Connecting device between an igniter of a propellant charge and a combustible casing of ammunition, combustible casing and elastic washer cooperating with such a connecting device

Description

[0001] The technical field of the invention is that of combustible cases for ammunition and in particular for large caliber ammunition (greater than 45mm).

[0002] Combustible cartridge cases have been used for many years in tank ammunition. They offer the advantage of reducing the volume of spent cartridges, which are then limited to the metal obturator base that ensures a tight seal after firing. This base can contain some of the ignition components after firing.

[0003] For example, patent FR2365096 describes a method of attaching a cartridge case to a combustible cartridge case using an elastic washer. This solution allows for limited relative movement of the cartridge case and the case. The connection is made internally, for example, by an elastic ring attached to the cartridge case and pressed against the washer. The main drawback of this design is that it does not allow the case to be loaded with propellant powder from the rear.

[0004] To facilitate rear loading, patent EP1092939 proposed linking the base to the combustible casing with an interposed plastic bowl. The mechanical connection of the base is achieved via a rear nut that screws onto an igniter support piece attached to the bowl. However, the connection between the bowl and the casing remains fragile, and this solution requires the assembly of a significant number of parts.

[0005] Also known from patent EP463904 is a combustible case that is connected to the cartridge base by means of an axial plastic connecting piece, itself glued to the case. The cartridge base clips onto this connecting piece. Although the case can be loaded with propellant powder from the rear, before the cartridge base is attached, through vents in the base of the case, it is no longer possible to remove the cartridge base once it has been attached to the case.

[0006] Furthermore, installing the igniter in such a powder charge is complicated. In particular, it requires an additional sleeve that defines the location of the igniter tube and is attached to the axial connecting piece. Finally, this solution does not allow for the placement of a spring washer between the combustible sleeve and the base.

[0007] Today, efforts are underway to develop ammunition whose ignition system is no longer a simple igniter tube but incorporates cords that extend through the propellant charge. Patent EP3715776 describes such an ignition system architecture.

[0008] It is clear that these ignition devices require, firstly, rear loading after the ignition device has been installed, and secondly, that the ignition device cannot be rotated after installation. The same applies to a so-called conventional ignition device (for example, an igniter tube) which is used in conjunction with rear loading of the powder.

[0009] Patents DE 600 11 011 T2 and DE 601 04 950 T2 also constitute a relevant prior art.

[0010] Therefore, there is a need to define a device to ensure the connection between the propellant ignition mechanism and the propellant case. This device must simultaneously allow for rear loading of the propellant powder, the insertion of a spring washer to ensure a flexible connection between the base and the propellant case, and the final securing of the base to the case. All operations must be performed without rotating the ignition mechanism.

[0011] The purpose of the invention is to provide such a connection device.

[0012] Thus, the invention relates to a device for connecting a means for igniting a propellant charge to a combustible cartridge case comprising a base pierced with an axial opening through which the ignition means is placed and at least one peripheral vent intended to allow the cartridge case to be loaded with the propellant charge, a device in which the ignition means is intended to be made integral with a sealing cap after the combustible cartridge case has been loaded, a cap which is placed over the base of the combustible cartridge case, a device comprising a means for retaining the ignition means on the combustible cartridge case, a means which ensures the immobilization of the ignition means before the combustible cartridge case is loaded and before the sealing cap is attached,the retaining means comprising, on the one hand, a stop ring integral with the ignition means and bearing against an internal surface of the case base via a spring washer, and on the other hand, a retaining ring integral with the ignition means which cooperates with at least one stop surface integral with the case base.

[0013] Depending on one characteristic, the stop ring may include a cylindrical extension onto which the retaining ring will be fixed.

[0014] Advantageously, the stop ring may include a crown extending at a distance from the ignition means and having a face intended to be applied against the spring washer.

[0015] According to one embodiment of the invention, the stopping surface may consist of at least one combustible tab attached to the bottom of the case in the vicinity of the axial opening.

[0016] In this case, and advantageously, the spring washer and the stop ring may include at least one notch intended to cooperate with the tab so as to ensure rotational locking of the washer and the stop ring relative to the case.

