viewed in the cross-sectional view of FIG. 25B by the stop member 512, against which the surface 513 of the striker mass release member 510 is biased by the preloaded torsion spring 504 via the step member 507 transmitting the preloading torque of the torsion spring to the striker mass release member 510 via the step member 509. As a result, in the normal state of the inertial igniter 500 of FIG. 25, as can be seen in the cross-sectional view of FIG. 25B, the striker mass release member 510 is prevented from rotation over the shaft 503.
As can also be seen in the schematic of FIG. 25, a preloaded compressive spring 514, which could slide the striker mass release member 510 away from the rotary striker mass 502 over the shaft 503 if its motion was not constrained by the stop member 515 of the rotary release mass 516 as later described.
FIG. 25C shows the view “C” of FIG. 25, as viewed without the end stop 517, which is fixedly attached to the structure 501 of the inertial igniter 500. As can be seen in FIG. 25C, the rotary release mass 516 is also mounted on the shaft 503 by a sleeve bearing 518, which allows it to freely rotate over the shaft 503. The positioning of the stop member 515 over the opposite side of the rotary release mass 516, as viewed in the direction of the arrow “C”, is also shown with dashed lines. A relatively large mass 519 is also provided on the rotary release mass 516, A preloaded compressive spring 521 is then provided to bias the mass 519 against the stop member 520, which is provided on the structure 501 of the inertial igniter 500. The preloaded compressive spring 521 is attached to the structure 501 of the inertial igniter on one end and to the mass 519 on the other end.
It is appreciated that in the normal position of the inertial igniter 500 of FIG. 25, the rotary release mass 516 is positioned as shown in the schematic of FIG. 25C, which positions the stop member 515 as shown by dotted line in front of the striker mass release member 510 as seen in FIGS. 25B and 25. As can be seen in FIG. 25B, in the normal state of the inertial igniter, the stop member 515 is positioned below the “cutout” 522 in the striker mass release member 510.
The inertial igniter embodiment 500 of FIG. 25 would then operate as follows. When the device to which the inertial igniter is attached is accelerated in the direction of the arrow 523, FIGS. 25A-25D, if the applied acceleration magnitude and duration satisfies the prescribed acceleration level and duration thresholds, then the dynamic force due to the applied acceleration acting on the center of mass of the rotary release mass 516, which is configured to be close to the large mass member 519, would overcome the preloading of the compressive spring 521, FIG. 25C, and rotate the rotary release mass 516 in the counterclockwise direction as viewed in the direction of the vector “C” of FIG. 25 and the view of FIG. 25C. Then as the rotary release mass 516 rotates in the counterclockwise direction, FIG. 25C, the stop member 515 is forced to slide over the surface 524 of the stationary striker mass release member 510 and be rotated towards the “cutout” 522. Then at some point, the stop member 515 clears the surface 524 of the stationary striker mass release member 510 and drops into the “cutout” area 522. At this point, the striker mass release member 510 becomes free to translate away from the rotary striker mass 502 by the preloading force of the compressive spring 514. Then as the striker mass release member 510 is displaced away from the rotary striker mass 502, the stop member 509 disengaged the step member 507.
Then once the stop member 509 has disengaged the step member 507, the rotary striker mass 502 is free to be rotationally accelerated in the counterclockwise direction as viewed in the direction of the arrow “C” in FIG. 25 and as observed in FIG. 25A, by the preloaded torsion spring 504. The rotary striker mass 502 would then continue to be rotationally accelerated in the counterclockwise direction until its provided sharp tip 505 strikes the percussion primer 525, FIGS. 25 and 25A, which is mounted firmly in the structure 501 of the inertial igniter embodiment 500 as shown in the schematic of FIG. 25D.
The mass and stiffness of the rotary striker mass 502 and the preloading level of the torsion spring 504 and its rate are selected such that the rotary striker mass 502 would gain enough kinetic energy before the sharp tip 505 strikes the percussion primer 525 (or other proper pyrotechnic material) for its reliable initiation. The ignition flame and sparks would then exit the provided opening 526 in the structure of the inertial ignite housing 501.
In general, the effective mass of the rotary release mass 516, the amount of counterclockwise rotation that the rotary release mass has to undergo to disengage the striker mass release member 510, and the preloading level of the compressive spring 521 and its rate are selected such that if the prescribed activation acceleration level and duration thresholds are not reached, the striker mass release member 510 is not release, thereby the inertial igniter is not activated as was described above.
It is appreciated that in the inertial igniter embodiment 500 of FIG. 25, the direction of the flame and spark exit following the initiation of the provided percussion primer (or other pyrotechnic material) is in the opposite direction of the activation acceleration, i.e., opposite to the direction of the arrow 523, FIG. 25D. However, in certain applications, the direction of flame and spark exit is required to be perpendicular to the direction of activation acceleration. Such applications can be readily accommodated by merely repositioning the percussion primer as shown in the schematic cross-sectional view A-A of FIG. 26A, showing the cross-sectional A-A of FIG. 25 with the repositioned percussion primer 527. Then when the inertial igniter is subjected to the prescribed acceleration level in the direction of the arrow 523 and duration thresholds, then the rotary striker mass 502 is similarly released and rotationally accelerated in the counterclockwise direction until its provided sharp tip 505 strikes the percussion primer 527 as shown in FIG. 26B. The ignition flame and sparks would then exit the provided opening 528 in the structure of the inertial ignite housing 501.
It is also appreciated that in certain applications, the inertial igniter embodiment 500 of FIG. 25 may be required to provide flame and spark exit in the direction of the activation acceleration, i.e., in the direction of the arrow 523 as viewed in FIG. 25A. The inertial igniter embodiment 500 may be readily modified to achieve the change in the direction of flame and spark exit by minor changes to the geometry of the striker mass release member 510 and the mounting of the rotary release mass 516 as described below.
