GB2072809A - Bottom fuse particularly for a gun grenade - Google Patents

Abstract

The fuse provides safety against striking objects before the effluxion of the predetermined arming period and comprises a fixed striker 17, a slidable detonator 14, a locking ball 28 and two inertia sleeves 21, 22 separated by a spring 25. When the grenade is fired, the sleeve 21 sets back and, upon the cessation of acceleration, moves forward under the action of spring 25 to relase the ball 28 with a delay determined by the engagement in a zig-zag groove 24 of a pin 23 extending from the sleeve 21. If the grenade should strike an obstacle before the sleeve 21 has moved sufficiently far fowards to release the ball, the sleeve 21 is thrown forwards against the sleeve 21 and moves forwards with it to prevent the release of the locking ball which otherwise would occur. <IMAGE>

Description

SPECIFICATION Bottom fuse particularly for a gun grenade The present invention concerns a mechanical bottom fuse intended to equip a projectile, in particular a gun grenade.

There are such fuses which give a storing and transport security. Even often the fuse is mounted in the projectile shortly before its use or at least after its long term storage. These fuses have also a mouth security, that is, means enabling to inhibit the firing of the explosive charge if the projectile strikes an obstacle placed in the immediate proximity of the mouth of the launching device, that is on the first meters of the trajectory of the projectile.

These two securities which are present in the known fuses can however be enhanced. In fact if the projectile encounters an obstacle during the first meters of its trajectory the known fuses avoid the immediate explosion of the projectile but this projectile is however armed and later on the slightest choc can cause its explosion.

This present heavy dangers for the personnel and the aim of the present invention is to realize a bottom fuse comprising the storage and transport as well as mouth securities of the older embodiments but which on top ensures the nonarmament of the projectile if it strikes an obstacle close to the servant so that the projectile, having not exploded at the moment of the impact, thus be harmless even afterwards when he falls down so as to be easily carried away, recuperated or destroyed without calling for explosive specialists.

This bottom fuse distinguishes itself by the characteristics enumerated in claim 1.

The attached drawing shows schematically and by way of eXample a gun grenade equipped with a bottom fuse according to the invention.

Figure 1 is a cross-section of a first embodiment of the gun grenade provided with the bottom fuse.

Figure 2 shows a detail of the bottom fuse.

Figure 3 shows the baffle of the bottom fuse retarding the armament of the projectile at the firing.

Figure 4 is a longitudinal cross-section of the bottom fuse in inactive storing and transporting position.

Figure 5 is a longitudinal half cross-section showing the position of the parts of the fuse after the firing.

Figure 6 is a longitudinal half cross-section showing the position of the parts of the fuse when the projectile is on its trajectory, after the timing of the mouth security.

Figure 7 is a half longitudinal cross-section showing the position of the parts of the fuse at the impact of the projectile at the end of its normal trajectory onto the objective.

Figure 8 is a longitudinal half cross-section showing the position of the parts of the fuse after the projectile has undergone a negative acceleration during the timing of the mouth security, that is on the first meters of its trajectory.

Figure 9 is a longitudinal half cross-section showing the parts of the fuse after that the projectile having been submitted to a negative acceleration during the timing of the mouth security but before the masses have reached their maximum displacement.

Figure 10 is a longitudinal cross-section of another projectile provided with the bottom fuse.

Figure 11 is a longitudinal cross-section of a modification of the bottom fuse, in inactive storage position.

The present bottom fuse 1 is intended to equip different explosive projectiles 2 and particularly gun grenade. This fuse is said to be a bottom fuse since it is located in the projectile rearwardly of the explosive charge 3 of the projectile 2.

This bottom fuse 1 comprises a tight envelope constituted by a housing 4 which is rigid and have an important thickness located outside of the explosive charge 3 of the projectile 2. This housing is closed at its rear end by a body 5 fastened by means of a skirt 6 of said housing 4. The housing 4 is extended forwardly by a thin case 7 closed at its fore end by a slot 8 provided with a pin constituting the striker 1 7.

The body 5 comprises a central void, receiving a movable detonator, limited by a skirt 9 bearing through its front edge against a shoulder 10 of the housing 4 through the intermediary of the case which is thus rigidly fixed to the skirt 9.

The movable detonator slides within the central void of the body 5 and in the case 7 and comprises a mass 11 provided with a periphericai locking groove 12 and a thin skirt 1 3 extending forwardly containing a primary charge 1 6 and a secondary charge 14 which is fitted within a body 15.

The striker 1 7 is located in the upper part of the case 7 and may enter in contact with the primer 1 6 of the detonator, when this latter displaces itself forwardly with respect to the fuse due to inertial forces.

A spring 1 8 tends to maintain the movable equipment (detonator) within the body 5 spaced from the striker 1 7.

The skirt 9 of the body comprises at least one bore 19 located, when the movable equipment is in rear position, in front of the locking groove 1 2.

A space 20 is provided between the housing 4 and the body 4 in which are located two annular sliding masses 21, 22.

Each of these annular masses comprises a head or flange having a thickness approximately equal to the one of the space 20 to guide and center the mass in its longitudinal displacements.

Each mass 21, 22 comprises also a skirt of lower thickness, which can overlap in the space 20 and the lengths of which are such that whatever the relative positions of the masses 21, 22 these skirts are always overlapping at least partially.

