Pyrotechnic cartridge and launcher for a flammable gas premix
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Filing Date
- 2024-08-30
- Publication Date
- 2026-07-08
Smart Images
Figure FR2024051137_06032025_PF_FP_ABST
Abstract
Description
[0001] Description
[0002] Title: PYROTECHNIC CARTRIDGE AND LAUNCHER FOR FLAMMABLE GAS PREMIXTURE
[0003] FIELD OF THE INVENTION
[0004]
[0001] The present invention relates to the field of pyrotechnic cartridges and launchers, in particular for mixtures of flammable and / or inert gases under pressure, and possibly containing propellant powders. In particular, the invention provides a new cartridge with an flammable charge that is ready to use, reusable and has a chamber geometry that optimizes its performance. The invention also provides a launcher incorporating said optimized chamber geometry.
[0005] STATE OF THE ART
[0006]
[0002] Different types of pyrotechnic cartridges are known from the state of the art, the design of which varies depending on the desired application.
[0007]
[0003] In the ballistic sense, a "cartridge" secures a "projectile" (or "mobile" more generally), a "case" (or a "casing"), itself containing a "propellant" (reactive material releasing the propulsion energy), as well as a means of "igniting" or "priming" said propellant. In particular, on powder pyrotechnic cartridges, a "primer" which contains a small quantity of reactive material sensitive to shock allows, by its combustion, to ignite the main charge of propellant powder. The combustion of the powder causes the release of a large volume of very hot gas which, confined in the cartridge, causes a high overpressure. When the pressure increases sufficiently to overcome the force of forcing or retaining the projectile at the neck of the case, the projectile detaches from the case and, pushed by the high-pressure gases expanding behind it, accelerates inside the barrel and exits through the muzzle at a determined speed.Once the projectile has left the "launch tube" or "gun", the driving gases are fully expanded to the external pressure and the projectile continues its flight freely until impact with a target.
[0004] Propellant powders are generally used in ballistics because they allow a mobile to be propelled at high speed. However, they are not without drawbacks. Propellant powders generate strong erosion of the weapon tubes by the high temperatures reached on the surface of the metal, and by the high-speed powder grains abrading the wall. They also result in the production of a muzzle flash, due among other things to the solid residues of powder combustion and the post-combustion of the chemical species which can generate this reaction, which is handicapping in a military context (high visibility).In addition, pyrotechnic regulations are restrictive for the use, supply and storage of these propellant powders in a civil context.
[0008]
[0005] Gas cartridges represent an interesting alternative to propellant powder cartridges. However, the latter have mainly been used with inert gases (such as CO2 or N2O) for various civilian uses, and in vehicle airbag systems with a mixture of cold gas in the cartridge and pyrotechnic material in another compartment.
[0009]
[0006] Indeed, applications in ballistics remain quite limited and often reserved for air pistols or airsoft guns, where gas is used to propel the projectile. Inert gas cartridges (without combustion) do not allow military projectiles to be pushed at useful speeds in a reasonable space. These cartridges do not contain flammable premixes under pressure, nor propellant powder, and do not allow their contents to be primed, which results in insufficient power for most of the intended applications.
[0010]
[0007] On the other hand, when comparing the thrust capacity per unit mass of propellant as well as the achievable speeds, it turns out that light gas charges are more advantageous than pyrotechnic powder charges. In addition, the use of gas as a propellant charge allows for cleaner combustion which is less polluting for the environment compared to the use of propellant powders. It is therefore interesting to have pyrotechnic cartridges suitable for containing premixes of flammable gases or mixtures of propellant powder and inert gas under high pressure for the propulsion of projectiles. International patent application WO 2014 / 144104 gives an example of a gas rifle and its cartridge.
[0011]
[0008] However, it is still necessary to optimize the performance of pyrotechnic cartridges with flammable gas charges to consider their use in ballistic applications.
[0012]
[0009] The same problem is found in gas-fired flammable charge launchers. These do not use a cartridge as a casing for the flammable charge, but integrate a combustion chamber directly into the breech of the launcher, which is loaded with a gas mixture. However, the models ensuring the best propulsive performance also have larger dimensions, and it is desirable to reduce its size and / or increase its performance.
