SELF-DESTRUCT FUZE DELAY MECHANISM

Abstract

An exemplary self-destruct fuze delay for a submuntion includes an ampoule filled with an activation fluid, a spring-loaded pin to break the ampoule upon deployment of the munition, and a wick to collect and retain the activation liquid in contact with a spring loaded restraining link having an embedded firing pin. The activation liquid contacts the restraining link, preferably via the wick. The action of the activation liquid on the restraining link over time causes the link to fail at the predetermined location, allowing a severed portion with the embedded firing pin to move under force (e.g., spring, gas) and impact or initiate a secondary detonator. The secondary detonator is in close proximity to a primary detonator typically used to initiate a main charge of the submunition. Initiation of the secondary detonator destroys the primary detonator and, depending upon slide location, either sterilizes the submunition, or destroys the entire submunition.

Description

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to fuzes for submunissions of the type which are disbursable by a vehicle such as a projectile or carrier shell, and in particular, to a self-destructing fuze that automatically self-destructs or self-neutralizes the submunition if the primary mode of detonation fails.

2. Description of Related Art

For many years, submunitions included in the family of Improved Conventional Munitions (ICM) employed a simple, low cost point detonating fuze for initiating a main charge upon impact. Reliability of the fuze was in the 95% range, meaning fairly large quantities of subminitions would not function for various reasons. This failure rate of about 5% presents both an environmental and a humanitarian hazard. Hazardous duds (e.g., armed but unexploded submunitions) remained on the battle field indefinitely and with potentially undesirable consequences to friendly troops and/or civilians.

The currently used M223 fuze incorporated unique and effective safety features for personnel and property protection during the manufacturing and loading process. Key among these safety features is a stabilizer ribbon attached to an arming screw that, in its engaged position, locks a detonator-containing slide in an unaligned position, thereby preventing any possible contact of a primary firing pin with the detonator. Upon deployment of the submunition from its carrier (e.g., howitzer projectile) the stabilizer ribbon becomes exposed to the air stream wind resistance and unfurls. The combination of wind resistance, induced spin of the submunition, and/or vibration causes the submunition to rotate relative to the ribbon, causing an arming screw to back out, which in turn releases a spring loaded slide that shifts, allowing the firing pin to align with the detonator. Upon impact, the firing pin, which is typically attached to a small weight, drives into the detonator causing initiation of the main charge.

In the case of projectile carrier, the entire submunition is spinning at a very high rate at ejection and the ribbon's resistance to spinning causes the arming screw to back out. However, a missile is a non-spin carrier so rotation is not available to arm the unit. Instead, the arming screw backs out because of the vibration induced as the submunition descends. That is, a loose fit between the arming screw and weight allows the arming screw to back out, which releases the spring loaded slide to align the firing pin with the detonator.

The failure of the armed submunitions described above results in hazardous duds. Incidence of death and injury to innocent victims from such hazardous duds, coupled with an international moratorium on antipersonnel mines, demonstrates a need to find a solution that would minimize these residuals on the battle field. It would be beneficial to provide a Self-Destruct Fuze (SDF) that, in the event of failure of the fuze in the primary mode, would cause a secondary action to either explode the entire submunition or at least destroy the detonator (e.g., sterilize the submunition, otherwise referred to as sterilization).

U.S. Pat. No. 5,373,790, to Chemiere, et al., discloses a mechanical system for self-destruction of a submunition, having a warhead initiated by a pyrotechnic sequence, a main striker and a priming device composed of a slide movable between a safety position and an armed position, and which has a device for priming the charge. The self-destruction system includes a secondary striker mounted inside a receptacle of the slide, and a control device that releases the secondary striker after a delay. The secondary striker is integral with a holding element held abutting a seat by the urging of an arming spring. The control device of the secondary striker has a corrosive agent stored in a glass ampoule that, when broken by the holding element, chemically attacks the holding element to release it from its seat. When the holding element is released, the arming spring moves the secondary striker to contact the detonator and destroy the munition.

U.S. Pat. No. 4,653,401, to Gatti, discloses a self-destructing fuze having a first striker member movable within the body of the fuze and able to come into contact with a detonator to cause it to explode, and a slide that is movable in a direction substantially orthogonal to the direction in which the first striker member is movable. A second striker member is disposed in the slide, and is movable from a first position in which it elastically deforms a spring and is held at a predetermined distance from the detonator, to a second position in which it comes into contact with the detonator to cause it to explode. The movement of the second striker member is delayed by a section of wire that under a force exerted by the spring is plastically deformed over time. The plastic deformation eventually frees the second striker member allowing its movement to the second position and against the detonator to cause it to explode.

U.S. Pat. No. 5,932,834, to Lyon, et al., discloses an auto-destruct fuze that provides a primary mode detonator and a delayed auto-destruct/self-neutralize mode detonator for a grenade. The mechanics for the primary mode detonator is similar to the M223 fuze. Operation of the auto-destruct/self-neutralize is based on a Liquid Annular Orifice Device (LAOD) that is released from a locked position upon expulsion of the LAOD from a storage container. The LAOD moves slowly under the urging of a spring and eventually releases a clean-up firing pin which activates a clean-up detonator to activate the primary mode detonator and destructs or self-neutralizes the grenade.

U.S. Pat. No. 4,998,476, to Rudenauer, et al., discloses a fuze for a bomblet including a slide having a detonator triggered in response to an impact and which undergoes a transition during the free flight of the bomblet from a safe position into an armed position. The slide also includes a hydraulic or pneumatic cylinder-piston retarding device and a spring biased self-destruct pin which is operatively coupled to the device and has a self-destruct detonator associated therewith. The retarding device is freed upon movement of the slide to the armed position, and releases the movement of the self-destruct pin after a time delay to trigger the self-destruct detonator and, if needed, the primary detonator.