Furthermore, the skirt of the front annular mass 28 has a length such that when this mass 21 is in its forward most position, its head is abutting against the housing 4, the bore 1 9 of the body 5 be liberated.

The rear annular mass 21 comprises a pin 23 located in a groove 24 provided in the cylindrical wall of the skirt 9 of the body 5. This groove 24 is shown in plan view at Figure 3 and comprises a locking branch 24a and a time-lag branch 24b presenting a certain number of baffles forming a zig-zag line slowing the forward axial displacement of the mass 21.

A spring 25 tends to separate the two annular masses 21,22 the one from the other.

Finally, the rear annular mass 22 comprises a peripherical groove housing a resilient ring 26 intended to lock this mass 22 in its foremost position in cooperation with the locking groove 27 provided in the internal wall of the housing 4.

In inactive storing and transporting position the bottom fuse is in the state shown at Figure 4. The movable detonator is in rear position, at the bottom of the central void of the body 5. This movable detonator is locked in this position by a ball 28 located in each bore 19 of the body and merging into the locking groove 12 of the mass 11. The ball 28 is maintained in this position by the skirt of the forward mass 21. The rear mass 22 is in its rear upmost position whereas the fore mass 21 is maintained in an intermediate position by its pin 23 which is located at the summit of the locking branch 24a of the groove 24.

The normal working of the fuse described is the following.

At the firing (Figure 5), that is at the launching of the projectile 2, the fuse undergoes a great acceleration and the fore mass 21 moves back with respect to the body 5 up to the moment when the pin 23 is located in the lower position 24c of the locking groove 24.

At the time where the acceleration of the firing ceases, the front mass 21 displaces forwardly under the action of the spring 25. This displacement is however braked and retarded by the zig-zag baffles of the branch 24b of the locking groove 24 which pin 23 follows.

When the mass 21 abuts against the housing (Figure 6) and that the first meters or first tens of meters of the trajectory have been fulfilled without shocks, the ball 28 is liberated by the skirt of the mass 21 and this ball liberates at its turn the mass 11 of the movable detonator. The fuse is thus armed.

At the impact (Figure 7) the movable detonator moves forward under the action of the brutal deceleration and the primer 1 6 of the detonator strikes the striker 1 7 causing the firing of the secondary charge of the detonator which is now located within the explosive charge 3 and thus causes the explosion of this latter.

At the same time, the mass 22 displaces forwardly under the action of the deceleration but this is without effect on the working of the fuse.

However, when the projectile accidentally hits an obstacle during the first meters of its trajectory, that is to say before the fore mass 21 has reached its foremost position, the mass 22, under the action of the decleration of the projectile, displaces itself forwardly against the action of the spring 25 and comes in contact with the fore mass 21 (Figure 9) and displaces jointly with it up to its forward most position (Figure 8). In these conditions the head of the rear mass 22 locks the ball 28 at the moment where the skirt of the fore mass 21 liberates said ball so that the movable detonator remains locked.

When the two masses 21 and 22 reach their foremost postion (Figure 8) the resilient ring 26 bf the mass 22 is located in front of the grooove 27 and can expand resiliently causing the final locking of the masses 21 and 22 in their forward most position and ensures therefore the definitive locking of the movable detonator in its inactive position.

In this way, the projectile is not armed and remains inactive. It is thus harmless.

Figures 9 and 10 show a variant of the bottom fuse the working of which is identical to the one described here above.

It is evident that in non-illustrated variants the detonator could be mounted within a movable equipment which would be locked as said movable detonator. This movable equipment could comprise further a pyrotechnic time-lag or any other elements.

Claims (7)

1. Bottom fuse for explosive projectile comprising, located within an envelope, a fixed striker and a movable equipment comprising a detonator, displaceable between an inactive position housed in a hollow body, separated from the striker and an active position in contact with this striker; a spring tending to space the movable equipment away from the striker and comprising further locking means of this movable equipment in its inactive position comprising a mass mounted slidingly within the hollow body and submitted to a resilient action as well as to the action of retarding means of its forward displacement under the action of the said resilient action, characterized by the fact that it comprises a second sliding mass outside of the hollow body submitted to resilient action tending to separate it from the first mass, said second mass causing the definitive locking of the movable equipment in its inactive position when the two masses are located in their foremost position.

2. Bottom fuse according to claim 1 characterized by the fact that the resilient actions acting on the masses are made by only one spring.

3. Bottom fuse according to claim 1 or 2 characterized by the fact that it comprises locking means of the second mass in its foremost position.

4. Bottom fuse according to claim 3, characterized by the fact that these locking means are constituted by a resilient ring located in a peripheric groove of the second mass intended to cooperate with a peripherical groove provided in the internal wall of a housing forming part of the envelope.

5. Fuse according to claim 4 characterized by the fact that the two masses are annular and slide within an annular space comprised between the hollow body and the housing.

6. Fuse according to one of the precedent claims characterized by the fact that the envelope is tight and that it comprises the housing and the case, the striker being fixed to one end of that case.

7. A fuse for an explosive projectile constructed and arranged substantially as hereinbefore described and shown in Figs. 1-9, 10, or 11 of the accompanying drawings.