Gas generator with gas storage device for a protection device

Abstract

A gas generator comprising:-a gas chamber (10) comprising a bleed opening (11),-a sealing cover (20),-an expansion gas (30) stored in the gas chamber (10),-an opening piston (40), movable between a rest position and an open position,-pyrotechnic means arranged to move the opening piston (40), characterized in that the sealing cover (20) is arranged in the opening piston (40), the gas generator comprises:-at least one securing means (71) of the opening piston (40) for securing the opening piston (40) in a rest position before the pyrotechnic device is triggered, and / or-at least one locking means (71) of the opening piston (40) for locking the opening piston (40) in the rest position or in the triggered position after the pyrotechnic device is triggered.

Description

TECHNICAL FIELD

[0001] The present invention relates generally to a gas generator, in particular for equipping a protection device, such as a protection device integrated in a vehicle (car, truck, two-wheeler, etc.) or a personal protection device, such as:

[0002] a motorcycle helmet (containing an inflatable pad, such as an airbag),

[0003] a bicycle helmet (containing an inflatable pad, such as an airbag),

[0004] a hip belt (containing an inflatable pad, such as an airbag),

[0005] a motorcycle rider protective jacket (containing an inflatable pad, such as an airbag), etc.

[0006] Generally, the gas generator according to the invention can have a pressurized gas storage device to rapidly supply the protection device with an inflation gas. BACKGROUND

[0007] It is known, for example from document US 5 653 463, to provide a gas generator having a gas storage device closed with a sealing cover plate, and an opening piston for opening the sealing cover plate and ensuring the evacuation of the gas storage device. On the other hand, this system can have drawbacks in terms of repeatability of the opening and evacuation, in particular due to the gas passage cross section after opening, which can be related to the position of the opening piston. SUMMARY

[0008] The object of the present invention is to solve the above-mentioned drawbacks of the prior art, in particular, first, to propose a gas generator comprising a pressurized gas chamber, the operation of which is repeatable, in particular in terms of opening and evacuation after opening of the gas chamber.

[0009] To this end, a first aspect of the invention relates to a gas generator for a user protection device, comprising:

[0010] - a gas chamber comprising a discharge opening,

[0011] - a sealing cover plate closing the discharge opening;

[0012] - an inflation gas stored under pressure in the gas chamber closed with the sealing cover plate and intended to deploy the protection device after opening of the sealing cover plate,

[0013] - an opening piston arranged to be movable between a rest position and an opening position, wherein the movement of the opening piston from the rest position to the opening position causes the opening of the sealing cover plate,

[0014] - a pyrotechnic device arranged to move the opening piston from the rest position to the opening position,

[0015] characterized in that the gas generator comprises:

[0016] - at least one fixing member of the opening piston for fixing the opening piston in a rest position at least before the triggering of the pyrotechnic device, and / or

[0017] - at least one locking member of the opening piston for locking the opening piston in a rest position or in a triggered position (arranged between the open position and the rest position) after the triggering of the pyrotechnic device.

[0018] In the above embodiments, the gas generator can perform a repeatable operation because the position of the opening piston is well controlled before and / or after the opening of the sealing cover:

[0019] - before opening, the fixing member of the opening piston fixes or locks or stops or holds the opening piston in the rest position, and / or

[0020] - after opening, the locking member of the opening piston fixes or locks or stops or holds the opening piston in the open position or in the triggered position (arranged between the open position and the rest position).

[0021] Thus, before opening, the rest position of the opening piston is always the same, which ensures that the movement always starts from the same position, whatever the conditions of use (e.g. when new, or after a series of falls, impacts or vibrations, etc.). Likewise, after opening, the position of the opening piston is always the same (rest position or triggered position), which ensures that the cross-section of the passage and the flow of pressurized gas are repeatable.

[0022] After opening, it can be noted that the position of the opening piston is not the open position, but the rest position or the triggered position (arranged between the open position and the rest position), which means that as soon as the sealing cover is opened, the opening piston retracts to leave a larger cross-section of the passage and / or not to block the discharge opening: the emptying is fast and not affected by the cross-section and / or the size of the opening piston.

[0023] The gas generator can be defined by the following individual features or combinations of features.

