Magnetic torque-limiting device and method
In a torque-limiting device, a first end engages a fastener, a second end receives an applied torque, and a magnetic torque limiter transmits the applied torque from the second end to the first end to rotate the first end in conjunction with the second end when the applied torque is less than a predetermined limit.
This application claims priority to U.S. Provisional Patent Application Ser. No. 60/799,650, filed on May 12, 2006, titled “MAGNETIC TORQUE LIMITING DEVICE AND METHOD,” the disclosure of which is incorporated herein by reference in its entirety.
FIELD OF THE INVENTIONThe present invention generally relates to a magnetic torque-limiting device and method. More particularly, the present invention pertains to a device and method for limiting an amount of torque applied by the device.
BACKGROUND OF THE INVENTIONIn various manufacturing, construction, and medical industries, fasteners are utilized that are threaded or screwed into place. These fasteners may include a predetermined amount of torque that has been determined to be optimal for a given fastening situation. In addition, the fastener may include a predetermined amount of torque that has been determined to fatigue or break the fastener. Often, these predetermined torque values are determined by the manufacturer or by a testing facility. In use, a technician or user may employ a device such as a torque-limiting device or torque wrench to set the fastener according to the predetermined amount of torque. In a particular example, bone screws may be employed by surgeons to reconstruct bones or attach replacement components to bones of patients. In such circumstances, applying a proper amount of torque may be critically important.
Conventional torque-limiting devices utilize forces from coil springs and spring washers along with friction to limit the amount of torque applied. Unfortunately, as components within these conventional torque-limiting devices slide by one another, wear may alter the torque setting of the conventional torque-limiting device. As such, conventional torque-limiting devices need to be re-calibrated to maintain their torque limit range.
Conventional torque-limiting device mechanisms may also fail and bind or lock-up thereby eliminating the torque-limiting effect and essentially converting the tool to a rigid, non-limiting tool with torque-limiting now regulated to the tool users ability to discern torque forces by hand. This could lead to over-torqueing, an unsafe condition.
An additional aspect of conventional torque-limiting devices is that the torque-limiting event occurs through the same axis as the tool shaft thereby sending shock waves along the tool axis and into the fastener.
Accordingly, it is desirable to provide a device and method capable of overcoming the disadvantages described herein at least to some extent.
SUMMARY OF THE INVENTIONThe foregoing needs are met, to a great extent, by the present invention, wherein in one respect a device and method of limiting an amount of torque applied is provided.
An embodiment of the present invention pertains to a torque-limiting device. The torque-limiting device includes a first end to engage a fastener, a second end to receive an applied torque, and a magnetic torque limiter to transmit the applied torque from the second end to the first end to rotate the first end in conjunction with the second end when the applied torque is less than a predetermined limit.
Another embodiment of the present invention relates to a torque-limiting device. The torque-limiting device includes a shaft, housing, first magnet, second magnet, first lever, and second lever. The shaft includes a distal end to engage a fastener and a proximal end. The shaft defines an axis around which a clockwise rotation vector is aligned towards the distal end. The housing is pivotally secured to the proximal end. The housing includes an outer surface and an inner surface. The inner surface includes at least a first lug protruding radially inwardly into the housing and at least a second lug protruding radially inwardly into the housing. The first magnet is disposed within the housing. The first magnet is secured to the proximal end. The first magnet includes a first bearing surface. The second magnet is juxtaposed in attractive cooperative alignment with the first magnet. The second magnet includes a second bearing surface. The first magnet is drawn towards the second magnet with an attractive magnetic force. The first lever is pivotally secured to the proximal end. The first lever has a first lever lug arm to bear against the first lug. The first lever has a first lever magnet arm to bear against the first bearing surface. A clockwise external torque applied to the outer surface urges the first lug to bear against the first lever lug arm and urges the first lever to pivot clockwise. The first lever magnet arm bears against the first bearing surface to urge the first magnet away from the second magnet in response to the clockwise urging of the first lever lug arm. The second lever is pivotally secured to the proximal end. The second lever has a second lever lug arm to bear against the second lug. The second lever has a second lever magnet arm to bear against the second bearing surface. The clockwise external torque applied to the outer surface urges the second lug to bear against the second lever lug arm and urges the second lever to pivot clockwise. The second lever magnet arm bears against the second bearing surface to urge the second magnet away from the first magnet in response to the clockwise urging of the second lever lug arm and the rotation of the housing relative to the shaft is impeded until the first magnet and second magnet are separated by exceeding the attractive magnetic force between them.