In this modified inertial igniter 500 of FIG. 25, as can be seen in the view “C” of FIG. 27A, as compared to the view “C” of FIG. 25C of the original inertial igniter, the positions of the stop member 520 and the preloaded compressive spring 521 are exchanged as can be seen in the schematic of FIG. 27A, and which are indicated by the numerals 529 and 530, respectively. As a result, as the device to which the inertial igniter is attached is accelerated in the direction of the arrow 531 for activation, FIG. 27A, as opposed to the activation acceleration direction of the original inertial igniter, i.e., in the direction of the arrow 523 in FIG. 25C, the rotary release mass 532 (516 in FIG. 25C) is rotated in the clockwise direction from its stop member 529 as viewed in the schematic of FIG. 27A. The stop member 529 is similarly provided on the structure 501 of the inertial igniter and the preloaded compressive spring 530 biases the relatively large mass 533 (519 in FIG. 25C) of the rotary release mass 532 against the stop member 529. The preloaded compressive spring 530 is attached on one end to the structure 501 of the inertial igniter and to the mass 533 of the rotary release mass 532 on the other end.
In the modified inertial igniter 500 of FIG. 25, as can be seen in the cross-sectional view B-B of FIG. 27B, as compared to the cross-sectional view of FIG. 25B of the original inertial igniter, the cutout 522 (FIG. 25B) is taken out and replaced by the cutout 534, which is positioned close to the positioning of the stop member 535 (515 in FIG. 25B) as can be seen in the schematic of FIG. 27B.
The inertial igniter embodiment 500 of FIG. 25 with the modifications shown in FIGS. 27A and 27B would then operate as follows.
When the device to which the inertial igniter is attached is accelerated in the direction of the arrow 531, FIGS. 27A-27B, if the applied acceleration magnitude and duration satisfies the prescribed acceleration level and duration thresholds, then the dynamic force due to the applied acceleration acting on the center of mass of the rotary release mass 532, which is configured to be close to the large mass member 533, would overcome the preloading of the compressive spring 530, FIG. 27A, and rotate the rotary release mass 532 in the clockwise direction as viewed in the direction of the vector “C” of FIG. 25 and the view of FIG. 27A. Then as the rotary release mass 532 rotates in the clockwise direction, the stop member 535 is forced to slide over the surface 524 (FIG. 25) of the stationary striker mass release member 536 (510 in FIG. 25) and be rotated towards the “cutout” 534. Then at some point, the stop member 535 clears the surface 524 of the stationary striker mass release member 536 and drops into the “cutout” area 534. At this point, the striker mass release member 536 becomes free to translate away from the rotary striker mass 502 by the preloading force of the compressive spring 514. Then as the striker mass release member 536 is displaced away from the rotary striker mass 502, the stop member 537 (509 in FIG. 25) disengaged the step member 507.
Then once the stop member 537 has disengaged the step member 507, the rotary striker mass 502 is free to be rotationally accelerated in the counterclockwise direction as viewed in the direction of the arrow “C” in FIG. 25 and as observed in FIG. 25A, by the preloaded torsion spring 504. The rotary striker mass 502 would then continue to be rotationally accelerated in the counterclockwise direction until its provided sharp tip 505 strikes the percussion primer 525, FIGS. 25 and 25A, which is mounted firmly in the structure 501 of the inertial igniter embodiment 500 as shown in the schematic of FIG. 25D.
The mass and stiffness of the rotary striker mass 502 and the preloading level of the torsion spring 504 and its rate are selected such that the rotary striker mass 502 would gain enough kinetic energy before the sharp tip 505 strikes the percussion primer 525 (or other proper pyrotechnic material) for its reliable initiation. The ignition flame and sparks would then exit the provided opening 526 in the structure of the inertial ignite housing 501.
In general, the effective mass of the rotary release mass 532 (516 in FIG. 25), the amount of clockwise rotation that the rotary release mass has to undergo to disengage the striker mass release member 536 (510 in FIG. 25), and the preloading level of the compressive spring 530 (521 in FIG. 25C) and its rate are selected such that if the prescribed activation acceleration level and duration thresholds are not reached, the striker mass release member 536 is not release, thereby the inertial igniter is not activated as was described above.
In certain applications, the device in which an inertial igniter is mounted may be subjected to the aforementioned “very high acceleration” events, i.e., accidental accelerations that are significantly higher than the prescribed activation acceleration threshold and durations that may also be longer than the prescribed activation duration threshold. Then similar to the previous inertial igniter embodiments, the inertial igniter embodiment 500 of FIG. 25 may be provided with the means of preventing activation when the device in which they are mounted is subjected to such accidental “very high acceleration” events.
The method of preventing activation of the inertial igniter 500 of FIG. 25 when the direction of activation acceleration is in the direction of the arrow 523 or 531, as can be seen in the schematics of FIGS. 25C and 27A, respectively, is described below with its application to the inertial igniter with acceleration in the direction of the arrow 523 of FIGS. 25A-25D.
Similar to the previous embodiments, the method of preventing inertial igniter activation when it is subjected to a “very high acceleration” in the direction of activation acceleration is to prevent full rotation of the rotary release mass 516, FIG. 25C, of the inertial igniter to disengage the striker mass release member 510, FIG. 25, thereby causing inertial igniter activation. The added mechanism to the inertial igniter embodiment 500 of FIG. 25 is shown in the view “C” of the top view of the inertial igniter in FIG. 28A.
