AU2016243800B2

AU2016243800B2 - Forward ejection system of casing

Info

Publication number: AU2016243800B2
Application number: AU2016243800A
Authority: AU
Inventors: Cheng Hok Aw; Tuck Wah Chee; Kheng Hong Samuel PANG; Wei Qiang TANG
Original assignee: ST Engineering Advanced Material Engineering Pte Ltd
Current assignee: ST Engineering Advanced Material Engineering Pte Ltd
Priority date: 2015-03-31
Filing date: 2016-03-31
Publication date: 2020-09-24
Anticipated expiration: 2036-03-31
Also published as: AU2016243800A1; AT519342A1; SG11201708040SA; WO2016159888A1

Abstract

The present invention describes a casing ejection system (300) for a firearm that employs a bolt carrier assembly (100). The casing ejection system (300) includes an actuator rod (305) and an L -shaped deflector (350) to sweep a casing (12) laterally into an ejection chute (500). The actuator rod (305) is disposed substantially above the bolt carrier assembly (100). The casing (12) in the ejection chute is then ejected through an ejection port (600) located at a position forward of a trigger and to one side of the firearm. A bolt (230) of the bolt carrier has a latch cam pin (250) pivotedly connected to the bolt. When the bolt is not received in the bolt carrier, the latch cam pin (250) obstructs a central bore inside the bolt to prevent a firing pin (235) from being inserted.

Description

Forward Ejection System Of Casing Field of Invention

[001] The present invention relates to a casing ejection system for a firearm which is configured with a bolt assembly. In particular, the casing is ejected both forward and to one side of the firearm, this is, at a safe distance away from the shooter of the firearm. The bolt assembly is also configured with a latch cam pin to prevent accidental assembling of a firing pin without an associated cam pin (234) during assembling of the bolt assembly and casing ejection system.

Background

[002] A bolt assembly 10 for a firearm includes a bolt carrier 20 and a bolt 30 for moving inside the bolt carrier 20. A front end of the bolt 30 has an extractor 34 and a plurality of lugs 36. The lugs 36 are matched with cooperating slots at the rear f the barrel, for locking the bolt during firing and for unlocking the bolt after firing. After firing a cartridge, the high-pressure gas in the cartridge chamber is used to drive a piston assembly 50 which, in turn, moves the bolt carrier 20 rearward; as the bolt carrier is moved rearward, the bolt 30 is also rotated; rotation of the bolt 30 unlocks the lugs from the cooperating slots at the barrel rear-end and then allows the extractor 34 to pull the casing 12 of the spent cartridge from the cartridge chamber. In US Patent No. 6,625,917, issued to Heckler & Koch GmbH, the rearward moving casing hits an ejector rod; this causes the casing 12 to be tilted laterally and become dislodged from the extractor 34; the kinetic energy of the casing then causes the casing to eject out of the firearm.

[003] Conventionally, most firearms are designed for right-hand use and the hot casings 12 are ejected to the right hand side. A left hand shooter using such a right-handed firearm faces the hazard of being struck by the hot casings. This problem is more serious when the firearm is of the bullpup design in that the hot casings 12 are ejected closer to the arm or face of the shooter. [004] It can thus be seen that there exists a need for another type of mechanism to eject the hot casings a safe distance away from the shooter.

Summary

[005] The following presents a simplified summary to provide a basic understanding of the present invention. This summary is not an extensive overview of the invention, and is not intended to identify key features of the invention. Rather, it is to present some of the inventive concepts o this invention in a generalised form as a prelude to the detailed description that is to follow.

[0063 The present invention seeks to provide a casing ejection system for a firearm, especially that of a bull pup design. Preferably, the firearm incorporating the casing ejection system is usable by both right-handed and left-handed users. A latch cam pin is provided at the bolt assembly to prevent accidental assembling of a firing pin without assembling an associated cam pin (234) during assembling of the bolt assembly and casing ejection system.

