EP1273875A1 - Igniter for propellant charges - Google Patents

Abstract

The ignition device for a propellant charging comprises a squib (2). It comprises a diffuser tubes (3b,3c,3d) extending through a part of the propellant charge allowing the flame generated by the squib to be guided to a propellant charge receiver zone (31). There is a collected propulsive powder unit (26b,26c,26d) carrying a blind ignition channel (28b,28c,28d) receiving the diffuser tubes. An Independent claim is included for a propulsive charge.

Description

The technical field of the invention is that of ignition devices, in particular for propellant charging ammunition.

Known ignition devices use a ignition pyrotechnic component or igniter.

It is known to provide ignition distributed over substantially the entire length of a propellant charge in using an igniter which initiates a formed igniter tube of a stack of black powder tablets.

Patent FR2593905 describes such an igniter tube. However, current cartridge munitions present generally very long projectiles whose rear part or tail unit is housed in the vicinity of the igniter. It is therefore not possible to places in such ammunition an igniter tube long enough.

To solve the problem of the ignition of these loads it is known to use ignition means flexible in the form of pyrotechnic cords including the ignition action is both axial and radial.

Patent EP344098 describes such an ignition device. This device has the disadvantage of implementing a cord containing a pyrotechnic substance. This substance is likely to be initiated accidentally, leading to an unexpected ignition of the propellant charge.

Such a risk is even greater during the phases mounting and integration of a propellant charge.

We are also seeking today to increase the density of propellant charges, therefore performance firing, by the use of agglomerated loads.

In order to improve shooting ballistics, it is desirable to control the time and location of the ignition of such agglomerated blocks. This mastery is made difficult by the implementation of the cords conventional ignition systems which provide distributed ignition over their entire length.

Finally, it is planned in the coming years to increase firing performance by the use of igniters to plasma. These igniters use a share of energy electric to increase the temperature and pressure of propellants, so the initial velocity of the projectile.

Known plasma igniters (or torches) have a cylindrical structure close to that of an igniter tube conventional and they are difficult to associate with ammunition in which the projectile penetrates deeply to inside the propellant charge.

It is the aim of the invention to propose a ignition device to overcome such disadvantages.

Thus the ignition device according to the invention can be associated with ammunition incorporating a projectile penetrating deep inside the load.

The ignition device according to the invention can be safely installed in a load and it allows precisely control the ignition of a load chipboard.

Thus, the subject of the invention is an ignition device for a propellant charge, comprising at least one means igniter, device characterized in that it comprises at least one inert diffuser tube extending through part of the propellant charge and allowing guide the flame generated by the inflammatory medium to an area receiving propellant charge.

The diffuser tube will preferably be made of material flexible plastic and it may have a thickness included between 0.7 and 1.5 mm.

The diffuser tube may have an internal diameter between 3 and 6 mm.

According to a particular embodiment, the means igniter could be an electrical igniter generating a plasma (plasma torch).

Advantageously, the device may include a relaxation room arranged between the outlet of the plasma igniter and the diffuser tube (s).

The invention also relates to a loading propellant incorporating such an ignition device.

This propellant charge will include at least one block of agglomerated propellant powder, block carrying at least one blind ignition channel intended to receive a tube Streamer.

According to a particular embodiment, the loading may include at least two blocks of propellant powder agglomerated stacked on top of each other, at least a first block carrying at least one through link channel which is intended to receive a diffuser tube passing through said first block to be housed in an ignition channel fitted out on a second block.

Each block could thus have three channels blind lighting regularly distributed angularly and intended to receive a diffuser tube.

According to another embodiment, the loading includes at least three agglomerated blocks that have each three blind channels regularly angularly distributed and intended to receive a tube diffuser, the block closest to the igniter comprising also six through connecting channels and a block intermediate with three connecting channels the through.

