WO2008099352A1

WO2008099352A1 - Recoil advance mechanism for a multi-shot projectile launcher

Info

Publication number: WO2008099352A1
Application number: PCT/IB2008/050520
Authority: WO
Inventors: Hendrik Nicolaas Pieterse
Original assignee: Rippel Effect Weapon Systems (Proprietary) Limited
Priority date: 2007-02-14
Filing date: 2008-02-13
Publication date: 2008-08-21

Abstract

The invention concerns an advance mechanism for a multi-shot projectile launcher, typically a 40mm grenade launcher. The mechanism has an advancing means for advancing rounds which are to be fired sequentially into a firing position for firing, and a locking means (42, 54) for locking the advancing means when each shot is at the firing position. In addition, an unlocking means (20) is provided which is operated by the recoil of the launcher when a round is fired to release the locking means (42, 54) and thereby allow the advancing means to advance the next successive round to the firing position. This avoids the problem with conventional systems that a portion of the gas pressure generated by firing the round is used to drive the advance mechanism and is then not available to propel the round.

Description

"RECOIL ADVANCE MECHANISM FOR A MULTI-SHOT PROJECTILE

LAUNCHER"

BACKGROUND TO THE INVENTION

THIS invention relates to a recoil advance mechanism for a multi-shot projectile launcher. In one application, the invention relates to a recoil advance mechanism for a multi-shot grenade launcher, typically a 40mm grenade launcher.

A conventional 40mm grenade launcher has a revolving cylinder with multiple chambers for accommodating rounds which are to be fired sequentially. An advancing spring is arranged to rotate the cylinder about its axis in order to bring the rounds sequentially into alignment with the firing pin of the weapon for firing. A detent arrangement is provided to hold the cylinder in each sequential position of alignment. When the round is fired, gas pressure generated by ignition of the propellant charge is utilised to release the detent, allowing the advancing spring to advance the cylinder incrementally to align the next round with the firing pin, ready for firing.

A disadvantage of the conventional arrangement as described above is the fact that the use of gas pressure to initiate the advance of the cylinder reduces the gas pressure available for propulsion of the projectile, and accordingly reduces the muzzle velocity of the projectile and the range which can be achieved. SUMMARY OF THE INVENTION

According to the present invention there is provided an advance mechanism for a multi-shot projectile launcher, the mechanism comprising advancing means for advancing rounds which are to be fired sequentially into a firing position for firing, locking means for locking the advancing means when each shot is at the firing position and unlocking means which is operated by the recoil of the launcher when a round is fired to release the locking means and thereby allow the advancing means to advance the next successive round to the firing position.

The projectile launcher is of the type having a cylinder with angularly spaced chambers for holding respective rounds, the advancing means of the advance mechanism comprising an advancing spring for applying a constant rotational force to the cyiinder.

The preferred mechanism comprises angularly spaced detents on the cylinder, the locking means comprising a pawf arranged to engage successive detents on the cylinder when respective rounds are in the firing position. The unlocking means may then comprise a plunger arranged to move forwardly relative to the launcher when the launcher recoils rearwardly on the firing of a round and, during such relative forward movement, to act on the pawl and cause it to release a respective detent, thereby allowing the advancing spring to rotate the cylinder incrementally to a new rotary position in which the pawl engages the next successive cylinder detent with the next successive round in the firing position.

There may be a pawl return spring to urge the pawl into a locking position in which it engages the successive detents. In the preferred arrangement one end of the pawl has a hook formation to engage the detents, the pawl return spring acts on an opposite end of the spring and the pawl is arranged to pivot about an axis between the respective ends. The plunger may have a trailing end and the pawl may include an inclined cam surface, between the respective ends of the pawl, on which the trailing end of the plunger acts thereby to pivot the pawl about the axis and disengage the hook formation from a detent. The mechanism may include a plunger return spring for returning the plunger to a rest position after the plunger has moved forwardly relative to the launcher when the launcher recoils on the firing of a round.

Typically the detents are in the form of index pins projecting from the cylinder, each index pin being associated with a chamber in the cylinder in which a round is held.

The plunger is preferably slidable axially relative to the launcher on an axiaϋy extending bar carrying a plate, the bar being mounted in use to the launcher and the plunger return spring acting between the plate and the plunger.