[0024] In one embodiment, the opening piston in the rest position can be arranged at a predetermined distance from the sealing cover and / or the discharge opening. In particular, it can be provided that the distance between the opening piston in the rest position and the sealing cover (and / or the discharge opening) is at least 1 mm, preferably at least 1.5 mm, more preferably at least 2 mm. Thus, during the operation of the gas generator, the opening piston can reach a minimum speed before contacting or colliding with the sealing cover. The opening of the sealing cover is more repeatable and better controlled.

[0025] In one embodiment, the opening piston in the rest position can be separated from the sealing cover by a space or without any other components. Thus, once opened, the gas flow is not disturbed.

[0026] In one embodiment, the opening piston, in particular when it is moved from the rest position to the opening position, can be free or not in contact with any reset mechanism. In other words, the gas generator can be free of any reset mechanism exerting a reset force on the opening piston when the opening piston leaves the rest position, with the exception of the expanding gas expelled from the gas chamber after the gas chamber is opened. In other words, the opening piston can only be subject to the holding force of the holding member when the opening piston is in the rest position or in the trigger position.

[0027] In one embodiment, the holding member and / or the locking member of the opening piston for holding and / or locking the opening piston in the rest position or in the trigger position, respectively, before and after the pyrotechnic device is triggered, can be used to ensure a resilient and / or reversible holding and / or locking.

[0028] In one embodiment, the holding member and / or the locking member of the opening piston can be used to hold and / or lock the opening piston only in the rest position or in the trigger position, respectively. In other words, the holding member and / or the locking member of the opening piston can be used to release the opening piston:

[0029] - after the opening piston leaves the rest position, and

[0030] - before the opening piston returns to the rest position or reaches the trigger position.

[0031] In particular, the holding member and / or the locking member of the opening piston can be used to release the opening piston when the opening piston is in the opening position and in the vicinity of the opening position (e.g. within a four millimeter stroke before / after the opening position).

[0032] In one embodiment, the holding member of the opening piston can be a mechanical holding member of the opening piston and / or the locking member of the opening piston can be a mechanical locking member.

[0033] In particular:

[0034] - the holding member of the opening piston can be a reversible, resilient, flexible, non-plastically deformable, non-shearing mechanical holding member, which remains intact (the holding member has no material loss,

[0035] the holding member has no flaking, the holding member has no separable parts) and / or

[0036] - the locking member of the opening piston can be a reversible, elastic, flexible, non-plastically deformable, non-shearing mechanical locking member, which remains intact (the locking member does not lose material, the locking member does not flake, the locking member does not have separable parts). Such non-plastic deformation and / or non-material flaking allows to ensure that there are no flaking particles that are detrimental to the opening piston movement and / or to the integrity of the safety device. In other words, it can be provided that the fixing member and / or the locking member are used to perform the engagement and / or disengagement work without involving plastic deformation and / or without flaking or cutting material from the associated parts. In particular, the movement of the opening piston from the rest position to the opening position during the work can be completed without plastic deformation and / or material flaking. Likewise, the retraction movement of the opening piston from the opening position to the trigger position or to the rest position during the work can be completed without plastic deformation and / or material flaking. This does not exclude that the fixing member and / or the locking member can be plastically deformed during the initial installation of the gas generator (mounting of the opening piston in the rest position).

[0037] In one embodiment, the fixing member of the opening piston can be merged with the locking member of the opening piston, the fixing member of the opening piston can be identical to the locking member of the opening piston, the fixing member of the opening piston can have the same structure as the locking member of the opening piston. In one embodiment, the fixing member of the opening piston can be the locking member of the opening piston. This allows to limit the number of parts formed on the opening piston, to optimize the costs and the overall space.

[0038] In one embodiment, the gas generator can comprise at least one reference part, which is adjacent to the opening piston, and which is for example the igniter holder, or the igniter molded on its holder, or the safety shell, or the combustion chamber,

[0039] and the fixing member of the opening piston and / or the locking member of the opening piston can comprise:

[0040] - at least one male protrusion, for example a rib, provided on one of the opening piston and the reference part, and / or

[0041] - at least one female complementary shape, for example a groove, provided on the other of the opening piston and the reference part.