• la figure 1 représente en coupe longitudinale un dispositif d'allumage selon un premier mode de réalisation de l'invention,
• la figure 2 est une vue externe de ce premier mode de réalisation de l'invention,
• la figure 3 représente en coupe longitudinale partielle une munition équipée d'un dispositif d'allumage selon un deuxième mode de réalisation de l'invention et renfermant un chargement propulsif selon l'invention,
• les figures 4, 5 et 6 sont des coupes transversales de cette munition, coupes réalisées respectivement suivant les plans DD, CC et AA dont la trace est représentée à la figure 3,
• la figure 7 est une vue d'un détail du chargement propulsif selon l'invention.

The invention will be better understood on reading the description which follows of different embodiments, description made with reference to the appended drawings and in which:

• FIG. 1 shows in longitudinal section an ignition device according to a first embodiment of the invention,
• FIG. 2 is an external view of this first embodiment of the invention,
• FIG. 3 represents in partial longitudinal section an ammunition equipped with an ignition device according to a second embodiment of the invention and containing a propellant charge according to the invention,
• FIGS. 4, 5 and 6 are cross sections of this munition, sections made respectively along the planes DD, CC and AA, the trace of which is shown in FIG. 3,
• Figure 7 is a detail view of the propellant charge according to the invention.

Figures 1 and 2 thus show a device ignition 1 according to a first embodiment of the invention.

This device comprises an inflammatory means 2 to which three diffusing tubes 3 are connected.

The device is shown here alone. The way igniter 2 is intended to be secured to a ammunition base (not shown). The body 5 of the means inflammator carries for this purpose a thread 4 which is intended to cooperate with a thread of the base.

The inflammatory medium is here a plasma generator and it has two electrodes 6 and 7 separated by a case insulating cylindrical 8 made of a plastic material likely to ablate, i.e. to generate gas light by the action of a plasma. We could for example make the case 8 in polyethylene, polyoxymethylene or made of polytetrafluoroethylene. We could also realize the case 8 of an energetic material for example in nitrocellulose.

Such a case is generally called a capillary in known plasma igniters.

The electrodes 6 and 7 are produced for example in a copper alloy. They are intended to be connected to a electric generator 35 via connections 36 and 37. A first connection 36 is in electrical contact by an appropriate means (e.g. a touch spring (not shown) with the rear electrode 6. A second connection 37 is in electrical contact with the metal body 5, for example by a touch to spring rests on the back of it or on the metal base of the ammunition (not shown).

The generator 35 is designed to be able to deliver energy from 10 ³ Joule to 10 ⁶ Joule in the form of voltage pulses from 10 ³ Volts to 20.10 ³ Volts. Such a generator is conventional and includes, for example, capacitors, an inductor, thyristors and a stabilized power supply.

The rear electrode 6 is generally cylindrical and of same axis as body 5. It extends inside case 8.

The front electrode 7 is tubular and its axial bore has a nozzle profile having a conical profile converge 9 which is open on the side of the rear electrode 7 and which is followed by a divergent conical profile 10. This nozzle reduces thermal losses during level of plasma generated by the torch. Indeed the nozzle allows to return in the axis of the torch the gases located in periphery. These gases are thus heated by the plasma.

The front electrode 7 is electrically connected to the body 5 of the igniter by the tight adjustment of its surface external cylindrical.

The stack of the two electrodes and of the case 8 is immobilized by a nut 11, which is screwed into a thread 12 of the body 5, and which applies to a shoulder 6a of the rear electrode 6. The nut 11 is made in one insulating material.

A fuse 13 is arranged between the electrodes 6 and 7. It has the shape of a tube produced in a conductive material associated with at least one material energetic or likely to react with the material driver.

By energetic material is meant a material capable of supplying chemical energy in the form of a flame when it is initiated by the Joule effect generated by the flow of current through the material driver with whom he is intimately associated.

By reactive or susceptible to react material with the conductive material a material, isolated in isolation, but likely to react chemically with the material conductor during the heating of this one by effect Joule. Chemical energy is then provided by this reaction in the form of a flame.