[007] In one embodiment, the present invention provides a casing ejection system for a firearm employing a bolt carrier assembly, with the system comprising: an elongate bolt disposed to move along and rotate about a longitudinal axis in a bolt carrier, with a front face of the bolt having an extractor for holding a casing thereon; an elongate actuator rod disposed parallel to the longitudinal axis of the bolt and bolt carrier, with a front end of the actuator rod having a L-shaped deflector, and a rear end having a cam pin and an engaging cam slot in a sleeve disposed around the rear end, wherein the L-shaped deflector is at a home position that is forward and clear from the front face of the bolt; an ejection chute that is parallel to the actuator rod and having a longitudinal opening for receiving a casing held by the extractor at the front face; and an ejector extends from the bolt carrier into the ejection chute near a rear end of the longitudinal opening and is movable to a front end of the longitudinal opening according to a longitudinal stroke of the cam pin in the cam slot; wherein, after an initial predetermined rearward motion, further rearward motion of the cam pin in the engaging cam slot causes the actuator rod to rotate and to strike the casing laterally into the ejection chute through the longitudinal opening. The return stroke of the piston subassembly moves the bolt earner forward via a recoil spring, and the casing in the ejection chute is pushed by the ejector out of the firearm to a safe distance forward and to one side of the firearm.

[008] In an embodiment of the ejection system, the initial predetermined rearward motion of the actuator rod is accompanied by a combined longitudinal motion and rotation of the bolt, with the combined longitudinal and rotation of the bolt being generated by a transverse pin on the bolt engaging with a curved slot formed in the bolt carrier. The initial predetermined rearward motion of the actuator rod is generated by the cam pin traveling in an initial straight longitudinal section of the cam slot.

[009] Preferably, the bolt carrier is driven by a piston subassembly. The piston subassembly and the ejection chute are located on opposite sides of the bolt carrier.

[0010] Preferably, a torsion spring is disposed around the actuator rod to rotational ly return the L-shaped deflector to the home position from an actuated position. A dog clutch limiter may be used to rotationally define or adjust the home and actuated positions of the reshaped deflector.

[0011] Preferably, a tension spring is located adjacent to the longitudinal opening of the ejection chute such that the contact force on the casing is operable to deflect the tension spring as the casing enters the ejection chute and the tension spring then retains the casing inside the ejection chute.

[0012] Preferably, a latch cam pin latch is provided along a side of the bolt to obstruct a central bore cavity. The latch cam pin is spring-loaded and the central bore cavity is normally obstructed until a cam pin (234) is inserted into the bolt. The normally obstructed central bore cavity ensures that the firing pin is blocked during assembling of the bolt assembly and the casing ejection system.

Brief Description of the Drawings [0013] This invention will be described by way of non-limiting embodiments of the present invention, with reference to the accompanying drawings, in which:

[0014] FIG. 1A illustrates a top, left and rear perspective view of a firearm incorporating a bolt carrier and a casing ejection system according to an embodiment of the present invention; FIG. IB illustrates a right hand view of the firearm shown in FIG. 1A; FIG. 1 C illustrates a left hand side of the firearm shown in FIG. 1A without the hand guard, upper receiver and magazine;

[0015] FIG. 2A illustrates a gas-driven bolt carrier assembly and the easing ejection system, with a bolt and a deflector of the casing ejection system in their home positions, whilst FIG. 2B illustrates the bolt carrier and casing ejection mechanisms. FIG. 2C illustrates the bolt in a locked position during use; FIG. 2D illustrates the deflector being actuated and the casing being pushed into an ejector chute; and FIG. 2E illustrates a plan view of the firearm with a spent casing being ejected at the ejection port; and

[0016] FIG. 3 A illustrates the bolt assembly, whilst FIG. 3B shows exploded parts o the bolt assembly.

Detailed Description

[0017] One or more specific and alternative embodiments of the present invention will now be described with reference to the attached drawings. It shall be apparent to one skilled in the art, however, that this invention may be practised without such specific details. Some of the details may not be described at length so as not to obscure the invention. For ease of reference, common reference numerals or series of numerals will be used throughout the figures when referrin to the same or similar features common to the figures.

[0018] FIG. 1 A shows a bullpup firearm that incorporates a gas-driven bolt carrier assembly 100 and a casing ejection system 300 according to the present invention. As shown, the firearm has a barrel 1, a hand guard 2, an upper receiver 3, a lower receiver 4, a magazine 5 and a stock 6. FIG. IB is a right hand view and shows an ejection port 600 from which spent casings 12 are ejected from the firearm. The ejection port 600 is forward with respect to the trigger of the firearm; the ejection port 600 is also shown in FIG. 2E. FIG. 1C shows a left hand view of the firearm and parts of the bolt carrier assembly 100 and casing ejection system 300.