[0042] In one embodiment, the gas generator can comprise:

[0043] - at least one reference part, which is adjacent to the opening piston, and which is for example the igniter holder,

[0044] - a first fixing member of the opening piston and / or a first locking member of the opening piston, formed by at least one male protrusion, for example a rib, provided on one of the opening piston and the reference part,

[0045] - the second fixing member of the opening piston and / or the second locking member of the opening piston, formed by at least one female complementary shape, for example a groove, provided on the other of the opening piston and the reference component. It can be provided that the engagement between the first fixing member of the opening piston and the second fixing member of the opening piston is such as to fix the opening piston in the rest position. It can be provided that the engagement between the first locking member of the opening piston and the second locking member of the opening piston is such as to lock the opening piston in the rest position or in the triggering position.

[0046] It can be provided, in particular, that, once the gas generator is installed, an elastic engagement, reversible engagement, elastic nesting, clamping is formed between the male protrusion and the female complementary shape. In any case, it can be provided that the engagement and / or disengagement between the male protrusion and the female complementary shape takes place without plastic deformation and / or without material peeling. Such plastic deformation and / or material peeling free engagement and / or disengagement allows to ensure that no particles that can be detrimental to the movement of the opening piston and / or to the integrity of the safety device are released. In other words, it can be provided that the male protrusion and the female complementary shape are used to perform the engagement and / or disengagement work without involving plastic deformation and / or without peeling or cutting material from the relevant components. In particular, the movement of the opening piston from the rest position to the opening position during the work can be completed without plastic deformation and / or material peeling. Likewise, the retraction movement of the opening piston from the opening position to the triggering position or to the rest position during the work can be completed without plastic deformation and / or material peeling. This does not exclude that, during the initial installation of the gas generator (mounting of the opening piston in the rest position), elastic deformation of the opening piston and / or of the adjacent components can be caused, in particular when the male protrusion and / or the female complementary shape are made of metal.

[0047] In one embodiment, at least one of the male protrusion and the female complementary shape can comprise an engagement portion, which engages with the other of the male protrusion and the female complementary shape, said engagement portion comprising an inclined surface inclined by less than 35° and preferably less than 20° with respect to the direction of travel of the opening piston. In other words, at least one of the male protrusion and the female complementary shape can comprise a chamfer or an inclined portion to facilitate the engagement or disengagement.

[0048] In one embodiment, the male protrusion and / or the female complementary shape:

[0049] - can be asymmetric with respect to the direction of travel of the opening piston, and / or

[0050] - can be continuous or discontinuous in a direction transverse to the direction of travel of the opening piston, and can be segmented.

[0051] In an embodiment, the opening piston can comprise a guiding side wall, which is arranged to ensure guiding of the opening piston in the gas generator when the opening piston is moved between the rest position and the opening position, and which has a guiding length in the direction of movement of the opening piston between the rest position and the opening position which is smaller than a characteristic dimension (typically a diameter) of the opening piston in a transverse direction of the movement of the opening piston between the rest position and the opening position.

[0052] In an embodiment, the guiding side wall has a continuous outer surface, typically a cylindrical surface with a circular base surface. This ensures that the gas generator does not have an open flame when operated according to the US standard SAE-USCAR24-2, April 2013, section 3.2.4 “inflator flaming”. In other words, the guiding side wall is free of lugs, bosses or gaskets.

[0053] In an embodiment, the opening piston can be cylindrical, for example having a circular cross-section.

[0054] In an embodiment, the opening piston can comprise a central recess and / or bore, and the securing means of the opening piston and / or the locking means of the opening piston can be arranged in the central recess and / or bore. In other words, the securing means of the opening piston and / or the locking means of the opening piston can be separate and / or distinct from the side wall, that is to say, the securing means of the opening piston and / or the locking means of the opening piston can be separate or distinct from the outer surface of the opening piston.

[0055] In an embodiment, there is a gap between the guiding wall and the gas generator at a radius of less than or equal to 0.075 mm, advantageously less than or equal to 0.05 mm.

[0056] In an embodiment, the guiding wall can be free of the securing means of the opening piston and / or the locking means of the opening piston and / or the sealing means. Thus, the securing means of the opening piston and / or the locking means of the opening piston do not influence the guiding of the opening piston when moving.