Yet another embodiment of the present invention pertains to a torque-limiting device. The torque-limiting device includes a shaft, housing, first magnet, second magnet, first gear and second gear. The shaft includes a distal end to engage a fastener and a proximal end. The shaft defines an axis of rotation along which a rotation vector is aligned towards the distal end. The housing is pivotally secured to the proximal end. The housing includes an outer surface and an inner surface. The inner surface includes at least a first toothed region having teeth protruding radially inwardly into the housing and at least a second toothed region having teeth protruding radially inwardly into the housing. The first magnet is disposed within the housing. The first magnet is secured to the proximal end. The first magnet includes a first toothed carrier. The second magnet is juxtaposed in attractive cooperative alignment with the first magnet. The second magnet includes a second toothed carrier. The first magnet is drawn towards the second magnet with an attractive magnetic force. The first gear is pivotally secured to the proximal end. The first gear has teeth to engage the first toothed region and the first toothed carrier. A clockwise external torque applied to the outer surface urges the first toothed region to engage the first gear and clockwise rotate the first gear. The clockwise urging of the first gear urges the first magnet away from the second magnet. The second gear is pivotally secured to the proximal end. The second gear has teeth to engage the second toothed region and the second toothed carrier. The clockwise external torque applied to the outer surface urges the second toothed region to engage the second gear and clockwise rotate the second gear. The clockwise urging of the second gear urges the second magnet away from the first magnet and the rotation of the housing relative to the shaft is impeded until the first magnet and the second magnet are separated by exceeding the attractive magnetic force between them.
Yet another embodiment of the present invention relates to a torque-limiting device. The torque-limiting device includes a shaft, first magnetic assembly, housing and second magnetic assembly. The shaft includes a distal end to engage a fastener and a proximal end. The first magnetic assembly is secured to the proximal end. The first magnetic assembly includes a first plurality of magnets. Each one of the first plurality of magnets has a North side adjacent to a South side of another one of the first plurality of magnets. The housing is pivotally secured to the proximal end. The housing includes an outer surface to receive an applied torque. The second magnetic assembly is secured to the housing. The second magnetic assembly includes a second plurality of magnets. Each one of the second plurality of magnets having a North side adjacent to a South side of another one of the second plurality of magnets. Each of the North and South sides of the second magnetic assembly is juxtaposed in attractive cooperative alignment with respective opposite South and North sides, respectively of, the first magnetic assembly to generate an array of attractive magnetic forces between the shaft and the housing.
Yet another embodiment of the present invention pertains to a torque-limiting device. The torque-limiting device includes a shaft, housing, first magnet, second magnet, first gear, and second gear. The shaft includes a distal end to engage a fastener and a proximal end. The shaft defines an axis of rotation along which a rotation vector is aligned towards the distal end. The housing is pivotally secured to the proximal end. The housing includes an outer surface and an inner surface. The inner surface includes at least a first toothed region having teeth protruding radially inwardly into the housing and at least a second toothed region having teeth protruding radially inwardly into the housing. The first magnet is disposed within the housing. The first magnet is secured to the proximal end. The first magnet includes a first toothed carrier. The second magnet is juxtaposed in attractive cooperative alignment with the first magnet. The second magnet includes a second toothed carrier. The first magnet is aligned with the second magnet with an attractive magnetic force between them. The first gear is pivotally secured to the proximal end. The first gear has teeth to engage the first toothed region and the first toothed carrier. A clockwise external torque applied to the outer surface urges the first toothed region to engage the first gear and clockwise rotate the first gear. The clockwise urging of the first gear urges the first magnet to laterally slide out of alignment with the second magnet. The second gear is pivotally secured to the proximal end. The second gear has teeth to engage the second toothed region and the second toothed carrier. The clockwise external torque applied to the outer surface urges the second toothed region to engage the second gear and clockwise rotate the second gear. The clockwise urging of the second gear urges the second magnet to laterally slide out of alignment with the first magnet and wherein rotation of the housing relative to the shaft is impeded until the first magnet and the second magnet laterally slide past each other by exceeding the attractive magnetic force between them.
Yet another embodiment of the present invention relates to a torque-limiting device. The torque-limiting device includes a shaft, housing, first magnet, second magnet and lever. The shaft includes a distal end to engage a fastener and a proximal end. The shaft defines an axis of rotation along which a rotation vector is aligned towards the distal end. The housing is pivotally secured to the proximal end. The housing includes an outer surface and an inner surface. The inner surface includes at least one lug protruding radially inwardly into the housing. The first magnet is disposed within the housing. The first magnet is secured to the proximal end. The second magnet is slidably secured to the proximal end and juxtaposed in attractive cooperative alignment with the first magnet. The second magnet includes a magnet bearing surface. The first magnet is urged towards alignment with the second magnet with an attractive magnetic force. The lever is pivotally secured to the proximal end. The lever has a lug bearing surface to bear against the lug. The lever has an arm to bear against the magnet bearing surface. A clockwise external torque applied to the outer surface urges the lug to bear against the lug bearing surface and urges the lever to pivot clockwise. The arm bears against the magnet bearing surface and urges the second magnet out of alignment from the first magnet in response to the clockwise urging of the arm and the rotation of the housing relative to the shaft is impeded until the first magnet and the second magnet laterally slide past each other by exceeding the attractive magnetic force between them.