[0013] STATEMENT OF THE INVENTION
[0014]
[0010] The present invention aims to improve the combustion performance of a pyrotechnic cartridge and a launcher for a flammable gas charge, possibly containing a powder charge complementary to the gas charge. To this end, the invention proposes a new combustion chamber geometry making it possible to increase the combustion speed of a flammable charge containing gas alone, or gas and powder.
[0015]
[0011] In particular, the present invention relates to a pyrotechnic cartridge for an inflammable gas charge comprising a case having a proximal end provided with a base, and a distal end adapted to receive a mobile or a manometric enclosure head, (i.e. a closed manometric enclosure measuring tool).
[0016]
[0012] The cartridge of the invention is particular in that:
[0017] - the case has two chambers, an upstream chamber and a downstream chamber forming a longitudinal conduit with variable section, and in which
[0018] - said conduit has a convergent nozzle shape at an outlet of the upstream chamber opening into the downstream chamber, and a sharply flared shape at an inlet of the downstream chamber and relative to said outlet of the upstream chamber, said flared shape being capable of generating a highly turbulent gas jet in the downstream chamber.
[0019]
[0013] The invention thus proposes a cartridge comprising a geometry of internal chambers making it possible to generate by jet a high level of turbulence in the downstream chamber, and suddenly and significantly increasing the combustion speed once the flame enters it.
[0020]
[0014] In one embodiment, the pyrotechnic cartridge is intended for ballistic applications and therefore receives a mobile at its distal end. The optimized geometry of the cartridge will therefore ensure a high combustion speed in the ballistic phase, when the gas is released and pushes the mobile.
[0021]
[0015] In another embodiment, the pyrotechnic cartridge is intended for use as a pressure vessel, and therefore receives a pressure vessel head. The optimized geometry of the cartridge will therefore be used for measurement and research purposes on the combustion of flammable gas charges.
[0022]
[0016] Whatever the intended use of the pyrotechnic cartridge, the cartridge will be designed with an optimized internal chamber geometry to improve combustion. More particularly, the conduit formed by the upstream chamber and the downstream chamber has:
[0023] - at the level of the upstream chamber, a first part of constant section of a first diameter followed by a second part of convergent section becoming a neck of narrowed section of a second diameter, said neck being located at the level of the outlet of said upstream chamber, and
[0024] - at the downstream chamber, an inlet portion of constant section with a third diameter greater than said second diameter.
[0017] The cartridge case may incorporate a dynamic seal between the outlet of said upstream chamber and the inlet of the downstream chamber, such as a sealing valve. It is thus possible to use the upstream chamber as a storage chamber dedicated to the gas.
[0025]
[0018] In one embodiment of the pyrotechnic cartridge, the conduit also comprises a convergent nozzle shape at the outlet of said downstream chamber.
[0026]
[0019] A second objective of the invention is to provide a pyrotechnic cartridge with optimized geometry which is reusable and easy to manufacture.
[0027]
[0020] To this end, the invention proposes to produce the cartridge case in two parts, a first part integrating the upstream chamber, and a second part integrating the downstream chamber, as well as to connect the two parts together in a sealed and secure manner at an outlet of the upstream chamber. Preferably, in a connection between said two parts, a distal end of the first part is inserted into the second part, and integrates attachment means, such as clip-on or screw-on attachment means, and a seal.
[0028]
[0021] For its part, the base of the pyrotechnic cartridge comprises a gas filling and adjustment port, said port incorporating a support plug followed at its bottom by a sealing valve and a return spring, as well as comprising a sealing system with said base. Similarly, the base incorporates a pair of through-lugs having a coating of insulating material, and opening out as a pair of uncoated projections on an internal side of the base.
[0029]
[0022] Furthermore, the charge of the cartridge is not limiting of the invention. The cartridge may comprise a charge chosen from a gas or mixture of flammable and / or inert gases, with or without propellant powder.
[0030]
[0023] In the embodiment intended for ballistic applications, the cartridge comprises said mobile assembled in the downstream chamber by means of a sealing system and one or more fixing means capable of fracturing under the effect of pressure, and of releasing said mobile during a rise in pressure in said downstream chamber. For example, the mobile can be screwed into the downstream chamber and said fixing means or means correspond to threads.