The conductive material may consist of carbon or by a metal such as copper, aluminum, silver, tungsten or magnesium.

We can for example make a tube 13 formed of a layer of chlorofluoroethylene copolymer (known as Viton registered trademark) deposited on a layer of aluminum.

Such a type of plasma igniter using a energy fuse is described by the patent application FR00 / 04734 and will not be described here in more detail. We may also consult patent application FR00 / 04735 which describes a plasma igniter without a fuse and having a front electrode in the form of nozzle.

Other examples of plasma igniters, including fuse wire, are finally described by patents FR2754969 and FR2768810.

In accordance with the invention, the ignition device includes 3 diffuser tubes integral with the igniter

These diffuser tubes are made of plastic and are completely inert because they do not contain pyrotechnic composition.

The tubes are made integral with the igniter by a connection sleeve 14 which is screwed at a threaded front end 5a of the body 5 of the igniter 2. This sleeve 14 carries three internal threads 15 regularly angularly distributed and whose axes 17 form an angle with the axis 16 of the body 5 of the igniter 2. Each internal thread 15 receives a tubular screw 18 on which fixes a lock nut 19.

The tubular screw 18 has a conical surface 18a which cooperates with a complementary conical bearing 19a of the nut to ensure pinching, therefore immobilization and the tightness of the diffuser tube 3.

The latter is made of a flexible plastic material, for example polyamide, polyethylene or polyolefin. The thickness of the diffuser tube is included between 0.7 and 1.5 mm, and the internal diameter of the tube diffuser is between 3 and 6 mm.

The screw 18 and the nut 19 thus constitute a means of securing of the diffuser tube 3 with the sleeve connection 14, therefore with the igniter 2.

Each diffuser tube 3 is intended to extend to the through part of the propellant charge (not represented). It guides the flame generated by the inflammatory medium to a receptor area of the propellant charge (not shown here). We can by example fix the diffuser tubes on the internal wall a round of ammunition.

Thus thanks to the invention the flame produced by the medium igniter 2 is precisely conducted in one desired place of loading without an ignition effect radial through the diffuser tube is not to be feared.

The thermal inertia of the material used is sufficient so that the flame is thus conducted without destroying the diffuser tube and this even when the ignition means generates a plasma (temperature of the order of 5000 K).

The diffuser tube will be destroyed later by the temperature and pressure of the gases developed during the combustion of the whole propellant charge.

The sleeve 14 delimits with the body 5 of the igniter 2 an expansion chamber 20 which is located disposed between the output of the plasma igniter 2 and the diffuser tubes 3. This expansion chamber allows to homogenize the plasma pressure and its chemical composition.

As a variant, it is of course possible to vary the number of diffuser tubes connected to the igniter.

It is also possible to associate with these tubes diffusers a conventional igniter using a pyrotechnic composition without generation of plasma. In in this case the body 5 of the inflammatory medium will contain a flame-generating pyrotechnic composition. She may include an associated flame intensifier relay to an electrically initiated igniter.

Figure 3 shows in partial longitudinal section a ammunition 21 equipped with an ignition device according to a second embodiment of the invention.

This embodiment essentially differs from the previous in that it comprises nine diffuser tubes 3, divided into three groups, the tubes of the different groups having different lengths (here for clarity of the figure, only a few tubes are shown).

Ammunition 21 includes a socket 22 made in a combustible material, for example cardboard impregnated with nitrocellulose, socket at the base of which is fixed a shutter base 23 which carries the inflammatory means 2 and receives on its internal surface a bowl 40 of material plastic. The base is fixed to the socket 22 by rivets radials 41 regularly distributed angularly.

Ammunition 21 also includes a projectile 24 (here an under calibrated projectile stabilized by empennage) which is fixed to the socket 22 by a connecting piece 25 made for example plastic. Fixing the socket 22 on the connecting piece 25 will be secured by rivets (not shown).