Yet another embodiment of the present invention pertains to a torque-limiting device. The torque-limiting device includes a shaft, first magnetic assembly, housing, and second magnetic assembly. The shaft includes a distal end to engage a fastener and a proximal end. The first magnetic assembly secured to the proximal end. The first magnetic assembly includes a first plurality of magnets. The housing is pivotally secured to the proximal end. The housing includes an outer surface to receive an applied torque and the housing includes an inner surface. The inner surface includes at least one lug protruding radially inwardly into the housing. The second magnetic assembly is pivotally secured to the proximal end. The second magnetic assembly includes a second plurality of magnets, an axis about which the second magnetic assembly rotates, and a lip offset from the axis. The second magnetic assembly is juxtaposed in attractive cooperative alignment with the first magnetic assembly to generate an attractive magnetic force between them. The rotation of the housing relative to the shaft urges the lug to bear upon the lip and rotate the second magnetic assembly away from and out of alignment with the first magnetic assembly. The rotation of the housing relative to the shaft is impeded until the separation of the first magnetic assembly and the second magnetic assembly in response to exceeding the attractive magnetic force between them.
Yet another embodiment of the present invention relates to a torque-limiting device includes a shaft, housing, race, first magnet, and second magnet. The shaft includes a distal end to engage a fastener and a proximal end. The shaft defines an axis of rotation along which a rotation vector is aligned towards the distal end. The housing is pivotally secured to the proximal end. The housing includes an outer surface and an inner surface. The inner surface includes at least one lug protruding radially inwardly into the housing. The race is secured to the proximal end. The race is oriented perpendicularly relative to the shaft. The first magnet is slidably disposed within the race. The first magnet includes a bearing surface to bear against the lug. The second magnet is slidably disposed within the race and juxtaposed in repulsive cooperative alignment with the first magnet. The first magnet is repulsed from the second magnet with a repulsive magnetic force that urges the bearing surface against the lug to impede rotation of the housing relative to the shaft. An applied torque to the outer surface urges the lug to bear against the bearing surface and urges the first magnet towards the second magnet and the rotation of the housing relative to the shaft is impeded until the applied torque exceeds a predetermined limit.
Yet another embodiment of the present invention pertains to a torque-limiting device. The torque-limiting device includes a shaft means, handle means, and magnetic limiting torque means. The shaft means engages a fastener. The handle means receives an applied torque. The magnetic torque-limiting means couples the shaft means and handle means and magnetically limiting an amount of torque externally applied to the handle means from being transmitted to the fastener. The magnetic torque-limiting means is configured to transmit the applied torque from the handle means to the shaft means in response to the applied torque being less than a predetermined torque limit.
Yet another embodiment of the present invention relates to a torque meter. The torque meter includes a cam and a magnetic coupling. The cam receives an applied torque. The magnetic coupling includes a pair of magnetically active components that are urged together by an attractive magnetic force. The cam is configured to urge the pair of magnetically active components apart in response to the applied torque.
Yet another embodiment of the present invention pertains to a torque meter. The torque meter includes a first magnet, cam and second magnet. The cam receives an applied torque. The second magnet is juxtaposed in repulsive cooperative alignment with the first magnet. The cam is configured to urge the first magnet towards the second magnet in response to the applied torque.
There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
The present invention provides a magnetic torque-limiting device and method. A detailed description of the magnetic method utilized in the preferred embodiment will clarify the understanding of the phenomenon of magnetic coupling and the magnetic circuit that is created in the preferred embodiment. The individual magnets are made from a rare earth material, such as Samarium Cobalt, SmCo, or Neodymium Iron Boron NdFeB, the former being preferred over the later. NdFeB, due to its iron component, will rust, SmCo contains no iron and will not rust. The shaft and tube are made from a magnetically conductive stainless steel, such as T410 SmIs Annealed or similar magnetically conductive materials. The shaft assembly includes magnets connected to the shaft. They are arranged so that the separate magnetic elements, i.e. the magnets are in a mutually magnetically attractive arrangement. The magnetic lines of force pass from one magnet, through the shaft and into the adjacent magnet; opposite poles adjacent to and attracting each other. See
A similar arrangement is made between the tube and the tube magnets with magnetic lines of force traveling from magnet to magnet through the tube.
When the shaft is positioned inside the tube the north magnets on the shaft will align with the south magnets on the tube, opposite poles attracting. This arrangement is done by design. The lines of force that flow through the shaft magnets and shaft will join with the lines of magnetic force flowing through the tube and tube magnets. These lines of force form a complete circle or closed loop and as such are called a magnetic circuit.