[0031]
[0024] The invention also relates to a launcher for an inflammable gas charge, with the possible addition of powder, comprising a breech comprising an internal conduit integrating a combustion chamber capable of receiving said inflammable charge, and further comprising a plug on a proximal side of said breech and a projectile housing at the outlet of the combustion chamber, characterized in that the combustion chamber has an internal geometry according to which:
[0032] - the combustion chamber is divided into two parts, an upstream chamber and a downstream chamber forming a longitudinal duct with variable section, and according to which - said duct has a convergent nozzle shape at an outlet of the upstream chamber opening into the downstream chamber, and a flared shape at an inlet of the downstream chamber and relative to the outlet of the upstream chamber, said flared shape being capable of generating a jet of gas in the downstream chamber, i.e. a sharply flared shape.
[0033]
[0025] In one embodiment, the invention proposes to integrate said internal geometry of the combustion chamber by means of a sleeve with variable internal section, and inserted into an internal duct of the cylinder head.
[0034]
[0026] The liner may be made in one piece or in several segments assembled longitudinally. Advantageously, when the liner is composed of several segments, the invention proposes to provide on a single segment called "convergent segment" or "turbulator segment" with said convergent nozzle shape, making it possible to also divide the combustion chamber into two parts. It is thus possible to move the positioning of the convergent nozzle by changing the position of said convergent segment.
[0027] Other characteristics and advantages of the invention will be apparent on reading the following description of a non-limiting example of embodiment of the invention with reference to the appended drawings.
[0035] LIST OF FIGURES
[0036]
[0028] Fig. 1 represents a longitudinal sectional view of a cartridge according to one embodiment of the invention;
[0037]
[0029] Fig. 2 represents a longitudinal sectional view of a cartridge according to another embodiment of the invention;
[0038]
[0030] Fig. 3 shows an enlarged view of a connection between the upstream chamber and the downstream chamber of the cartridge according to the embodiment illustrated in Fig. 1;
[0039]
[0031] Fig. 4 represents an enlarged view of the fixing of the mobile in the downstream chamber of the cartridge according to the embodiment illustrated in Figure 1;
[0040]
[0032] Fig. 5 represents a front view of the inner side of the cartridge cap according to the embodiment illustrated in Fig. 1 and in section along the section lines AA and BB;
[0041]
[0033] Fig. 6 shows different embodiments of a cartridge; and
[0042]
[0034] Fig. 7 illustrates the effect of the internal geometry of the cartridge according to one embodiment of the invention on the optimization of combustion, in particular at the level of the pressure rise rate following the ignition of a premix of flammable gas from a cartridge.
[0043]
[0035] Fig. 8 represents a longitudinal sectional view of a launcher according to an embodiment of the invention.
[0036] Fig. 9 represents an alternative embodiment of the jacket defining the internal geometry of the combustion chamber of the launcher.
[0044]
[0037] Fig. 10 represents a longitudinal sectional view of a launcher according to a second embodiment of the invention, and incorporating the jacket of Fig. 9.
[0045] DETAILED DESCRIPTION OF THE INVENTION
[0046]
[0038] The present invention relates to a novel pyrotechnic cartridge and a launcher with an optimized design and geometry for containing an inflammable charge, in particular a mixture of flammable gas under pressure, possibly mixed with a propellant powder charge, or a propellant powder charge immersed in an inert gas. More particularly, the invention proposes the use of a novel combustion chamber geometry making it possible to optimize the combustion of said inflammable charge, whether in a cartridge or in a launcher.
[0047]
[0039] The invention will first be described with respect to the implementation of the invention in a cartridge, and with reference to Figures 1 to 7.
[0048]
[0040] In a non-limiting embodiment of the invention, the cartridge is intended for the propulsion of a mobile. Figure 1 illustrates such an embodiment of the cartridge.
[0049]
[0041] The cartridge 1 comprises a case 10 defining a cylindrical conduit with variable section provided with a base 2 on a proximal side and a mobile 3 on a distal side of the cartridge.