[0017] According to another embodiment of the invention, the stopping surface may consist of a ring intended to be positioned in the axial opening of the case, the ring having an external collar intended to be applied to an external surface of the bottom of the case and an internal collar on which the retaining ring will be applied.

[0018] In this case, and advantageously, the spring washer may include at least one upper blade intended to cooperate with a slot in the stop ring so as to ensure rotational locking of the washer relative to the stop ring.

[0019] Advantageously, the elastic washer may also include at least two lower blades which are intended to be positioned against the edges of one or more vents of the case so as to ensure rotational locking of the washer relative to the case.

[0020] The invention also relates to a combustible cartridge case intended to be equipped with an ignition means using a linking device according to one of the preceding characteristics, the cartridge case having a base pierced with an axial opening intended to receive the ignition means and at least one peripheral vent intended to allow the cartridge case to be loaded with a propellant charge, the cartridge case characterized in that it has at least one combustible tab integral with the base of the cartridge case in the vicinity of the axial opening, the tab intended to constitute a stopping surface for a retaining ring of the ignition means.

[0021] The invention also relates to an elastic washer intended to be interposed between a combustible casing and a stop ring of a means for retaining a connecting device according to one of the preceding characteristics, an elastic washer which is characterized in that it comprises means ensuring its rotational connection with the combustible casing and / or with the stop ring of the retaining means.

[0022] According to one embodiment, the means ensuring the rotational connection of the elastic washer with the combustible casing and / or with the stop ring consist of at least one notch provided on an internal circular profile of the washer, notch intended to cooperate with a tab of the combustible casing so as to ensure rotational locking of the washer relative to the casing.

[0023] According to another embodiment, the means ensuring the rotational connection of the elastic washer with the combustible casing and / or with the stop ring consist of at least one upper blade disposed on an upper face of the washer and intended to cooperate with a slot in the stop ring, and at least two lower blades which are intended to be positioned against edges of one or more vents of the casing so as to ensure rotational locking of the washer relative to the casing.

[0024] The invention will be better understood upon reading the following description of different embodiments, a description made with reference to the attached drawings, in which: [ Fig. 1 ] is a cross-sectional view of a cartridge case base and bottom carrying an ignition means connected to the case by a linking device according to a first embodiment of the invention; [ Fig. 2 ] represents, alone and in cross-section, the stop ring of the device according to this first embodiment; [ Fig. 3 ] represents, alone and in perspective, the stop ring of the device according to this first embodiment; [ Fig. 4 ] represents a cross-sectional exploded view of the different parts of the device according to this first embodiment; [ Fig. 5 ] represents, in internal view, a combustible casing according to this first embodiment of the invention, equipped with the elastic washer; [ Fig. 6 ] represents in perspective an elastic washer according to this first embodiment of the invention; [ Fig. 7 ] is a cross-sectional view of a cartridge case base and a case bottom carrying an ignition means connected to the case by a linking device according to a second embodiment of the invention; [ Fig. 8 ] represents, alone and in perspective, the stop ring of the device according to this second embodiment; [ Fig. 9 ] represents a cross-sectional exploded view of the different parts of the device according to this second embodiment; [ Fig. 10 ] represents in perspective an elastic washer according to this second embodiment of the invention; [ Fig. 11 ] represents, in internal view, a combustible case according to this second embodiment of the invention, equipped with the elastic washer.

[0025] By referring to the figure 1 A munition 1 comprises a case 2 made of combustible material, for example, cardboard impregnated with nitrocellulose. The case 2 delimits an internal volume 3 which is intended to receive a propellant charge of grains (not shown), as well as a projectile which is also not shown and which is, for example, attached to the case at a front part thereof.

[0026] The invention relating to the linking device between ignition means and case, we have therefore limited ourselves to representing the base of the case 2 on which a metal base 4 is fixed. In a conventional way, the metal base 4 is provided with a sealing lip 5 made of rubber and which is fixed at the level of an annular hooking bead 6 provided at the front end of the base 4.

[0027] The base 4 is fixed by a nut 7 on an ignition means 8 of the propellant charge.