The invention extends to a multi-shot projectile launcher fitted with an advance mechanism according to any one of the preceding claims. The projectile launcher is typically a grenade launcher and is most preferably a 40mm grenade launcher.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a front view of an advance mechanism according to the present invention, in a position ready for the firing of a round; -A-

Figure 2 shows a top perspective view of the mechanism seen in Figure 1 ;

Figure 3 bottom perspective view of the mechanism seen in Figure 1 ;

Figure 4 shows a different top perspective view of the mechanism seen in Figure 1 ;

Figure 5 shows a different bottom perspective view of the mechanism seen in Figure 1 ;

Figure 6 shows a side view of the mechanism seen in Figure 1 ;

Figures 7 to 12 show views corresponding to those of Figures 1 to 6 and illustrating the same mechanism shortly after the firing of a round;

Figures 13 to 18 show views corresponding to those of Figures 1 to 6 and illustrating the same mechanism after full depression of the advance lever by the plunger;

Figures 19 to 24 show views corresponding to those of Figures 1 to 6 and illustrating the same mechanism after advance of the cylinder;

Figure 25 shows a perspective view of the advance lever of the mechanism; and

Figure 26 shows a perspective view of the plunger of the mechanism. DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

The accompanying drawings illustrate a recoil advance mechanism for a 40mm grenade launcher. Referring initially to Figures 1 to 6, the grenade launcher has a cylinder 10 formed with angularly spaced chambers 12 for 40mm grenades which are to be fired in a forward direction indicated by the arrow 14 in Figures 2 and 4. The cylinder has six such chambers, only the upper ones of which are visible in Figures 1 to 6. An advancing means in the form of a spring (not shown) acts constantly on the cylinder to drive it in rotation in the direction of the arrow 16 {Figure 1) about the cylinder axis 18 (Figure 5).

The numeral 20 indicates an unlocking means in the form of a plunger. A plunger return spring 22 acts between the plunger and a plate 24. The plate is attached integrally to a rearwardly extending bar 26 on which the plunger can slide. The plate and bar are fixed to the grenade launcher with the spring 22 urging the plunger rearwardly towards a rest position. As seen in Figures 6 and 26 the plunger has a tail portion 28 carrying a downward projection 30 having an inclined lower surface 32.

Referring also to Figure 25, the numeral 34 indicates a pawl in the form of an advance lever which is pivoted, on a pin 38, between side plates 40 fixed to the grenade launcher. The advance lever 34 has a hook formation 42 at one end, an upward projection presenting an inclined cam surface 44 and a tail 46 to which a pawl return spring 48 is connected. The spring 48 has two coils, one of which is located on a pin 50 extending between the side plates 40. The action of the spring 48 is to bias the advance lever 34 about the axis of the pin 38 in the direction indicated by the arrow 52 in Figure 25.

The advance lever carries laterally extending pins 51 which ride in arcuate slots 53 in the plates 40, the slots defining the limits of pivotal movement of the advance lever about the axis of the pin 38. The cylinder 10 carries a series of detents in the form of rearwardly extending index pins 54, one being provided adjacent the forward end of each chamber 12. The hook formation 42 of the advance lever 34 is axially aligned with the pins 54, Figures 1 to 6 illustrate the advance mechanism of the invention when a round (not illustrated, but in this example a 40mm grenade), is in a firing position in the uppermost chamber 12.1. In this position of the round, a percussion cap at the rear of the round is aligned with the firing pin 55 of the grenade launcher. The cylinder is locked in this position, against the constant action of the advancing spring, by engagement of the hook formation 42 with the index pin indicated by the numeral 54.1 in Figure 1.

When the round is fired, the grenade launcher recoils rearwardly in the normal way. As a result of its inertia the plunger tends to remain stationary, i.e. to move forwardly relative to the rearwardly moving launcher, thereby compressing the plunger return spring 22. As the advance lever 34 moves to the rear relative to the plunger, the surface 32 of the plunger engages the cam surface 44 of the advance lever, thereby applying a downward force to the plunger to cause it to rotate clockwise, as viewed in Figure 25, about the axis of the pin 38, against the action of the pawl return spring 48.

Figures 7 to 12 illustrate the mechanism when the plunger has undergone approximately half of its relative forward movement relative to the remainder of the grenade launcher, and is stilt pressing down on the advance lever. As shown, the hook formation 42 at the end of the advance lever has at this stage moved upwardly relative to the index pin 54.1.