[0019] FIG. 2 A shows a top and front closed-up view of the bolt carrier assembly 100 and the casing ejection system 300. FIG. 2B shows assemblies of the bolt carrier and casing ejection system when separated from the firearm. FIG. 2C shows a plan view of the bolt earner assembly 100 and casing ejection system 300 with an L-shaped deflector 350 in the bolt carrier's locked position, whilst FIG. 2D shows the L-shaped deflector 350 in its actuated position. The bolt carrier assembly 100 and casing ejection system 300 are generally made of high- strength alloy steel. As shown in FIGs. 2A-2D, the gas-driven bolt carrier assembly 1 0 includes a gas-piston subassembly 50 that is connected to a bolt 230 and a bolt carrier 200.

[0020] In FIG. 2 A, the bolt 230 is partially visible. The bolt 230 is more clearly shown in FIGs. 3A-3B. The bolt 230 is elongate and is disposed to both translate and rotate in a longitudinal bore 220 in the bolt carrier 200. The bore 220 has a longitudinal axis 221 (more clearly shown in FIG. 2C) that is co-axial with a longitudinal axis of the barrel 1. The rear end of the bore 220 houses a firing pin 235.

[0021] As seen from FIGs. 3A-3B, the front end of the bolt 230 has an extractor 34 and a plurality of lugs 36. The lugs 36 are shaped and dimensioned to rotationally cooperate with slots or grooves (not shown in the figures) at the rear of the barrel 1, so that a front face 230a of the bolt 230 is in contact with the rear of the casing or cartridge 12. The extractor 34 is elongate and is pivoted about an axis transverse (about pin 40) to the longitudinal axis 221 of the bolt 230 so that a proximal c law-like tooth 35 is operated to latch onto a rim of the casing or cartridge 12. The extractor 34 is biased by a spring 41 so that the claw-like tooth 35 is normally in the latched position. Preferably, a rubber insert 42 is provided inside the spring 41 to keep the spring in position. Preferably, the extractor 34 is at a 12 o'clock position. The extractor's 34 position is not so restricted and the claw-like tooth 35 can be in another position at the front face 230a of the bolt 230. [0022] At a distal end of the bolt 230 is a cam pin 234. The cam pin 234 extends transverse to the longitudinal axis 221 of the bolt 230 and is arranged to slide along a curved slot 224 formed along part of the cylindrical bore 220. After a cartridge 12 is fired, high-pressured gas in the cartridge chamber is tapped out to drive the piston subassembly 50; the high- pressured gas then pushes both the bolt 230 and bolt earner 200 rearward. The twisting motion of the cam pin 234 along the curved slot 224 causes the bolt 230 to rotate and the lugs 36 to unlock from the slots at the rear of the barrel 1; after moving an initial or first predetermined rearward motion, the L-shaped deflector 350 becomes aligned in front of the front face 230a of the bolt 230 just clear from the extractor 34 and lugs 36. Further rearward motions of the bolt 230 and bolt carrier 200 are accompanied by a rearward motion of an actuator rod 305 that drives the L-shaped deflector 350. The actuator rod 305 is disposed above and substantially parallel to the bolt 230; the centerline of the actuator rod 305 is indicated by numeral 306. A distal end of the actuator rod 305 has a transverse cam pin 310 that cooperates with a cylindrical sleeve 320. The cam pin 310 is constrained to slide in a cam slot 324 formed along a longitudinal axis the cylindrical sleeve 320, thereby causing the actuator rod 305 to rotate anticlockwise (as seen from the rear in FIG. 2A) through an angle of substantially 110 degree. The cam slot 324 has an initial slot 324a that is straight and parallel to the cylindrical sleeve's longitudinal axis, with a length of the initial slot 324a corresponding to the initial or first predetermined rearward motion of the bolt 230. When a casing 12 is held onto the front face 230a of the bolt by the extractor 34, rotation of the actuator rod 305 (subsequent to the initial predetermined rearward motion) causes the L-shaped deflector 350 to strike a lateral side of the casing 12 and to push the casing to the right hand side to enter an ejector chute 500. The side of the ejector chute 500 adjacent the L-shaped deflector and bolt carrier has a longitudinal opening 502 for the casing to enter therethrough. As seen in FIGs. 2A-2C. the actuator rod 305 is disposed above and parallel to the bolt 230, so that a contact area or contact line 352 along a contact face f the I .-shaped deflector 350 with the casing 12 is substantially at a radius R of swing about the actuator rod's axis 306. Preferably, the contact area 352 at the L-shaped deflector 350 is profiled, so that a contact force is in a direction to push the casing through the longitudinal opening 502 and into the ejection chute 500. Also as seen in FIGs. 2C and 2D, a torsion spring 360 returns the L-shaped deflector 350 to its angular home position after the piston subassembly 50 springs back, and the actuator rod 305 and bolt 230 return to their locked positions. An ejector 370 extends from the bolt carrier 200 into the ejector chute 500 through the longitudinal opening 502; the forward return movement of the bolt carrier 200 causes the ejector 370 to push the casing 12 forward along the ejector chute 500. The casing 12 is finally driven out through an ejection port 600 disposed at the right hand side of the firearm, as seen in FIG. 2E.

