EP1530020B1 - Ignition device of at least two pyrotechnical compositions or propulsive charges of a projectile - Google Patents

Abstract

Mechano-pyrotechnic module has at least two separate pyrotechnic chains integrated in a mechanical system (15, 16, 17) and initiated by a single igniter (10). Each chain operates through a relay (13, 14) to initiate one of the charges (P2), and the chains have different rates of combustion one slower and one faster. The mechanical system interrupts the slower chain if the faster one is not functioning correctly.

Description

The technical field of the invention is that of ignition safety devices of a pyrotechnic composition or a propellant charge of ammunition.

Known igniters include a pyrotechnic component capable of generating a flame whose temperature is sufficient to ignite a propellant charge or a useful pyrotechnic composition (smoke composition, illuminant or gas generator for example).

Such a pyrotechnic component is initiated by an electric current. It may be a component with hot wire, exploded wire or semiconductor bridge. The components usually used are safety components type 1Ampere / 1Watt, that is components that do not operate powered by a current of an ampere and under a power of one watt for a predefined period. These components consume a lot of electrical energy.

In the case of certain projectiles, the propulsion is ensured by several propulsive charges initiated successively. Other projectiles include several pyrotechnic compositions lit successively.

One solution for igniting these different propellant charges or compositions is to use as many ignition devices as there are propellant charges or compositions to be ignited, the time delay between the ignition of the different charges being managed by an electronic module .

A disadvantage of this type of solution lies in the fact that it requires a large electrical energy, so storage means of this energy.

Patent DE325292, which forms a basis for the preamble of claim 1, discloses a pyrotechnic double-chain starting device. The two pyrotechnic chains allow to initiate a single charge. The second chain to overcome a possible malfunction of the first pyrotechnic chain.

The object of the present invention is to provide a pyrotechnic device initiating several pyrotechnic chains simultaneously from a single initiator and thus making it possible to switch on successively different pyrotechnic compositions or different propellant charges of ammunition.

The subject of the invention is therefore a safety device for igniting at least two pyrotechnic compositions or propellant charges of a projectile, characterized in that it comprises at least two distinct pyrotechnic chains integrated into a mechanical device and initiated by a single igniter, each pyrotechnic chain allowing via at least one relay to initiate the pyrotechnic composition or corresponding propellant charge, at least a first pyrotechnic chain being slower combustion than a second pyrotechnic chain combustion or action rapid, the mechanical device consisting of movable elements relative to each other, to ensure an interruption of the slow pyrotechnic chain or chains if the combustion chain or rapid action did not work properly.

Advantageously, the mechanical device consists of a piston sliding in an inner sheath itself slidably mounted in a bore of a body, the sheath carrying at least one opening allowing, when the sheath is in an armed position to connect the or slow pyrotechnic strings to at least one of the relays.

Advantageously, the piston is movable under the action of the combustion gases of a pyrotechnic composition or a propellant charge initiated by the rapid pyrotechnic chain, against the action of a spring bearing on a support integral with the body.

Advantageously, the piston consists of a massive portion extended by a skirt provided with a radial bore and enclosing the pyrotechnic relay.

Advantageously, the device comprises means ensuring the locking of the piston and the sheath after displacement of the piston under the action of the combustion gases of the composition or propellant charge initiated by the rapid pyrotechnic chain.

The means ensuring the locking of the piston and the sheath may be constituted by a finger disposed in a radial hole of the piston and subjected to the action of a spring, finger for cooperating with a first opening carried by the sheath.

The body may comprise two longitudinal channels, at least one of the channels containing a delay pyrotechnic composition, a radial opening of the body making the body communicate with one another. channel enclosing the slow pyrotechnic chain with radial drilling of the piston skirt.

According to one embodiment, one of the channels of the body may be empty and will thus directly connect the igniter to one of the relays.

The body may have a radial opening disposed at the level of the pyrotechnic composition or propellant charge P2, opening closed by the sheath when it is in the safety position.

A first advantage of the device according to the invention lies in the fact that it allows to initiate several pyrotechnic compositions or propellant charges with a single igniter.

Another advantage lies in the fact that such a device requires very little electrical energy, which avoids the use of particularly bulky electrical capacity.

Another advantage lies in the fact that the electrical energy can be supplied to the device at the last moment (for example during its ejection), which avoids any risk of accidental ignition during the handling of the projectile.