As can be seen in the view “C” of FIG. 28A, the rotary release mass 538 (516 in FIG. 25C) is modified by adding an extended member 540 to its large mass 539 (519 in FIG. 25C). The added “very high acceleration” event activation prevention mechanism is also seen to consist of a mass member 541, which is free to displace parallel to the direction of the activation acceleration, shown by the arrow 523, in the guide 544 provided in the structure 501 of the inertial igniter 500, FIG. 25. The links 542 and 543, which are attached together by the rotary joint 545, are then attached to the mass member 541 by the link 542 by the rotary joint 546, and to the structure 501 of the inertial igniter by the rotary joint 547, via the support 548. A preloaded tensile spring 549 is also provided, which is attached to the mass member 541 on one end and to the structure 501 of the inertial igniter on the other end. A sliding member 550, which is free to displace in the guide 551 in the structure 501 of the inertial igniter, is then attached to the rotary joint 545 as shown in the schematic of FIG. 28A. The guide 551 is configured to be wide enough relative to the width of the sliding member 550 to accommodate downward displacement of the joint 545 as the mass member 541 is displaced leftward. In the normal configuration of FIG. 28A, the preloading level of the tensile spring 549 is selected so that the tip 552 of the sliding member 550 would clear the tip 553 of the extended member 540 as it would rotate in the counterclockwise direction during the process of the inertial igniter embodiment 500 activation described later. A stop 554 is also provided as can be seen in FIG. 28A to bias the link 543 against the stop by the preloaded tensile spring 549, thereby positioning the tip 552 of the sliding member 550 close, but clear of the tip 553 of the extended member 540 of the rotary release mass 538.
It is appreciated that the view of FIG. 28A illustrates the pre-activation state of the inertial igniter embodiment 500 of FIG. 25. In this pre-activation state of the inertial igniter, the tip 552 of the sliding link 550 is positioned such that it would clear the path of counterclockwise rotation of the rotary release mass 538. The tip 552 of the sliding link 550 is, however, positioned very close to the tip 553 of the extended member 540 of the rotary release mass 538 so that with a relatively small leftward displacement of the mass member 541, the tip 552 is moved in the path of counterclockwise rotation of the tip 553 of the extended member 540 of the rotary release mass 538, thereby preventing activation of the inertial igniter embodiment 500 as was previously described.
The inertial igniter embodiment 500 of FIG. 25 that is provided with the “very high acceleration” activation prevention mechanism of FIG. 28A would then operate as follows. When the device to which the inertial ignite is attached is accelerated in the direction of the arrow 523, if the applied acceleration magnitude and duration satisfies the prescribed acceleration level and duration thresholds, then the dynamic force due to the applied acceleration acting on the effective center of mass of the rotary release mass 538 would overcome the preloading of the compressive spring 521 and begin to rotate it in the counterclockwise direction. Then as the rotary release mass 538 rotates in the counterclockwise direction, FIG. 28A, the stop member 515 is forced to slide over the surface 524 of the stationary striker mass release member 510, FIG. 25, and be rotated towards the “cutout” 522, FIG. 25B. Then as it was previously described for the inertial igniter 500 of FIG. 25, at some point, the stop member 515 clears the surface 524 of the stationary striker mass release member 510 and drops into the “cutout” area 522. At this point, the striker mass release member 510 becomes free to translate away from the rotary striker mass 502 by the preloading force of the compressive spring 514. Then as the striker mass release member 510 is displaced away from the rotary striker mass 502, the stop member 509 disengaged the step member 507.
Then once the stop member 509 has disengaged the step member 507, the rotary striker mass 502 is free to be rotationally accelerated in the counterclockwise direction as viewed in the direction of the arrow “C” in FIG. 25 and as observed in FIG. 25A, by the preloaded torsion spring 504. The rotary striker mass 502 would then continue to be rotationally accelerated in the counterclockwise direction until its provided sharp tip 505 strikes and initiates the percussion primer 525, FIGS. 25 and 25A, which is mounted firmly in the structure 501 of the inertial igniter embodiment 500 as shown in the schematic of FIG. 25D. The generated ignition flame and sparks would then exit from the opening 526 provided in the structure 501 of the inertial igniter.
In meantime, the applied acceleration would also apply a dynamic force at the center of mass of the mass member 541, FIG. 28A, which would tend to displace it leftward as viewed in FIG. 28A. However, the preloading level of the tensile spring 549 is selected so that the indicated dynamic force would not overcome the opposing preloading force of the tensile spring as long as the applied acceleration in the direction of the arrow 523 does not exceed the prescribed activation acceleration level threshold. As a result, the sliding link 550 would not displace downward as viewed in FIG. 28A, and its tip 552 would not block counterclockwise rotation of the rotary release mass 538 and the inertial igniter is activated as was described above.
In general, the effective mass of the rotary release mass 538 and is mass member 539, the amount of counterclockwise rotation that the rotary release mass has to undergo to disengage the striker mass release member 510, and the preloading level of the compressive spring 521 and its rate are selected such that if the prescribed activation acceleration level and duration thresholds are not reached, the striker mass release member 510 is not release, thereby the inertial igniter is not activated and returns to its normal (pre-activation) configuration.
However, if the magnitude of the applied acceleration in the direction of the arrow 523, FIG. 28A, is larger than that of the prescribed activation acceleration threshold, the preloading level and rate of the tensile spring 549 is selected not to overcome the larger dynamic force that is applied to the mass member 541, thereby allowing the mass member 541 to begin to displace leftward as viewed in FIG. 28A. Then as the mass member 541 is displaced leftward, the link 543 (542) is forced to rotate in the clockwise (counterclockwise) direction, thereby displacing the joint 545 and thereby the sliding link 550 downward a significantly larger distance. The tip 552 of the sliding link 550 is thereby displaced downward and positioned in the path of rotation of the tip 553 of the extended member 540 of the rotary release mass 538 as shown in FIG. 28B. It is appreciated that by positioning the tip 552 of the sliding link 550 very close to the path of rotation of the tip 553 of the extended member 540 of the rotary release mass 538, a relatively small leftward displacement of the mass member 541 would position the tip 552 in the path of counterclockwise rotation of the rotary release mass 538 as shown in FIG. 28B, thereby preventing the rotary release mass 538 to rotate enough in the counterclockwise direction to release the striker mass release member 510. The inertial igniter embodiment 500 of FIG. 25 is thereby prevented from being activated.
It is appreciated that smaller the angle between the links 542 and 543 with the direction of the line connecting the rotary joints 554 and 546, the larger would be the displacement of the sliding link 550 relative to the leftward displacement of the mass member 541.
