ELECTRIC IGNITION OF A FIREARM IGNITIONER

Description

Subject of the invention

[0001] The present invention relates to an electric primer as well as to a small caliber ammunition comprising such an electric primer, a firearm as well as an associated method. A primer of the prior art is known from FR 2438820 A1. State of the art

[0002] Electrical priming of small caliber ammunition is known for example from US10415944. This type of primer comprises numerous assembled parts, with electrical contacts obtained by pressure between the different parts. In particular, in this document, a pole piece insulated from the rest of the primer cup by an elastic material comes into electrical contact by pressure on the rear face of an insulating plate. The front face of said plate comprises an electrical resistor allowing the ignition of the priming charge, a metallized through hole allowing one terminal of the resistor to be connected to the rear face of the plate, and metallized tracks connecting the other terminal to the walls of the cup.Although such a configuration provides good mechanical resistance during detonation by using a thick pole piece, it has the disadvantage of significant assembly complexity in addition to the risk of poor electrical contact, or even false contact. Summary of the invention

[0003] The invention aims to overcome at least one of the drawbacks of the aforementioned state of the art. More particularly, the invention aims to adapt a primer to small or medium calibers without causing additional cost.

[0004] By small or medium caliber, we mean portable individual weapons, as opposed to weapon systems requiring the intervention of several users. In particular, the invention relates to so-called "reduced lethality" launchers (or weapons) in which the impact energy density (projectile energy on impact divided by the impact surface) is low, generally less than 100J / cm 2< , preferably less than 50J / cm 2< , typically 30J / cm 2< ). Advantageously, this kinetic energy density on impact is nevertheless at least 7J / cm 2< , preferably at least 15J / cm 2< .

[0005] The invention relates to a primer for an individual firearm comprising: a primer cup comprising a cylindrical side wall closed at an external end by a bottom; a pyrotechnic (or explosive) charge arranged in the primer cup; an electrical component adapted to produce the thermal energy necessary for initiating the pyrotechnic charge, said charge being in contact with the electrical component; a printed circuit, said printed circuit comprising an internal face comprising the electrical component in contact with the pyrotechnic charge, characterized in that said printed circuit forms at least in part the external bottom of the primer cup.

[0006] According to advantageous embodiments of the invention, the primer comprises one or more of the following technical characteristics, in any suitable combination: said internal face of the printed circuit has a surface representing at least 40%, preferably at least 60%, in particular at least 70% and in particular at least 80% of the surface defined by π / 4.D2, D being the diameter of the primer; an external face of the printed circuit is flush with the rear base of the cylindrical side wall of the primer cup; the printed circuit is in the form of a disc comprising a shoulder configured so that the printed circuit can be inserted by form-fitting into the primer cup; the two cylindrical surfaces of different diameters are connected to each other at one of their ends by the annular shoulder, the two cylindrical surfaces being respectively closed by the internal face and the external face at their other end;the printed circuit comprises a conductive annular portion, the starter cup being in electrical contact with the printed circuit either via a conductive washer bearing on said conductive annular portion and on a corresponding portion of an internal surface of the cylindrical side wall of the starter cup, or via a conductive glue or solder applied between said conductive annular portion and a corresponding portion of an internal surface of the cylindrical side wall of the starter cup; the printed circuit comprises a first electrode passing through a central portion of the printed circuit, said electrode extending from the internal face to the external face and a second electrode of annular shape and positioned at the periphery of the printed circuit;the first electrode has two ends, one of which is connected to the electrical component and the other to a conductive plate, preferably without perforation, arranged on the external face of the printed circuit; the electrical component is electrically connected to the second electrode; the electrical component comprises a resistor adapted to initiate the pyrotechnic charge; an annular radial projection extends from the end of the lateral cylindrical wall towards the inside of the primer and a lateral face of said projection bears against the shoulder of the printed circuit; the external face of the printed circuit is flush with the other radial lateral face of the annular radial projection; the electrical component is positioned on the axis of the primer cup; the pyrotechnic charge is a primary charge configured to initiate ignition;Primer (2) according to any one of the preceding claims, characterized in that at least a portion of a peripheral edge of the printed circuit (16) bears against a corresponding portion of cylindrical side wall (6).

[0007] The invention also relates to a munition comprising a primer according to the invention, characterized in that the munition comprises a projectile, in particular a projectile with reduced lethality.

[0008] The invention also relates to a firearm comprising an electrical priming circuit comprising a control unit making it possible to measure a quantity of the electrical circuit of the ammunition of the invention when the latter is placed in the firearm, said control unit determining, as a function of said measurement, the presence of ammunition in accordance with the invention.

