IL34727A - A pyrotechnical fuze with displaceable detonator and safety device - Google Patents

Description

Δ PYHOTBCHNICAL FUZE WITH DISPLACEABLE DETONATOR AKD SAFETY DEVICE This invention relates to a pyrotechnical fuze having a detonator which can be displaced by a propelling force out of a safe position into a Uve position and which is restrainable in the safe position by a safety device.

In the case of a shell fuze it is known to secure a detonator in a safe position by a pyrotechnically-releasable safety member. After the shell is fired, the detonator is armed by the burning off of a pyrotechnical composition softening the safety member and is put into a live position by spring force.

There is described in our U.S.A. Patent No. 3505959 a fuze having detonator means held in a safe or incactive position by safety means which are - o.":. softenable, by heat developed by a pyrotechnical charge or preparation when the latter is ignited, to release the detonator means for action upon a secondary charge, but a difference between such construction described in said U.S.A.

Patent and the construction claimed herein is that in the construction claimed herein there is provided, in addition to a fusible member softenable by heat developed by a pyrotechnical charge to release a detonator support for movement towards a secondary charge, safety means which prevent ignition of the secondary charge so long as the detonator support is not displaced into a live position.

There is described in french specification Ho.1567318 an actuating element having an elongated member retained in a first position against the action of a resilient member by a metal member located between a combustible charge and the elongated member, ignition of the combustible charge resulting in melting of the metal member to release the elongated member and allow it to move into a second position, but said French specification does not described a pyrotechnical fuze which has a detonator support connected to a stationary part of the fuze through a fusible member softenable by heat developed by a pyrotechnical charge to release the detonator support for movement towards a secondary charge, with there being provided safety means which prevent ignition of the secondary charge so long as the detonator support is not displaced into a live position.

An object of the invention is to provide safety devices on f zes^r provided with pyrotechnical compositions, for throwing grenades which ensure high operational reliability. A grenade provided with the fuze is, upon conventional use, to detonate only when the grenade, upon throwing, has definitely left the thrower and a specific time thereafter h¾a passed. Moreover, the result to be aimed at is that, in case of any manufacturing defects, the fuze does not undergo premature detonation, but remains safe.

According to the invention, a pyrotechnical fuze having a detonator displaceable bya propelling force out of a safe position into a live position and which is restralnable in the safe position by a fusible member, s support for the detonator being connected through the fusible member to a stationary part of the fuze and being mounted so as to be axially displaceable in a tubular fuze casing provided in its lowermost part with a secondary charge, said support, as sson as a pyrotechnical composition in the fuze has been ignited through an ignition cap of the fuze and has softened the fusible member so that the latter no longer restrains the support for the detonator, being displaced, together with the detonator, by a propelling force to the secondary charge, and the detonator charge there ignited by a pyrotechnical composition, characterised in that there are provided safety means which prevent ignition of the secondary charge so long as the detonator support is not displaced into the live position.

Serving as a safety means there can be a flap valve, the flap of which is held closed in the safe position of the detonator support by an insulating disc and bent open in the live position of the said support by a fire jet from the pyrotechnical composition by which the detonator charge is ignitable. A cup-shaped insert for the reception of the detonator cap can be provided in the region of the secondary charge, in which connection the insert can have a base having, Qa the secondary charge side, a coned recess, whereby the ignition impulse is transmitted from the detonator charge to the secondary charge only when the detonator cap is pushed into the insert. As a furthe safety means the detonator charge can be rovid^in tubular detonator cap manufactured from nons=piintering materi and the outlet cross section of which is at least equal to th greatest internal cross section of the tube and the external diameter of which corresponds to the internal diameter of the aforesaid insert. Moreover, a throttle valve can be provided between the ignition cap and the detonator. Advantageously t propelling force can be produced by a compression spring and t pyrotechnically-releasable safety device can be designed as a fusible member.

