GB2159931A

GB2159931A - Detonator safety device

Info

Publication number: GB2159931A
Application number: GB08512121A
Authority: GB
Inventors: Josef Liebhardt
Original assignee: Messerschmitt Bolkow Blohm AG
Current assignee: Airbus Defence and Space GmbH
Priority date: 1984-06-09
Filing date: 1985-05-14
Publication date: 1985-12-11
Also published as: FR2565681A1; GB8512121D0; GB2159931B; FR2565681B1; DE3421572C2; DE3421572A1

Abstract

A safety device for detonators used in small rockets includes a piston 3 carrying a stop pin 4 engaging an edge of a detonator slide 1 which contains a detonator chain element 2. The slide 1 is retained by a pin 8 which can be driven by a force element 10. To arm the detonator device, the piston 3 is driven by gas pressure against spring 6 so that pin 5 is sheared and tension is applied to the slide 1 via a draw spring 14. Pin 4 clears pin 8 to allow same to be driven clear of recess 11 by element 10 upon receipt of a detonation signal. This allows the slide 1 to move into the armed position where arm 19 cuts a bridge 18 to arm the detonator. Further safety at elevated temperature is provided by a plate 24 deformable to lock the slide and by a fusion element 23 for venting gas. <IMAGE>

Description

SPECIFICATION Safety Device for Detonators This invention relates to a safety device for the detonators of warheads in small rockets, the detonators having a spring-loaded slide housing the detonator which can move from an unarmed into an armed position, the slide being held in the unarmed position by means of spring-loaded locking elements.

Safety devices of this kind are intended to effect the arming of detonators in accordance with certain criteria automatically or to hold the detonator in the unarmed position in the event of failure in the operation.

In DE 23 5831 OA there is known a safety device for the detonators of explosive charges, the device having a slide which can be moved from an unarmed into an armed position and back again and which carries a detonator which is subject to the action of at least one spring for effecting movement.

In one advantageous embodiment the safety device has a propulsive charge within the propulsion gases are used to move the slide. This safety device acts as soon as a criterion is fulfilled, in this case a voltage surge.

An object of this invention is to provide a safety device for warheads in small rockets which only arms in the event of two mutually independent physical criteria occurring in the correct order and which, if the two criteria occur in the incorrect order, is completely unarmed after the detonation check.

According to this invention there is provided a safety device for a detonator used in warheads of small rockets, the detonator having a spring-loaded slide with a detonator positioned therein, the slide being movable from an unarmed position into an armed position, and the slide being retained in the unarmed position by means of spring-loaded locking elements, the device including:: (a) a piston axially movable in opposition to the force of a spring by gas pressure after shearing of a shear pin, the piston applying tension to a draw spring through a locking pin secured radially to the piston, (b) a locking slide connected with the draw spring and housing a detonator, the slide being held in an unarmed position both by the locking pin of the piston acting against an edge of the slide and also by a headed pin sitting partly in a transverse bore of the slide with a free end engaging a recess in a guide in which the locking slide moves, (c) the locking slide in an armed position, operating an electrical contact through an actuating element and (d) the locking pin being associated with a force applying means to move same from the recess into the transverse bore of the slide.

The safety device may have a short-circuit contact which can be made inactive and is provided with a locking device for the armed position and contains two mutually independent temperature-operated safety devices.

An embodiment by way of an example is illustrated in the accompanying drawing and described hereinafter in more detail. In the drawings: Figure 1 shows a section in simplified form through a safety device, and Figure 2 shows the device in a general view partly broken-away.

Figure 1 shows an embodiment of a safety device according to this invention for detonators used in the warheads of small rockets. The detonator housing 27, not shown in detail, contains a locking slide 1 lying in a guide 28. The detonator 2, which in Figure 1 is shown in the unarmed position, rests in a boring in the slide 1. The locking slide 1 is locked by means of two independent locking elements, one locking element is formed by the piston 3, which carries a locking bolt 4 positioned radially with respect to the piston and which, by an edge 7, blocks the slide 1. The piston 3 is secured in a position of rest by shear pin 5.

The second locking element is formed by a.

locking pin 8 which lies approximately in the middle of a transverse boring 29 in the slide 1. The mobility of this pin in the longitudinal direction is delimited at one end by the end face of the locking bolt 4 and at the other end by the piston rod 9 of a pressure force element 10. The shaped free end 8a of the locking pin 8 extends into a recess 11, thus blocking the slide 1.