• la figure 1 représente en coupe un projectile équipé d'un dispositif de sécurité d'allumage selon l'invention,
• le figure 2a représente en coupe longitudinale le dispositif de sécurité d'allumage selon l'invention,
• les figures 2b à 2e sont des vues en coupe des pièces constituant le module mécano-pyrotechnique, et
• les figures 3a à 3d illustrent le dispositif de sécurité d'allumage selon l'invention à différentes étapes de fonctionnement.

Other characteristics, details and advantages of the invention will emerge more clearly from the description given below as an indication in relation to drawings in which:

• FIG. 1 is a sectional view of a projectile equipped with an ignition safety device according to the invention,
• FIG. 2a is a longitudinal section of the ignition safety device according to the invention,
• FIGS. 2b to 2e are sectional views of the parts constituting the mechano-pyrotechnic module, and
• Figures 3a to 3d illustrate the ignition safety device according to the invention at different stages of operation.

FIG. 1 represents in partial section a projectile 100 equipped with an ignition safety device 1 according to the invention. In this exemplary embodiment, the projectile 100 comprises two propulsive charges P1 and P2 that can be wish to initiate with some delay between them. The ignition safety device 1 is arranged to trigger the firing of the two propellant charges successively.

It is supplied with energy from a source not shown which may be a battery incorporated in the projectile or secured to a launch tube (not shown) and connected to the projectile by son broken during firing.

FIG. 2a is a longitudinal sectional view of the ignition safety device 1 according to the invention in its safety position. The ignition safety device 1 consists of a casing 4 of substantially cylindrical tubular shape enclosing an electronic module 2 and a mechanical-pyrotechnic module 3 arranged in the present case in the extension of one another. Alternatively, these modules could be arranged side by side. The electronic module 2 is connected at one end to a connector 6, itself connected to a power source (not shown in this figure). The electronic module 2 consists of conventional electronic elements 34, such as energy accumulators, an electronic timer, as well as speed and / or acceleration sensors making it possible to know the ejection parameters of the projectile and that it is not necessary to describe for the understanding of the invention.

In order to protect the electronic elements 34 from thermal and mechanical stresses that would hinder the correct operation of the electronic module 2, it could be embedded in a coating 9, for example of the silicone elastomer type.

The mechano-pyrotechnic module 3 comprises at one end an igniter support 30 extended by a body 15 within which an internal sheath 16 slides. Body and sheath may be made of metallic material or of a synthetic material that is sufficiently resistant to the stresses mechanical. The mechano-pyrotechnic module 3 comprises at its other end a tubular outlet 5 cooperating with the thruster P1

Figures 2b to 2e represent separately different mechano-pyrotechnic module elements in order to better highlight their technical characteristics. FIG. 2b is a longitudinal sectional view of support 30 and body 15 alone, FIG. 2c is a longitudinal sectional view of sheath 16 alone, and FIG. 2d is a longitudinal sectional view of piston 17.

The body 15 is in abutment against one end of the tubular casing 4 which carries the tubular outlet 5. It has an internal bore 15b whose bottom constitutes an abutment surface 15a whose role will be explained below. The body 15 comprises at its lateral wall two longitudinal cylindrical channels 21 and 22 (the latter shown in dashed lines) intended to respectively contain the pyrotechnic chains 11 and 12. Here the channel 21 encloses a slow pyrotechnic chain 11 and the channel 22 is empty.

The side wall of the body 15 is pierced with a radial opening 19 which is arranged opposite the propellant P2 (not shown). The channel 22 communicates with a chamber 45 connected to the tubular outlet 5 carrying a relay 13. The channel 21 also communicates with the internal bore 15b by a radial opening 40 whose role will be explained below.

The inner sheath 16 is slidably mounted inside the body 15 and is provided with two radial openings 24 and 35 axially offset from one another and with respect to the opening 19 of the body 15. This sheath 16 is present in the form of a simple sheath. It contains a piston 17 slidably mounted against the action of a spring 20. This piston comprises a solid portion 41 extended by a skirt 42. The solid portion 41 is in abutment against the abutment surface 15a of the body 15 and the skirt 42 partially surrounds the spring 20 which bears against the igniter support 30. The solid portion 41 carries a shearable peripheral collar 46 which axially immobilizes the sheath 16 relative to the piston 17 and to the body 15 in the safety position of FIG. 2a.