In the case of a percussion fuze, mounted in pendulous fashion in a stationary part of the fuze casingj there can be provided a striker which is provided with a priming channel an which, in the safe position of the detonator, is retained in t radial and axial directions by the detonator support restraine by the safety member and a headpiece of which projects into a chamber of the stationary part and i¾ enclosed by a priming composition, which, after the displacement of the detonator support into the live position, is ignitable, upon the impact of the grenacle, by deflection of the striker. With a view to ensuring a safs storage of the fuze, there can be provided a On premature penetration of the pyrotechnical composi ion the ignition il .sh (in the aforesaid case where a flap valve servec as safety means) rebounds on the closed fla valve and therefore cannct ignite the detonator charsre standing in the safe position. The heat thereby generated by the pyrotechnica composition is kept away irom the detonator charge by the insulating disc By this means, even an ignition of the detonator charge by overheating is precluded. If, nevertheles the detonator charge is ignited in the safe position, the base of the cup-shaped insert, when the said insert is provided, prevents the transfer of the ignition impulse to the secondary charge, in that the ignition impulse acting on the insert base can bend the base into the coned recess without affecting the secondary charge. If the pyrotechnical composition and flap valve are missing, the throttle valve, when provided, prevents the ignition flash from the ignition cap irom igniting the detonator charge.

In the case of th impact fuze provided with the aforesai striker, a further security is afforded in that a grenade thro too short by the soldier, whereby its impact occurs prior to t release of the striker by the detonator, does indeed become li ' endanger the soldier. On the other hand, the ignition c^the · armed detonator ensues upon a slight motional impulse, which . brough about in the case of a rolling grenade by a correspondi movement of the striker.

The arrangement may be such, in the case where the propelling force is produced by a compression spring and the pyrotechnically-releasable safety member is a fusible member, that the detonator, after triggering of the ignition cap, remai in the safe position until, after approximately two thirds of the delay time, there ensues, through the pyrotechnic compositi a softening of the melting member and only then is the detonato put into the live position by the spring. It can be arranged that the ignition of the ignition cap can only take place when the grenade has left the hand of the thrower. With these safet devices it can be ensured that the throwing grenade can be thro by the soldier in each case without personal danger, but, with satisfactory operation of the fuze, the opponent does not have sufficient time to throw the grenade back again,, In the accompanying drawings, which show, by way of exampl hand grenade fuzes constructed in accordance with the invention Figure 1 shows a time -lelay fuze in longitudinal section; Fi ure 2 shows on a lar er scale a detail of the fuze of Figure 5 shows a variation of part of t'.*e fuze of Figure 1; Figure k shows in perspective view a variation different from the arrangement shown in Figure 2; Figure 5 s ows an impact fuze in longitudinal section; a Figure 6 shows a variation of part of the fuze of Figure Referring to Figures 1 to k of the drawings, a tubular fu casing 1, represented in Figure 1, of a time delay fuze shown in the basic position has screwed thereon a headpiece 2, on which a handle k is pivoted by a pivot pin 3 and is secured in a safe position by a safety cotter 5. A stressed spring plate 6 butts internally against the handle ka An arm 7 having a hammer 9 is svingably mounted, under the force of a spring 8, on the pivot pin 3. An ignition cap 10 is fastened in an ignition cap support 11, which is interlocked with the upper end of a sleeve part 14 secured in the fuze casing 10 A chamb 12 is provided between the ignition cap support 11 and a pyrotechnical delay composition 13. The delay »;omposition 13 " sealed at the lower end of the part Ik (see also Figure 2) by throttle valve, designed as a cup 15» having approximately radially extending holes 16 and a flap valve 17. The flap val to surround approximately one-half of the leneth of the fitte and is connected at its upper end by au annular fusible member 18 to the part 14. A stressed spiral compression spring 21 is arranged between a shoulder 1 ' of the sleeve part 14 and the front face 20 of the detonator support 19.

Screwed in at the lower end of the detonator support 19 i a detonator cap 22 with a detonator charge 23. A tetrafluoro-ethylene heat insulating disc 24, leaving free a priming chann to the detonator charge 23 , is seated fast on the detonator ca 22 and butts against the flap valve 17.

