GB2172970A - A pyrotechnic chain for priming an exploding charge - Google Patents

Abstract

A pyrotechnic chain for priming an exploding charge, in particular for anti-tank mines, affords safety even with a detonator inserted. The detonator 8 is mounted on a pin 9 so as to be pivotable by the action of a lever 10 between an activation position, in which the detonator is disposed between a striker 5 and a charge 3 and a blocking lug 7 is disengaged from the firing device 4, and a deactivation position in which the detonator faces a protected chamber (12). Shaped teeth 17 held in engagement by a compression spring 18 facilitate movement to the activation position. An ejection spring 19 acting against a dog stop (20) removes the lever 10 at the end of its travel. <IMAGE>

Description

SPECIFICATION A pyrotechnic chain for priming an exploding charge This invention relates to a pyrotechnic chain for priming an exploding charge, in particular for anti-tank mines.

As is known, there are available several devices of the exploding type which comprise on their interior a striker, a detonator engageable by percussion with the striker, and a charge to be primed by firing the detonator. Among these devices are also anti-tand mines.

Of substantial interest with these devices are safety features effective to prevent incidental blasting before the devices are placed in their operational setting for activation in the desired manner. These safety requirements are currently met by making said detonator removable from the device and taking the detonator out each time that the device is to be deactivated, such as during storage or the like.

This situation poses a number of practical problems. In fact, the detonator must be stored separately from the device with the main charge, and the two re-united on their removal from depots. Furthermore, activating such devices is a time-consuming operation because the detonators must be assembled accurately and carefully.

It should be also considered that even after said devices have been assembled as indicated, safe conditions must still be ensured if incidental blasting is to be prevented while moving around or handling the devices. From this standpoint, danger is involved not only by incidental projection of the striker onto the detonator, but also by the mere presence of the detonator in the vicinity of the main charge; incidental causes may result in the detonator blasting without any percussion and priming the main explosive.

In this situation, it is the general object of this invention to provide a pyrotechnic chain for priming an exploding charge being so structured as to afford a position of real safety even with a detonator inserted therein.

This object is substantially achieved by a pyrotechnic chain comprising a striker, a detonator to be fired by said striker, and an exploding charge to be primed by the blasting of siad detonator, characterised in that said detonator is mounted on an arm jutting out of a pin set pivotable about its axis on command from an oscillable lever, and in that said lever, pin, and arm are pivotable between an activation position at which said detonator is disposed along the line of action of said striker and faces said charge, and a deactivation position at which said detonator faces a protected chamber isolated from said charge.

Further features will become apparent from the following detailed description of a preferred embodiment of a pyrotechnic chain according to the invention, illustrated in the accompanying drawings, where: Figure 1 shows in section and in elevation the pyrotechnic chain according to the invention complete with a striker; Figure 2 shows a detail of Fig. 1; Figure 3 shows diagrammatically a fragmentary plan view of some elements of the pyrotechnic chain of Fig. 1 in their activated positions; Figure 4 is similar to Fig. 3 and shows the same pyrotechnic chain in the deactivated position; and Figure 5 brings out, in an enlarged section, a portion of Fig. 1.

With reference to the cited drawing figures, a pyrotechnic chain according to this invention is comprehensively designated 1 in Fig. 1, and is inserted in a device 2 containing an exploding charge 3. The device 2 may be, as in the instance illustrated, an anti-tank-aimed mine produced by this same Applicant and identified as Model SP-81. The device 2 comprises, in a manner known per se, a firing device 4 connected to a striker 5. According to the invention, the firing device 4 is formed with a groove 6 wherein a blocking lug 7 may be fitted which is part of the pyrotechnic chain 1, as explained herein below.

Also in manner know per se, the pyrotechnic chain 1 comprises, in addition to said striker 5, a detonator 8 to be fired by the striker 5 and one said charge 3 to be primed by the detonator when this confronts the charge 3.

According to the invention, the detonator 8 is mounted offcentered cantilever-like to a rotatable pin 9 about its own axis and extending parallel to the line of action of the striker 5.

The pin 9 is operated from a manually operable lever 10 located exteriorly of the device 2.

The detonator 8 is supported on the pin 9 through a perpendicular arm 11 of the pin 9 overlapping a portion of the charge 3.

The lever 10 and the arm 11 can swing angularly, together with the pin 9, from an activated position (Fig. 3) where the detonator is disposed along the line of action of the striker 5 and faces the charge 3 to be primed, to a deactivated position (Fig. 4) where the detonator 8 faces a protected chamber 12 (Figs. 3 and 4) isolated from the charge 3 to be primed. The protected chamber 12 is contiguous to the charge 3 and can also be overiapped by the detonator 8. The wall between the charge 3 and the protected chamber 12 is indicated at 13.