The solid portion 41 of the piston 17 is provided with a radial hole 43 intended to house a finger 18 subjected to the action of a spring 23. The finger assembly 18 and spring 23 constitutes a system for securing the piston 17 and of the sheath 16 in a configuration which will be explained below. The skirt 42 is provided with a radial bore 44.

This mechanical assembly which has just been described contains the pyrotechnic elements necessary for the operation of the device according to the invention. The support 30 carries an igniter 10 which is electrically connected to the electronic module 2 and which faces the two pyrotechnic chains 11 and 12 housed in the respective channels 21 and 22. A first pyrotechnic relay 13 is disposed in the tubular outlet 5. It receives directly the gases produced by the igniter 10 which are led through the channel 22 and the chamber 45. It ensures the ignition of the thruster P1. A second pyrotechnic relay 14 is disposed in a housing 25 of the skirt 42 of the piston 17, in the vicinity of the bore 44.

In Figure 2a, the device 1 is in the safety position. In this position the sheath 16 closes the openings 19 and 40 of the body 15. The sheath 16 thus isolates the relay 14 from both the slow pyrotechnic chain 11 and the propellant P2.

Figure 2e is a cross-sectional view of the body alone, section taken along the plane AA. This sectional view shows the disposition of the cylindrical channels 21 and 22 placed side by side in the body 15, without communicating with each other, the channel 21 enclosing the pyrotechnic chain 11 the channel 22 being empty .

FIGS. 3a to 3d illustrate the different operating phases of the device according to the invention.

When the trigger conditions are met (the projectile has been ejected from its launch tube, its speed is verified above a predetermined threshold and after an electronic delay ensuring the firing safety distance), the electronic module 2 controls the initiation of the igniter 10 (Figure 3a). The gases of the latter penetrate simultaneously into the two channels 21 and 22. They ensure the initiation of the slow pyrotechnic chain 11 while directly lighting the first relay 13 through the empty channel 22 and the chamber 45.

The ignition of the first relay 13 (Figure 3b) causes the initiation of the thruster P1.

The firing of the thruster P1 then creates an increase in pressure in the chamber 45 which causes the recoil of the piston 17 and causes the shearing of the flange 46. The piston 17 compresses the spring 20 as shown in Figure 3c. The finger 18 then comes opposite the opening 24 of the sheath 16 and is pushed by the spring 23 into this opening. The piston 17 and the sheath 16 are thus secured. At the same time, the bore 44 of the piston 17 is positioned opposite the opening 35 of the sheath 16.

At the end of the combustion of the thruster P1, the pressure in the chamber 45 decreases and under the preponderant force of the spring 20 the piston 17 returns to its initial position, driving the sheath 16 which it is integral as far as the stop against the abutment surface 15a of the body 15 as illustrated in Figure 3d. The device is then in its armed position.

This translation of the sheath 16 positions the bore 44 of the piston and the opening 35 of the sheath 16 opposite the opening 40 of the body 15.

The end of the slow combustion pyrotechnic chain 11 is thus connected to the second pyrotechnic relay 14.

Moreover, the displacement of the sheath 16 releases the opening 19 of the body 15.

Thus, the chain 11 with slow combustion, through the opening 35 of the sheath 16 and the bore 44 of the piston 17, initiates, at the end of its combustion, the second relay 14 disposed in the housing 25, then the thruster P2 via the opening 19 of the body 15. It was thus made in a simple manner a device allowing from a single igniter to provide a successive and delayed initiation of two thrusters P1 and P2.

The operation of the device according to the invention is of course identical when the charges to be initiated are pyrotechnic timed ignition compositions, for example smoke compositions.

If the thruster P1 is not initiated, for example as a result of a fault of the first relay 13, the piston 17 and the sheath 16 do not move and the second relay 14 can not be initiated by the slow pyrotechnic chain. The device according to the invention thus ensures ignition safety of the second thruster. The latter can be turned on only after the delay whose duration is determined by the pyrotechnic delay composition 11 and only if the first thruster has operated and completed its combustion.

Relays 13 and 14 are pyrotechnic relays. They will be made and arranged so as to create a sufficient gas evolution and whose temperature will be high enough to ignite the pyrotechnic compositions of propellants P1 and P2.