The magnetic relationship between shaft and tube is static with neither part seeking a different alignment. The number of magnets used in the preferred embodiment permits the creation of three complete magnetic circuits. These three magnetic circuits magnetically couple the tube to the shaft. When the tube is used as a handle and rotated the shaft will follow. However, the magnetic force between the tube and shaft is finite and pre-established by its design.
When the shaft is connected to a fastener, rotation of the tube or handle will force the shaft to rotate thereby installing the fastener. However, when the resistance on the fastener exceeds the magnetic force between the tube and shaft the shaft will stop rotating but the tube will continue to rotate as long as turning forces are applied that exceed the magnetic force. When this occurs the magnetic circuit is first distorted and then breaks as the tube magnets rotate to re-align with the next set of shaft magnets and create the next set of magnetic circuits. The circuit is broken when the turning force exceeds the magnetic force. However, the turning force has no effect on the magnetic force; that force is predetermined in the design of the magnetic circuit.
The peak magnetic force is achieved when the circuit is complete and the lines of force are not being distorted. The moment the magnets are moved relative to one another the lines of force become distorted and the magnetic attraction begins to lessen. This is an inherent safety feature of the design in that the predetermined force cannot be exceeded but only lessened. Furthermore, the magnetic force has no mechanical dependencies and as such does not require recalibration or maintenance.
In one example of a preferred embodiment, the torque-limiting device is utilized to install fasteners into a bone of a patient. Bones varies in density from surface to core and this presents a number of difficulties with regard to fastening. Primary among these difficulties are the inherent hardness of the bone outer surface and the varying density of the bones core. To install a fastener in bone generally calls for a quantifiable torque force. This torque force limit is established by the fastener manufacturer and is usually expressed as a “not to exceed” value. (Excessive torque can break the fastener). Torque limiting devices are typically made to meet but not exceed the proscribed torque value. When installing a fastener, applying excessive torque may have negative consequences. It is an advantage of embodiments of the invention that the magnetic torque-limiting device substantially and/or continually maintains a pre-set, non exceedable, torque limit. It is another advantage that this pre-set torque limit is essentially unaffected by frictional wear, as the working components do not touch one another. As such, the need for testing and recalibration of the torque-limiting device may be eliminated. It is yet another advantage of embodiments that the magnetic torque-limiting device may reduce or eliminate shock loads upon the fastener and/or patient. This is a result of the non-parallel relationship of the axis of magnetic torque-limiting and the axis of the tool. In contrast, a conventional torque-limiting device may generate shock loads that may break or damage the fasteners. These shock loads can be attributed to the mechanical nature of current tools, their actions are abrupt mechanical movements, with metal to metal components snapping into detents with force and considerable speed. The action of the magnetic assembly is one of smooth rotation and realignment without the necessity of mechanical components snapping into place. As described herein, suitable magnets may be utilized to generate attractive and/or repulsive forces that are used to predetermine and limit the amount of torque which that can be applied.
An advantage of magnetically induced torque is that the specific magnetic force, or torque limit, is relatively stable, cannot in and may remain essentially the same over the lifetime of the torque-limiting device.
Preferred embodiments of the invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. As shown in
In general, the torque-limiting device 10 is configured such that in response to turning the handle 16 in direction A, an applied torque will urge the shaft 18 to rotate in a similar fashion. The shaft 18 defines an axis X around which a clockwise rotation vector R is aligned towards the distal end 18D of the shaft 18. In general, the rotation vector R is defined as a direction and magnitude of the torque applied to the handle 16 (applied torque) as the applied torque is transmitted along an axis X towards the distal end 18D (the point of application of the force). Typically, to install the fastener 12, a clockwise rotation is applied to the fastener (from a view in-line with the rotation vector R).
The torque-limiting device 10 is configured such that at a threshold or max torque, the shaft 18 ceases to rotate in direction A in response to rotating the handle 16 in direction A. In general, the maximum torque can be defined as the maximum magnetic attraction between the two magnetic assemblies. Once established by the design of the magnetic components, that force cannot be exceeded. In conventional devices, the limit at this threshold torque is affected by frictional forces of one member sliding against another. Unfortunately, this friction results in mechanical wear that may alter the characteristics of the torque applied through the device. It is an advantage of the various embodiments of the magnetic torque-limiting device that friction is a substantially negligible component of the applied torque. As such, the embodiments are essentially unaffected by frictional or mechanical wear.
