Firearms, chain removers for firearms and methods for using the same

Abstract

A firearm that includes a chain wheel, a cartridge feed chain that engages the chain wheel, and a chain remover to remove the cartridge feed chain from the chain wheel is disclosed. An example chain remover includes a U-shaped guide region through which at least a portion of the chain wheel passes. The chain wheel further includes a shoulder surface and the U-shaped region of the chain remover includes an inner radial surface wherein the inner radial surface and the shoulder surface are coupled.

Description

TECHNICAL FIELD

This disclosure relates generally to firearms and, more particularly to chain removers that remove cartridge feed chains from gear wheels and firearms including the same.

BACKGROUND

The operation of traditional chain conveyor systems, in which large masses are accelerated, depends on conventional measures such as chain tension, acceleration and the loads carried by the pull and return chain strands. However, due to the relationship of these factors, conventional chain conveyors are inadequate for use in firearms. In particular, stable operating conditions, in which chain speed is constant or relatively constant, that occur in conventional conveyor systems do not occur in firearm cartridge feed chains that supply ammunition to automatic weapons. The cartridge feed chains used in automatic weapons experience extremely high acceleration and deceleration during weapon firing, such as burst firing. Conventional conveyor chain systems used in this environment could easily malfunction by, for example, the chain becoming kinked. Further, although high acceleration forces act on all the components in modern firearms because of the high firing rates and relatively large bullet masses, these high acceleration forces are particularly experienced by the cartridge feed chain system and its associated link chains during firing, i.e., during discontinuous operation of the weapon.

One effort to address this problem was disclosed in German patent DE 199 03 346, which is hereby incorporated in its entirety by reference herein. The cartridge feed chain system disclosed therein includes two highly tear proof, parallel guided transport chains (link chains), that are distanced, with respect to each other, a length that essentially corresponds to the length of the bullets or cartridges. The two parallel link chains are held at a constant separation distance and connected to each other via cross bridges. Further, the cartridge feed chain system is endless and is configured in several loops led over pulleys through an ammunition magazine. During operation, the cartridge feed chain system transfers the ammunition to an automatic firearm that collects and fires the bullets and that supplies the cartridge feed chain system with the detonated shells or spent shell casings to carry them back to the magazine. The speed of this procedure is determined by the firing process, particularly the rate of fire, which is dependent on the cartridge feed chain system and the associated gears.

Several aspects of the magazine and the cartridge feed chain system disclosed in DE 199 03 346 are, in general, designed to ensure that the cartridge feed chain system and the ammunition experience reduced acceleration and that chain tension is maintained, particularly with respect to the return portion of the chain carrying detonated cartridges. However, although the magazine and the various components included therein, incorporate various measures to ensure the integrity of the cartridge feed system, several problems occur, partly attributable to the drive wheels of the cartridge feed chain system. For example, this configuration does not sufficiently reduce the initial acceleration to constantly secure the chain links to the chain wheel, particularly with respect to the return strand of the cartridge feed chain. This increases slack in the corresponding chain link, which then loosely follows the circumference of the chain wheel and ultimately kinks. In addition this increases the already extreme loads experience by the link chain and the chain wheel. The result is increased wear and tear of the corresponding components or, in the extreme case, an interruption of the cartridge feed chain system that interrupts or completely blocks the operation of the weapon.

German Patent No. 199 03 347, which is also hereby incorporated in its entirety by reference herein, discloses constructive measures developed to improve the behavior of a cartridge feed chain system 2 during operation of the firearm, as shown in FIG. 1. In particular, tightening elements were included for tightening the pull and return strands 4, 6 of the cartridge feed chain system 2, and mass compensating couplers of the pulley loop were also included. These features aided the performance of the cartridge feed chain 4, 6 and the weapon as a whole. However, as depicted in FIG. 1, these added features were insufficient to prevent a kink 8 being formed in a chain. The kink 8 is formed because there are high surface pressures at the beginning of a firing due to chain acceleration. The high surface pressures cause teeth 10 on chain wheels 12 to maintain contact with flanks 14 of the chain 6, between pins 16 and pull the chain 6 along the circumference of the chain wheel 12 in the direction of rotation, instead of releasing the chain 6 at the point where the chain 6 would continue in the proper direction. When the chain 6 is not released at the proper time, the kink 8 forms.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is the side view of a chain wheel having a kinked link chain.

FIG. 2 is a cross-sectional view of a section of an example ammunition magazine.