[0028] In this description, we have limited ourselves to representing a portion of the ignition means 8 that enables mechanical interaction with the cartridge case 2 and the base 4. The portion of the ignition means specific to igniting the propellant charge is not described. For the sake of simplicity, we will subsequently refer to this single interface portion of the complete ignition means as the ignition means 8.

[0029] The ignition means 8 comprises a metallic body 8a having an axial bore 9 which is intended to receive an igniter and an ignition relay (not shown).

[0030] Ignition cords (not shown, as described in patent EP3715776) will be attached to the body of the ignition means 8 in such a way that they can be ignited by the relay installed in the axial bore 9. The cords will be attached to a forward extension 8b of the body 8a. The ignition cords could be replaced by any other means of igniting the propellant powder, for example a black powder wand (often referred to by the abbreviation "TPA" or Primer Tube).

[0031] The metal body 8a of the ignition means 8 also includes a rear extension 8c onto which the base 4, which has an axial bore 10 for this purpose, will be positioned. An annular groove 11 is formed on the rear extension 8c. It allows for the fitting of an annular sealing gasket (not shown).

[0032] The metal body 8a finally has a central portion 8d with a diameter larger than those of the other two portions 8b and 8c. This central portion 8d has an external thread 8e onto which a stop ring 12 is screwed, the latter having a tapped hole 12a for this purpose. The stop ring 12 has an internal flange 13 which bears against an underside face 8f of the metal body 8a ( figure 4 ). Thus, after screwing the stop ring 12 onto the metal body 8a, these two parts are completely joined together.

[0033] The connection can be secured by a suitable means to prevent unscrewing, for example, a thread locker, such as a plastic ring positioned on part of the thread 8e, or a drop of glue between the two parts. As an alternative, the stop ring 12 and the metal body could be made as a single unit.

[0034] The thrust ring 12 is particularly visible on the figures 2 And 3 It is noted that it comprises a flared ring 14 extending away from the ignition means 8 and interrupted here by three notches 15 regularly spaced at an angle. It is understood that the number of notches 15 could be different. The flared ring 14 has a bearing surface 16 designed to bear against an internal surface 2a of the base of the case 2, with an interposed spring washer 17.

[0035] Furthermore, the stop ring 12 has a cylindrical extension 18 whose external cylindrical surface is threaded. This cylindrical extension is designed to receive a retaining ring 19, which is here equipped with a threaded hole.

[0036] According to one variant, the retaining ring 19 could be made in the form of an elastic ring. In this case, the external cylindrical surface of the extension 18 will not have threads but will have a groove allowing the retaining ring to be fitted.

[0037] As can be seen on the figures 1 , 4 And 5 The combustible casing 2 has an axial opening 20 through which the ignition means 8 is placed. figure 5 Figure 2 shows in particular the base 2a of the fuel casing 2. It can be seen that the casing 2 has three peripheral vents 21, regularly spaced angularly around the axis of the casing 2. These vents 21 are designed to allow the casing 2 to be loaded with a propellant charge. At least one vent would be sufficient for loading, but three vents further facilitate the homogeneous distribution of the propellant charge within the casing. It is, of course, possible to use a different number of vents: for example, two vents or more than three vents.

[0038] As can be seen on the figure 5 , the base of the case has three combustible tabs 22 which are regularly distributed angularly and which are made integral with the base 2a of the case 2 in the vicinity of the axial opening 20.

[0039] The 22 tabs have an S-shaped profile as seen in the figure 1 , profile whose free end extends above the axial opening 20. They are glued to the case 2, for example by a combustible adhesive. Such adhesives are well known to those skilled in the art.

[0040] The tabs 22 are intended to provide a stopping surface for the retaining ring 19 of the ignition means 8.

[0041] When the ignition means 8 is positioned in the case 2, it covers the opening 20 of the case and comes to rest against the tabs 22. It is indeed noted that the notches 15 of the stop ring 12 have a profile 23 ( figures 1 et 2 ) which comes to rest against the upper end of the tabs 22.

[0042] Once the ignition means 8 and the stop ring 12 are positioned in this way, screwing the retaining ring 19 onto the cylindrical extension 18 will cause the ends of the combustible tabs 22 to be pinched between the ring 19 and the profile 23. This results in the ignition means 8 being held relative to the case 2, a hold which allows the case 2 to be loaded through the vents 21 which remain largely unobstructed.