[0009] The measures of the invention are interesting in that they make it possible to advantageously combine the field of cartridge making (essentially stamping) and the field of electronics (electronic card assembly).

[0010] By using on the one hand a widely industrialized mechanical part, the primer cup, and on the other hand an electronic part that is also widely industrialized, a printed circuit, it is possible to obtain a simple and therefore inexpensive overall assembly.

[0011] Furthermore, a printed circuit board has good insulating properties and fire resistance suitable for the constraints of using a firearm.

[0012] This type of primer is particularly suitable for so-called "reduced lethality" weapons in which the pyrotechnic charges used to propel the projectile are reduced, thereby reducing the mechanical stress on the bottom of the cartridge.

[0013] Finally, the measures of the invention make it possible to improve the safety of use and can advantageously serve as a means of error detection. Brief description of the figures

[0014] There figure 1 represents a cross-section of an example of a primer according to the invention. The figure 2 represents an exploded view of an example of a primer cup according to the invention. The figure 3 represents a munition comprising a primer according to the invention. The figure 4 represents a rear perspective view of a primer cup according to an example of the invention. The Figure 5 represents a rear perspective view of a primer cup according to an example of the invention. The figure 6 represents a priming circuit and an interface adapted to the primers according to the invention. Legend of the figures

[0015] 1. Ammunition 2. Primer 4. Primer cup 5. Case sidewall 6. Cylindrical primer sidewall 8. Base 10. Projectile 12. Primary charge 14. Secondary charge 16. Printed circuit board 18. Internal face of printed circuit board 20. External face of printed circuit board 22. Electrical component (Resistor) 24. First electrode 26. Second electrode 28. Conductive plate 30. Conductive washer 31. Conductive solder 32. Annular shoulder 34. Annular radial projection 36. Additional annular plate 38. Electrical contacts 42. Voltage source 44. Capacitor Detailed description of the invention

[0016] There figure 1represents a schematic view of a cross-section of a primer 2 according to the invention. The primer 2 comprises a primer cup 4 comprising a cylindrical side wall 6, one end of which is closed by a bottom 8 and the other end, open, is adapted to be inserted into a munition 1. The primer 2 comprises a pyrotechnic charge 12, called primary charge 12. This primary charge 12 can be configured to optimize the ignition of a secondary charge 14 included in the munition 1 (cf. Fig. 3 )., or serve directly as a propellant charge, in particular, advantageously in the case of low-power munitions such as reduced-lethality launchers.

[0017] By "reduced lethality launcher" we mean firearms with reduced probabilities of causing serious injury. This reduced lethality can be achieved by using specific projectiles with low penetration (plastic projectile, rubber, breakable casing containing shot that disintegrates on impact, etc.) and / or density with reduced kinetic energy (i.e. the kinetic energy related to the impact surface is typically around 30 joules / cm 2). These projectiles can nevertheless be disabling, causing pain and / or a recoil effect sufficient to dissuade an attacker from continuing their action. They also allow, in the case of certain projectiles, to "mark" the target using easily identifiable dyes.

[0018] In the figure 1, a printed circuit 16 (Printed Circuit Board (PCB) in English) has two opposite faces 18, 20, said circuit 16 forming at least in part the bottom 8. The two opposite faces comprise an internal face 18 oriented towards the front of the primer 2 in the firing direction and an external face 20 oriented towards the rear. Preferably, the opposite faces 18, 20 are circular. The printed circuit 16 comprises at least one electrical component 22, in particular a resistor 22, or even several arranged in parallel or in series to optimize (multipoint ignition) or guarantee the priming of the pyrotechnic charge 12 by redundancy. The resistor(s) 22 are arranged on the internal face 18 (facing the pyrotechnic charge 12) of the printed circuit 16 so that at least the resistor(s) 22 are in thermal contact with the pyrotechnic charge 12. The figure 1presents an embodiment with a resistor 22 which is connected in series to a first 24 and a second 26 electrode. Preferably, the first electrode 24 is arranged in a central portion of the printed circuit 16. This first electrode 24 comprises a conductive rear face 28, a via passing through the PCB and a front contact in electrical contact with the electrical component 22.

[0019] The electrical component 22, in particular an electronic compound, preferably a resistor 22, makes it possible to initiate, by heating, the primary pyrotechnic charge 12. For example, the component is either a resistor 22 mounted using an automatic placement machine widely used in electronics, or a simple track whose width is calculated to heat up (or even melt) to the desired temperature.

[0020] Advantageously, the electrical component 22 may comprise a wire or a strip of metal or alloy connected to two connection parts, said wire or said strip being able to be in direct contact with the pyrotechnic charge 12 (primary).