It is appreciated by those skilled in the art that the added “very high acceleration” event activation mechanism of FIG. 28A may also be similarly added to the inertial igniter of the type of embodiment 500 of FIG. 25, to prevent their activation when subjected to a “very high acceleration” event.
As it was previously indicated, in some applications, once an inertial igniter has been subjected to a “very high acceleration” event, the inertial igniter is required to become non-functional, i.e., not be capable of being initiated even by the application of the prescribed activation acceleration level and duration thresholds. The method of preventing inertial igniter activation following a “very high acceleration” event used for the inertial igniter embodiment 480 of FIG. 22 shown in the schematics of FIGS. 24A and 24B may similarly be applied to the inertial igniter embodiment 500 of FIG. 25. The added mechanism that would render the inertial igniter embodiment 500 of FIG. 25 non-functional following a “very high acceleration” event is shown in the view “C” of the inertial igniter in FIG. 29A.
FIG. 29A illustrates the view “C” inertial igniter embodiment 500 of FIG. 25 of FIG. 28A with the added mechanism that would render the inertial igniter non-functional, also referred to as the no-return mechanism, following a “very high acceleration” event while the inertial igniter is in its normal state. As it was previously described, if the device in which the inertial igniter 500 of FIG. 25 is subjected to a “very high acceleration” event, the sliding link 550 moves downward a significantly larger distance. The tip 552 of the sliding link 550 is thereby displaced downward and positioned in the path of rotation of the tip 553 of the extended member 540 of the rotary release mass 538 as shown in FIG. 28B, thereby preventing the inertial igniter to be activated. Then once the “very high acceleration” event has ceased, the sliding link 550 would return to its normal state of FIG. 28A. The added mechanism shown in FIGS. 29A and 29B is added to the inertial igniter activation prevention mechanism shown in FIGS. 28A and 28B and is configured to prevent the inertial igniter activation mechanism to return to its normal state, i.e., the state before the “very high acceleration” event.
As can be seen in FIG. 29A, which illustrates the mechanism positioning in the normal state of the inertial igniter embodiment 500 of FIG. 25, the added mechanism consists of a sliding member 555, which is free to slide in the guide 556 provided in the structure 501 of the inertial igniter embodiment 500 of FIG. 25. In the normal state of FIG. 29A, the sliding member 555 is biased against the surface 557 of the mass member 541 by the preloaded compressive spring 558. The preloaded compressive spring 558 is attached to the sliding member 555 on one end and to the structure 501 of the inertial igniter on the other end.
The inertial igniter embodiment 500 of FIG. 25 that is provided with the above-described mechanism of FIG. 29A would then operate as follows when subjected to a “very high acceleration” event, i.e., an acceleration in the direction of the arrow 523 that is larger in magnitude than the prescribed activation acceleration threshold.
When the inertial igniter embodiment 500 of FIG. 25 that is provided with the mechanism shown in the view of FIG. 29A is subjected to an acceleration in the direction of the arrow 523, if the applied acceleration magnitude and duration satisfies the prescribed activation acceleration level and duration thresholds, then the dynamic force due to the applied acceleration acting on the effective center of mass of the rotary release mass 538 would overcome the preloading of the compressive spring 521 and rotates it in the counterclockwise direction 515 enough for its stop member 515 to disengage the striker mass release member 510. In meantime, the applied acceleration would also apply a dynamic force at the center of mass of the mass member 541, FIG. 29A, which would tend to displace it leftward. However, the preloading level of the tensile spring 549 is selected so that the indicated dynamic force would not overcome the opposing preloading force of the tensile spring as long as the applied acceleration in the direction of the arrow 523, FIG. 22, does not exceed the prescribed activation acceleration level threshold. As a result, the sliding link 550 would not displace to the downward as viewed in FIG. 29A, and its tip 552 would not block counterclockwise rotation of the rotary release mass 538 and the inertial igniter is activated as was described for the inertial igniter embodiment 500 of FIG. 25.
In general, the effective mass of the rotary release mass 538 and its center of mass, the amount of counterclockwise rotation it has to undergo to disengage the striker mass release member 510, and the preloading level of the compressive spring 521 and its rate are selected such that if the prescribed activation acceleration level and duration thresholds are not reached, the striker mass release member 510 is not released, thereby the inertial igniter is not activated as described below and returns to its normal (pre-activation) configuration.
It is appreciated that if the acceleration in the direction of the arrow 523 is less than the prescribed acceleration threshold or if its duration is less than the prescribed duration threshold, FIG. 25, the preloaded compressive spring 521 is configured to limit counterclockwise rotation of the rotary release mass 538 and prevent it from disengaging the striker mass release member 510.
However, if the magnitude of the applied acceleration in the direction of the arrow 523, FIG. 25, is larger than that of the prescribed activation acceleration threshold, the preloading level and rate of the tensile spring 549 is selected not to overcome the larger dynamic force that is applied to the mass member 541, thereby allowing the mass member 541 to begin to displace leftward. Then as the mass member 541 is displaced leftward, the link 543 (542) is forced to rotate in the clockwise (counterclockwise) direction, thereby displacing the joint 545 and thereby the sliding link 550 downward a significantly larger distance. The tip 552 of the sliding link 550 is thereby displaced downward and positioned in the path of counterclockwise rotation of the tip 553 of the extended member 540 of the rotary release mass 538 as shown in FIG. 29B.
It is appreciated that by positioning the tip 552 of the sliding link 550 very close to the path of rotation of the 553 of the rotary release mass 538, a relatively small leftward displacement of the mass member 541 would position the tip 552 in the path of counterclockwise rotation of the rotary release mass 538 as shown in FIG. 29B, thereby preventing the rotary release mass 538 to rotate enough in the counterclockwise direction for its stop member 515 to disengage striker mass release member 510. The inertial igniter embodiment 500 of FIG. 25 is thereby prevented from being activated.
In the meantime, when the inertial igniter embodiment 500 of FIG. 25 is provided with the “no-return mechanism” of FIG. 29A, the inertial igniter is prevented from activation following a “very high acceleration” event as described below.