A support body 26 for a secondary charge 27 having a positively secured cup-shaped insert 25 and a secondary charge is screwed in at the lower end of the fuze casing 1 . A gap 23 ' ' is provided between the support body 26 and the detonato cap 22. The insert has a base 28 which has a coaxially-arrang coned recess 29. The secondary charge 27 is separated from th recess 29 , and from a bursting charge (not shown) of the hand grenade indicated in dot-dash lines, by cover dides 30 and 31 . Instead of the throttle valve 15 between the pyrotechnical composition 13 and the detonator cap £2 , a disc 32 (Figure 3 ) between the ignition cap 10 and the composition 13 can serve the part 14 by upsetting the xvall of the chamber 12.

A flap valve 34 represented in Figure 4 consists of a circular disc which is secured to the part 1 by a flange and which has, between the ends of annular slot 35, a web 36 serving as a hingee The construction of the impact fuze represent d in the basic position in Figure 5 differs as described hereinunder from the time delay fuze represented in Figures 1 to , in the followin details Two mutually separate chambers 12 and 38 are provided in a part 37„ A pyrotechnical heating composition 39 for the fusible member 18 is arranged in the upper chamber 12, whilst a headpiece 41, provided with a pyrotechnical priming compositio 40, of a striker 43 provided with a priming channel 42 project into the lower chamber 38. The striker 43 is mounted in pendu fashion in a disc 44, which is secured to the lower end of the part 37.

The striker 45 has a foot part 45 seated positively in a recess 46 of the detonator support 19, in which connection a rubber-elastic pad 47 is arranged on the base of the recess. The lower mouth of the priming channel it> closed by the flap valve 17. fastened with a case 49 in the lower chamber of the pa^^t 37 The head 50 projects, free of contact, into the priming composition ¾8. The effect of this arrangement is similar to the construction described with x gard to Figure 5.

Operation of the time delay fuze of Figure 1.

If the safety cotter 5 is removed, then the handle h is swung anti-clockwise by the spring plate 6 and by the bias spring 8, and finally the handle and the spring plate 6 are thrown off from the headpiece 2. Subsequently the hammer 9 encounters the ignition cap 10, which sets the pyrotechnicai: delay composition 13 alight. The heat generated by the dela composition 13 softens the fusible member 18, so that the spir spring 21 can press the detonator support 19 downwards into th live position. In the live position the detonator cap 22 has its lower aperture engaged on the insert base 28. Only upon burnout of the delay composition 13 is the /lap valve 17 bent open by a fire jet, which then encour/ters the detonator charge through the priming channel 23'. The initial impact of the detonator charge 2 strikes directly on the insert base 28 and ignites the secondary charge 27, which initiates the detonation of the hand grenade. In the case of a fuze function which is If the detonator support 19 is standing -.n the safe ¾?>sit then, with premature piercing of the delay composition 13, the flr.p valve 17 prevents the fire jet from igniting the detonato charge 23 „ The flap valve 17 cannot be opened by the abutting heat insulating disc 2k. An ignition of the detonator charge is therefore attainable neither through opening of the flap va 17 nor through heat flow.

If the delay composition 13 and the flap valve 17 is missing, then an ignition of the detonator charge 23 standing in the safe position is prevented by the throttle valve 15. The fire jet of the ignition cap 10 impinges centrically on the throttle valve 15, whereby only a small part of the igniti jet energy is transmitted through the lateral holes 16 into th subsequent hollcw space and there becomes turbulent. This sma part of the ignition jet is not sufficient to ignite the detonator charge 23.

If provision of the delay composition 13, the flap valve and the throttle valve 15 are overlooked and if therefore the detonator charge 23 is ignited in the safe position, then the initial impact of the detonator charge 23 spreads all around in +.h'e gap 23''. In this connection, the initial impact wealm 28 bends slightly into the recess 29 ; without affecting secondary charge 27.

Finally, if the dela composition 13 is missing and the detonator support 19 were already in the live position ai. the instant of the triggering of the ignition cap 10, then the fir jot of the ignition cap is weakened by the throttle valve 15 t such an extent that the fire jet cannot open the flap valve 17 and ignite the detonator charge 23. Even with the flap valve missing, the energy of the throttled ignition ray is not sufficient to ignite the detonator charge 23. Upon correct manufacture of the fuze as well as undisturbed course of the ignition procedure, the described effect of the respectively incorporated throttle valves 15 or 3 does not occur.