This ammunition is not described in detail, we can advantageously refer to patent FR2620214 which describes such a connecting ring.

According to the invention the propellant charge of this ammunition comprises at least one block of powder agglomerated propellant (here four blocks 26a, 26b, 26c, 26d).

The blocks are produced for example by compression uniaxial (around 30 MPa) and hot (around 80 ° C) of propellant powder in grains impregnated with a binder thermoplastic or energetic. The compression will be done in a mold whose shape allows to obtain the geometry of the desired block.

The rear unit 26a is in abutment against the bowl 40 disposed in the base 23. This block has a recess 42 which allows the radial deployment of the different tubes diffusers 3 around the inflammatory medium 2.

The other three agglomerated blocks 26b, 26c and 26d carry three blind 28 ignition channels, regularly angularly distributed, each intended to receive a tube diffuser 3. Block 26b thus carries three channels 28b, the block 26c three ignition channels 28c and the block 26d three ignition channels 28d.

Figure 7 shows an enlarged view of the blind end an ignition channel 28. This channel has an axis 29 parallel to axis 30 of ammunition 21 and it receives a diffuser tube 3.

The tube 3 is not fixed to the block 26. A set 43 of a few tenths of a mm remain between the tube 3 and the channel 28. The diffuser tube 3 does not extend to the bottom of the ignition channel 28. There thus remains a chamber ignition 31 in which the flame conducted by the tube diffuser 3 can act and ensure localized ignition (but divided into three zones) of the propulsion unit 26.

This perfectly controls the location of the ignition of the different blocks. Thanks to the invention, each block 26 simultaneously receives the flame supplied by igniter 2 and at its three ignition zones. he the result is better control over the evolution of pressure in the gun chamber and better ballistic performances.

In order to allow the passage of the diffuser tubes to through different blocks to their ignition channel, some agglomerated blocks also have canals through link 32 whose axis is also parallel to the axis 30 of the munition 21 (see Figures 4, 5 and 6).

Thus a first intermediate block 26c carries (in addition of its three blind ignition channels 28c) three channels of 32c link which allow the passage of the diffusing tubes 3d intended for the ignition of the upper unit 26d (see the figure 5).

The second intermediate block 26b carries (in addition to its three blind ignition channels 28b) six link 32b which allow the passage of the diffuser tubes 3c and 3d intended for the ignition of the intermediate block 26c and of the upper block 26d (see FIG. 6).

The angular distributions of the different channels are more particularly visible on the sections of the ammunition 21 shown in Figures 4, 5 and 6.

It will also be noted that each agglomerated block 26b, 26c and 26d has an axial housing having a shape corresponding to that of projectile 24, and allowing in particular to receive the fins 34 of the empennage 33 of the projectile.

Pawns 38, made of plastic, are disposed between the propulsion units 26b and 26c as well between propellants 26c and 26d. These pawns are regularly distributed angularly and allow ensure the angular connection of the different blocks to prevent shearing of the diffuser tubes 3. They also provide angular indexing of the blocks which allows the alignment of the different channels, thus authorizing the introduction of the tubes 3 after stacking of the blocks.

For example, three pawns 38 will be provided between each block.

Similarly, three other pawns 39 are interposed between the rear block 26a and the intermediate block 26b.

On fixe tout d'abord le bloc supérieur 26d sur le projectile 24, on met ensuite en place sur celui ci les pions d'indexation 38.

On met ensuite en place successivement sur le projectile le bloc intermédiaire 26c et le bloc intermédiaire 26b, en interposant entre eux des pions d'indexation 38.

On place les pions d'indexation 39. On glisse la douille 22 autour des blocs propulsifs et on rivette celle ci sur la pièce de liaison 25.

On met alors en place les différents tubes 3 au travers des canaux 28. Les tubes ont été préalablement raccordés au manchon 14 du moyen d'allumage.