Now as the mass member 541 is displaced leftward, the tip 559 of the sliding member 555 slides over the surfaces 557 of the mass member 541, FIG. 29A, and at some point, clears the surface 557 of the mass member and is pushed down behind the mass member 541 by the preloaded compressive spring 558 as can be seen in the schematic of FIG. 29B.
Now after the “very high acceleration” event has ceased, even though the preloaded compressive spring 549 would tend to displace the mass member 541 rightward and bias the link 543 against the stop 545, but the sliding member 555 prevents its rightward displacement, and the tip 552 of the sliding member 550 remains positioned in the path of counterclockwise rotation of the tip 553 of the rotary release mass 538 as can be seen in FIG. 29B. As a result, the inertial igniter embodiment 500 of FIG. 25 can no longer be activated even if it is subjected to the prescribed activation acceleration level and duration thresholds.
It is appreciated by those skilled in the art that many different mechanisms may be configured based on the method described for performing the function of preventing the above inertial igniter embodiments when subjected to “very high acceleration” events, with or without the means of rendering the inertial igniter non-functional, i.e., not capable of initiating even when subjected to the prescribed acceleration level and its duration thresholds. For example, the “very high acceleration” event activation prevention mechanism with the mechanism to render the inertial igniter non-functional post such an event illustrated in the schematics of FIGS. 16, 19A and 19B for the inertial igniter embodiment 420 of FIG. 13 may also be provided to perform the same function for the inertial igniter embodiment 500 of FIG. 25 as shown in the schematics of FIGS. 30A and 30B as described below.
In FIG. 30A, the view “C” of FIG. 25 shown in FIG. 28A is shown with the adapted “very high acceleration” event activation prevention mechanism with the mechanism to render the inertial igniter non-functional post such an event illustrated in the schematics of FIGS. 16, 19A and 19B. As can be seen in FIG. 30A, the said adapted mechanism consists of a mass member 560, which is attached to the common rotary joint 561 of the links 562 and 563. The link 563 is attached to the rotary joint 561 on one end and to the structure 501 of the inertial igniter via the rotary joint 564 via the support member 565. The link 562 is attached to the rotary joint 561 on one end and to the sliding member 566 by the rotary joint 567 on the other end. The sliding member 566 is free to displace in the guide 568, which is provided in the structure 501 of the inertial igniter, in the direction perpendicular to the direction of the activation acceleration 523. A preloaded tensile spring 569 is also provided that in normal state of the inertial igniter would bias the mass member 560 against the stop member 570, which is provided in the structure 501 of the inertial igniter. The preloaded tensile spring 569 is attached on one end to the structure 501 of the inertial igniter and on the other end to the mass member 560. As can be seen in the schematic of FIG. 30A, the geometrical parameters of the “very high acceleration” mechanism are selected such that in the normal state of the inertial igniter, the tip 571 of the sliding member 566 clears the path of counterclockwise rotation of the rotary release mass 538, i.e., the tip 533 of the extended member 540 of the rotary release mass 538.
As it was previously described, if the device to which the inertial igniter embodiment 500 of FIG. 25 with the added mechanisms shown in FIG. 30A is attached is accelerated in the direction of the arrow 523, if the applied acceleration magnitude and duration satisfies the prescribed acceleration level and duration thresholds, then the dynamic force due to the applied acceleration acting on the center of mass of the rotary release mass 538 would overcome the preloading of the compressive spring 521 and begin to rotate the rotary release mass 538 in the counterclockwise direction until at some point the stop member 515 disengages the striker mass release member 510 and the inertial igniter embodiment 500 is initiated as was previously described. In meantime, the applied acceleration would also apply a dynamic force to the mass member 560, FIG. 30A, that would tend to displace it and its connecting rotary joint 561 leftward. However, the preloading level of the compressive spring 569 is selected so that the indicated dynamic force would not overcome the opposing preloading force of the compressive spring 569 as long as the applied acceleration in the direction of the arrow 523 does not exceed the prescribed inertial igniter activation acceleration level threshold. In which case, the mass member 560 is not displaced leftward and therefore the tip 571 of the sliding member 566 would not displace downward as described later to block counterclockwise rotation of the rotary release mass 538. As a result, the inertial igniter embodiment 500 of FIG. 25 is activated as was previously described.
However, if the magnitude of the acceleration in the direction of the arrow 523, FIG. 30A, is larger than the prescribed activation acceleration level threshold, the preloading level and rate of the compressive spring 569 are selected such that the mass member 560 is allowed to be displaced leftward towards the stop 572. Then leftward displacement of the mass member 560 and thereby the joint 561 of the links 562 and 563 would cause the joint 567 of the sliding member 566 to be displaced downward, thereby displacing the sliding member 566 downward and position its tip 571 in the path of counterclockwise rotation of the tip 553 of the rotary release mass 538 as shown in FIG. 30B, thereby preventing the inertial igniter embodiment 500 of FIG. 25 from being activated when it is subjected to a “very high acceleration” event.
Now when the inertial igniter embodiment 500 of FIG. 25 is also provided with the “no-return mechanism” of FIG. 39A, the inertial igniter is prevented from activation following a “very high acceleration” event as described below.
As can be seen in the blow-up view of FIG. 30A, the added “no-return mechanism” consists of the sliding member 573, which is free to slide in the guide 574 provided in the structure 501 of the inertial igniter embodiment 500 of FIG. 25. In the normal state of the inertial igniter, the sliding member 573 is biased to stay in contact with the top surface 576 (FIG. 30B) of the mass member 573 by the preloaded compressive spring 575. The preloaded compressive spring 575 is connected to the sliding member 573 on one end and to the inertial igniter structure 501 on the other end.
The inertial igniter embodiment 500 of FIG. 25 that is provided with the above-described mechanism of FIG. 30A would then operate as follows when subjected to a “very high acceleration” event.