In addition, while not explicitly shown in
Two magnets may be brought into attachment by disposing the north sector of one magnet in close proximity to the south sector of the other magnet. As shown in
In various embodiments, the magnets 22A and 22B may include any suitable magnets, magnetic devices, and/or magnetically attractive material. Suitable magnets may include, for example, permanent magnets, dipoles, electromagnets, and the like. Specific examples of permanent magnets include ferrous or ferrite magnets, rare earth magnets, Neodymium magnets such as Neodymium Iron Boron (“NdFeB”), Samarium-Cobalt (“SmCo”) magnets, ceramic magnets, alnico magnets, and the like. Furthermore, the magnets 22A and 22B may include a magnetic intensifier such as an iron or iron bearing cup or shaft. Moreover, the magnets 22A and/or 22B may include any suitable magnetically active material. For the purpose of this disclosure, magnetically active materials include magnets, magnetically inducible materials such as iron, materials with relatively high permeability, and the like.
As shown in
As shown in
As shown in
When the force acting on the magnetic assembly and its associated shaft, induced by the handle lug(s) exceeds the predetermined magnetic force or torque value, the magnets will separate, by means of the levers, and the torque force exerted on the tool shaft will diminish. This is the moment of torque-limiting. The predetermined torque force is reached but not exceeded and the fastener is prevented from being over-torqued.
By varying the length of the arm 36 compared to the arm 38, the force required to separate the magnets may be altered. For example, by increasing the length of the arm 38 as compared to the arm 36, the separating force may be reduced for a given amount of torque placed upon the handle 16. In a particular example, the magnets 22A and 22B and the lever 34 are held in a fixture that is securely attached to the shaft 18 of the torque-limiting device. One or both of the magnets 22A and 22B are free to move away from the other magnet along a path described by the common axis running through both magnets 22A and 22B. In response to an amount of torque being applied to the handle 16, the magnets 22A and 22B are levered apart by the lever 34, as shown in
Therefore, the embodiment shown in
Similarly, the gear 40B may mesh with the toothed region 42B and urge the toothed assembly 44B in direction C′. In this manner, the magnets 22A and 22B are urged apart, as shown in
Therefore, the embodiment shown in
As shown in
An air gap separates the shaft magnet assembly 50 from the handle magnet assembly 52. To increase the magnetic force between the shaft magnetic assembly and the handle magnetic assembly, this gap may be made as small as possible given the available manufacturing tolerances. In a particular example, the shaft magnet assembly 50 and/or the handle magnet assembly 52 may be machined in a rounded manner. As such, the gap may be reduced to one or a few thousandths of an inch. This gap facilitates rotation of the shaft magnet assembly 50 with respect to the handle magnet assembly 52. In this manner, in response to an applied torque exceeding the ability of the magnets to remain in attractive alignment, the handle 16 may rotate without also rotating the shaft 18. The rotation of handle 16 also separates or breaks the magnetic circuit between the two corresponding magnets thereby reducing the magnets mutual attractive force, creating the torque limit of the tool.
To adjust the torque limit of the torque-limiting tool 10, the shaft magnet assembly 50 may be axially displaced relative to the handle magnet assembly 52. In this regard,
As shown in FIG. SB, turning the handle 16 causes the handle magnet assembly 52 to urge the shaft magnet assembly 50 to rotate in the same direction and thereby rotates the shaft 18. In this regard, the shaft magnet assembly 50 are magnetically linked to the handle magnet assembly 52 and as such are driven by the handle 16. However, in this and other embodiments, there may be essentially no physical connection between the handle 16 and shaft 18. In response to the torque applied to the handle 16 exceeding the maximum amount of torque which can be translated to the shaft, the shaft 18 may cease to rotate in direction “A” regardless of the action of the handle 16. That is, the torque limit has been exceeded and the magnetic element alignment is separated or broken. If the handle 16 continues to turn, the magnets realign to the next circuit alignment.
In addition, portions of the tool shaft 18 and the handle 16 which contact the magnets may be made from magnetically conductive materials. The use of these materials permits the magnetic lines of force to become a complete magnetic circuit. In a particular example, suitable conductive materials include steel and magnetically permissive stainless steels such as type 440 series stainless steel, series 630/17-4 cond.A stainless steel, and the like.
The magnetic disk 60 is secured to the body 65 and the magnetic disk 62 is secured to the handle 16. The handle 16 and the body 65 are secured to one another in a freely rotating manner. By turning the handle 16, the magnetic disk 62 urges the magnetic disk 64 to rotate in a similar fashion. In operation, when the resistive force on a fastener coupled to the shaft 18 exceeds the magnetic attraction ability between the magnetic disks 60 and 62, then the handle will began to distort the magnet fields attraction, causing a reduction in magnetic attraction and a comparable reduction of the torque capable of being applied to the fastener 12. Once the magnetic field separation has occurred the magnets are permitted to realign for the next torque-limiting event.
In addition, embodiments of the invention may include multiple magnetic disks 60 and 62. For example, any suitable number of magnetic disks may be stacked along the axis of the torque-limiting device 10 with alternating disks being secured to either the shaft 18 or the handle 16. In this manner, the torquemax may be varied.