FIG. 3 is a top cross-sectional view of an example drive and deflection section of a cartridge feed chain.

FIG. 4 is an enlarged perspective view of an example drive source with an example chain wheel and an example chain remover in operating position.

FIG. 5 is a side view of the example chain wheel with the example chain remover and a portion of an example link chain.

DETAILED DESCRIPTION

Throughout this patent, position designations such as “above,” “below,” “top” “forward,” “rear,” etc. are referenced to a firearm held in a normal firing position (i.e., pointed away from the shooter in a generally horizontal direction).

The example firearm disclosed herein includes a chain remover that removes a cartridge feed chain, such as a link chain, from a drive wheel at an appropriate location such that the chain does not kink, particularly on a return side of the chain.

FIG. 2 shows an ammunition magazine 20 in which a guided cartridge feed chain system 22 supplies bullets 24 in supply direction A. The cartridge feed chain system.22 includes two, highly tear proof, parallel guided link chains 26, that are spaced from each other by a distance that essentially corresponds to the length of the bullets 24. The two parallel link chains 26 are connected and spaced from one another via cross bridges 30. The distance between the cross bridges 30 along the length of the chain 26 is essentially equal to the bullet 24 diameter plus the diameter of a cross bridge 30 and a certain tolerance for the clearance of the bullets 24. Further, in one example, the two parallel link chains 26 are endless and guided in several loops over pulleys 32, 34 through the ammunition magazine 20 shown in FIG. 2.

FIGS. 2 and 3 show that the cross bridges 30, which are rigid and thin, separate adjacent bullets 24, or detonated cartridges 36, depending on whether the cross bridges 30 are on the pull side, i.e., the portion of the cartridge feed chain system 22 on the way to a firearm 38, or on the return side. Further, the cross bridges 30 serve as pushers of the bullets 24, or detonated cartridges or shells 36 to guide them through a guide track 40 in the interior of the casing 42 of the ammunition magazine 20. The guide track 40 has slide and roll regions made from appropriate materials such as, for example, low-wear synthetic materials.

In one example, the cross bridges 30 could each have a profile that is adapted to the shape of the bullets 24 or shells 36 such as, for example, a concave profile to complement the convex shape of a side of a bullet 24 or shell 36. Also, the shape of the cross bridges 30 may be adapted to help avoid tilting of the bullets 24 or shells 36. Furthermore, the cross bridges 30 may be axially rotatable between the two link chains 26 to facilitate the rolling of the bullets 24 and the shells 36, inside the guide region 40, as well as rolling of the cross bridges 30 themselves. Each cross bridge 30 may include guide heads 44 that are extensions of the cross bridges 30, which extend through the chains 26. The guide heads 44 may ride along an interior surface of the ammunition magazine 20 to guide the cartridge feed chain system 22 in guide regions 40 through the ammunition magazine 20.

As shown in FIG. 3, in one example, the link chains 26 include lateral flanks 46 that are coupled to one another via pins 48. The flanks 46 are interconnected in the running direction of the link chain 26. The link chains 26 are flexible about the pins 48 so that the chains 26 are flexible in the plane running perpendicular to the axis of the pins 48 to allow the chains 26 to be guided over a corresponding chain wheel 50, whose teeth, or sprockets 52, form a toothed rim 54 and engage the flanks 46 in areas between pins 48 (see FIG. 4).

In the illustrated example, two chain wheels 50 are arranged on a shared drive source 56. Each of the chain wheels 50 includes a central opening 58 having a tooth-shaped profile. The outer surface 60 of the drive source 56 also has a corresponding tooth-shaped profile such that the central opening 58 and the outer surface 60 mate when the chain wheels 50 are coupled to the drive source 56. This configuration arranges the chain wheels 50 in a substantially torque-proof manner. One chain wheel 50 is coupled at or near either end of the drive source 56. The axis 62 of the drive source 56 is substantially linear so the teeth 52 of the two chain wheels 50 are aligned. Alignment of the teeth 52 of the chain wheels 50 aligns the chains 26 to ensure that the cross bridges 30 of the cartridge feed chain system 22 run parallel to the axis 62 of the drive source 56 (FIG. 3). The drive source 56 is housed inside the casing 42 of the ammunition magazine 20 and driven by a gear system (not shown), while maintaining alignment of the chain wheels 50. The gear system drives the drive source 56 so that the cartridge feed chain system 22 supplies the automatic firearm 38 with bullets 24 according to the firing rhythm of the firearm 38.