When the inertial igniter embodiment 500 is subjected to a “very high acceleration” event, the preloading level and rate of the compressive spring 569 are selected as was previously described to allow the mass member 560 to be displaced leftward and cause the sliding member 566 to be displaced downward and position its tip 571 in the path of counterclockwise rotation of the tip 553 of the rotary release mass 538 as shown in FIG. 30B, thereby preventing the inertial igniter embodiment 500 of FIG. 25 from being activated when it is subjected to a “very high acceleration” event. In the meantime, as the mass member 561 is displaced leftward, the tip 577 of the sliding member 573 slides over the top surface 576 of the mass member 560, FIG. 30B, and at some point, clears the surface 567 and is pushed over the top surface side surface 578 of the mass member 560 by the preloaded compressive spring 575 as can be seen in the schematic of FIG. 30B.
Now after the “very high acceleration” event has ceased, even though the preloaded compressive spring 569 would tend to displace the mass member 560 rightward against the stop 570, but the sliding member 573 prevents its rightward displacement, and the tip 571 of the sliding member 566 remains positioned in the path of counterclockwise rotation of the tip 553 of the rotary release mass 538 as shown in FIG. 30B. As a result, the inertial igniter embodiment 500 of FIG. 25 can no longer be activated even if it is subjected to the prescribed activation acceleration level and duration thresholds.
It is noted that all the above embodiments are configured to initiate a primer or an appropriately provided pyrotechnic material when subjected to a prescribed activation acceleration level and duration thresholds. The operating mechanism of these embodiments may also be used to construct normally open (closed) electrical switches that close (open) a circuit when subjected to a similar prescribed acceleration shock loading level and duration. Such electrical switches are hereinafter referred to as “electrical impulse switches” In addition, similar to the above inertial igniter embodiments, the “electrical impulse switches” may also be provided with similar means to prevent their activation when subjected to an aforementioned “very high acceleration” event and with or without the means of rendering non-functional following a “very high acceleration” event.
It is appreciated by those skilled in the art that each one of the above embodiments may be converted to an “electric impulse switch” by replacing the inertial igniter percussion primer and the striking pin of the striker mass member, for example the percussion primer 527 and the sharp tip 505 of the rotary striker mass 502 of FIG. 26A, with the electrical switching components described below to convert the inertial igniter configuration to an “electric impulse switch” of a given type. For this reason, the construction of different types of “electrical impulse switches” are described below for the inertial igniter embodiment of FIG. 25 with the activation acceleration direction and percussion primer 527 and rotary striker mass 502 configuration shown in the schematics of FIGS. 26A and 26B.
In the embodiment 500 of FIG. 25 and its modified embodiments, including the modified version shown by the cross-sectional view A-A of FIGS. 26A and 26B, as the rotary striker mass 502 is released in response to the applied acceleration in the direction of the arrow 523 with the prescribed acceleration magnitude and duration thresholds, the rotary striker mass is rotationally accelerated in the counterclockwise direction by the preloaded torsion spring 504 until its sharp tip 505 strikes the percussion primer 527 and causes it to initiate. The same mechanism used for the release of the rotary striker mass 502 due to the described prescribed activation acceleration event, i.e., a prescribed “impulsive shock” threshold, can be used to provide the means of opening or closing or both of at least one electrical circuit, i.e., act as a so-called “impulse switch”, that is actuated only if it is subjected to the above described prescribed “impulsive shock” event, even if the acceleration level is higher than the prescribed minimum acceleration level but its duration is significantly shorter than the prescribed duration threshold. Such “electrical impulse switches” may also be provided with the previously described means of preventing activation when subjected to a “very high acceleration” event, which may also be provided with the means of rendering then non-functions following a “very high acceleration” event.
Such “impulse switches” also have numerous non-munitions applications. For example, such impulse switches can be used to detect events such as impacts, falls, structural failure, explosions, etc., and open or close electrical circuits to initiate prescribed actions.
Such “impulse switch” embodiments for opening/closing electrical circuits, with and without latching features, are described herein together with alternative methods of their configuration.
In the embodiment 500 of FIG. 25 and its modified embodiments, including the modified version shown by the cross-sectional view A-A of FIGS. 26A and 26B
The disclosed “impulse switches” function like the disclosed inertia igniter embodiments. They similarly comprise of two mechanisms so that together they provide for mechanical safety, which can be described as a preloaded delay mechanism, and the switching mechanism, which provides the means to open or close electrical circuits. The function of the safety system is to prevent activation of the switching mechanism until the prescribed acceleration level and duration thresholds have been reached and would only then releases the switching mechanism, thereby allowing it to undergo its actuation motion to open or close the electrical circuit by connecting or disconnecting electrical contacts. The switching mechanism may be held in its activated state, i.e., may be provided with a so-called latching mechanism, or may move back to its pre-activation state after opening or closing the circuit.
The configuration and operation of such electrical impulse switches and the required modifications to the above inertial igniter embodiments is herein described using the inertial igniter embodiment 500 of FIG. 25 with is modifications presented in the schematics of FIGS. 26A and 26B. However, it is appreciated by those skilled in the art that other inertial igniter embodiments may also be similarly modified to function as electrical impulse switches.
The cross-sectional view A-A of the embodiment 500 of FIG. 25 and its modified embodiments of FIGS. 26A and 26B are shown in FIGS. 31A and 31B, respectively. The configuration of the resulting electrical impulse switch, hereinafter referred to as the electrical impulse switch embodiment 580, is like the inertial igniter embodiment 500 of FIG. 25, except that its percussion primer is removed and its assembly region of the inertial igniter, is modified to assemble the electrical switching contacts and related elements described below to convert the inertial igniter into electrical impulse switches for opening or closing electrical circuits.