[0050]
[0042] The case 10 of the cartridge is designed with two chambers called “combustion chambers”, an upstream chamber 11, and a downstream chamber 12. The upstream chamber 11 is closed by the base 2 on a proximal side of the cartridge and is intended to contain the charge of the cartridge. The base 2 integrates the functions of filling, adjusting the gas mixture, purging and ignition of the premix, as will be described later. According to another embodiment, the cartridge corresponds to a closed manometric enclosure (figure 2).
[0051]
[0043] Contrary to technical prejudice, it turns out that by optimizing the geometry of the chambers, and in particular of the longitudinal duct that they define, it is possible to increase the combustion speed while avoiding a combustion accident at the operating pressures necessary to have interesting performances.
[0052]
[0044] According to this optimized geometry (see fig. 1 and fig. 2), the upstream chamber 11 comprises a portion of convergent section 111 followed by a neck 120 defining a passage of reduced section opening into the downstream chamber 12. The downstream chamber 12 has for its part a sudden flare in its section at and relative to the outlet of the neck 120. A convergent nozzle (illustrated circled by dotted lines in fig. 2) is thus formed making it possible to maintain a laminar flow at the level of the upstream chamber, and to concentrate the flame in a jet which will become turbulent when passing into the downstream chamber 12, also called the “turbulent chamber”. For its part, the inlet of the downstream chamber 12 has a sharply flared shape to ensure the generation of a turbulent jet. Indeed, a progressive flaring would be less effective in generating this turbulence.
[0053]
[0045] More particularly, the upstream chamber 11 comprises a first part of constant section having a first diameter D1, followed by said convergent nozzle shape. This latter shape is defined by a part with convergent section 111 gradually narrowing down to the neck 120 of narrowed section and having a second diameter D2. For its part, the downstream chamber 12 has an inlet portion of constant section with a third diameter D3, greatly increased compared to the diameter D2 of the neck, and similar or close to the first diameter D1. As illustrated in the figures, the parts of the upstream and downstream chambers follow one another along a longitudinal axis of the cartridge, and the section of said parts corresponds to their respective cross section.
[0054]
[0046] This chamber geometry generates a high level of turbulence in the downstream chamber 12 by jet, suddenly and significantly increasing the combustion speed once the flame enters it. It is thus possible to ensure a high combustion speed in the ballistic phase, when the mobile 3 is released and enters a launch tube not shown, despite the high dilution of the mixtures.
[0055]
[0047] As regards the geometry of the downstream chamber 12, the latter may have a constant section (fig. 1) or have the geometry of the upstream chamber, i.e. a first part of constant section, followed by a converging section and a neck of reduced section (Fig. 2). The geometry of the downstream chamber is chosen as a function of a caliber of the mobile (or of the head) to be connected to the cartridge, a constant section being suitable when the caliber of the mobile is compatible with a diameter of said constant section. On the contrary, when the caliber of the mobile to be connected is less than said constant section, the downstream chamber is provided with a converging section and a neck of reduced section at its outlet, this geometry serving as a progressive hydrodynamic connection up to said mobile.
[0056]
[0048] According to a preferred embodiment of the invention, and as illustrated in the figures, the case is made in two parts P1, P2, one part P1 integrating the upstream chamber 11, and one part P2 integrating the downstream chamber 12. The two parts P1, P2 of the case are assembled together in a sealed manner at the neck 120 of the upstream chamber 11. According to a non-restrictive embodiment (figure 3), one of the parts is inserted into the other at one of its ends, and the low-pressure seal is ensured by an O-ring 9 disposed between the two. The dynamic seal for its part is ensured by means of a dynamic seal 7 whose internal pressure deforms the wings of the seal, which generates a linear contact between the seal and the adjacent parts thus ensuring the seal of the assembly. This embodiment is very advantageous in that it allows said parts to be manufactured by traditional means of single-piece parts.
[0049] As illustrated in Figure 3, the first part P1 of the case is configured at its distal end with a reduced external section, so as to define a tenon 130 sliding inside the second part P2. The O-ring 8 is arranged in a groove of said tenon 130 and the dynamic seal 7 is arranged at an interface between the upstream chamber 11 and the downstream chamber 12. A connection between the two parts P1, P2 also comprises attachment means, such as clip-on or screw-on means. According to another embodiment, not illustrated, the case is designed as a single block.