Operation of the impact fuze of Figure 5 After ignition of the pyrotechnic heating composition 39, which softens the fusible member 18 through its heat, the spir spring 21 presses the detonator support 19 into the live posit In this connection, the detonator support 19 releases ^ e flap valve 17 and the striker previously retained in the radial and axial direction in the recess 46 of the detonator support If the fuze now receives ar impact, then the headpiece 41 with the m n om osition 40 strikes a ainst the wall of the flap valve 17, so that the ignition jet encounters w thou^ hindrance the detonator charge 23 standing in the live positi ami ignites this latter. This in turn ignites family the secondary charge 27 and thereby initia es the detonation of the hand grenade.

If the detonator charge 23 is ignited inadvertently in the safe position of the detonator support 19 and with the fla valve 17 missing, then the initial impact thereoy arising is absorbed in the manner above described, by the cup-shaped inse 25, so that the secondary charge 27 is not ignited.

Claims (11)

1. What I claim isi- 1· A pyrotechnical fuze having a detonator displaceable by a propelling force out of a safe position into a live position and which is restrainable in the sae position by a fusible member, a support for the detonator being connected through the fusible member to a stationary part of the fuze and being mounted so as to be axially displaceable in a tubular fuze casing provided in its lowermost part with a secondary charge, said support, as soon as a pyrotechnical composition in the fuze hasbbeen ignited through an ignition cap of the fuze and has softened the fusible member so that the latter no longer restrains the support for the detonator, being displaced, together with the detonator, by a propelling force to the secondary charge, and the detonator charge there ingnited by a pyrotechnical composition, characterised in that there are provided safety means which prevent Ignition of the secondary charge so long as the detonator support is not displaced into the live position.
2. 2· A fuze as claimed in claim 1, wherein the safety means prevent ignition both of the detonator charge and of the secondary charge so long as the detonator support is not displaced into the live position.
3. 3. A fuze as claimed in claim 1 , having a valve which blocks a priming channel to the detonator charge in the safe position of the detonator support and which is formed by a closure clamped, in said safe position of the detonator support, between a stationary part of the fuze and said support.
4. 4. A fuze as claimed in claim 3» wherein the valve is a flap valve, the fap of which is held closed in the safe. position of the detonator support by an insulating disc a¾d ca be bent open in the live position of said support by a fire je from the pyrotecanical composition ¾y which the detonator char is ignitable.
5. 5· i. A £uze as claimed in Claim 1, wherein the secondary c has, facing the detonator cap, a cup-shaped insert for the reception of the detonator cap, said insert having a base wh c has, facing the secondary charge, a coned recess, whereby the ignition impulse is transmitted from the detonator charge to the secondary charge only when the detonator cap is pushed int the insert.
6. 6· £. A fuze as claimed in claim 1, wherein the detonator charge is provided in a tubular detonator cap which is manui'ac from nonsplintering material and the outlet cross section of which is at least equal to the greatest internal cross section of the tube and the external diameter of which corresponds to the internal diameter of the insert.
7. 7· . A fuze as claimed in Claim 1, wherein a throttle valv is provided between the ignition cap and the detonator.
8. 8. „ A fuze as claimed in Claim 1} wherein mounted pendulously in a stationary part of the fuze casing is a strik which is provided with a priming channel and which in the safe directions by the detonator support restrained by the safe y . device, said striker having a headpiece projecting into a chamber of the stationary part and said headpiece being enclos by a priming charge which, after the displacement of tht detonator support into the live position, is ignitable upon th impact of the grenade, by deflection of the striker. 8
9. 9» 0. A fuze as claimed in Claim jt wherein the striker bas an axial ly-extending centric priming channel.
10. 10· J$. A fuze as claimed in Claim 1 , wherein the propelling force is produced by a compression spring and the pyrotechnica releasable safety device is designed as a fusible member. 1 1 · A time delay fuze, substantially as herein described with reference to Figures 1 to k of the accompanying drawings.
11. 11 ./(d. An impact fuze, substantially as herein described with reference to Figures 5 and 6 of the accompanying drawings Att