[0043] As we can see in figures 5 et 6 The elastic washer 17 has a crown 24 carrying on its periphery three elastic wings 25. The wings 25 are curved relative to the crown 24 and are intended to come into contact with the case 2 along the curved part 2b of the latter which connects the bottom 2a to the cylindrical part 2c of the case.

[0044] The wings 25 are perforated and have openings 26 which facilitate the combustion of the case 2 when firing while allowing control of the elasticity of the wings.

[0045] As we can see at the figure 5 , the three wings 25 are positioned alternately with the three loading vents 21.

[0046] This positioning is ensured by means of 27 notches ( figure 6 ) which are arranged on the internal circular profile of the washer 17. These notches are intended to cooperate with the tabs 22 of the combustible casing 2. They thus ensure a rotational locking of the washer 17 relative to the casing 2.

[0047] Therefore, there is no possible modification of the angular position of washer 17 relative to case 2.

[0048] Furthermore, it was noted previously that the notches 15 of the stop ring 12 also cover the tabs 22. These notches have the same width as the tabs 22 and therefore constitute a means preventing the rotation of the stop ring 12 (and therefore of the ignition means 8) relative to the case 2.

[0049] It is therefore observed that the retaining means according to the invention, which comprise, on the one hand, the stop ring 12 attached to the ignition means 8 and, on the other hand, the retaining ring 19 attached to the ignition means 8 and which cooperates with the stopping surface formed by the tabs 22, ensure a positioning of the ignition means 8 relative to the case 2 which allows the case 2 to be loaded with the propellant powder, while prohibiting any rotation and translation of the ignition means 8 relative to the case 2.

[0050] Once the loading is complete, the base 4 is positioned on the rear extension 8c of the metal body 8a of the ignition means 8 and the base 4 is fixed to the ignition means and to the case 2 by fitting the nut 7.

[0051] It is noted that tightening the nut 7 will cause the stop ring 12 to be firmly applied to the internal surface of the bottom 2a of the case 2 and the spring washer 17 to be pinched.

[0052] The elasticity of the connection between the base 4 and the case 2 is therefore preserved and subsequent disassembly remains possible.

[0053] No mechanical stress will be exerted on the retention means according to the invention during the insertion of the munition. These means are therefore designed simply to ensure the retention of the ignition element 8 during the loading phase of the cartridge case 2.

[0054] THE figures 7 à 11 show another embodiment of a linking device according to the invention.

[0055] This mode differs from the previous one essentially by the nature of the stopping surface against which the retaining ring 19 is applied.

[0056] The previous solution requires attaching combustible tabs to the combustible casing. This represents a certain cost and necessitates manufacturing the tabs from combustible material, then positioning and gluing these tabs onto the combustible casing.

[0057] This second embodiment proposes to make the stopping surface in the form of a ring 28 which is intended to be positioned in the axial opening 20 of the case.

[0058] Ring 28 is particularly visible at the figure 9 It has an S-shaped section and includes an external collar 29 which is intended to be applied to an external surface 2d of the bottom of the case 2. The ring 28 also includes an internal collar 30 which extends inside the opening 20 and onto which the retaining ring 19 will be applied.

[0059] Thus, it is sufficient to position (with or without gluing) the ring 28 in the axial opening 20 of the case and then to carry out the operations for fixing the ignition means 8 described previously: Positioning of the ignition means 8 in the case 2: the ignition means 8 covers the opening 20 of the case and the stop ring 12 integral with the ignition means 8 comes to rest against the internal surface of the bottom 2a of the case 2 by means of the elastic washer 17; Screwing of the retaining ring 19 onto the cylindrical extension 18 of the stop ring 12, which leads to the pinching of the internal collar 30 of the ring 28 between the retaining ring 19 and the stop ring 12.

[0060] This results in the ignition means 8 being held in relation to the case 2, a holding which allows the case 2 to be loaded through the vents 21 which remain largely unobstructed.