Numerous variations of self-destruct (SD) devices, working in conjunction with proven safety features of the stabilizer ribbon arming screw, and sliding arrangement have been developed with various degrees of success. In one variant, the SD feature centers around a microelectronic battery and circuit with a complicated attendant initiating device. Two other variants employ a critical pyrotechnic delay column to achieve the necessary time lapse. Even if successful, the critical manufacturing process and high costs of these candidates raise long term and expensive productabilty concerns.

Even with the current self-destruct fuze development, it would still be beneficial to provide reliable low-cost and improved self-destruct delay devices or mechanisms for automatically destroying or self-neutralizing submunitions after a time delay to minimize undesirable consequences to friendly troops and/or civilians. All references cited herein are incorporated herein by reference in their entireties.

BRIEF SUMMARY OF THE INVENTION

In accordance with the preferred embodiments of the invention, a self-destruct fuze delay device for a submunition is provided, with the submunition having a longitudinal access, a main charge, and a detonating fuze with a movable slide for initiating the main charge upon impact. The self-destruct fuze delay device includes a detonator mounted to the fuze slide, a delay mechanism arranged within the submunition offset and substantially orthogonal to the submunition's longitudinal axis, and an activation mechanism. The delay mechanism includes an energizing source (e.g., compression spring, gas chamber), a restraining link (e.g., plunger, rod), and a self-destruct firing pin attached to the restraining link at a first portion thereof proximate to the detonator. The restraining link also has a second portion longitudinally extending from the first portion away from the detonator and attached to the fuze slide. The first portion is movable from a first position, in which it is held by it attachment to the second portion at a predetermined distance from the detonator, to a second position in which the first portion is separated from the second portion and the self-destruct firing pin is urged toward the detonator by the energizing source. The activation mechanism separates the first portion from the second portion after a predetermined delay, with the second portion remaining attached to the fuze slide after separation from the first portion.

While not being limited to a particular theory, the activation mechanism may include a container (e.g., glass ampoule) holding a fluid (e.g., acid, solution, reactant, liquid) for corroding the restraining link between the first portion and the second portion to separate the first portion form the second portion, and a breaking member (e.g., ampoule weight that impacts the container to release the fluid toward the restraining link). Moreover, this embodiment may also include a wick adjacent the restraining link at a predetermined area between the first portion and the second portion that collects the fluid from the container and isolates the collected fluid onto the predetermined area to facilitate the corroding of the restraining link. In accordance with the preferred embodiments, the detonating fuze may also have a main detonator in the fuze slide moveable between a safety position and an armed position, wherein the urging of the self-destruct firing pin toward the detonator by the energizing source causes the detonator to explode, which causes the main detonator to explode.

In another preferred embodiment of the invention, a self-destruct fuze delay device is provided, preferably for a submunition having a longitudinal axis, a main charge and a detonating fuze having a movable slide for initiating a main charge upon impact. The self-destruct fuze delay includes a detonator mounted to the fuze slide, a delay mechanism arranged within the submunition substantially orthogonal to the submunition's longitudinal axis, and an activating mechanism. The delay mechanism includes an energizing source (e.g., compression spring, pressurized gas container), a restraining link (e.g, piston, rod) having a first end attached to the self-destruct firing pin and a second end attached to the fuze slide. The restraining link is moveable from a first position, in which it is held by its attachment to the fuze slide at a predetermined distance from the detonator, to a second position in which the restraining link is separated from its attachment to the fuze slide and the self-destruct firing pin is urged toward the detonator by the energizing source. The activation mechanism separates the restraining link from its attachment to the detonating fuze slide. The activation mechanism includes a container (e.g., glass ampoule) holding a fluid (e.g., acid, solution, liquid) for corroding the restraining link, and a wick adjacent a predetermined area of the restraining link, with the wick being porous to absorb and draw the fluid from the container onto the restraining link at the predetermined area to facilitate the corroding and separation of the restraining link from attachment to the fuze slide.

While not being limited to a particular theory, the restraining link of this preferred embodiment may include a first portion proximate to the detonator, a second portion distal to the detonator and attached to the fuze slide, with the first portion and the second portion defined by the predetermined area. In this arrangement, the restraining link is separated from its attachment to the fuze slide at the predetermined area with the second portion remaining attached to the fuze slide after the separation. In the preferred embodiments, the predetermined area between the first portion and the second portion is preferably structurally weaker (e.g., undercut, thinner) than the first portion and the second portion to pulling forces along the longitudinal axis of the restraining link.

Another preferred embodiment of the invention includes a method or means for self-destructing a detonator of the submunition having a detonating fuze with a moveable slide upon deployment into the air. The method includes releasing an activation liquid from a container, absorbing the activation liquid with a porous wick, directing the absorbed activation liquid onto a predetermined area of a restraining link having a firing pin and held in place via attachment to the fuze slide, corroding the predetermined area with the directed activation liquid, separating the restraining link at the predetermined area, urging the firing pin toward the detonator, and colliding the firing pin into the detonator to destroy the detonator. The method may also include separating the restraining link at the predetermined area into a first portion having the firing pin and the second portion remaining attached to the fuze slide.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

The invention will be described in conjunction with the following drawings in which like reference numerals designate like elements and wherein:

FIG. 1 is a top sectional view of the self-destruct fuze delay device in accordance with the preferred embodiments;

FIG. 2 is a side sectional view of the self-destruct fuze delay device shown in FIG. 1;

FIG. 3 is another side sectional view orthogonal to the view of FIG. 2 of the self-destruct fuze delay device;

FIG. 4 is an exploded view of a delay mechanism for the preferred self-destruct fuze delay device;