In the cross-sectional view of the electrical impulse switch embodiment 580 of FIG. 31A, an element 579, which is constructed of an electrically non-conductive material is fixed to the impulse switch structure 501. The electrically non-conductive element 579 may be attached to the impulse switch structure 501, for example, by fitting its smaller diameter top portion 581 through a provided hole in the electrical switch body structure. The element 579 is provided with two electrically conductive elements 582 and 583 with contacts ends 584 and 585, respectively. The electrically conductive elements 582 and 583 may be provided with the extended ends 586 and 587, respectively, to form contact “pins” for direct insertion into provided holes in a circuit board or may alternatively be provided with wires 588 and 589, respectively, for connection to appropriate circuit junctions, in which case, the wires 588 and 589 may be desired to exit from the sides of the electrical impulse switch (not shown).
Previously described rotary striker mass 590 (502 in FIG. 26A), which is identical to the rotary striker mass 502, except for the removed sharp tip 505 section, is provided with a flexible strip of electrically conductive material 591, which is fixed to the rotary striker mass 590 as shown in FIG. 31A, for example, with fasteners 592 or by soldering or other methods known in the art.
The operation of the impulse switch 580 of FIGS. 31A and 31B is very similar to that of the inertial igniter 500 of FIG. 25. Here again and as was described for the inertial igniter embodiment 500, when the electrical impulse switch 580 is accelerated in the direction of the arrow 523, FIG. 31A, as the prescribed acceleration level and duration thresholds are reached, the rotary release mass 516 (590 in FIG. 31A) is rotated in the counterclockwise direction, FIG. 25C, until the striker mass release member 510 is released and is displaced leftward by the preloaded compressive spring 514, FIG. 25, and the rotary striker mass 590 (502 in FIGS. 25 and 26A) is released, FIG. 31A. Then as it was described for the inertial igniter embodiment 500 of FIG. 25 and its cross-sectional view of FIG. 26A, the preloaded torsion spring 504, FIGS. 25 and 31A, would apply a torque to the rotary striker mass 502 to accelerate it rotationally in the counterclockwise direction.
The stored mechanical (potential) energy in the preloaded torsional spring 504 would then begin to rotate the rotary striker mass 590 in the counterclockwise direction until the strip of the electrically conductive material 591 comes into contact with the contact ends 584 and 585, thereby closing the circuit to which the electrical impulse switch 580 is connected through the extended ends 586 and 587 or wires 588 and 589 as shown in the cross-sectional view of FIG. 31B.
It is noted that electrical impulse switch embodiment 580 shown with the cross-sectional view A-A of FIG. 31A with the assembled electrically non-conductive element 583 and the aforementioned electrical contact elements constitute a normally open electrical impulse switch in its pre-activation state and in FIG. 31B in its activated state for closing a circuit to which it is connected as was described above. Such electrical impulse switches are indicated as being “normally open electrical impulse switches”.
It is also appreciated by those skilled in the art that the electrical impulse switch embodiment 580 shown with the cross-sectional view A-A of FIG. 31A is a latching type, i.e., after activation and closing the connected circuit, the impulse switch keeps the circuit closed. The impulse switch embodiment 580 may also be configured as a “normally open impulse switch” that is of a non-latching type. To make the impulse switch embodiment 580 into a “latching normally open impulse switch” type, the level of preload in the torsional spring 504 is selected such that once the electrical impulse switch is activated as shown in its activated state in the cross-sectional view of FIG. 31B, the torsional spring 504 has passed its unloaded torsional position, thereby after closing the circuit, it would be rotating the rotary striker mass 590 back certain amount in the clockwise direction, thereby separating the electrically conductive material 591 from contact ends 584 and 585, thereby opening the circuit to which the electrical impulse switch is connected. The resulting electrical impulse switch would thereby become a “normally open and non-latching type electrical impulse switch”.
The normally open impulse switch 580 of FIGS. 31A and 31B may also be modified to function as a normally closed electrical impulse switch. The schematic of such a normally closed electrical impulse switch embodiment 595 is shown in FIG. 32A. The configuration and operation of the impulse switch 595 is identical to that of the normally open impulse switch embodiment 580 of FIGS. 31A and 31B, except for its electrical switching contacts and related elements described below to convert it from a normally open to a normally closed impulse switch.
In the normally closed impulse switch embodiment 595 of FIG. 32A, like the normally open impulse switch 580 of FIG. 31A, an element 596, which is constructed of an electrically non-conductive material is fixed to the electrical impulse switch structure 501. The electrically non-conductive element 596 may be attached to the electrical impulse switch structure 501 by fitting its smaller diameter top portion 599 through a provided hole as can be seen in FIG. 32A. The element 596 is provided with two electrically conductive elements 597 and 598 with flexible contact ends 593 and 594, respectively. The flexible electrically conductive contact ends 593 and 594 are biased to press against each other as seen in the schematic of FIG. 32A. As a result, a circuit connected to the electrically conductive elements 597 and 598 is normally closed in the pre-activation state of the electrical impulse switch 595 as shown in the configuration of FIG. 32A.
The electrically conductive elements 597 and 598 may be provided with the extended ends 600 and 601, respectively, to form contact “pins” for direct insertion into provided holes in a circuit board or may alternatively be provided with wires 602 and 603, respectively, for connection to appropriate circuit junctions, in which case, the wires 602 and 603 may be desired to exit from the sides of the electrical impulse switch (not shown).
The previously described rotary striker mass 590 (502 in FIG. 26A), which is identical to the rotary striker mass 502, except for the removed sharp tip 505 section, is provided with an electrically nonconductive wedge element 604, which is fixed to the surface of the rotary striker mass 590 as shown in FIG. 32A, for example, by an adhesive or using other methods known in the art.
The operation of the electrical impulse switch 595 of FIG. 32A is very similar to that of the inertial igniter 500 of FIG. 25 as was previously described for the electrical impulse switch 580 of FIGS. 31A and 31B. Here again and as was described for the inertial igniter embodiment 500, when the electrical impulse switch 595 is accelerated in the direction of the arrow 523, FIG. 32A, as the prescribed acceleration level and duration thresholds are reached, the rotary release mass 516 (590 in FIG. 32A) is rotated in the counterclockwise direction, FIG. 25C, until the striker mass release member 510 is released and is displaced leftward by the preloaded compressive spring 514, FIG. 25, and the rotary striker mass 590 (502 in FIGS. 25 and 26A) is released, FIG. 31A. Then as it was described for the inertial igniter embodiment 500 of FIG. 25 and its cross-sectional view of FIG. 26A, the preloaded torsion spring 504, FIGS. 25 and 31A, would apply a torque to the rotary striker mass 502 to accelerate it rotationally in the counterclockwise direction.