The movement of the slide 1 takes place as a result of the gas pressure which is extracted, for example, from a propulsion unit and which flows into the expansion chamber 13 through the gas channels 12. As a result of the gas pressure the piston 3 is moved in the direction shown by the arrow and in opposition to the force of spring 6 after the pin 5 has been sheared off. This tensions draw spring 14 which is secured at one end to the locking bolt 4 and at the other end by means of a pin 15 to the slide of the locking slide 1. At the same time the first locking effect of the slide 1 on the edge 7 is removed and the slide 1 is prestressed in the direction of the arrow by means of the draw spring 14. The locking slide 1 is now only held by the pin 8 which is drawn by its shaped free end 8a into a notch 16 serving as a force threshold.The gas pressure in the expansion chamber 13 must be maintained until the second locking operation has been nullified.

If an electronic detonation system (not shown) feeds a detonation signal, in accordance with certain criteria, to the pressure force element 10, the gas pressure occurring in the latter expels the piston rod 9 and thus forces the pin 8 out of the recess 11. This overcomes the second locking operation, and the locking slide 1 moves into the armed position, so that the detonation chain, not shown in the drawing, is closed by the detonator 2. The activation of the detonation chain takes place via electrical detonation devices, not shown in the drawing, and short-circuited for safety reasons by a wire 18 soldered between two contact plates 17, until the final arming operation takes place. The said wire 18 is cut by an insulating pin 15 affixed to the locking slide 1 when the said locking slide 1 moves into the armed positiOn.From this point onwards the safety device is in readiness for detonation. At the same time the locking slide 1 is held in the armed position by a spring-mounted casing 20 which engages edge 21.visual indication of the armed position is provided by the pin 22 moving out beyond the external contour of the housing 27.

If for some reason the arming operation proceeds in an incorrect sequence, that is if the pressure force element 10 is fired before the gas pressure in the channels 12, then the safety device will be permanently blocked, because the locking bolt 4 occupies the initial position and the force element 10, after detonation, cannot force the locking pin 6 out of the recess 11, because the pin is held by the end surface of the said locking bolt 4. The energy of the force element is absorbed without any effect occurring. If gas pressure is fed to the gas channels 12 now the first unarming operation (shear pin 5, piston 3 and locking bolt 4) is nullified and the draw spring 14 is subjected to tension. In this process the locking pin 8 becomes locked by the notch 16 and exerts a continuous blocking effect.

After the fall in gas pressure the draw spring 14 is relieved of tension and the piston 3 forced into the initial position by the pressure spring 6. The safety device is thus completely unarmed and can be removed without risk.

In order to prevent the safety device from being armed when subjected to excess heat, for example if fire breaks out, a temperature-controlled safety system is included. This is provided on the one hand by a locking plate 24, which may comprise a shape retaining alloy or bimetal strip. If temperatures above about 90"C upwards occur the locking plate 24 undergoes deformation and engages the recess 25. As a second temperature-actuated safety system the gas channel 12 contains a fusion device 23 through which the gas pressure can escape.

The particular advantage of the safety device provided by the invention for detonators of warheads of small rockets is that it provides a reliable arming operation in a simple manner, using two mutually independent physical environmental criteria, the construction and moderate weight making the device universally usable.

Claims

1. A safety device for a detonator used in warheads of small rockets, the detonator having a spring-loaded slide with a detonator positioned therein, the slide being movable from an unarmed position into an armed position, and the slide being retained in the unarmed position by means of spring-loaded locking elements, the device including:: (a) a piston axially movable in opposition to the force of a spring by gas pressure after shearing of a shear pin, the piston applying tension to a draw spring through a locking pin secured radially to the piston, (b) a locking slide connected with the draw spring and housing a detonator, the slide being held in an unarmed position both by the locking pin of the piston acting against an edge of the slide and also by a headed pin sitting partly in a transverse bore of the slide with a free end engaging a recess in a guide in which the locking slide moves, (c) the locking slide in an armed position, operating an electrical contact through an actuating element and (d) the locking pin being associated with a force applying means to move same from the recess into the transverse bore of the slide.

2. A safety device in accordance with Claim 1, wherein the electrical contact comprises two spaced plates connected by a shorting wire which can be broken by means of a cutting pin when the slide moves from the unarmed into the armed position.

3. A safety device in accordance with Claims 1 or 2, wherein the locking slide is provided on a side guide surface with a further recess accommodating a spring loaded casing which engages an edge of the locking slide guide when the locking slide is in the armed position.

4. A safety device for detonators in accordance with any one of Claims 1 to 3 wherein the locking slide has a recess on a lateral guide surface which when in an unarmed position is adjacent a locking tongue which engages the recess following deformation under excess temperature to prevent movement of the slide.

5. A safety device for detonators in accordance with any one of Claims 1 to 4, wherein the gas channel to the piston can be vented by a closure element fusible on temperature increase.

6. A safety device as described herein and exemplified in the drawings.