[0057]
[0050] Figure 4 illustrates the distal side of the cartridge integrating the mobile 3, the latter being inserted into a distal end of the case and serving as a shutter for the latter. A pair of seals 6a, 6b ensure sealing, in particular a first internal O-ring seal 6a for static sealing between the mobile and the case, and a second external seal 6b for sealing between the case and the launch tube (not shown).
[0058]
[0051] In a non-limiting embodiment of the invention, the mobile 3 is provided with one or more threads 31 making it possible to screw said mobile 3 into the downstream chamber 12 provided with a thread. The threads 31 are designed to fracture when a certain breaking pressure is reached, and to release the mobile by the shearing of these threads. In order to control the desired breaking pressure, the threads 31 have a truncated profile and / or their number is adjusted. In another embodiment, this breaking at the desired pressure can be envisaged by other fixing means 31 which can be fractured under the effect of pressure.
[0059]
[0052] As already mentioned, at its proximal side, the cartridge integrates the base 2 ensuring the functions of filling, adjusting the gas mixture, purging and ignition of the premix under pressure. Figure 5 illustrates the design details of the base 2 according to different views and sections. In general, the base 2 has a body defining a head 21 provided with a shutter body 22 which is inserted into the upstream chamber. The base 2 comprises a port 23 for filling and adjusting the gas integrating a support plug 24 followed at its bottom by a sealing valve 5, the latter being positioned in a cavity 25 in the head 21 of the base opening into a gas injection channel 26 passing through the shutter body 22, and also comprising a return spring 27 (see Figure 5, section AA).It should be noted that the cartridge has only one filling port, and is therefore designed to be charged with a gas premix, i.e. a mixture of gases previously combined outside the cartridge.
[0060]
[0053] The sealing at the filling port 23 is ensured by a series of seals 4a, 4b, 4c, 4d, also called a sealing system. A first seal 4a is arranged at an inlet of the injection port 23 on an external surface of the support plug 24. A second seal 4b is arranged at the interface between the side walls of the support plug 24 and the cavity 25. A third seal 4c is arranged at the interface between the sealing valve 5 and a bottom of the support plug 23. During the injection or adjustment of the gas, the sealing valve 5 can be actuated by an injector located on a system intended to receive the cartridge or on dedicated tooling on the external side. In addition, the base comprises a fourth sealing gasket 4d at an external groove of the shutter body of the shutter body 22 to ensure sealing with the upstream chamber 11.
[0061]
[0054] The base 2 also incorporates two terminals 28 mounted across the partition, electrically insulated by the interposition of an insulator 29, typically made of plastic or ceramic material (see section BB, figure 5). Due to their shape, the terminals and the insulating parts are sealed against internal pressure. The cartridge can be primed with a conventional ignition system.
[0062]
[0055] More particularly, the cartridges of the invention use a premixture of flammable, inert gas, with or without propellant powder or any combination of the preceding elements. The combustible fraction of the mixture may consist, in a non-limiting manner, of all types of usual reducing gases such as dihydrogen H2 or light alkanes such as methane CH4, propane C3H8, etc. Similarly, the oxidizing fraction may consist, in a non-limiting manner, of all types of oxidizing gases such as dioxygen O2.
[0056] Figure 6 shows different embodiments of the cartridge. From top to bottom, this figure illustrates a longitudinal section and an external view of a .308 caliber cartridge and its dedicated mobile, a 25 mm cartridge and its dedicated mobile, as well as a manometric enclosure and its dynamic pressure measuring equipment, also called head 3bis of the cartridge.In the illustrated embodiment, the manometric enclosure has a downstream chamber geometry allowing the combustion of a small caliber cartridge to be reproduced, and therefore has a convergent section and a reduced neck at the outlet of the downstream chamber. The invention is scalable up to large calibers (typically 155 mm, or even more).
[0063]
[0057] Whatever the embodiment of the invention, the cartridge will be designed with a geometry defining two internal chambers connected to each other by a converging nozzle making it possible to generate a high level of turbulence by jet in the downstream chamber, and as has already been described.