Fig. 1 brings out how the pin 9 is positioned by a block 14 serving as a support movingly engageable and a casing 15 of the device 2 by means of a ring nut 16. That portion of the block 14 which confronts the arm 11 is cutout to present teeth 17 (Fig. 2) so directed as to permit easy rotation of the arm 11 from the deactivated position of Fig. 4 to the activated position of Fig. 3, and to prevent rotation in the opposite direction, where the same is not expressedly commanded, as explained further herein. The arm 11 is held in an engaged position with the teeth 17 by a compression spring 18 clamped between the pin 9 and an expansion 14a on the block 14. It is also advantageously envisaged that the pin 9 can be raised partway against the compression spring 18 by acting through the lever 10.

Fig. 5 shows, in combination with Fig. 1, that the lever 10 engages with the pin 9 and that the lever is removable from the device 2.

In fact, between the lever 10 and the block 14 there is an ejection spring 19 which acts against a dog stop 20. The latter projects radially out of a bush 21 encircling the bottom end of the pin 9 and being movable in a groove 22 formed in the block 14. At one end of the groove 22 there is provided a passageway 23 for the dog 20. The passageway 23 is engaged by the dog stop 20 with the lever 10 in the activated position brought out in Figs. 1 and 3.

The arm 11 has, on the opposite end to its face engaged with the teeth 17, the cited blocking lug 7 which, with the detonator 8 aligned to the striker 5, fits into the groove 6 so as to allow the striker to move. By contrast, with the detonator 8 overlying the protected chamber 12, the lug 7 engages with the firing device 4 inhibiting its movement.

The pyrotechnic chain of this invention operates as follows. In the deactivated condition, the device 2 has the pyrotechnic chain 1 out of alignment, that is with the detonator 8 shifted from the axis of the striker 5 and the charge 3 (Fig. 4), and the blocking lug 7 fits into the firing device 4 to block it. In this situation, even incidental blasting of the detonator8could not prime the charge 3 because the detonator is above the protected chamber 12. To activate the device 2, the lever 10 should be pivoted around the axis of the pin 9. With this pivotal movement, the detonator 8 is brought to align itself to the striker 5 and the charge 3, and the blocking lug 7 is disengaged from the firing device 4.

The teeth 17 make this activation a stable irreversible one, thanks also to the action of the compression spring 18.

At one end of its travel, the lever 10 is ejected by the ejection spring 19.

The whole block 14, in its safe position, can be taken out by threading the ring nut 16 out.

The device 2 can be deactivated even after it has been already put in operation. In fact, one can again place the detonator 8 out of alignment using the lever 10. To this aim, the lever 10 should be re-inserted in its housing, pushed against the pin 9 so as to compress the compression spring 10 and disengage the teeth 17, and then turned in the opposite direction to the former activation direction. This deactivation can only be performed, of course, if the instance of anti-tank track-aimed mines, if these lack an anti-removal device.

Thus the invention achieves its object.

It should be pointed out that any device incorporating the pyrotechnic chain of this invention can be stored ready for use with the detonator mounted directly, since the same is out of alignment to the explosive and the striker. This situation is highly safe because even in the event of incidental detonator blasting the main explosive would not be primed, thanks to the cited protected chamber.

Claims (7)

1. A pyrotechnic chain for priming an exploding charge, comprising a striker, a detonator to be fired by said striker, and an exoloding charge to be primed by the blasting of said detonator, characterised in that said detonator is mounted to an arm jutting out of a pin pivotable about its axis on command from an oscillable lever, and in that said lever, pin, and arm are pivotable between an activation position at which said detonator is disposed along the line of action of said striker and faces said charge, and a deactivation position at which said detonator faces a protected chamber isolated from said charge.

2. A pyrotechnic chain according to claim 1, characterised in that said pin lies parallel to the line of action of said striker and engages with said detonator through one said arm sustantially parallel to said lever, and in that said protected chamber adjoins said charge, said protected chamber being substantially defined by an area free of said charge and bound by a wall.

3. A pyrotechnic chain according to claim 2, characterised in that said pin is surrounded by a fixed block, and in that between said arm and said block there are formed shaped teeth for enabling rotations in one direction only of said arm and pin with the teeth meshing together.

4. A pyrotechnic chain according to claim 3, characterised in that said teeth are held in mutual mesh relationship by a compression spring acting on said pin and being squeezable on direct command from said lever.

5. A pyrotechnic chain according to any preceding claim, characterised in that said lever may be taken out on impulse from an ejection spring, the lever being engaged with a block surrounding said pin through a dog stop movable in a groove shaped after an arc of a circle and having a passageway at its end for said dog stop.

6. A pyrotechnic chain according to any preceding claim, characterised in that from said pin there extends in an offcentre position a blocking lug from said striker, said blocking lug fitting in a groove with said detonator aligned to said striker.

7. A pyrotechnic chain for priming an explosive charge, substantially as herein described with reference to the accompanying drawings.