In the illustrated example (FIG. 2), the cartridge feed chain system 22 passes the pulley 64 that is supported by transmission gears 66, 68. At this point, the cartridge feed chain system 22 supplies bullets 24 to an ammunition supply system 70 that is arranged in between the ammunition magazine 20 and the weapon 38. The loaded bullets 24 from the cartridge feed chain system 22 are passed to the ammunition supply system 70 and then guided to the weapon 38. The empty shells 36, which result from the firing of the weapon 38, are transported back by the ammunition supply system 70 to the cartridge feed chain system 22 in the magazine 20 by the pulley 64. The empty shells 36 are then guided in several loops over pulleys 72, 74 in the magazine 20.

FIGS. 4 and 5 illustrate one example of a chain remover 76 that prevents kinking of the chain 26, such as that caused by the high surface pressures as described above. FIG. 4, for clearer visualization, only depicts the drive source 56, a chain wheel 50, and the chain remover 76.

In an example, the chain remover 76 is constructed in one piece from a plate of a material that can be used in the temperature range of −80 to 200° C., particularly between −40° C. and 110° C. The chain remover 76 may be made from a metal such as a metal with a steel quality of, for example, 42CrMo4. Other, non-metallic materials with similar properties can be used such as, for example, fiber-reinforced composites. The example chain remover 76 includes four guide regions or plates 78a, 78b, 78c, two on either side of the chain wheel 50. FIG. 4 only depicts three guide regions 78a, 78b, 78c, but there is a fourth guide region across from guide region 78c on the same side of the chain remover 76 as guide region 78b. The guide regions 78a, 78b, 78c overcome any high surface pressure between the teeth 52 and the flanks 46 to guide the flanks 46 of the chain 26 tangentially off the chain wheel 50 to avoid forming a kink in the chain 26.

The chain remover 76 may be constructed as a split disk manufactured from a single initial piece by a mechanical process such as, casting or a forged molding. The chain remover 76 may also be a fiber-reinforced composite piece as stated above. The scope of the mechanical post-processing depends on the manufacturing tolerances with which the semi-finished blank product can be manufactured. The chain remover 76 may also be manufactured without any post-processing such as, for example, in a precision casting.

The chain remover 76 may be formed as a bifurcated piece with a U-shaped slit 80 between the guide regions 78a, 78b. The slit 80 runs perpendicular to the rotation axis 62 of the drive source 56 and is at least as wide as the teeth 52 of the chain wheel 50. The chain remover 76 has an inner radial surface 82 between the guide plates 78a, 78c. The distance between two, opposing guide plates 78a, 78c, i.e., the diameter of the inner radial surface 82 is substantially equivalent to the diameter of a shoulder 84 that projects from a root circle 86 of the chain wheel 50. The root circle 86 is the base of the chain wheel 50 exclusive of the teeth 52. The shoulder 84 has cylindrical or conical shoulder surface 88 that supports the chain remover 76 by the inner radial surface 82 of the chain remover 76 along the axis of rotation 62. The guide plates 78a, 78b, 78c also have outer surfaces 90a, 90b, 90c that run tangential to the diameter of the root circle 86 so that the chain remover 76 surrounds a portion of the toothed rim 54 of the chain wheel 50.

The chain remover 76 is operatively coupled to the chain wheel 50 at the radial surface 88 of the shoulder 84 so that the toothed rim 54 rotates about the axis of rotation 62 through the guide plates 78a, 78b, 78c. The chain remover 76 is fixed between the pull and the return strands of the chain 26. To secure the chain remover 76 in operable position with the chain wheel 50, a indentation or notch 92 included at the end of the chain remover 76 that is located at a distance from the chain wheel 50. Through the notch 92 a support 94 clamps into and fixes the chain remover 76. The support 94 may be, for example, a rod running between the casing parts 42 parallel to the rotation axis 62 of the drive source 56. However, the support 94 may also be any mechanical fastener, such as a bolt, rivet, screw, etc. The example chain remover 76 is thus mounted between the support 94 and the chain wheel 50. Also, the chain remover 76 may be mounted in a floating manner such that it is self-centering. Furthermore, all active surfaces are processed and toleranced in such a way to provide a low-tear utilization of the corresponding components. In the illustrated example, the thickness of the chain remover 76 is reduced at the end near the notch 92. In alternative examples, the thickness of the chain remover 76 may remain constant over its total length.