FIG. 5 is an exploded view of an activation liquid assembly for the preferred self-destruct fuze delay device;

FIG. 6A is a side sectional view of the delay mechanism at a first state;

FIG. 6B is another side sectional view of the delay mechanism at a second state;

FIG. 6C is yet another side sectional view of the delay mechanism at a third state;

FIG. 6D is still another side sectional view of the delay mechanism at a fourth state;

FIG. 7 is a top sectional view of another preferred embodiment of the self-destruct fuze delay device;

FIG. 8 is a side view partially in section of an exemplary fuze delay device before deployment into the atmosphere;

FIG. 9 depicts the fuze device shown in FIG. 8 from a side view substantially orthogonal to the view of FIG. 8;

FIG. 10 is a flow diagram depicting an exemplary function sequence of events for the self-destruct fuze delay device of the preferred embodiments;

FIG. 11 is a side view of the exemplary fuze delay device shown in FIG. 8 after deployment;

FIG. 12 is a side view of the exemplary fuze delay device shown in FIG. 9 after deployment;

FIG. 13 is a side view of the exemplary fuze delay device of FIG. 7 after breaking of the reactant container; and

FIG. 14 is a side view of the exemplary fuze delay device of FIG. 13 after separation of the restraining link.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Exemplary embodiments for a self-destruct fuze delay device are described with reference to FIGS. 1-13. While not being limited to a particular theory, in general, an exemplary self-destruct fuze delay for a submuntion includes an ampoule filled with an activation fluid (e.g., reactant, acid, solution, liquid), a spring-loaded pin to break the ampoule upon deployment of the munition, and a wick to collect and retain the activation fluid in contact with a spring loaded restraining link having an embedded firing pin. The activation fluid contacts the restraining link, preferably via the wick, at a predetermined area that is preferably weakened (e.g., undercut). The action of the activation fluid on the restraining link causes the link to fail at the predetermined area, allowing a severed portion with the embedded firing pin to move under force (e.g., spring, gas) and impact or initiate a detonator (e.g., M55). The detonator is in close proximity to a primary detonator (e.g., M55) typically used to initiate a main charge of the submunition. Initiation of the detonator, which is a secondary detonator, destroys the primary detonator and either sterilizes the submunition, or depending upon slide location, destroys the entire submunition.

The time required for the activation fluid to react with the restraining link and achieve failure at the predetermined location of the restraining link is the predetermined time necessary to satisfy desired delay requirements for the self-destruct fuze. The primary fuze also retains the positive operation of the M223 fuze, that is, it utilizes the stabilizer ribbon, firing pin and slide to retain the known out-of-line safety features.

Although the preferred self-destruct fuze delay device is applicable to all the various ICM items, in the interest of brevity, the exemplary self-destruct fuze devices are generally tailored toward use in the Guided Multiple Launch Rocket System (GMLRS). The GMLRS warhead typically contains 404 submunitions, each with its own self-destruct (SD) fuze. While not being limited to a particular theory, the submunitions typically are disbursed via a center core burster that explodes in flight creating ample pressure to burst the warhead casing, and allowing the currently-used submunition's random dispersion into the atmosphere.

In general, as each submunition is disbursed into the atmosphere, the impact of the air stream causes the submunition's stabilizer ribbon to unfurl, allowing an arming screw to back out and a slide to move to its armed position. Upon impact, the firing pin is free to pierce the primary detonator and cause a subsequent main charge explosion, which destroys the submunition. Damaged fuzes and fuzes that arm properly but come into contact with the ground or a target via side impact may fail to initiate the main charge resulting in residual hazardous duds. A hazardous dud is a submunition that still has its fuze attached and its primary detonator present that together could potentially initiate the main charge. A hazardous dud is different than an unexploded ordinance, which is a submunition that has no means of initiation (e.g., primary detonator is missing or destroyed).

The delay necessary for the activation liquid to corrode the restraining link to failure (e.g., about 25 seconds minimum to 30 minutes) is greater than the foreseeable flight time of the submunition, which ends when the submunition reaches the ground or target. This delay allows the primary detonator to initiate the main submunition charge when the submunition strikes the ground or target. The self-destruct fuze delay device is designed to destroy the submunition if the submunition fails to explode after it strikes the ground or target.

Other advantages, characteristics and details of the invention will emerge from the explanatory description thereof provided below with reference to the attached drawings and examples, but it should be understood that the present invention is not deemed to be limited thereto. Toward that end, FIG. 1 depicts an exemplary self-destruct fuze delay device 10 as a detonating fuze 14 encased within a submunition 12. The submunition 12 includes a fuze slide 16 housing a primary detonator 18 that is movable with the slide between a safety position (shown), where the primary detonator is not aligned with a main striker 20, and an armed position, where the primary detonator is located opposite the main striker and aligned along the longitudinal axis of the submunition between the main striker and the submunition. The slide 16 also houses the self-destruct (SD) fuze delay device 10.

Still referring to FIG. 1, the SD fuze delay device 10 includes a secondary detonator 22 aligned with a delay mechanism 24 that is arranged in the slide 16 offset and substantially orthogonal to the longitudinal axis of the submunition 12. The SD fuze delay device 10 also includes an activation mechanism 25 adjacent the delay mechanism 24 for activating the delay mechanism and causing the secondary detonator 22 to explode. The explosion of the secondary detonator 22 activates the primary detonator 18, causing it to explode and set off the main charge 20 if the primary detonator is aligned therewith. Preferably, the secondary detonator 22 remains adjacent the primary detonator 18 regardless of the position of the primary detonator to ensure that output from an explosion of the second detonator initiates the primary detonator. This ensures one of the three potential outcomes upon dispersion of the submunition 12 into the atmosphere, as set forth below.