[0021] The first electrode 24 is made of a conductive material such as a metal. One end of the first electrode 24 is secured to a conductive plate 28 disposed on the external face 20 of the printed circuit 16 as illustrated in figures 4 And 5 The other end of the primary electrode is connected to a terminal (conductive part) of the resistor 22. The other terminal (conductive part) of the resistor 22 may be integral with an electrically conductive element arranged radially on the printed circuit 16, extending from its periphery to its central portion, said element being able to be integral with the second electrode when it is formed on the periphery of the printed circuit 16.

[0022] There figure 2 shows an exploded view of a primer 2 according to the invention comprising a primer cup 4, a printed circuit 16 and a fixing washer 30. The printed circuit 16 may be in the form of a plate, in particular a disc comprising a plastic material preferably with a polymer matrix. This material advantageously comprises a filler of mineral fibers such as glass fibers, woven or not. An example of this type of material is an epoxy / glass fiber composite. The printed circuit 16 may be delimited laterally by two cylindrical surfaces of different diameters connected by an annular shoulder 32. The second electrode 26 may be formed at the periphery of the printed circuit 16. The second electrode 26 may be an electrically conductive annular plate.

[0023] As illustrated in figure 2, the washer 30 is held in the primer cup 4 by friction. The washer 30 may bear against a peripheral portion of the printed circuit 16 and a portion of the internal surface of the primer cup 4. The washer 30 may be made of a current-conducting material, such as metal. The washer 30 may also serve as a means for retaining the printed circuit 16. Indeed, when the cylindrical side wall 6 of the primer cup 4 has an annular radial projection 34 directed towards the center of the primer 2, the printed circuit 16 is sandwiched (“pincer-like”) between the annular radial projection 34 (forming an annular surface in contact with a peripheral edge of the printed circuit 16) and the washer 30.

[0024] According to a preferred alternative, and as shown in figure 1, the printed circuit is held in place by a conductive glue or by soldering forming a solder ring 31 between the cylindrical side wall 6 and a conductive annular zone at the periphery of the internal face 18 of the printed circuit 16.

[0025] The choice of the ratio between the internal surface 18 of the printed circuit 16 and the surface defined by π 4 .D 2< where π = 3.1415 and D defines the diameter of the primer 2, is linked to the diameter D of the primer 2 and to the desired level of electrical insulation of the printed circuit 16. A surface ratio defined by the following ranges: at least 50%, preferably at least 60%, in particular at least 70% and notably at least 80%, allows optimized operation of the primer 2.

[0026] An electrical circuit of the primer 2 described in the figure 1comprises in series at least one or all of the following components integral with the printed circuit 16: the conductive plate 28 (central), the first electrode 24, the electrical component 22 (resistance), the radial conductive element, the annular plate, as well as at least one or all of the following components integral with the starter cup 4: the washer 30 (or a conductive glue or conductive solder), the cylindrical side wall 6, the annular radial projection 34 and optionally an additional annular plate 36 concentric contiguous with said projection as illustrated in Figure 5 . The solution of the Figure 5 allows electrical contactors 38 to be brought together without the annular radial projection 34 being extended. The annular radial projection 34 can be obtained by deformation of the initiator cup 4.

[0027] Preferably, the central conductive plate 28 and the annular radial projection 34 or the additional annular plate 36 serve as electrical contacts with the electrical contactors 38 disposed on the firearm as illustrated in Figure 5 (solution with additional ring plate 36, see the figure 4 ).

[0028] There Figure 5 shows a schematic perspective view of the priming system at the firearm. The electrical interface between the firearm and the primer 2 may comprise two electrical contactors 38 intended to be held in contact against the bottom 8 by return means (e.g.: springs) when the primer is housed in the breech.

[0029] The electrical power supply circuit may be of the capacitive type. A capacitive type circuit is well known, for example, in the automotive field for ignition. Typically, a capacitive circuit comprises one or more electronic switches, in particular at least one transistor 40 configured to control the flow of current, at least one voltage source 42 and / or current, as well as a capacitor 44 configured to initially accumulate electrical energy which will then be restored and partially dissipated in the resistor 22 of the primer 2 after the electrical circuit has been closed by at least one of the transistors 40 after a firing request. An electronic switch 40 is also understood to mean a power switch / transistor capable of absorbing the current peak occurring in the electrical circuit when the electrical component 22, in particular the resistor 22, is short-circuited with the capacitor 44.

[0030] The firearm according to the invention also makes it possible to avoid the priming of a primer that does not conform to the firearm and that has been lodged by mistake in the breech, thus improving the safety of use by mechanical (e.g.: size of the primer) and electronic (e.g.: predefined electrical response to an electrical signal produced by the firearm) error prevention.