In an alternative example, the casing 42 may be provided with guide regions that operate in substantially the same manner as the guide plates 78a, 78b, 78c of the chain remover 76 to enable low friction removing of the link chain 26. This example eliminates the need for a separate chain remover and fastener. In this alternative example, there may be a projection from the casing 42 that would be tangential to the inner circle 86 of the chain wheel 50 to ensure that the chain 26 is removed from the teeth 52 of the chain wheel 50 of the appropriate point. Further, the projection from the casing 42 may be a substantially U-shaped projection through which the chain wheel 50 runs and which operates in a substantially similar manner to the chain remover 76 described herein with respect to FIGS. 2-5.

In other examples, in place of the tribological pairing between the radial surfaces 82, 88, a tribological pairing between the radial head regions 96 of the teeth 52 and the inner back wall surface 98 of the slit 80, which faces the radial head regions 96 of the teeth 52 as the teeth 52 rotate through the slit 80. To create the tribological pairing between the radial heads 96 and the inner back surface 98, the inner back surface 98 must be constructed as a surface radial with respect to the rotation axis 62, which has about the same radius as the base circle 86 plus the length of a tooth 52.

As stated above, the example firearm 38 disclosed herein includes a chain remover 76 that guarantees that an endless cartridge feed chain system 22, which is a link chain 26, is properly and timely released from a drive wheel 50 such that the chain 26 and does not kink, particularly on the return side. The example disclosed herein enables the chain 26 to be freely and unproblematically removed from the chain wheel 50 even during high accelerations. As shown in FIG. 5, when the chain 26 returns to the magazine 20, the flanks 46 of the chain 26 engage the teeth 52 of the chain wheel 50 as the chain wheel 50 rotates the chain 26 around the axis of rotation 62. The guide plates 78a, 78b, 78c of the chain remover 76 border the edges of the teeth 52 as the chain wheel 50 rotates about the axis 62. As the teeth 52 near the guide plates 78a, 78b, 78c, the guide plates 78a, 78b, 78c come into contact with the top sides of the flanks 46 of the chain 26. This contact causes the flanks 46 and, thus the chain 26, to release contact with the teeth 52 and run substantially tangentially with respect to the chain wheel 50.

In the illustrated example, the width of the two guide plates 78a, 78b and the slit 80 corresponds at least to the thickness of the side flank 46 of a chain 26. Further, the length of a guide plate 78a, 78b, or 78c corresponds at least to the length of a chain link 46, 48. Further, the guide plates 78a, 78b are substantially parallel to each other and are connected, or formed from the same piece of material, such that the slit 80 is bifurcated and substantially U-shaped, as described above.

Also, as shown in FIG. 4, there are guide plates 78a, 78b on the top portion of the chain remover 76 at the pull strand of the chain 26, and there are guide plates 78c at the return strand of the chain 26, as described above. This allows a change of direction of the chain 26 without that additional measures for guidance have to be taken. However, as will be readily appreciated by those having ordinary skill in the art, guide plates may be provided on a single (i.e., the top or bottom) of the chain remover 76.

Further, as stated above, the chain remover 76 may be produced in a few simple mechanical production steps from a plate-shaped blank or as complete molding piece. The chain remover 76 may be produced as a single piece, and may have a width that corresponds to the width of the chain 26. Further, the height of the chain remover 76 at the end near the chain wheel 50 substantially corresponds to the diameter of the root circle 86. The chain remover 76 may also be constructed to accommodate an angle of contact with the chain 26 that is less than or equal to 180°. Thus, the pull and return strands of the chain 26 may separate from each other or approach each other as the distance from the chain wheel increases.

The illustrated example chain remover 76 may be easily and economically coupled to the chain wheel 50 for operation without costly fixings and adjustments. The chain remover 76 is positioned in the radial direction of the chain wheel 50 and coupled thereto at corresponding radial guide surfaces—namely, the shoulder surface 88 and the inner radial surface 82, which is a clearance shaped as a circle segment to complement the circular shape of the shoulder surface 88 and with a radius similar to that of the shoulder surface 88, as described above. The opposite end of the chain remover 76 has a notch 92 into which a mechanical fastener 94 secures the chain remover 76 in place. There is a second axis of rotation 100 that that runs through the center of the mechanical fastener 94. The chain remover 76 is arranged such that it can rotate around this second axis of rotation 100. Essentially the chain remover 76 is coupled to the chain wheel 50 and the attachment element 94 in such a way that the chain remover floats in the axial direction from the toothed rim 54 of the chain wheel 50 to the mechanical fastener 94 in the plane that runs transversely to the rotation axis 62. The floating embedment of the chain remover 76 prevents the chain remover 76 from freeing itself from the chain wheel 50. Thus, in practice, the chain remover 76 acts as a self-adjusting element that, according to the operation conditions, takes in an optimal working position, and has low-tear characteristics.