[0057] In an embodiment, the pyrotechnic device can comprise an electric pyrotechnic igniter, and wherein the gas generator can comprise a safety shell arranged around the electric pyrotechnic igniter and / or at least partially between the opening piston and the electric pyrotechnic igniter. Typically, the safety shell is a component distinct from the electric pyrotechnic igniter, which allows the use of a standardized electric pyrotechnic igniter in the gas generator.

[0058] In an embodiment, the safety shell can comprise a filter arranged at least partially between the opening piston and the electric pyrotechnic igniter. The filter can typically be a wall with a through-hole and / or a grating.

[0059] In an embodiment, the electric pyrotechnic igniter can comprise:

[0060] - pyrotechnic material,

[0061] - a charge box containing the pyrotechnic material and serving to open the lid after the pyrotechnic material has been ignited,

[0062] - an electrically insulating lid, for example a plastic lid, which covers the charge box. The charge box can be metallic, with a weak area for forming a petal during operation. In general, debris of the charge box and / or of the electrically insulating lid can fall off. The filter can block these debris, which allows a reliable movement of the opening piston (even back from the opening position or back-off), which can otherwise be prevented or hindered in its movement by the particles produced during operation of the electric pyrotechnic igniter.

[0063] A second aspect of the present application can relate to a protection device or user protection device integrated in a vehicle (car, truck, two-wheeler, etc.) comprising at least one gas generator according to the first aspect of the present application. A motorcycle helmet (containing an inflatable pad, for example an airbag), a bicycle helmet (containing an inflatable pad, for example an airbag), a hip belt (containing an inflatable pad, for example an airbag), a motorcycle rider protective jacket (containing an inflatable pad, for example an airbag), a safety belt (containing an inflatable pad, for example an airbag), a ski vest (containing an inflatable pad, for example an airbag) can be provided. In particular, the present application can relate to a gas generator which does not produce any open flame during operation (for example according to the American standard SAE-USCAR24-2, April 2013, paragraph 3.2.4 "inflator flaming"); in other words, the present application can relate to a generator in which the pyrotechnic combustion produced by the electric pyrotechnic igniter is confined within the generator. BRIEF DESCRIPTION OF DRAWINGS

[0064] Other features and advantages of the present application will be more clearly understood from the following detailed description which is given, by way of non-limiting example, in relation to the present application and is illustrated by the figures in which:

[0065] [ Figure 1 ] shows a sectional view of the gas generator before operation;

[0066] [ Figure 2 ] shows a detail of the sectional view in Figure 1 ;

[0067] [ Figure 3 ] shows the gas generator in Figure 1 during operation;

[0068] [ Figure 4 ] shows the gas generator in Figure 1 after operation. DETAILED DESCRIPTION

[0069] Figure 1 A gas generator for a user / passenger protection device is shown, comprising:

[0070] - a gas chamber 10 comprising a discharge opening 11,

[0071] - a sealing cover plate 20 closing the discharge opening 11,

[0072] - an expanding gas 30 stored under pressure in the gas chamber 10 closed by the sealing cover plate 11,

[0073] and for deploying the protection device after opening of the sealing cover plate 20,

[0074] - an opening piston 40 arranged in a rest position,

[0075] - a pyrotechnic device, in the present example formed by an electric pyrotechnic igniter 50. Figure 1

[0076] In the present example, the gas chamber 10 is assembled from several components:

[0077] - a chamber body 12,

[0078] - a base part 60 with the discharge opening 11 welded to the chamber body 12 at the bottom,

[0079] - a plug 14 also welded to the chamber body 12. The gas chamber 10 also comprises a regulating nozzle 13 near the discharge opening 11, the cross section of which is smaller than the cross section of the discharge opening 11.

[0080] The discharge opening is closed or blocked by a sealing cover plate 20, which can be a thin metal (stainless steel or Inconel) part welded to the bottom of the base part 60.

[0081] The expanding gas 30 can be stored under a pressure of between 20 MPa and 70 MPa and can comprise inert gases such as argon and helium. Other gases are also conceivable.