A non-return valve (not shown) may also be provided in the channel 22 of the fast-combustion chain 12 in order to prevent the gases from the combustion of the propellant P1 coming through this channel 22 to disturb the operation of the the chain 11 with slow combustion.

Such an anti-return valve is conventional. It may include a ball applied on a conical seat by a return spring and closing a gas passage opening. The gases can then flow only in one direction in the channel 22.

The sealing of the ignition device according to the invention can be improved by using sealing elements such as O-rings disposed between the concentric parts (body 15 / casing 4, sheath 16 / body 15, piston 17 / sheath 16). ).

The invention has been described here with the association of a slow pyrotechnic chain, comprising a pyrotechnic delay housed in a channel, and a fast chain in which the channel 22 is free of any composition.

Depending on the operational requirements, it is of course possible to provide an ignition safety device according to the invention in which each channel 21 and 22 contains a pyrotechnic delay composition. The combustion rates and / or the lengths of each pyrotechnic chain 11, 12 will be chosen different according to the needs.

It is also possible to define a device comprising more than two delayed pyrotechnic chains. In this case another relay will be provided, arranged in a separate chamber of the piston, and which will communicate when the device is in its armed position, on the one hand with the third pyrotechnic chain and on the other hand with a third composition or propellant charge. to initiate.

Claims (9)

1. An ignition safety device (1) for at least two pyrotechnic compositions or propellant charges for a projectile (100), comprising at least two separate pyrotechnic trains (11, 12) integrated into a mechanical device (15, 16, 17) and ignited by a single squib (10), each pyrotechnic train enabling, by means of at least one relay (13, 14), the corresponding pyrotechnic composition or propellant charge (P1, P2) to be ignited, at least a first pyrotechnic train (11) being of slower combustion than a second pyrotechnic train (12) with faster action or combustion, characterised in that the mechanical device (15, 16, 17) is formed of elements able to move with respect to one another enabling the interruption of the slow pyrotechnic train(s) to be ensured should the pyrotechnic train with faster action or combustion not have functioned correctly.
2. An ignition safety device (1) according to Claim 1, characterised in that the mechanical device is constituted by a piston (17) sliding in an internal sheath (16) itself mounted able to slide in a bore hole (15b) in a body (15), the sheath having at least one opening (35) which, when the sheath (16) is in its armed position, enables the slow pyrotechnic train or trains to be connected to at least one of the relays (14).
3. An ignition safety device (1) according to Claim 2, characterised in that the piston (17) can move under the action of the combustion gases of a pyrotechnic composition or a propellant charge ignited by the fast pyrotechnic train, against the action of a spring (20) pressing on a support (30) integral with the body.
4. An ignition safety device (1) according to Claim 3, characterised in that the piston (17) is constituted by a solid part (41) extended by a skirt (42) provided with a radial drill hole (44) and enclosing the pyrotechnic relay (14).
5. An ignition safety device (1) according to one of Claims 3 or 4, characterised in that it incorporates means to ensure the piston (17) and sheath (16) are locked in place after the piston (17) has moved under the action of the combustive gases from the composition or propellant charge ignited by the fast pyrotechnic train (12).
6. An ignition safety device (1) according to Claim 5, characterised in that the means locking the piston (17) and sheath (16) in place are constituted by a finger (18) positioned in a radial hole (43) in the piston (17) and subject to a spring (23), such finger intended to cooperate with a first opening (24) in the sheath (16).
7. An ignition safety device (1) according to one of Claims 4 to 6, characterised in that the body (15) incorporates two longitudinal canals (21, 22), at least one of which encloses a pyrotechnic delay composition (11), a radial opening (40) in the body (15) enabling the canal (21) enclosing the slow pyrotechnic train (11) to communicate with the radial drill hole (44) in the skirt (42) of the piston (17).
8. An ignition safety device (1) according to Claim 7, characterised in that one of the canals (22) in the body (15) is empty enabling the squib (10) to be directly connected to one of the relays (13).
9. An ignition safety device (1) according to Claim 7, characterised in that the body (15) has a radial opening (19) arranged near the pyrotechnic composition or propellant charge P2, such opening being blocked by the sheath (16) when this is in the safety position.

Images