[0023] After a casing 12 is ejected, the cam pin 310 is moved back along the initial longitudinal portion 324a of the cam slot 324, and the bolt 230 is then returned to its home position so that the front bolt face 230a comes into contact with the rear of the next casing 12. This cycle of motions of the piston subassembly 50. bolt carrier 200. bolt 230, reshaped deflector 350 and actuator rod 305 allow spent casings 12 to be extracted automatically from the barrel chamber and be ejected through the ejection port 600.

[0024] A convention approach in solving the right-handed and left-handed shooter issue is to make the conventional casing ejection mechanism laterally reversible. However, in the present invention, the casings 12 are ejected a safe distance forward with respect to the trigger or the barrel 1, through the forward ejection port 600 in the hand guard 2; the hot spent casings 12 are thus ejected safely away from the shooter and therefore there is no need to make the casing ejection system 300 of the present invention laterally reversible.

[0025] Also as seen in FIG. 2A, the bolt carrier 200, at which the actuator rod 305 is journal ed in, has a forward end that has dog clutch limiter 380. The dog clutch limiter 380 is made up of an angular recess 381 at a forward end face of the bolt carrier and a cogged collar 382. The angular recess 381 allows substantially 110 degree of rotation of the cogged collar 382. The cogged collar 382 is angularly fixed onto the actuator rod 305, for example, with a set screw. The dog clutch limiter 380 thus allows the actuator rod 305 to be assembled into the bolt carrier 200 and allows the angular position of the T-shaped deflector 350 to adjust with respect to the actuator rod 305 during assembly. The torsion spring 360 acting on the actuator rod 305 keeps the two components of the dog clutch limiter 380 always in contact with each other. [0026] Preferably, a tension spring 364 is disposed adjacent to the longitudinal opening 502. In use, when the L-shaped deflector 350 sweeps a casing 12 into the ejection chute 500, the force on the casing deflects the body of the tension spring 364 as the casing is moved into the ejection chute 500; once a casing is pushed over the body of the tension spring 364, the tension spring 364 ensures that the casing 12 remains inside the ejection chute 500.

[0027] In the above description, the piston subassembly 50 is located to the left hand side of the bolt carrier assembly 100 as seen in FIG. 2A, whilst the ejection chute 500 is located to the right hand side. The principle of the present invention remains true even if the piston subassembly is located to the right hand side of the bolt carrier assembly and the ejection chute is located to the left hand side; thus, there is no further need to describe this alternate arrangement of the bolt carrier assembly and ejection chute.

[0028] Referring back to FIGs. 3A-3B, the bolt assembly is also configured with a latch cam pin 250. which is elongate and has a distal end and a proximal end; a distal (rear) end terminates with a claw 254, to prevent accidental inserting of the firing pin 235 without assembling the latch cam pin 250 during assembling of the bolt assembly and casing ejection system. When installed in the recess 252. the latch cam pin 250 is held in place by a pivot pin 257 with a compression spring 258 exerting a bias force on the proximal end. so that the claw 254 obstructs a central bore that receives the firing pin 235 in the bolt. When the bolt 230 is assembled correctly, the proximal end is depressed by the bolt carrier and the claw 254 becomes tilted out and the central bore becomes un-obstructed. During the process of assembling or dismantling (for example, for cleaning of the firearm) and when the bolt 230 is not received in the bolt carrier, the central bore is obstructed by the claw 254. thereby preventing the firing pin 235 from extending inside the bolt 230. In this way, the latch cam pin 250 provides a safety feature to prevent incomplete assembly of the bolt 230; in the same way, this prevents accidental firing of a cartridge without proper assembling of latch cam pin 250.