[0064]
[0058] Figure 7 illustrates the evolution of the pressure during a shot of a cartridge having the geometry proposed by the invention and without said geometry. On the 2 shots, the effect is observed at the level of the speed at the exit of the barrel (muzzle velocity) rising to 740 m / s with the geometry optimization instead of 675 m / s without the optimization, all other things being equal, to the extent of the experimental variabilities; that is to say 10% more speed, representing 20% additional useful kinetic energy.
[0065]
[0059] The downstream chamber, also called turbulent, allows a rise in pressure by accelerating combustion at the moment when this is most effective, at the start of the mobile's ballistics. The invention makes it possible to completely or partially replace the use of powders as propellants, and therefore it makes it possible to limit the effects of erosion in the weapon tubes, as well as to reduce the temperature in the combustion chamber and therefore to limit the phenomena of surface fusion. In addition, the flammable gas premix cartridges according to the invention make it possible to obtain muzzle velocities higher than those obtained with the powder alone, greater ranges, to increase the permitted firing rates thanks to the lower temperatures of the gases generated, and to reduce or eliminate the muzzle flash caused by the powder for a lesser visual signature.
[0066]
[0060] The cartridge of the invention is also designed to ensure a reliable and secure seal, whether at the static pressure of the gas mixture or at the dynamic pressure generated during the combustion of the gas premix, with or without powder.
[0067]
[0061] Advantageously, the cartridge of the invention is reusable, in particular the base and the case. Furthermore, apart from the mobile, the cartridge uses consumables from standard articles that are easy to supply and store, such as the various static and dynamic sealing joints. The use of the cartridge presents no difficulty and can be implemented by standard personnel as well as with launch tubes existing on the market. Maintenance and repair operations are also simple and easy, and large-scale production is possible.
[0068]
[0062] As already mentioned, the optimized geometry of the combustion chamber can also be integrated into a launcher to optimize the combustion of an inflammable charge.
[0069]
[0063] The invention therefore proposes a launcher comprising a combustion chamber with an optimized geometry according to which the combustion chamber is divided into two chambers, an upstream chamber and a downstream chamber, and comprising a convergent nozzle at an outlet of the upstream chamber, and a sharply flared shape at an inlet of the downstream chamber and relative to the outlet of the upstream chamber, said flared shape being capable of generating a jet of gas in the downstream chamber. That is to say with the same combustion chamber geometry which has been described for the cartridge.
[0070]
[0064] Just as for the cartridge, this chamber geometry generates by jet a high level of turbulence in the downstream chamber, suddenly and significantly increasing the combustion speed once the flame enters it. These two embodiment variants therefore relate to a weapon device integrating a combustion chamber for an inflammable gas charge receiving a plug on a proximal side and a mobile or projectile on a distal side, and whose combustion chamber is configured with the optimized geometry making it possible to improve its combustion.
[0071]
[0065] Exemplary embodiments of the mode of implementation of the invention in a launcher will then be described with reference to FIGS. 8 to 10.
[0072]
[0066] Figure 8 illustrates a longitudinal section of a launcher 100 incorporating a new combustion chamber geometry according to the invention. At the top of the figure, a longitudinal view of the launcher and its longitudinal section are shown. Conventionally, the launcher 100 comprises on a distal side a launch tube 101 for guiding a mobile 3, also called projectile 3, to the mouth of the launch tube. On a proximal side, the launcher 100 comprises a breech 102 comprising a combustion chamber for directly receiving a mixture of flammable gas, possibly comprising a propellant powder. The breech 102 also comprises a housing for receiving the projectile 3 at the inlet of the launch tube and at the outlet of the combustion chamber, as well as a plug 2 integrating ignition means, a filling port, a purge port, etc.The projectile 3 is fixed to the outlet of the combustion chamber by means of a collar that can be broken under pressure. In the example illustrated, the housing of the projectile 3 is located at a section adapter 104 making it possible to define a convergent at the outlet of the combustion chamber, compatible with a diameter of the launch tube 101. This breech configuration is given as a non-limiting example to help understand the invention. However, numerous launcher breech configurations can be envisaged, in particular with regard to the movable or non-movable connection with the launch tube 101, the connection with a type of plug and the use of a desired type of projectile. Indeed, combustion can be optimized regardless of the model of the launcher by adapting the internal geometry of the combustion chamber of the breech.