Further, in the illustrated example, the chain remover 76 in configured such that the chain remover 76 has no affect on the chain 26 when the chain is in proper operation. That is, the chain remover 76 serves to facilitate proper operation of the chain 26 in the event of a malfunction such as, for example, to avoid the formation of kinks.

Although certain example methods, apparatus and articles of manufacture have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.

Claims

1. A firearm comprising: a chain wheel; a cartridge feed chain that engages the chain wheel; and a chain remover to remove the cartridge feed chain from the chain wheel, the chain remover further comprising a U-shaped region through which at least a portion of the chain wheel passes.

2. A firearm as defined in claim 1, wherein the chain wheel further includes a shoulder surface and the U-shaped region of the chain remover includes an inner radial surface wherein the inner radial surface and the shoulder surface are coupled.

3. A firearm as defined in claim 1, wherein the chain remover further comprises: guide plates that run substantially tangential to a root circle of the chain wheel; and a notch located at an end of the chain remover distant from the guide plates through which a fastener may secure the chain remover in place.

4. A firearm as defined in claim 3, wherein the chain remover is coupled to the chain wheel and the fastener in such a way that the chain remover floats in the axial direction from the chain wheel to the fastener in the plane that runs transversely a rotation axis that runs through the chain wheel.

5. A firearm as defined in claim 3, wherein the cartridge feed chain comprises links and the combined width of the guide plates and chain wheel is substantially the same as the width of a link in the cartridge feed chain.

6. A firearm as defined in claim 1, wherein the chain remover is constructed as one piece from a plate.

7. A firearm as defined in claim 6, wherein the initial thickness of the plate corresponds to the chain width.

8. A firearm as defined in claim 1, wherein the chain remover comprises guide plates at both the pull and the return strands of the cartridge feed chain.

9. A firearm as defined in claim 8, wherein the distance between outer edges the guide plates at the pull strand and outer edges the guide plates at the return strand is substantially equal to the diameter of the root circle of the chain wheel.

10. A firearm as defined in claim 1, wherein the chain remover does not affect normal operation of the cartridge feed chain.

11. A firearm as defined in claim 1, wherein the chain remover is composed of a material that can be used in a temperature range of −80 to 200° C., in particular −40° C. to 110° C., in particular of 42 CrMo4.

12. A chain remover for use in a firearm magazine comprising: a U-shaped guide region through which at least a portion of a chain wheel passes; guide plates that run substantially tangential to a root circle of the chain wheel; and a notch located at an end of the chain remover distant from the guide plates through which a fastener may secure the chain remover in place.

13. A chain remover as defined in claim 12, wherein the U-shaped region of the chain remover further includes an inner radial surface and the chain wheel includes a shoulder surface wherein the inner radial surface and the shoulder surface are coupled.

14. A chain remover as defined in claim 12, wherein the chain remover is coupled to the chain wheel and the fastener in such a way that the chain remover floats in the axial direction from the chain wheel to the fastener in the plane that runs transversely a rotation axis that runs through the chain wheel.

15. A chain remover as defined in claim 12, wherein the combined width of the guide plates and chain wheel is substantially the same as the width of a link in a cartridge feed chain that engages the chain wheel.

16. A chain remover as defined in claim 12, wherein the chain remover is constructed as one piece from a plate.

17. A chain remover as defined in claim 12, wherein the chain remover comprises guide plates at both the pull and the return strands of the cartridge feed chain.

18. A chain remover as defined in claim 17, wherein the distance between outer edges the guide plates at the pull strand and outer edges the guide plates at the return strand is substantially equal to the diameter of the root circle of the chain wheel.

19. A chain remover as defined in claim 12, wherein the chain remover is composed of a material that can be used in a temperature range of −80 to 200° C., in particular −40° C. to 110° C., in particular of 42 CrMo4.

20. A method of removing a chain from a chain wheel, comprising: coupling a chain remover to the chain wheel wherein the chain remover has a generally U-shaped guide region in which a portion of the chain wheel rotates and guide plates at an end of the guide region wherein the guide plates remove the chain from the chain wheel.