[0061] As an alternative, the opening 20 may be countersunk on its outside. This countersinking will allow the thickness of the outer collar 29 of the ring 28 to be embedded within the thickness of the combustible casing.

[0062] In order to ensure the immobilization in rotation of the ignition means 8 relative to the case, this embodiment includes other modifications compared to the previous embodiment.

[0063] Thus, as can be seen in the figure 10 The elastic washer 17 has a crown 24 carrying on its periphery three elastic wings 25. The wings 25 are curved relative to the crown 24 and are intended to come into contact with the case 2 along the curved part 2b of the latter which connects the bottom 2a to the cylindrical part 2c of the case.

[0064] The wings 25 are perforated and have openings 26 which facilitate the combustion of the case 2 when firing while allowing control of the elasticity of the wings.

[0065] As we can see at the figure 11 , the three wings 25 are positioned alternately with the three loading vents 21 made on the case 2.

[0066] In order to prevent the elastic washer 17 from rotating relative to the case 2, this washer 17 has at least two lower fins 31 which are designed to be positioned against the edges of one or more vents 21 of the case 2. As can be seen in the figure 11 The lower slats 31 are positioned on the edges of the elastic wings 25. Indeed, each wing 25 of the washer 17 covers the entire area separating two consecutive vents 21. It is therefore easy to engage the lower slats 31, which are supported by the lateral edges of a wing 25, inside two adjacent vents 21.

[0067] Here, to facilitate the placement of the washer 17, there are two lower slats 31 per wing 25. Once the elastic washer 17 is positioned at the bottom of the case 2, there is therefore a rotational lock of the washer 17 relative to the case 2 thanks to the three pairs of lower slats 31.

[0068] Furthermore, the elastic washer 17 has at least one upper blade 32 which is carried by the ring 24 and which is intended to cooperate with a slot 33 of the stop ring 12.

[0069] Here there are four upper blades 32 regularly spaced angularly which engage in four slots 33 of the stop ring (see the figure 8 ). The number of upper slats (32) and slots could be different.

[0070] Thus, once the stop ring 12 carrying the ignition means 8 is positioned on the elastic washer 17, the stop ring 12 is rotationally linked to the elastic washer 17, and therefore also rotationally linked to the casing 2.

[0071] The upper and lower slats will be easily obtained by cutting and folding during the manufacture of washer 17.

[0072] It is therefore observed here again, for this second embodiment, that the retaining means according to the invention which comprise, on the one hand, the stop ring 12 integral with the ignition means 8 and on the other hand, the retaining ring 19 integral with the ignition means 8 and which cooperates with the stopping surface formed by the ring 28, ensure a positioning of the ignition means 8 relative to the case 2 which allows the case 2 to be loaded with the propellant powder, while prohibiting any rotation and translation of the ignition means 8 relative to the case 2.

[0073] Once the loading is complete, the base 4 is positioned on the rear extension 8c of the metal body 8a of the ignition means 8 and the base 4 is fixed to the ignition means and to the case 2 by fitting the nut 7.

[0074] It is noted that tightening the nut 7 will cause the stop ring 12 to be firmly applied to the internal surface of the bottom 2a of the case 2 and the spring washer 17 to be pinched.

[0075] The elasticity of the connection between the base 4 and the case 2 is therefore preserved and subsequent disassembly remains possible.

[0076] No mechanical stress will be exerted on the retention means according to the invention during the insertion of the munition. These means are therefore designed simply to ensure the retention of the ignition element 8 during the loading phase of the cartridge case 2.

[0077] Other variations are possible without departing from the scope of the invention.

[0078] It is therefore possible to replace the threaded retaining ring with a split elastic stop ring engaged in a groove of the cylindrical extension 18 of the stop ring 12.