Figures 13 to 18 illustrate the mechanism after the hook formation has completely released the index pin 54.1 , allowing the advancing spring to drive the cylinder rotationally in the direction of the arrow 16.

As the recoil force on the grenade launcher diminishes, the plunger return spring 22 pushes the plunger 20 back towards its original rest position. The surfaces 32 and 44 disengage from one another, allowing the pawl return spring 48 to rotate the advance lever in an anticlockwise direction as viewed in Figure 1, thereby lowering the hook formation 42 into the path of the next succeeding index pin 54.2, as shown in Figures 19 to 24. The advancing spring of the cylinder continues to drive the cylinder in rotation, such that the index pin 54.2 is engaged by the hook formation which then prevents further cylinder rotation. The round in the next chamber 12.2 is therefore brought into the firing position ready to be fired, and the process described above repeats itself when firing actually takes place.

An important advantage of the mechanism described above is the fact that the cylinder is freed for indexed rotation by the natural recoil of the weapon rather than by gas pressure generated in the weapon by the firing of a round. The gas pressure can accordingly be dedicated to the propulsion of the grenade projectile. It is perceived that this will contribute to the attainment of a higher muzzle velocity and an increased range of the projectile.

Although specific mention has been made of the application of the mechanism described above to a grenade launcher, it should be recognised that the invention is not limited to this application and that the described mechanism could be used with other types of multi-shot projectile launching weapons where the recoil energy of the weapon could be used to trigger the advance of rounds for sequential firing.

Claims

1.

An advance mechanism for a multi-shot projectile launcher, the mechanism comprising advancing means for advancing rounds which are to be fired sequentially into a firing position for firing, locking means for locking the advancing means when each shot is at the firing position and unlocking means which is operated by the recoil of the launcher when a round is fired to release the locking means and thereby allow the advancing means to advance the next successive round to the firing position.

2.

A mechanism according to claim 1 wherein the projectile launcher has a cylinder with angularly spaced chambers for holding respective rounds and wherein the advancing means of the advance mechanism comprises an advancing spring for applying a constant rotational force to the cylinder.

3.

A mechanism according to claim 2 and comprising angularly spaced detents on the cylinder, the locking means comprising a pawl arranged to engage successive detents on the cylinder when respective rounds are in the firing position.

4.

A mechanism according to claim 3 wherein the unlocking means comprises a plunger arranged to move forwardly relative to the launcher when the launcher recoils rearwardly on the firing of a round and, during such relative forward movement, to act on the pawl and cause it to release a respective detent, thereby allowing the advancing spring to rotate the cylinder incrementally to a new rotary position in which the pawl engages the next successive cylinder detent with the next successive round in the firing position.

5.

A mechanism according to claim 4 and comprising a pawl return spring to urge the pawf into a locking position in which it engages the successive detents.

6.

A mechanism according to claim 5 wherein one end of the pawl has a hook formation to engage the detents, the pawl return spring acts on an opposite end of the spring and the pawl is arranged to pivot about an axis between the respective ends.

7,

A mechanism according to claim 6 wherein the plunger has a trailing end and the pawl includes an inclined cam surface, between the respective ends of the pawl, on which the trailing end of the pfunger acts thereby to pivot the pawi about the axis and disengage the hook formation from a detent.

8.

A mechanism according to any one of claims 4 to 7 wherein the detents are in the form of index pins projecting from the cylinder, each index pin being associated with a chamber in the cylinder in which a round is held.

9.

A mechanism according to any one of claims 4 to 8 and comprising a plunger return spring for returning the plunger to a rest position after the plunger has moved forwardly relative to the launcher when the launcher recoils on the firing of a round.

10.

A mechanism according to claim 9 wherein the plunger is slidable axially relative to the launcher on an axially extending bar carrying a piate, the bar being mounted in use to the launcher and the plunger return spring acting between the plate and the piunger.

11.

An advance mechanism substantially as herein described with reference to the accompanying drawings.

12.

A multi-shot projectile launcher fitted with an advance mechanism according to any one of the preceding claims.

13.

A multi-shot grenade launcher fitted with an advance mechanism according to any one of claims 1 to 1 1.

14.

A multi-shot 40mm grenade launcher fitted with an advance mechanism according to any one of claims 1 to 1 1.