If the detonating fuze 14, which includes the primary detonator 18, the slide 16, and the primary striker 20, functions normally, the submunition 12 explodes and the SD fuze delay device 10 is destroyed in the process. If the detonating fuze 14 functions normally to the point that the slide 16 moves into its armed position, but the submunition 12 fails to explode, the SD fuze delay device 10 will initiate the primary detonator 18 and, in turn, will then fire the main charge to explode the submunition. If the detonating fuze 14 does not function normally so that the slide 16 remains in the safety position or does not reach the armed position, then the SD fuze delay device 10 will initiate the primary detonator 18 but likely not the main charge, resulting in a sterilized submunition or unexploded ordinance.

Referring in particular to FIGS. 1 and 2, the delay mechanism 24 includes a restraining link 26, a secondary firing pin 28 and a compression spring 30. The secondary or self-destruct firing pin 28 is attached to a front end 29 of the restraining link 26, which is transitionally movable in a receptacle or channel 32 of the slide 16. As can best be see in FIGS. 1, 2 and 6, the secondary firing pin 28 is partially embedded in a piston 34 of the restraining link 26. The piston 34 is extended opposite the secondary firing pin 28 by an axial rod 36 which freely passes inside the compression spring 30 and is attached at its distal end 38 to the slide 16 via a retainer pin 40. Preferably, the retainer pin 40 slides through a transverse opening of the axial rod 36 and within a spring retainer 40 that holds the compression spring 30, retainer pin 40 and axial rod 36 together and seated against an inner wall 44 of the slide 16. The compression spring 30 is mounted in a tensioned state around the axial rod 36 and is positioned between the piston 34 and spring retainer 42 to urge the piston, and thus the restraining link 26 and the secondary firing pin 28 toward the secondary detonator 22. Before deployment, a lockout pin 46 is attached to the slide 16 and abuts the first end 29 of the restraining link 26 to prevent movement of the restraining link towards the secondary detonator 22.

While not being limited to a particular theory, the axial rod 36 includes a weakened area 48 that defines a first portion 50 and a second portion 52 of the restraining link 26. The first portion 50 is proximate or adjacent to the secondary detonator 22 and includes the secondary firing pin 28, the piston 34 and part of the axial rod 36 extending from the piston. The second portion 52 is distal or away from the secondary firing pin 28 and is fixedly attached to the slide 16 via the retainer pin 40. The weakened area 48 is a predetermined part of the axial rod 36 that is constructed weaker than the remainder of the axial rod to fail upon application of a reactant (e.g., corrosive agent, acid, solution) and release the first portion 50 toward the secondary detonator 22. For example, the weakened area may include a circumferential plane or ring section that is undercut (e.g., having walls thinner than the walls of the adjacent first and second portions). Furthermore, a wick 54 is positioned adjacent, and preferably encircles the weakened area 48. The wick 54 is made of a porous material that absorbs the reactant fluid and directs it to the weakened area 48 to facilitate the corrosion of the restraining link 26 at the weakened area, as is described, for example, in greater detail below.

As can best be seen in FIGS. 1 and 3, the SD fuze delay device 10 also includes an activation mechanism 25 that communicates with and, after a delay, releases the first portion 50 of the restraining link 26 from the second portion 52, which allows the compression spring 30 to urge the secondary firing pin into the secondary detonator 22. While not being limited to a particular theory, the activation mechanism is offset from the channel 32 that houses the delay mechanism 24. The activation mechanism 25 includes a container 56 (e.g., glass ampoule) holding a reactant fluid 58. The reactant fluid 58 is a corrosive agent (e.g., acid or solution of liquid or gas) that when placed in contact with the retraining link, causes the axial rod 36 to corrode, fail and break, preferably at the weakened area 48, thereby allowing the compression spring 30 to separate and move the piston 34 and the secondary firing pin 28 toward the secondary detonator 22 and activate the detonator upon impact.

The activation mechanism 25 also includes an ampoule weight 60, a compression spring 62 and a spring retainer clip or pin 64. In the exemplary embodiment of FIGS. 1 and 3, and the exploded view of FIG. 5, the compression spring 62 is mounted in a tension state around the ampoule weight 60 between a shoulder 66 of the ampoule weight and an inner wall 68 of the slide 16. The spring retaining pin 64 keeps the compressed spring 62 in its tensioned state, and thereby keeps the container 56 safe from impact by the ampoule weight 60. The ampoule weight 60 is a breaking member that, but for the spring retainer pin 64, is urged by the compression spring 62 into impact with the container 56, causing the container to break and release the reactant fluid 58. Therefore, when placed as shown in FIGS. 1 and 3, the spring retainer pin 64 prevents activation of the SD fuze delay device 10. In addition to breaking the container 56, ampoule weight 60 also preferably acts as a plunger and pushes the released fluid 58 toward the delay mechanism 24 whereupon the fluid is absorbed by the wick 54 and corrodes the weakened area 48 to release the first portion 50 toward the secondary detonator 22.

FIG. 4 is an exploded view of the delay mechanism 24, the secondary detonator 22 and the wick 54. FIG. 5 shows an exploded view of the activation mechanism 25. FIGS. 4 and 5 are provided to help show the structure and association of the elements of the SD fuze delay device 10. FIGS. 6A-D illustrate a sequence of the delay mechanism 24 with the secondary detonator 22 and the wick 54 from a time prior to deployment of the submunition 12 to initiation of the secondary detonator, as will be described in greater detail below.

Upon deployment of the submunition 12, the self-destruct fuze delay device 10 self-destructs the submunition after a preset delay if the submunition fails to explode upon its impact with the ground or a target. FIG. 6A depicts the delay mechanism 24 before deployment into the atmosphere. When an exemplary submunition 12 hits the air stream at deployment, the spring retainer pin 64 and the safety lockout pin 46 are released out of their predeployment positions by the unfurling of the stabilizer ribbon or a secondary ribbon. The pins 46, 64 may otherwise be released by alternative known approaches. As is readily understood by a skilled artisan, this releases the compression spring 62 and removes the lockout from the delay mechanism 24.