[0073]
[0067] In particular, in the illustrated examples, the invention proposes to adapt the geometry of the combustion chamber by means of a liner comprising an internal section with variable diameter defining the internal duct of the combustion chamber, and configured to divide the combustion chamber into an upstream chamber 11, and a downstream chamber 12. The liner 103 is also configured to provide the convergent nozzle shape at the outlet of the upstream chamber 11. An external wall of the liner 103 is configured to match an internal wall of the cylinder head 102, and if necessary elements for connecting an internal duct of the cylinder head with the plug 2 or with the launch tube 101, such as the section adapter 104. This liner can be made of the same material as the body of the cylinder head or of a different and more corrosion-resistant material such as stainless steel.
[0074]
[0068] The launcher comprises means for preferably at least axially fixing the liner. For example, the liner will be fixed at the front and rear to prevent its axial displacement. In the example illustrated in Figure 8, the liner is fixed axially between the plug 2 and the section adapter 104, by means of a shoulder 105, 107 at each of its front and rear ends. In order to improve the fixing at the rear, in this embodiment, it is also possible to integrate a housing 108 to shoulder the rear end of the liner 103. Advantageously, the liner 103 can be assembled by shrink fitting,
Claims
so that it is fixed radially to the cylinder head. In particular, the liner is cooled and shrunk into the cylinder head duct while hot. [069] Figure 9 illustrates an alternative embodiment in which the liner 103 is composed of a plurality of segments assembled longitudinally and together defining the internal and optimized geometry of the combustion chamber. The liner is therefore formed by several independent parts. Advantageously, a single insert segment, called the convergent segment Sc, provides the convergent nozzle shape at the outlet of the upstream chamber 11, as well as the flare at the inlet of the downstream chamber 12. The convergent segment Sc also makes it possible to divide the combustion chamber into two parts. Liner segments called “straight segments” Sd, Sd' make it possible to define a constant diameter D1 of the upstream chamber 11, and a constant diameter D2 of the downstream chamber 12. The number of straight segments for defining the downstream chamber or the upstream chamber is not limiting, and it can be reduced or increased as needed.This embodiment is advantageous in that it allows the positioning of the converging nozzle to be modified and the size of the upstream 11 and downstream 12 chambers to be modified by repositioning the liner segments. Easy assembly and disassembly of the liner will also be possible. [070] Figure 10 illustrates the integration of the segmented jacket into a launcher according to a second embodiment. The segmented jacket 103 will also be fixed at the front and rear to prevent its axial displacement. In the present case, the rear end is directly supported in a recess at the level of the plug 2, and at the front against a connecting piece 105 between the duct of the breech and the launch tube. Of course, other axial fixing means are also conceivable. [071] Similar to the cartridge, the launcher incorporates a sealing system to prevent gas leaks between the different parts of the breech, as well as dynamic sealing “corner” joints. Similarly, the combustion chamber of the launcher forms a case in which the flammable charge is primed, and the pressure increase in the combustion chamber causes the collar of the projectile to rupture, and it is propelled through the launch tube. The optimized geometry of this combustion chamber ensures a high combustion speed in the ballistic phase, when the gas is released and pushes the projectile into the launch tube 101. In particular, this geometry makes it possible to maintain a laminar flow at the level of the upstream chamber, and to concentrate the flame in a jet which will become turbulent when passing into the downstream chamber, thus increasing the combustion speed. Claims 1. Pyrotechnic cartridge (1) for flammable gas charge comprising a case (10) having a proximal end provided with a base (2) and a distal end adapted to receive a mobile (3) or a manometric enclosure head, characterized in that: - the case (10) comprises two chambers, an upstream chamber (11) and a downstream chamber (12) forming a longitudinal conduit with variable section, and in which - said conduit has a convergent nozzle shape at an outlet of the upstream chamber (11) opening into the downstream chamber (12), and a flared shape at an inlet of the downstream chamber (12) and relative to the outlet of the upstream chamber, said flared shape being capable of generating a jet of gas in the downstream chamber (12).