On monte le bol 40 sur le culot 23 puis on colle le bloc propulsif arrière 26a dans le bol 40 (par des points de colle silicone). On pourra consulter le brevet FR2799831 qui décrit un mode de fixation d'un bol sur un culot.

On visse enfin l'allumeur sur le manchon 14 et on coiffe celui ci avec le culot qui sera fixé à l'allumeur par exemple par un écrou axial (voir le brevet FR2799831) et ensuite fixé par les rivets 41 à la douille 22.

The mounting of this ammunition is carried out as follows:

First of all, the upper block 26d is fixed on the projectile 24, and then the indexing pins 38 are placed on it.

The intermediate block 26c and the intermediate block 26b are then placed successively on the projectile, by interposing indexing pins 38 between them.

The indexing pins 39 are placed. The socket 22 is slid around the propulsion units and the latter is riveted on the connecting piece 25.

The different tubes 3 are then put in place through the channels 28. The tubes have been previously connected to the sleeve 14 of the ignition means.

The bowl 40 is mounted on the base 23 and then the rear propellant block 26a is glued to the bowl 40 (using dots of silicone glue). We can consult the patent FR2799831 which describes a method of fixing a bowl on a base.

Finally, the igniter is screwed onto the sleeve 14 and the latter is capped with the base which will be fixed to the igniter for example by an axial nut (see patent FR2799831) and then fixed by the rivets 41 to the socket 22.

Different variants are possible without leaving the part of the invention.

It is thus possible to carry out a loading comprising three agglomerated propellants but in which ignition will be ensured from the single block intermediate 26c. The diffuser tubes will then pass through block 26b and only intermediate block 26c will carry ignition channels 28.

We can also vary the number and angular distribution of the diffusing tubes. We can also vary the depth of the ignition channels by providing for example for a given block several channels different depths.

Claims (10)

Ignition device (1) for a propellant charge, comprising at least one igniter means (2), device characterized in that it comprises at least one inert diffuser tube (3) extending through part of the charge propellant and for guiding the flame generated by the igniter means (2) to a receiving zone of the propellant charge. Ignition device according to claim 1, characterized in that the diffuser tube (3) is made of flexible plastic. Ignition device according to claim 2, characterized in that the diffuser tube (3) has a thickness of between 0.7 and 1.5 mm. Ignition device according to claim 3, characterized in that the diffuser tube (3) has an internal diameter of 3 to 6 mm. Ignition device according to one of claims 1 to 4, characterized in that the igniter means (2) generates a plasma. Ignition device according to claim 5, characterized in that it comprises an expansion chamber (20) disposed between the outlet of the plasma igniter (2) and the diffuser tube (s) (3). Propellant charge for ammunition intended to be initiated by a device according to one of claims 1 to 6, characterized in that it comprises at least one block of agglomerated propellant powder (26b, 26c, 26d), block carrying at least one channel of blind ignition (28b, 28c, 28d) intended to receive a diffuser tube (3b, 3c, 3d). Propellant charge for ammunition according to claim 7, characterized in that it comprises at least two blocks (26b, 26c, 26d) of agglomerated propellant powder stacked one on the other, at least one first block (26b, 26c) carrying at least one through connection channel (32b, 32c) which is intended to receive a diffuser tube (3c, 3d) passing through said first block to come to be housed in an ignition channel (28c, 28d) arranged on a second block (26c, 26d). Propellant charge for ammunition according to claim 8, characterized in that each block (26b, 26c, 26d) carries three blind ignition channels (28b, 28c, 28d) regularly angularly distributed and intended to receive a diffuser tube (3b, 3c 3d). Propellant charge for ammunition according to claim 9, characterized in that it comprises at least three agglomerated blocks (26b, 26c, 26d) which each comprise three blind ignition channels (28b, 28c, 28d) regularly distributed angularly and intended for receive a diffuser tube (3b, 3c, 3d), the block closest to the igniter (26b) also comprising six through connecting channels (32b) and an intermediate block (26c) including three through connecting channels (32c) .

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