Upon its release, the compression spring 62 drives the ampoule weight 60 into the container 56, breaking the container and releasing the reactant fluid 58 to flow into and be absorbed by the felt wick 54. To help facilitate the flow of the released fluid 58 to the wick 54, a channel is provided therebetween, and preferably the ampoule weight 60 acts as a plunger and pushes the fluid through the channel to the wick. In other words, after breaking the container 56, the compression spring 62 continues to drive the ampoule weight 60, forcing the fluid 58 into the wick 54. At this time, the delay mechanism 24 appears as depicted in FIG. 6B, with the safety lockout pin 46 removed and the reactant fluid 58 flowing towards the wick 54.

The wick 54 encircles the weakened area 48 of the restraining link 26 allowing the reactant fluid 58 (e.g., activation liquid) to communicate with and attack (e.g., corrode) the axial rod 36 at the weakened area 48. FIG. 6C depicts the delay mechanism 24 with the wick 54 saturated with the fluid 58 that communicates with and attacks the axial rod 36. Over a predetermined minimum time delay (e.g., between about 25 seconds and 30 minutes) the axial rod 36 weakens to the point of failure and breaks, preferably at or about the weakened area 48. Upon the failure of the axial rod 36, the compression spring 30 drives the secondary firing pin 28 toward the secondary detonator 22, causing the firing pin to impact and explode the secondary detonator. See FIG. 6D, which depicts the delay mechanism 24 at impact with the seconday detonator 22 after the failure of the axial rod 36.

Output from the exploded secondary detonator 22 initiates the adjacent primary detonator 18, causing it to explode and sterilize the submunition. If at this time the fuze slide 16 is in its armed position, such that the primary detonator 18 is aligned with the main charge, then the initiation of the primary detonator from the secondary detonator 22 will then fire the submunition 12. Accordingly, the SD fuze delay device 10 is reliable since it ensures either sterilization or destruction of the submunition 12 depending on the relationship between the primary detonator 18 and the main charge.

FIGS. 7-13 depict a preferred embodiment of the self-destruct fuze delay mechanism. The drawings of the preferred embodiment exemplified in FIGS. 7-13 and in the embodiment exemplified in FIGS. 1-6 include like referenced numerals which designate like elements and which may not be further described to avoid unnecessary repetition.

FIG. 7 shows an exemplary self-destruct fuze delay device 100 as a detonating fuze 102 for use with a submunition. Like the delay device 10 discussed above, the delay device 100 is housed in a fuze slide 16 having a primary detonator 18 that is movable with the fuze slide between a safety position (shown), where the primary detonator is not aligned with a main striker 20, and an armed position, where the primary detonator is adjacent the main striker and preferably aligned along the longitudinal axis of the submunition with the main striker. The delay device 100 includes a secondary detonator 22 aligned with a delay mechanism 104 that is arranged in the fuze slide 16 offset and substantially orthogonal to the longitudinal axis of the submunition. The delay device 100 also includes an activation mechanism 106 offset and in fluid communication with the delay mechanism 104 for activating the delay mechanism and causing the secondary detonator 22 to explode. While not being limited to a particular theory, the fuze slide 16 shown in FIG. 7 houses the secondary detonator 22, the delay mechanism 104 and the activation mechanism 106 in a generally U-shaped aperture 108 bored into the fuze slide and defined by an inner wall 120 of the fuze slide. The fuze slide 16 includes a closure plate 122, preferably formed of a plastic or metal, that is bonded (e.g., by adhesives, crimping, friction, heat) to the inner wall 120 defining the aperture 108 to seal the secondary detonator 22, the delay mechanism 104 and the activation mechanism 106 within the aperture.

As noted above, the explosion of the secondary detonator 22 activates the primary detonator 18, causing it to explode and set off the main charge if the primary detonator is aligned therewith. Preferably, the secondary detonator 22 remains adjacent the primary detonator 18 regardless of the position of the primary detonator to ensure that output from an explosion of the second detonator initiates the primary detonator. This ensures one of the previously discussed potential outcomes upon dispersion of the submunition into the atmosphere.

Still referring to FIG. 7, the delay mechanism 104 includes a compression spring 30 as an energizing source, and a restraining link 114 extending from the closure plate 122 to a secondary firing pin 28. The secondary or self-destruct firing pin 28 defines a front end of an axial rod 110 proximate the secondary detonator 22. The axial rod 110 is movable in a receptacle or channel 32 of the slide 16, and includes the secondary firing pin 28 and a piston 112 abutting a compression spring 30 as set forth in greater detail below.

The axial rod 110 extends away from the secondary detonator 22 from the secondary firing pin 28, freely passes inside the compression spring 30 and is attached at its distal end 38 to the closure plate 122 of the fuze slide 16 via the restraining link 114 as set forth in greater detail below. The axial rod 110 and compression spring 30 are partially embedded in a cylindrical sleeve 124 of the piston 112, which extends away from the secondary firing pin 28 to form the cylindrical sleeve having a central bore that partially houses the axial rod and compression spring 30 therein. The compression spring 30 is mounted in a compressed state around the axial rod 110 and is positioned between the piston 112 and the closure plate 122 of the fuze slide 16 to urge the piston, and thus the axial rod and the secondary firing pin 28 toward the secondary detonator 22. As can best be seen in FIG. 7, the cylindrical sleeve 124 terminates at a flanged rim 116 extending radially outward to define a shoulder 118. Before deployment, as shown in FIG. 7, the shoulder 118 abuts a safety lockout pin 46 that slides through a transverse opening in the fuze slide 16 and prevents movement of the secondary firing pin 28 towards the secondary detonator 22.