Therefore, the embodiments shown in
Therefore, the embodiments shown in
By modulating the size and shape of the ridge 70, a resistive force as perceived by the user may be modified.
Also shown in
Therefore, the embodiments shown in
The frame 88 and pivoting holder 90 are operable to juxtapose the magnets 22A and 22B in cooperative alignment. The handle 16 is configured to slide over the frame 88 and pivoting holder 90. When assembled, the handle 16 and pivoting holder 90 may be retained by a cap 92. The pivoting holder 90 includes a pair of pins 94 configured to mate with a pair of bores 96 and rotate therein.
Therefore, the embodiments shown in
The pins 116 are configured to engage one or more cams 118. In a particular example, a matching and indexed set of the cams 118 may be disposed above and below the assembly 110 and may be configured to drive the pins inward in unison. As the handle 16 is rotated, these cams 118 urge the pins 116 inward. This action, in turn, urges the magnets 22A and 22B toward one another. As the magnets 22A and 22B get closer, the magnetic repulsion increases. Accordingly, by modulating the displacement or shape of the cams 118, the torquemax may be controlled. In addition, modifying the size, shape, magnetic material, degree of magnetism, and the like may also be utilized to adjust the torquemax.
Therefore, the embodiment shown in
In addition, the embodiments shown in
Furthermore, the embodiments shown in
Conventional torque measuring devices are based on torsion bar design in which applied torque is indicated by a pointer and scale attached to a conventional torque measuring tool. The conventional measuring tool is subject to metal fatigue and wear and the torque range changes, requiring that they be returned for periodic adjustment and maintenance. The conventional devices are calibrated and adjusted mechanically with the help of an electronic load cell transducer. These devices are composed of complicated high precision components that are assembled by hand and easily damaged. As such, these conventional instruments are costly to produce and maintain and require a high selling price.
In various embodiments of the present invention, a torque sensing device including a magnetic assembly having two magnetic elements that are either mutually attracting or mutually repelling each other. The force of such a (finite) magnetic assembly or magnetic circuit will be constant. As the predetermined magnetic circuit force is constant then a displacement force or movement or pressure will be constant and repeatable. Interfering with the circuit by applying a counter force will yield a displacement factor in the physical proximity of the two magnet elements. This displacement can be indicated, measured and recorded. The magnetic force is essentially constant and of unchanging value. As such, the need for calibration and adjustment may be reduced or eliminated. This force can be measured by means of a gauss meter or measured by applying a force greater than the magnetic force this greater force may be in the form of a physical displacement of the relationship between the two magnets. Furthermore the displacing force may take the form of slipping the magnets apart or by pulling the two magnets apart along their common axis or by tipping or bending the magnets apart.
In another embodiment, the torque sensing device 200 may be secured to the torque-limiting device 10. In this embodiment, the torque applied to the fastener 12 may be sensed as the fastener 12 is installed in the substrate 14 as shown in
The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.
Claims
1. A torque-limiting device comprising:
- a first end to engage a fastener;
- a second end to receive an applied torque; and
- a magnetic torque limiter to transmit the applied torque from the second end to the first end to rotate the first end in conjunction with the second end when the applied torque is less than a predetermined limit.
2. The torque-limiting device according to claim 1, wherein the magnetic torque limiter further comprises a plurality of magnetically active materials juxtaposed in cooperative alignment.
3. The torque-limiting device according to claim 1, wherein the cooperative alignment of the plurality of magnetically active materials generates a magnetic circuit between the plurality of magnetically active materials.
4. A torque-limiting device comprising:
- a shaft including a distal end to engage a fastener and a proximal end, the shaft defining an axis around which a clockwise rotation vector is aligned towards the distal end;
- a housing pivotally secured to the proximal end, the housing including an outer surface and an inner surface, the inner surface including at least a first lug protruding radially inwardly into the housing and at least a second lug protruding radially inwardly into the housing;
- a first magnet disposed within the housing, the first magnet being secured to the proximal end, the first magnet including a first bearing surface;
- a second magnet juxtaposed in attractive cooperative alignment with the first magnet, the second magnet including a second bearing surface, wherein the first magnet is drawn towards the second magnet with an attractive magnetic force;
- a first lever pivotally secured to the proximal end, the first lever having a first lever lug arm to bear against the first lug, the first lever having a first lever magnet arm to bear against the first bearing surface, wherein a clockwise external torque applied to the outer surface urges the first lug to bear against the first lever lug arm and urges the first lever to pivot clockwise, wherein the first lever magnet arm bears against the first bearing surface to urge the first magnet away from the second magnet in response to the clockwise urging of the first lever lug arm; and
- a second lever pivotally secured to the proximal end, the second lever having a second lever lug arm to bear against the second lug, the second lever having a second lever magnet arm to bear against the second bearing surface, wherein the clockwise external torque applied to the outer surface urges the second lug to bear against the second lever lug arm and urges the second lever to pivot clockwise, wherein the second lever magnet arm bears against the second bearing surface to urge the second magnet away from the first magnet in response to the clockwise urging of the second lever lug arm and wherein rotation of the housing relative to the shaft is impeded until the first magnet and second magnet are separated by exceeding the attractive magnetic force between them.