[0029] While specific embodiments have been described and illustrated, it is understood that many changes, modifications, variations and combinations thereof could be made to the present invention without departing from the scope of the invention. For example, the longitudinal axis 306 of the actuator rod 305 is described as being above the longitudinal axis 221 of the bolt 230; the longitudinal axis 306 of the actuator rod 305 can be offset laterally to the left or right hand side of the longitudinal axis 221 of the bolt 230, as long as the radial swing R of the L-shaped deflector 350 is relative to the position of the longitudinal opening 502 at the ejection chute and the angle of rotation of the actuator rod 305.

Claims

CLAIMS:

1. A casing ejection system for a firearm employing a bolt carrier assembly, the system comprising:

an elongate bolt disposed to move along and rotate about a longitudinal axis in a bolt carrier, with a front face of the bolt having an extractor for holding a casing thereon; an elongate actuator rod disposed substantially parallel to the longitudinal axis of the bolt and bolt carrier, with a front end of the actuator rod having a L-shaped deflector, and a rear end having a cam pin and an engaging cam slot in a sleeve disposed around the rear end, wherein the L-shaped deflector is at a home position that is forward and clear from the front face of the bolt;

an ejection chute that is parallel to the actuator rod and having a longitudinal opening for receiving a casing held by the extractor at the front face; and

an ejector extends from the bolt carrier into the ejection chute near a rear end of the longitudinal opening and is movable to a front end of the longitudinal opening according to a longitudinal stroke of the cam pin in the cam slot;

wherein, after an initial predetermined rearward motion, further rearward motion of the cam pin in the engaging cam slot causes the actuator rod to rotate and to strike the casin laterally into the ejection chute, therethrough the longitudinal opening, so that the casing in the ejection chute is pushed forward by the ejector to eject a safe distance forward and to one side of the firearm.

2. The casing ejection system according to claim 1 , wherein the initial predetermined rearward motion of the actuator rod is accompanied by a combined longitudinal motion and rotation of the bolt, with the combined longitudinal and rotation of the bolt being generated by a transverse pin on the bolt engaging with a curved slot formed in the bolt carrier.

3. The casing ejection system according to claim 2, wherein the initial predetermined rearward motion of the actuator rod is generated by the cam pin traveling in an initial straight longitudinal section of the cam slot.

4. The casing ejection system according to any one of claims 1 -3, further comprising a piston subassembly to drive the bolt carrier rearward, and a recoil spring in the piston subassembly drives the bolt carrier forward.

5. The casing ejection system according to claim 4, wherein the piston subassembly and the ejection chute are located on opposite sides of the bolt carrier.

6. The casing ejection system according to any one of claims 1-5, further comprising a torsion spring disposed around the actuator rod to rotationally return the L-shaped deflector to the home position from an actuated position.

7. The casing ejection system according to claim 6, further comprising a dog clutch limiter to rotationally define the home and actuated positions of the L-shaped deflector.

8. The casing ejection system according to any one of claims 1-7, wherein a radial swing R of the L-shaped deflector is relative to a distance of the actuator rod longitudinal axis from the bolt longitudinal axis.

9. The casing ejection system according to any one of claims 1 -8. wherein a contact face of the L-shaped deflector is profiled so that a contact force with the casing directs the casing into the ejection chute.

10. The casing ejection system according to any one of claims 7-9. wherein the torsion spring ensures two components of the dog clutch limiter are always in contact with each other.

11. The casing ejection system according to any one of claims 1-10, further comprises a tension spring disposed adjacent and substantially parallel to the longitudinal opening of the ejection chute such that the contact force on a casing is operable to deflect the tension spring as the casing is deflected into the ejection chute, and the tension spring then retains the casing inside the ejection chute.

12. The casing ejection system according to any one of claims 1-11 , wherein the bolt comprises a latch cam pin pivotedly connected thereto and a compression spring biases a proximal end of the latch cam pin so that a distal jaw end of the latch cam pin obstructs a central bore inside the bolt and prevents accidental assembling of a firing pin inside the central bore.

13. A firearm configured with a casing ejection system as defined by claims 1-1 1.

14. A firearm configured with a latch cam pin on a bolt to obstruct a central bore inside the bolt, so as to prevent accidental incomplete assembly of the bolt into a bolt carrier.

15. A bolt carrier assembly of a firearm comprising a latch pin pivotedly disposed on a body of a bolt to obstruct a central bore inside the bolt to prevent accidental movement of a firing pin until the latch cam pin is received in the bolt earner.