While not being limited to a particular theory, the restraining link 114 holds the axial rod 110 to the closure plate 122. The restraining link 114 is preferably a styrene based (e.g., polystyrene) shaft embedded and sealed (e.g., adhesively, frictionally) to aligned counter bores 126, 128 in the closure plate 122 and the axial rod 110, respectively. As such, the restraining link 114 is a weakened area that fails under chemical attack and breaks to release the firing pin and axial rod 110 from the closure plate 122. When broken, the restraining link 114 separates into two sections, which define adjacent edges of first and second portions 130, 132 of the restraining link. The first portion 130 is attached to the axial rod 110 which is attached to the secondary firing pin 28. The second portion 132 is distal or away from the secondary firing pin 28 and is attached to the closure plate 122.

The restraining link 114 is constructed of a material vulnerable to a reactant (e.g., corrosive agent, acid, solution), in particular, in comparison to the other elements of the delay mechanism 104 discussed above, to fail over time under application of the reactant. While not being limited to a particular theory, the reactant erodes the restraining link 114, causing the restraining link fail or break under the pulling stress of the compression spring 30 and release the first portion 130 toward the secondary detonator 22 (FIG. 11). Furthermore, a wick 54 is positioned adjacent, and preferably encircles the restraining link 114 between the axial rod 110 and the closure plate 122. The wick 54 is made of a porous material that absorbs and directs the reactant fluid 58 to the restraining link 114 to facilitate the erosion and failure of the restraining link, as described, for example, in greater detail below. It should be understood that the wick 54 is not critical to the operation of the fuze delay device 100, as the use of the wick is not required for the reactant fluid 58 to access and erode the restraining link to failure. However, the use of the wick 54 or an equivalent thereto is preferred to direct and focus the reactant fluid 58 onto the restraining link 114 for improved control and uninterrupted communication there between.

Still referring to FIG. 7, after deployment and a subsequent delay, the activation mechanism 106 activates the delay mechanism 104 by releasing the first portion 130 of the restraining link 114 from the second portion 132, which allows the compression spring 30 to urge the secondary firing pin 28 to the secondary detonator 22. While not being limited to a particular theory, the activation mechanism 106 is offset from the channel 32 that houses the delay mechanism 104. The activation mechanism 106 includes a container 56 (e.g., glass ampoule) holding a reactant fluid 58. The reactant fluid 58 is a corrosive agent (e.g., acid or solution of liquid or gas) that when placed in contact with the restraining link 114, chemically attacks and causes the restraining link to erode, fail and break, thereby allowing the compression spring 30 to separate and move the axial rod 110 and the secondary firing pin 28 toward and activate the secondary detonator 22.

The activation mechanism 106 also includes an ampoule breaker 134, a compression spring 62 and a spring retainer pin 136. As shown in FIG. 7, the ampoule breaker 134 and compression spring 62 are aligned with at least a portion of the container 56 in a channel 142 of the fuze slide 16 offset from the channel 32. The compression spring 62 is an energizing source mounted in a tension state inside the ampoule breaker 134 between an inner wall 138 of the ampoule breaker and an inner wall 140 of the slide 16. The spring retaining pin 136 is inserted into the fuze slide 16 and abuts a groove 142 of the ampoule breaker 134 to hold the ampoule breaker in a locked position away from the container 56 as shown, for example, in FIG. 7. When inserted into the fuze slide 16 as shown, the spring retaining pin 136 keeps the compressed spring 62 in its tensioned state, and thereby keeps the container 56 safe from impact by the ampoule breaker 134. Therefore, the inserted spring retainer pin 136 prevents activation of the SD fuze delay device 100.

Like the ampoule weight 60 described above, the ampoule breaker 134 is a breaking member that, but for the spring retainer pin 136, is urged by the compression spring 62 into impact with the container 56, causing the container to break and release the reactant fluid 58. In addition to breaking the container 56, the ampoule breaker 134 also preferably acts as a plunger and pushes the released fluid 58 toward the delay mechanism 104 whereupon the fluid corrodes the restraining link 114 to release the secondary firing pin 28 toward the secondary detonator 22 (FIG. 11).

In a preferred embodiment, such as exemplified in FIG. 7, the fuze delay device 100 also includes a cushion pad 144 between the container 56 and the closure plate 122. The cushion pad 144 is preferably a resilient member that serves as a cushion to the container 56 before the container is broken by the ampoule breaker 134. Submunitions 12 are subject to a range of vibrations, rattles and forces before deployment, for example during loading and transportation, which transfer to the elements inside the submunition. Since the container 56 is breakable, it is beneficial to include a cushion pad 144 adjacent the container to absorb the vibrations and prevent the container from moving and breaking prematurely. Accordingly, the cushion pad 144 is not required for the operation of the invention, but is helpful to protect the container 56.

The self-destruct fuze delay device 100 self-destructs the submunition 12 after a preset delay if the submunition fails to explode upon its impact with the ground or a target. FIG. 8 depicts an exemplary fuze assembly 150 for the submunition 12 in a side view partially in section, before deployment into the atmosphere. FIG. 9 depicts the fuze assembly 150 viewed from a side substantially orthogonal to the side view of FIG. 8. The fuze assembly 150 includes the fuze delay device 100 mountable on a submunition 12, a ribbon retainer 152 and a stabilizer ribbon 154. The ribbon retainer 152 is attached to the safety lockout pin 46 and the spring retainer pin 136, both of which are shown inserted into the fuze slide 16 to hold the secondary firing pin 28 and the ampoule breaker 134 in their respective locked positions as shown, for example, in FIG. 7. The ribbon retainer 152 also prevents premature unfurling of the stabilizer ribbon 154 as is well known to those skilled in the art. The fuze assembly 150 is shown in FIGS. 8 and 9 as having a safety spacer 156 that is a known in-process safety device for blocking the firing pin from engaging the primary detonator 18 during the assembly of the fuze assembly. The safety spacer 156 is removed from the fuze assembly 150 before the submunitions 12 are stacked or otherwise loaded into their carrier.