[0031] At least one of the electrical contactors 38 exerts a very low force on the base (i.e. the rear face of the bottom 8 of the primer cup 4) of the primer, i.e. less than 10 N or even less than 1 N. Therefore, no risk of percussion of the primer is conceivable with a firearm according to the invention.

[0032] In addition, the firearm includes a device configured to perform the steps of a securing process (electronic keying): measure an electrical quantity of the electrical circuit such as resistance; deactivate the firing control (or alert the user by means of a signal, in particular audible, vibratory and / or visible) when the detected quantity is outside a predefined range of values.

[0033] In particular, resistor 22 (or the filament acting as resistor) has a low heat resistance so that ignition of the primary charge destroys it. In this way, the detection of an infinite resistance on the priming circuit makes it possible to determine that the loaded ammunition has already been used and needs to be replaced. This characteristic is particularly useful in the case of multiple ammunition placed in a circuit intended for sequential ignition of different cartridges loaded simultaneously.

Claims

1. Primer (2) for a personal firearm, comprising: - a primer cup (4) including a cylindrical side wall (6) closed at one outer end by a bottom (8); - a pyrotechnic charge (12) arranged in the primer cup (4); - an electrical component (22) configured to produce thermal energy necessary for priming the pyrotechnic charge (12), said charge (12) being in contact with the electrical component (22); - a printed circuit board (16), said printed circuit board (16) comprising an inner face (18) comprising the electrical component (22) in contact with the pyrotechnic charge (12), characterized in that said printed circuit board (16) forms at least in part the outer bottom (8) of the primer cup (4).

2. Primer (2) according to claim 1, wherein said inner face (18) has a surface area representing at least 40%, preferably at least 60%, in particular at least 70% and notably at least 80% of the surface area defined by π 4 . D 2 , where D is the diameter of the primer (2).

3. Primer (2) according to claim 1 or 2, characterized in that an outer face (20) of the printed circuit board (16) is flush with the rear base of the cylindrical side wall (6) of the primer cup (4).

4. Primer (2) according to any one of the preceding claims, characterized in that the printed circuit board (16) is in the form of a disc including a shoulder (32) configured to permit the printed circuit board (16) to be inserted into the primer cup (4)by form-fitting.

5. Primer (2) according to the preceding claim, characterized in that the two cylindrical surfaces having different diameters are connected to one another at one of their ends by the annular shoulder (32), the two cylindrical surfaces being closed respectively by the inner face (18) and the outer face (20), at their other end.

6. Primer (2) according to any one of the preceding claims, wherein the printed circuit board (16) comprises a conductive annular portion, the primer cup (4) being in electrical contact with the printed circuit board (16) either via a conductive washer (30) bearing on said conductive annular portion and on a corresponding portion of an inner surface of the cylindrical side wall (6) of the primer cup (4), or via a conductive adhesive or brazing (31) applied between said conductive annular portion and a corresponding portion of an inner surface of the cylindrical side wall (6) of the primer cup (4).

7. The primer (2) according to any one of the preceding claims, characterized in that the printed circuit board (16) comprises a first electrode (24) crossing through a central portion of the printed circuit board (16), said electrode extending from the inner face (18) to the outer face (20) and a second electrode with annular shape and positioned at a periphery of the printed circuit board (16).

8. Primer (2) according to the preceding claim, characterized in that the first electrode (24) has two ends, one of which is connected to the electrical component (22) and the other to a conductive plate (28), preferably without perforation, arranged on the outer face (20) of the printed circuit board (16).

9. Primer (2) according to any one of the preceding claims, characterized in that the electrical component (22) is electrically connected to the second electrode (26).

10. Primer (2) according to any one of the preceding claims, characterized in that the electrical component (22) comprises a resistor configured to initiate the pyrotechnic charge (12).

11. Primer (2) according to any one of the preceding claims, characterized in that an annular radial protrusion (34) extends from the end of the lateral cylindrical wall (6) towards the inside of the primer (2) and a lateral face of said protrusion (34) bears against the shoulder (32) of the printed circuit board (16).

12. Primer (2) according to any one of the preceding claims, characterized in that the electrical component (22) is positioned on an axis of the primer cup (4).

13. Primer (2) according to any one of the preceding claims, characterized in that the pyrotechnic charge (12) is a primary charge (12) configured to initiate the ignition.

14. Primer (2) according to any one of the preceding claims, characterized in that at least a portion of a peripheral edge of the printed circuit board (16) bears against a corresponding portion of the cylindrical side wall (6).

15. Ammunition (1) comprising a primer according to any one of the preceding claims, characterized in that the ammunition (1) comprises a projectile (10), in particular a less lethal projectile (10).