Claims

1. - A connection device between an ignition means (8) of a propellant charge and a combustible case (2) of a round of ammunition that comprises a bottom pierced with an axial opening (20) through which the ignition means (8) is placed and with at least one peripheral vent (21) intended to allow the case (2) to be loaded with the propellant charge, in which device the ignition means (8) is intended to be secured to an obturator base (4) after the combustible case (2) has been loaded, base (4) which covers the bottom of the combustible case (2), wherein the device comprises means for holding the ignition means (8) on the combustible case (2), which means ensure the immobilization of the ignition means (8) before the loading of the combustible case (2) and before the attachment of the obturator base (4), the holding means comprising on the one hand a stop ring (12) secured to the ignition means (8) and bearing against an inner surface (2a) of the bottom of the case (2) by means of a spring washer (17) and on the other hand a retaining ring (19) secured to the ignition means (8) and which cooperates with at least one stop surface (22, 28) secured to the bottom of the case (2).

2. - The connection device between an ignition means of a propellant charge and a combustible case according to claim 1, characterized in that the stop ring (12) comprises a cylindrical extension (18) on which the retaining ring (19) is attached.

3. - The connection device between an ignition means of a propellant charge and a combustible case according to claim 2, characterized in that the stop ring (12) comprises a crown (14) extending at a distance from the ignition means (8) and carying a face (16) intended to be applied against the spring washer (17).

4. - The connection device between an ignition means of a propellant charge and a combustible case according to one of claims 1 to 3, characterized in that the stop surface is constituted by at least one combustible tongue (22) integral with the bottom of the case (2) in the vicinity of the axial opening (20).

5. - The connection device between an ignition means of a propellant charge and a combustible case according to claim 4, characterized in that the spring washer (17) and the stop ring (12) comprise at least one notch (15, 27) intended to cooperate with the tongue (22) so as to ensure rotational locking of the washer (17) and of the stop ring (12) relative to the case (2).

6. - The connection device between an ignition means of a propellant charge and a combustible case according to one of claims 1 to 3, characterized in that the stop surface consists of a ring (28) that is intended to be positioned in the axial opening (20) of the case (2), the ring comprising an outer flange (29) intended to be applied on an outer surface (2d) of the bottom of the case (2) and an inner flange (30) on which the retaining ring (19) is applied.

7. - The connection device between an ignition means of a propellant charge and a combustible case according to claim 6, characterized in that the spring washer (17) comprises at least one upper strip (32) intended to cooperate with a slot (33) of the stop ring (12) so as to ensure rotational locking of the washer (17) relative to the stop ring (12).

8. - The connection device between an ignition means of a propellant charge and a combustible case according to claim 7, characterized in that the spring washer (17) comprises at least two lower strips (31) which are intended to be positioned against edges of one or more vents (21) of the case (2) so as to ensure rotational locking of the washer (17) relative to the case (2).

9. - A combustible case for a round of ammunition intended to be equipped with an ignition means using a connection device according to one of claims 4 or 5, the case (2) comprising a bottom (2a) pierced with an axial opening (20) intended to receive the ignition means (8) and at least one peripheral vent (21) intended to allow the case to be loaded with a propellant charge, which case (2) is characterized in that it comprises at least one combustible tongue (22) integral with the bottom (2a) of the case (2) in the vicinity of the axial opening (20), which tongue (22) is intended to constitute a stop surface for a retaining ring (19) for the ignition means (8).

10. - A spring washer intended to be interposed between a combustible case (2) and a stop ring (12) of a holding means of a connection device according to one of claims 1 to 8, which spring washer (17) is characterized in that it comprises means (27, 31, 32) ensuring its connection in rotation with the combustible case (2) and / or with the stop ring (12) of the holding means.

11. - The spring washer according to claim 10 and intended to be associated with a connection device according to claim 5, characterized in that the means ensuring its connection in rotation with the combustible case (2) and / or with the stop ring (12) are constituted by at least one notch (27) provided on an inner circular profile of the washer (17), which notch (27) is intended to cooperate with a tongue (22) of the combustible case (2) so as to ensure rotational locking of the washer (17) relative to the case (2).

12. - The spring washer according to claim 10 and intended to be associated with a connection device according to claim 8, characterized in that the means ensuring its connection in rotation with the combustible case (2) and / or with the stop ring (12) are constituted by at least one upper strip (32) arranged on an upper face of the washer (17) and intended to cooperate with a slot (33) of the stop ring (12), and at least two lower strips (32) which are intended to be positioned against edges of one or more vents (21) of the case (2) so as to ensure rotational locking of the washer (17) relative to the case (2).