FIG. 10 is a flow diagram depicting an exemplary function sequence of events for the self-destruct fuze delay device 100 of the preferred embodiments. When an exemplary submunition 12 hits the air stream at deployment (Step 200), the spring retainer 10, 136 and the safety lockout pin 146 are released out of their predeployment positions by the unfurling of the stabilizer ribbon 154. In other words, upon deployment, atmospheric wind resistance against the submunition 112 separate the ribbon retainer 152 from the submunition, extracting the spring retainer pin 136 and the safety lockout pin 146 out to their predeployment positions by the unfurling of the stabilizer ribbon 154 at Step 202. As can be seen in the corresponding side views of FIGS. 11 and 12, the ribbon retainer's separation from the submunition 12 extracts the spring retainer pin 136 and the safety lockout pin 46 as the ribbon retainer 152 separates. The safety and retainer pins 46, 136 may otherwise be extracted from the fuze delay device 100 by alternative approaches, and the manner in which the pins are released from the fuze delay device is not critical to the operation of the invention.

The extraction of the safety lockout pin 46 removes the lockout from the delay mechanism 104, and the extraction of the spring retainer pin 136 releases the compression spring 62. Upon its release at Step 204, the compression spring 62 drives the ampoule breaker 134 into the container 56, breaking the container and releasing the reactant fluid 58 to flow to the restraining link 114, preferably via the wick 54. To help facilitate the flow of the released fluid 58 to the wick 54 and restraining link 114, a liquid passage 158 within the aperture 108 is provided therebetween.

As can best be seen in FIG. 13, after the ampoule breaker 134 breaks the container 56, the ampoule breaker continues to push beyond its impact point with the container 56. In this manner, the ampoule breaker 134 acts as a plunger and pushes the fluid 58 through the liquid passage 158 to the wick 54 and restraining link 114. In other words, after breaking the container 56, the compression spring 62 continues to drive the ampoule breaker 134, forcing the fluid 58 through the liquid passage 158 and into the wick 54 at Step 206. The fluid 58 is absorbed by the wick 54 and communicates with the restraining link 114. At this time, the detonating fuze 102 appears as can best be seen, for example, in FIG. 13 with the ampoule breaker 134 extended, the container 56 ruptured, and the wick 54 saturated by the reactant fluid 58. FIG. 13 also shows the cushion pad 144 saturated with the reactant fluid 58, which is not important to the invention, but is instead a byproduct of the fluid exposed to the resilient cushion pad.

The wick 54 encircles an area (e.g., weakened area) of the restraining link 114, and directs the reactant fluid 58 to access and attack (e.g., erode, corrode) the restraining link at Step 208. Preferably the fluid 58 erodes the restraining link in contact with the wick 54. In other words, the axial rod 110, the piston 112, the compression spring 30 and the secondary firing pin 28 are preferably made of metal and not vulnerable to erosion by the reactant fluid 58.

At Step 210, over a predetermined time period (e.g., between about 25 seconds and 30 minutes the restraining link 114 exposed to the reactant fluid 58 weakens to a point of failure and breaks, thus defining the first and second portions 130, 132. The predetermined time period typically varies in accordance with several factors, for example, the composition of the reactant fluid, the density of the restraining link and the ambient temperature, as would be readily understood by a skilled artisan. For example, at cold temperatures of about −25° F., the restraining link fails at about 20 to 29 minutes. Of course the failure time decreases as the temperature increases.

Upon the failure of the restraining link 114 at Step 212, the compression spring 30 drives the first portion 130 of the restraining link 114, the piston 112, the axial rod 110 and the secondary firing pin 28 toward the secondary detonator 22, causing the secondary firing pin to impact and explode the secondary detonator 22. See, for example, FIG. 14, which depicts the secondary firing pin 28 at impact with the secondary detonator 22 after the failure of the restraining link 114. While the restraining link 114 shown in FIG. 14 is separated adjacent the axial rod 110, it is understood that the failure of the restraining link occurs at its weakened area preferably adjacent the wick 54. In FIG. 14, the weakened area of the restraining link 144 extends within the wick 54 between the axial rod and the closure plate 122.

As can best be seen in FIG. 14, at Step 214 output from the exploded secondary detonator 22 initiates the adjacent primary detonator 18, causing it to explode and sterilize the submunition when the fuze slide 16 is not armed. However, if at this time the fuze slide 16 is in its armed position, such that the primary detonator 18 is aligned with the main charge, then at Step 216 the initiation of the primary detonator from the secondary detonator 22 will then fire the main charge and destroy the submunition 12 (e.g., grenade, rocket warhead munition). Accordingly, the self-destruct fuze delay device 100 also ensures sterilization or destruction of the submunition 12 depending on the relationship between the primary detonator 18 and the main charge.

It is understood that the method and mechanism for making and using the self-destruct fuze delay device described herein are exemplary indications of preferred embodiments of the invention, and are given by way of illustration only. It other words, the concept of the present invention may be readily applied to a variety of preferred embodiments, including those disclosed herein.