5. The torque-limiting device according to claim 4, wherein the outer surface is configured to mate with an anatomically human hand.
6. A torque-limiting device comprising:
- a shaft including a distal end to engage a fastener and a proximal end, the shaft defining an axis of rotation along which a rotation vector is aligned towards the distal end;
- a housing pivotally secured to the proximal end, the housing including an outer surface and an inner surface, the inner surface including at least a first toothed region having teeth protruding radially inwardly into the housing and at least a second toothed region having teeth protruding radially inwardly into the housing;
- a first magnet disposed within the housing, the first magnet being secured to the proximal end, the first magnet including a first toothed carrier;
- a second magnet juxtaposed in attractive cooperative alignment with the first magnet, the second magnet including a second toothed carrier, wherein the first magnet is drawn towards the second magnet with an attractive magnetic force;
- a first gear pivotally secured to the proximal end, the first gear having teeth to engage the first toothed region and the first toothed carrier, wherein a clockwise external torque applied to the outer surface urges the first toothed region to engage the first gear and clockwise rotate the first gear, wherein clockwise urging of the first gear urges the first magnet away from the second magnet; and
- a second gear pivotally secured to the proximal end, the second gear having teeth to engage the second toothed region and the second toothed carrier, wherein the clockwise external torque applied to the outer surface urges the second toothed region to engage the second gear and clockwise rotate the second gear, wherein clockwise urging of the second gear urges the second magnet away from the first magnet and wherein rotation of the housing relative to the shaft is impeded until the first magnet and the second magnet are separated by exceeding the attractive magnetic force between them.
7. The torque-limiting device according to claim 6, wherein the cooperative alignment of the first and second magnets generates a magnetic circuit between the first and second magnets.
8. A torque-limiting device comprising:
- a shaft including a distal end to engage a fastener and a proximal end;
- a first magnetic assembly secured to the proximal end, the first magnetic assembly including a first plurality of magnets, each one of the first plurality of magnets having a North side adjacent to a South side of another one of the first plurality of magnets;
- a housing pivotally secured to the proximal end, the housing including an outer surface to receive an applied torque; and
- a second magnetic assembly secured to the housing, the second magnetic assembly including a second plurality of magnets, each one of the second plurality of magnets having a North side adjacent to a South side of another one of the second plurality of magnets, wherein each of the North and South sides of the second magnetic assembly is juxtaposed in attractive cooperative alignment with respective opposite South and North sides, respectively of, the first magnetic assembly to generate an array of attractive magnetic forces between the shaft and the housing.
9. The torque-limiting device according to claim 8, wherein rotation of the housing relative to the shaft is impeded until the applied torque exceeds a predetermined limit associated with the attractive magnetic force.
10. A torque-limiting device comprising:
- a shaft including a distal end to engage a fastener and a proximal end, the shaft defining an axis of rotation along which a rotation vector is aligned towards the distal end;
- a housing pivotally secured to the proximal end, the housing including an outer surface and an inner surface, the inner surface including at least a first toothed region having teeth protruding radially inwardly into the housing and at least a second toothed region having teeth protruding radially inwardly into the housing;
- a first magnet disposed within the housing, the first magnet being secured to the proximal end, the first magnet including a first toothed carrier;
- a second magnet juxtaposed in attractive cooperative alignment with the first magnet, the second magnet including a second toothed carrier, wherein the first magnet is aligned with the second magnet with an attractive magnetic force between them;
- a first gear pivotally secured to the proximal end, the first gear having teeth to engage the first toothed region and the first toothed carrier, wherein a clockwise external torque applied to the outer surface urges the first toothed region to engage the first gear and clockwise rotate the first gear, wherein clockwise urging of the first gear urges the first magnet to laterally slide out of alignment with the second magnet; and
- a second gear pivotally secured to the proximal end, the second gear having teeth to engage the second toothed region and the second toothed carrier, wherein the clockwise external torque applied to the outer surface urges the second toothed region to engage the second gear and clockwise rotate the second gear, wherein clockwise urging of the second gear urges the second magnet to laterally slide out of alignment with the first magnet and wherein rotation of the housing relative to the shaft is impeded until the first magnet and the second magnet laterally slide past each other by exceeding the attractive magnetic force between them.
11. The torque-limiting device according to claim 10, wherein the attractive magnetic force determines a maximum amount of torque that may be transmitted to the fastener from the housing.