The stored mechanical (potential) energy in the preloaded torsional spring 504 would then begin to rotate the rotary striker mass 590 in the counterclockwise direction until the electrically nonconductive wedge element 604 is inserted between the contacting surfaces of the flexible electrically conductive contact ends 593 and 594, thereby opening the circuit to which the electrical impulse switch 595 is connected (through the extended ends 600 and 601 or wires 602 and 603) as shown in the cross-sectional view of FIG. 32B.
It is noted that electrical impulse switch embodiment 595 shown with the cross-sectional view A-A of FIG. 32A with the assembled electrically non-conductive element 596 and the aforementioned electrically nonconductive wedge element 604 constitute a normally closed electrical impulse switch in its pre-activation state and in FIG. 32B in its activated state for opening a circuit to which it is connected as was described above. Such electrical impulse switches are indicated as being “normally closed electrical impulse switches”.
It is also appreciated by those skilled in the art that the electrical impulse switch embodiment 595 shown with the cross-sectional view A-A of FIG. 32A is a latching type, i.e., after activation and opening the connected circuit, the impulse switch keeps the circuit open. The impulse switch embodiment 595 may also be configured as a “normally closed impulse switch” that is of a non-latching type.
To make the impulse switch embodiment 595 into a “non-latching normally closed impulse switch” type, the level of preload in the torsional spring 504 is selected such that once the electrical impulse switch is activated as shown in its activated state in the cross-sectional view of FIG. 32B, the torsional spring 504 has passed its unloaded torsional position, thereby after opening the circuit as shown in FIG. 32B, it would begin to rotate the rotary striker mass 590 back certain amount in the clockwise direction, thereby pulling the electrically nonconductive wedge element 604 away from the flexible electrically conductive contact ends 593 and 594, thereby closing the circuit to which the electrical impulse switch is connected. The resulting electrical impulse switch would thereby become a “normally closed and non-latching type electrical impulse switch”.
It is appreciated that in certain applications, the device in which one of the above disclosed electrical impulse switches is mounted may be subjected to the aforementioned “very high acceleration” events, i.e., accidental accelerations that are significantly higher than the prescribed activation acceleration threshold and durations and that may also be longer than the prescribed activation duration threshold. Then similar to the described inertial igniter embodiments, all disclosed electrical impulse switch embodiments may be provided with the means of preventing activation when the device in which they are mounted is subjected to such accidental “very high acceleration” events. Herein, the method of providing such means of electrical impulse switch activation due to “very high acceleration” events is described by its application to the electrical impulse switch embodiments 580 and 595 of FIGS. 31A and 32A, respectively, which are constructed by the aforementioned modification of the inertial igniter embodiment 500 of FIG. 25 with its view presented in the schematics of FIGS. 26A and 26B.
The method of preventing activation of the electrical impulse switch embodiments 580 and 595 of FIGS. 31A and 32A, respectively, when subjected to the aforementioned “very high acceleration” events is the same as the method used to prevent activation of the inertial igniter 500 of FIG. 25 when subjected to such “very high acceleration” events, as for example, shown in the view “C” of FIG. 28A.
It is appreciated that similar to the previous embodiments, the method of preventing inertial igniter activation when it is subjected to a “very high acceleration” in the direction of activation acceleration is to prevent their release mass from movement that is required to release the inertial igniter striker mass that initiates the inertial igniter percussion primer. In the case of the inertial igniter embodiment 500 of FIG. 25, preventing full rotation of the rotary release mass 516, FIG. 25C, of the inertial igniter embodiment 500 of FIG. 25 to disengage the striker mass release member 510, FIG. 25, thereby causing inertial igniter activation. The added mechanism to the inertial igniter embodiment 500 of FIG. 25 that is shown in the view “C” of the top view of the inertial igniter in FIG. 28A may for example be used for this purpose.
In the case of the electrical impulse switch embodiments 580 and 595 of FIGS. 31A and 32A, respectively, their “very high acceleration” event activation prevention mechanisms will be identical to those shown in the view “C” of the top view of the inertial igniter in FIG. 28A. Then when either of the electrical impulse switches is subjected to a “very high acceleration” event, the activation prevention mechanism would function as shown in the schematic of FIG. 28B and prevent counterclockwise rotation of the rotary release mass 538 as was described for the inertial igniter embodiment 500 of FIG. 25, thereby preventing the electrical impulse switches 580 and 595 of FIGS. 31A and 32A, respectively, to be activated.
As it was previously indicated, in some applications, once an inertial igniter has been subjected to a “very high acceleration” event, the inertial igniter is required to become non-functional, i.e., not be capable of being initiated even by the application of the prescribed activation acceleration level and duration thresholds. The same requirement may also exist for the electrical impulse switch embodiments 580 and 595 of FIGS. 31A and 32A, respectively. The method of preventing these electrical impulse switch embodiments from activation following a “very high acceleration” event may be identical to those used for the disclosed inertial igniter embodiments. As an example, the added mechanism shown in the schematic of FIG. 29A may also added to the aforementioned “very high acceleration” event activation prevention mechanism of FIG. 28A that is provided to the electrical impulse switches 580 and 595 of FIGS. 31A and 32A, respectively, to provide them with the capability of being rendered non-functional following experiencing a “very high acceleration” event.
While there has been shown and described what is considered to be preferred embodiments of the invention, it will, of course, be understood that various modifications and changes in form or detail could readily be made without departing from the spirit of the invention. It is therefore intended that the invention be not limited to the exact forms described and illustrated but should be constructed to cover all modifications that may fall within the scope of the appended claims.