While the invention has been described in detail and with reference to specific examples thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof. For example, the SD fuze delay device is applicable to all the various ICM items including the submunitions of the GMLRS warheads and even non-rotating submunitions (e.g., MLRS, rocket warhead). For non-rotating submunitions, deployment into the air stream causes vibration sufficient to move the fuze slide into its armed position. Accordingly and preferably, upon deployment of rotating or non-rotating submunitions into the atmosphere, the ribbon unfurls, the safety and retainer pins extract, and the fuze slide moves to its armed position. Moreover, while the wicks are shown encircling the weakened area of the restraining link, it is understood that such preferred relationship is not required, as long as the wick is adjacent the weakened area to expedite the desired failure. Without further elaboration, the foregoing will so fully illustrate the invention that other may, by applying current or future knowledge, readily adapt the same for use under various conditions of service.

Claims

1. A self-destruct fuze delay device for a submunition, the submunition having a longitudinal axis, a main charge and a detonating fuze for initiating the main charge upon impact, the detonating fuze having a movable slide, said self-destruct fuze delay device comprising:

a detonator mounted to the movable slide;

a delay mechanism arranged on the movable slide offset and substantially orthogonal to the longitudinal axis, said delay mechanism including an energizing source, a restraining link having a first portion and a second portion, and a self-destruct firing pin attached to said restraining link at said first portion proximate to said detonator, said second portion longitudinally extending from said first portion distal to said detonator and attached to the movable slide, said first portion being moveable from a first position, in which it is held by its attachment to said second portion at a predetermined distance from said detonator, to a second position in which said first portion is separated from said second portion, and said self-destruct firing pin is urged toward said detonator by the energizing source; and

an activation mechanism, in fluid communication with said delay mechanism, that releases said first portion from said second portion after a predetermined delay, with said second portion remaining attached to the movable slide after separation from said first portion.

2. The device of claim 1, wherein said restraining link has a material composition different than said self-destruct firing pin, said activation mechanism causing said restraining link to fail and release said first portion from said second portion.

3. The device of claim 1, wherein said activation mechanism includes a container holding a fluid for corroding said restraining link to release said first portion from said second portion, and a breaking member that impacts said container to release said fluid toward said restraining link.

4. The device of claim 3, wherein said activation mechanism further includes a second energizing source that causes contact between said container and said breaking member.

5. The device of claim 4, wherein said second energizing source is a compression spring.

6. The device of claim 4, wherein said container is a glass ampoule and said breaking member is an ampoule weight that is urged by said second energizing source to contact and break said glass ampoule to release said fluid.

7. The device of claim 3, wherein said fluid comprises a reactant to said restraining link.

8. The device of claim 3, further comprising a wick adjacent said restraining link at a predetermined area between said first portion and said second portion, said wick arranged to collect said fluid from said container and isolate said fluid onto said predetermined area to facilitate the corroding of said restraining link.

9. The device of claim 3, said activation mechanism further including a retainer pin that maintains separation between said container and said breaking member prior to a deployment of the submunition.

10. The device of claim 3, further comprising a cushion pad between said container and the moveable slide.

11. The device of claim 1, wherein said energizing source is a compression spring.

12. The device of claim 1, the detonating fuze having a main detonator movable between a safety position and an armed position, wherein the urging of said self-destruct firing pin toward the detonator by said energizing source causes said self-destruct firing pin to contact and explode said detonator, which explodes said main detonator.

13. The device of claim 12, wherein the explosion of said main detonator initiates the main charge and destroys the submunition to explode when said main detonator is in the armed position.

14. The device of claim 1, wherein said restraining link includes a predetermined weakened area between said first portion and said second portion that breaks to release said first portion from said second portion.

15. A self-destruct fuze delay device for a submunition, the submunition having a longitudinal axis, a main charge and a detonating fuze for initiating the main charge upon impact, the detonating fuze having a movable slide, said self-destruct fuze delay device comprising:

a detonator mounted to the movable slide;

a delay mechanism arranged within the submunition substantially orthogonal to the longitudinal axis, said delay mechanism including an energizing source, a restraining link having a first end attached to said self-destruct firing pin and a second end attached to the movable slide, said self-destruct firing pin being moveable from a first position, in which it is held by its attachment to the movable slide at a predetermined distance from said detonator, to a second position in which said restraining link is separated between said self-destruct firing pin and the movable slide, and said self-destruct firing pin is urged toward said detonator by said energizing source; and

an activation mechanism that releases said restraining link from attachment to the movable slide, said activation mechanism including a container holding a fluid for corroding said restraining link, and a wick adjacent a predetermined area of said restraining link, said wick being porous to absorb and draw said fluid from said container onto said restraining link at said predetermined area to facilitate the corroding and separation of said restraining link.

16. The device of claim 15, said restraining link having a first portion proximate to said detonator and attached to said self-destruct firing pin, and a second portion distal to the detonator and attached to the movable slide, wherein said restraining link separates under chemical attack, with said second portion remaining attached to the movable slide after the separation.

17. The device of claim 15, wherein said predetermined area of said restraining link is structurally weaker and more vulnerable to chemical attack than said self-destruct firing pin.

18. The device of claim 15, wherein said container is a glass ampoule, and further comprising a breaking member that contacts and breaks said ampoule to release said fluid toward said restraining link.

19. A method of self destructing a detonator of a submunition upon deployment into the air, the submunition having a detonating fuze with a movable slide, comprising:

(a) releasing an activation liquid from a container;

(b) absorbing the activation liquid with a porous wick;

(c) directing the absorbed activation liquid onto a predetermined area of a restraining link attaching a firing pin to the movable slide;

(d) corroding the predetermined area with the directed activation liquid;

(e) separating the restraining link at the predetermined area;

(f) urging the firing pin toward the detonator;

(g) colliding the firing pin into the detonator to destroy the detonator.

20. The method of claim 19, wherein Step (e) further comprises separating the restraining link at the predetermined area into a first portion attached to the firing pin and a second portion remaining attached to the movable slide.