12. A torque-limiting device comprising:
- a shaft including a distal end to engage a fastener and a proximal end, the shaft defining an axis of rotation along which a rotation vector is aligned towards the distal end;
- a housing pivotally secured to the proximal end, the housing including an outer surface and an inner surface, the inner surface including at least one lug protruding radially inwardly into the housing;
- a first magnet disposed within the housing, the first magnet being secured to the proximal end;
- a second magnet slidably secured to the proximal end and juxtaposed in attractive cooperative alignment with the first magnet, the second magnet including a magnet bearing surface, wherein the first magnet is urged towards alignment with the second magnet with an attractive magnetic force; and
- a lever pivotally secured to the proximal end, the lever having a lug bearing surface to bear against the lug, the lever having an arm to bear against the magnet bearing surface, wherein a clockwise external torque applied to the outer surface urges the lug to bear against the lug bearing surface and urges the lever to pivot clockwise, wherein the arm bears against the magnet bearing surface and urges the second magnet out of alignment from the first magnet in response to the clockwise urging of the arm and wherein rotation of the housing relative to the shaft is impeded until the first magnet and the second magnet laterally slide past each other by exceeding the attractive magnetic force between them.
13. The torque-limiting device according to claim 12, wherein the attractive magnetic force determines a maximum amount of torque that may be transmitted to the fastener from the housing.
14. A torque-limiting device comprising:
- a shaft including a distal end to engage a fastener and a proximal end;
- a first magnetic assembly secured to the proximal end, the first magnetic assembly including a first plurality of magnets;
- a housing pivotally secured to the proximal end, the housing including an outer surface to receive an applied torque and the housing including an inner surface, the inner surface including at least one lug protruding radially inwardly into the housing; and
- a second magnetic assembly pivotally secured to the proximal end, the second magnetic assembly including a second plurality of magnets, an axis about which the second magnetic assembly rotates, and a lip offset from the axis, wherein the second magnetic assembly is juxtaposed in attractive cooperative alignment with the first magnetic assembly to generate an attractive magnetic force between them, wherein rotation of the housing relative to the shaft urges the lug to bear upon the lip and rotate the second magnetic assembly away from and out of alignment with the first magnetic assembly, wherein rotation of the housing relative to the shaft is impeded until the separation of the first magnetic assembly and the second magnetic assembly in response to exceeding the attractive magnetic force between them.
15. The torque-limiting device according to claim 14, wherein the attractive magnetic force determines a maximum amount of torque that may be transmitted to the fastener from the housing.
16. A torque-limiting device comprising:
- a shaft including a distal end to engage a fastener and a proximal end, the shaft defining an axis of rotation along which a rotation vector is aligned towards the distal end;
- a housing pivotally secured to the proximal end, the housing including an outer surface and an inner surface, the inner surface including at least one lug protruding radially inwardly into the housing;
- a race secured to the proximal end, the race being oriented perpendicularly relative to the shaft;
- a first magnet slidably disposed within the race, the first magnet including a bearing surface to bear against the lug; and
- a second magnet slidably disposed within the race and juxtaposed in repulsive cooperative alignment with the first magnet, wherein the first magnet is repulsed from the second magnet with a repulsive magnetic force that urges the bearing surface against the lug to impede rotation of the housing relative to the shaft, wherein an applied torque to the outer surface urges the lug to bear against the bearing surface and urges the first magnet towards the second magnet and wherein rotation of the housing relative to the shaft is impeded until the applied torque exceeds a predetermined limit.
17. The torque-limiting device according to claim 16, further comprising:
- a second lug protruding radially inwardly into the housing;
- a second bearing surface to bear against the second lug and urge the second magnet towards the first magnet in response to the applied torque.
18. A torque-limiting device comprising:
- shaft means for engaging a fastener;
- handle means for receiving an applied torque; and
- a magnetic torque-limiting means coupling the shaft means and handle means and magnetically limiting an amount of torque externally applied to the handle means from being transmitted to the fastener, the magnetic torque-limiting means being configured to transmit the applied torque from the handle means to the shaft means in response to the applied torque being less than a predetermined torque limit.
19. The torque-limiting device according to claim 18, wherein the magnetic torque-limiting means is configured to allow the shaft means to rotate relative to the handle means in response to the applied torque being greater than the predetermined torque limit.
20. A torque meter comprising:
- a cam to receive an applied torque; and
- a magnetic coupling, the magnetic coupling including a pair of magnetically active components that are urged together by an attractive magnetic force, wherein the cam is configured to urge the pair of magnetically active components apart in response to the applied torque.
21. The torque meter according to claim 20, further comprising:
- an indicator to indicate the applied torque in response to rotation of the cam relative to the magnetic coupling.
Type: Application
Filed: Aug 31, 2006
Publication Date: Nov 15, 2007
Inventor: James R. Gross (Richmond, IL)
Application Number: 11/513,052
International Classification: E21B 15/04 (20060101);