2. Cartridge (1) according to claim 1, in which the case (10) comprises a dynamic seal (7) between the outlet of said upstream chamber (11) and the inlet of the downstream chamber (12), such as a sealing valve.
3. Cartridge (1) according to one of the preceding claims, in which the conduit formed by the upstream chamber and the downstream chamber has: - at the level of the upstream chamber (11), a first part of constant section of a first diameter (D1) followed by a second part of convergent section becoming a neck (120) of narrowed section of a second diameter (D2), said neck (120) being located at the level of the outlet of said upstream chamber (11), and - at the level of the downstream chamber (12), an inlet portion of constant section with a third diameter (D3) greater than said second diameter (D2).
4. Cartridge according to one of the preceding claims, in which the conduit also comprises a convergent nozzle shape at the outlet of said downstream chamber (12).
5. Cartridge according to one of the preceding claims, in which the case is made in two parts (P1, P2), a first part (P1) integrating the upstream chamber (11), and a second part (P2) integrating the downstream chamber (12), and in which the two parts are connected to each other in a sealed and secure manner at an outlet of the upstream chamber (11).
6. Cartridge (1) according to claim 5, wherein in a connection between said two parts (P1, P2), a distal end of the first part is inserted into the second part (P2), and incorporates attachment means, such as clip-on or screw-on attachment means, and a seal (9).
7. Cartridge (1) according to one of the preceding claims, in which the base (2) comprises a gas filling and adjustment port (23), said port (23) integrating a support cap (24) followed at its bottom by a sealing valve (5) and a return spring (27), as well as comprising a sealing system with said base (2).
8. Cartridge (1) according to one of the preceding claims, in which the base (2) incorporates a pair of through-lugs (28) having a coating (29) of insulating material, and opening out as a pair of uncoated projections on an internal side of the base (2).
9. Cartridge (1) according to one of the preceding claims, comprising an inflammable charge chosen from: - a flammable and / or inert gas or mixture of gases, with or without propellant powder.
10. Cartridge (1) according to one of the preceding claims, comprising said mobile (3) assembled in the downstream chamber (12) by means of a sealing system and one or more fixing means (31) capable of fracturing under the effect of pressure, and of releasing said mobile (3) during a rise in pressure in said downstream chamber (12).
11. Cartridge (1) according to claim 10, in which said mobile (3) is screwed into the downstream chamber (12) and said fixing means(s) correspond to threads (31).
12. Launcher (100) for a flammable gas charge comprising a breech (102) comprising an internal conduit integrating a combustion chamber capable of receiving said flammable charge, and further comprising a plug (2) on a proximal side of said breech and a projectile housing at the outlet of the combustion chamber, characterized in that the combustion chamber has an internal geometry according to which: -the combustion chamber is divided into two parts, an upstream chamber (11) and a downstream chamber (12) forming a longitudinal conduit with variable section, and according to which - said conduit has a convergent nozzle shape at an outlet of the upstream chamber (11) opening into the downstream chamber (12), and a flared shape at an inlet of the downstream chamber (12) and relative to the outlet of the upstream chamber, said flared shape being capable of generating a jet of gas in the downstream chamber (12).
13. Launcher according to claim 12, in which the cylinder head comprises a sleeve (103) with variable internal section configured to define said internal geometry of the combustion chamber, and to fit into an internal duct of the cylinder head (102).
14. Launcher according to claim 13, in which the liner (103) is composed of several segments defining after assembly the internal geometry of the combustion chamber.
15. Launcher according to claim 14, in which the segments of the jacket (103) comprise a convergent segment (Sc), and straight segments (Sd), and -said convergent segment (Sc) is configured to divide the combustion chamber into two parts and to integrate said convergent nozzle shape at an outlet of the upstream chamber (11) opening into the downstream chamber (12), and provide said flared shape at the inlet of the downstream chamber (12) and relative to the outlet of the upstream chamber, and, -the straight segments are configured to define a constant internal diameter of the upstream chamber 11 and the downstream chamber 12.