IGNITER FOR PROPULSION UNIT

Abstract

An igniter for propulsion unit including a receptacle having at least one opening through which passes a conducting line connected to an ignition carrier of a slapper contained within the receptacle, the igniter being characterized in that at least one elastomer material is disposed between the ignition carrier and the opening such that the pressure of the gases generated by the propulsion unit which is ignited pushes the elastomer material at the vicinity of the opening of the receptacle so that this elastomer material blocks the opening and avoids any gas leak through this opening.

Claims

1. An igniter for propulsion unit, the igniter comprising a receptacle having at least one opening through which passes a conducting line connected to an ignition carrier of a slapper contained within the receptacle, wherein at least one elastomer material is disposed between the ignition carrier and the opening such that the pressure of the gases generated by the propulsion unit which is ignited pushes the elastomer material at the vicinity of the opening of the receptacle so that this elastomer material blocks the opening and avoids any gas leak through this opening.

2. The igniter according to claim 1, wherein the elastomer material is a silicone elastomer.

3. The igniter according to claim 1, wherein the connection between the conducting line and the ignition carrier is provided by conducting pins allowing to dispose the conducting line away from the ignition carrier.

4. The igniter according to claim 3, wherein the pins pass through a separating plate located between the conducting line and the ignition carrier, wherein the elastomer material is at least arranged between the separating plate and the conducting line, wherein the separating plate is arranged so as to act as a piston under the pressure of gases of the propulsion unit (100) so as to apply a homogeneous force on the elastomer material.

5. The igniter according to claim 1, wherein the igniter has at least one layer of elastomer material between the conducting line and a cover of the receptacle wherein the elastomer material can wrap the conducting line or fill the free space on either side of this conducting line to prevent any contact of the conducting line with the receptacle.

6. The igniter according to claim 1, wherein the conducting line is embedded within a one-piece layer of elastomer material.

7. The igniter according to claim 5, wherein the elastomer material blocks the opening before ignition.

Description

[0021] According to FIG. 1, an end of a propulsion unit 100 for missile includes a propellant charge 101 intended to be ignited by an igniter 1. The igniter 1 has a receptacle 2, divided for the ease of manufacturing, into a lower part 2a, opening towards the propellant charge 101, and a cover 2b covering this lower part 2a. According to a pyrotechnic chain conventionally known by the person skilled in the art, the lower part 2a has an ignition primer 3 which is intended to cause the ignition of the propellant charge 101, this primer 3 being itself ignited by an initiator 11 of the slapper type, comprising a secondary explosive 4.

[0022] The explosive 4 is initiated by a flyer disk which is projected by an ignition carrier 5 of the slapper 11.

[0023] Triggering of the slapper 11 is controlled by an electrical discharge communicated to the ignition carrier 5 via conducting pins 7 connected to a conducting line 8 for supplying an electrical pulse from a control electronic board which is on board the missile (board and missile not shown).

[0024] This conducting line 8 passes through an opening 9 of the receptacle 2. For the ease of implementation, this opening 9 is provided at the matin surface between the cover 2b and the lower part 2a of the receptacle 2. The cover 2b and the lower part 2a of the receptacle are assembled with means known by the person skilled in the art, for example by screwing.

[0025] At least one layer of an elastomer material 10 is disposed between the conducting line 8 and the ignition carrier 5. This elastomer material 5 could, for example, be a silicone elastomer.

[0026] Thus, according to FIG. 2, when the igniter 1 ignites the propellant charge 101, the entire pyrotechnic chain described above (primer 3 and explosive 4) is destroyed, allowing the free communication of the gas generated by the propellant charge 101 between the interior of the propulsion unit 100 and the interior of the igniter 1.

[0027] The gas pressure then applies on the elastomer material 10 which is compressed between the gases on one side and the inner walls of the receptacle 2 on the other side. The deformability of the elastomer causes the latter to creep so as to block the opening 9, thereby avoiding any gas leak to the outside of the igniter. Furthermore, this deformability of the elastomer 10 under pressure prevents the cracking or breaking of the elastomer 10, thereby preserving the gas tightness, even when considering other potential mechanical stresses applied to the igniter, such as vibrations or impacts.

[0028] According to a second embodiment illustrated in FIG. 3, a rigid separating plate 6 is arranged between the layer of elastomer 10 and the ignition carrier 5. When igniting the propellant charge 101 of the propulsion unit 100 (FIG. 4), the gases exert then their pressure on this separating plate 6 which acts as a piston which will press the elastomer material 10 by applying a force evenly distributed, thereby pressing the elastomer material 10 against the inner walls of the receptacle 2 until it blocks the opening 9.

[0029] FIG. 5 shows a third embodiment of the invention in which another layer 10b of an elastomer material is arranged between the conducting line 8 and the cover 2b.

[0030] Thus, two layers of elastomer material 10a and 10b could be provided. The conducting line 8 could also be embedded within a single block 10 of elastomer material. To this end, the elastomer material 10 could be casted from a filling hole provided within the cover 2b and then blocked by a suitable plug (not shown).

[0031] Thus, the elastomer 10 is distributed all around the conducting line 8, which, under the gas pressure, avoids any gas leak (FIG. 6).

[0032] Moreover, the elastomer 10 wraps the conducting line 8, avoiding potential electrical leaks of this line 8 towards the structure of the missile and other missile equipments.

[0033] According to a particular embodiment of these FIGS. 5 and 6, the elastomer 10 could occupy the entire upper part of the igniter and could also block the opening 9 before ignition.

[0034] In any case, the invention thus allows to ensure that no propellant gas leaks via the igniter 1.

[0035] In addition, if the elastomer blocks the opening before ignition, it prevents the penetration of liquid or gas to the igniting carrier when the igniter is stored.

[0036] The deformability of the elastomer under pressure thus prevents the cracking or breaking of this material, thereby preserving the performance of gas tightness during the entire operation of the propulsion unit, despite the mechanical stresses (such as vibrations and impacts) undergone by the igniter.