[0082] The opening piston 40 is movable between a rest position (A) and an opening position (B). Figure 1 or Figure 4 The opening piston 40 is movable between a rest position (A) and an opening position (B). Figure 3 ​The opening piston 40 is a component that moves between the opening position and the base member 60 and includes a tip 41. Therefore, the movement of the opening piston 40 from the rest position to the open position causes the sealing cover plate 20 to open. To this end, the side wall or outer wall of the opening piston 40 can be configured to form a guide wall in the base member 60, and a gap between 0.02 mm and 0.1 mm can be provided at the radius (a gap of 0.075 mm can be provided at the radius, and advantageously, a gap of less than or equal to 0.05 mm can be provided). Utilizing such a gap, the guide length can be set to be less than the diameter of the opening piston, thereby achieving a smaller axial footprint.

[0083] The opening piston 40 may preferably be made of metal, but a plastic material component, or even a composite material component, may be provided.

[0084] The electropyrotechnic igniter 50 is fixed to the igniter bracket 52 by means of a gasket 51 and is covered on top by a containment shell 53 having a perforated wall disposed between the electropyrotechnic igniter 50 and the opening piston 40. The containment shell 53 can generally be made of metal, but plastic components that can withstand the operation of the electropyrotechnic igniter 50 are also contemplated.

[0085] The electropyrotechnic igniter 50 typically comprises:

[0086] -resistance bridge,

[0087] - pyrotechnic material that ignites when the resistance bridge is struck by an electric current,

[0088] - a containment vessel, usually metal (but plastic parts are conceivable) and containing the pyrotechnic material,

[0089] - an electrically insulating cover covering the top of the charging box. The electric pyrotechnic igniter 50 is configured to push the opening piston toward the Figure 1 The right side of the opening piston 40 moves from the rest position to the opening position.

[0090] The base member 60 has a central hole leading to the bleed port and containing the opening piston 40, and the electric pyrotechnic igniter 50 fixed to the igniter bracket 52, which is pressed onto the base member 60. The base member 60 is provided with a diffusion hole 61.

[0091] Figure 2 Shown Figure 1 Detail II of FIG. 1 shows the securing member 40 of the opening piston in the rest position and / or the locking member of the opening piston 40 in the open position. As described above, before the gas generator is operated, the opening piston 40 is in the rest position. To ensure this rest position before operation, the opening piston 40 is provided with a groove 42 and the igniter bracket 52 is provided with a boss 521.

[0092] Also note that:

[0093] The opening piston 40 may further comprise an inlet chamfer 44 which forms an angle A1 with the axial direction of the gas generator (or the travel direction of the opening piston 40 ), said angle A1 being in the range of 5°-30°, preferably 15°-25°,

[0094] - the boss 521 and the groove 42 may be asymmetrical,

[0095] The boss 521 may have an inlet ramp 522 that forms an angle A2 with the axial direction of the gas generator (or the travel direction of the opening piston 40 ), wherein the angle A2 is within a range of 5° to 30°, preferably 15° to 25°,

[0096] The groove 42 may have an outlet ramp 44 that forms an angle A3 with the axial direction of the gas generator (or the direction of travel of the opening piston 40 ), wherein the angle A3 is within a range of 25° to 45°, preferably 30° to 45°,

[0097] The opening piston 40 may comprise an outer constriction 43 which may extend opposite the groove 42 or at the level of the groove in order to facilitate positioning of the piston in the rest position or releasing it from the rest position.

[0098] exist Figure 2 When the opening piston 40 is in Figure 1 When in the static position, the groove 42 accommodates the boss 521. Since the inlet diameter of the central hole of the opening piston 40 is smaller than the diameter of the boss 521, the opening piston 40 cannot move freely, and it can be considered that:

[0099] - the boss 521 forms a fixing element for the opening piston 40, for fixing the opening piston 40 in a rest position, or

[0100] The groove 42 forms a fixing element for the opening piston 40, which is used to fix the opening piston 40 in the rest position, or

[0101] The boss 521 forms a first fixing element 71 of the opening piston 40 , and the groove 42 forms a second fixing element 72 of the opening piston 40 , in order to fix the opening piston 40 in the rest position.

[0102] However, the entrance diameter of the center hole of the opening piston 40 can be smaller than the diameter of the boss 521, with the difference being less than 0.1 mm, or less than 0.05 mm (in diameter), so that the opening piston 40 can be released from the static position under the action of thrust to reach the opening position.

[0103] like Figure 3 As shown, the electric pyrotechnic igniter 50 is ignited in the central hole of the opening piston 40 to generate smoke, and the opening piston is moved to Figure 3rightward movement in the housing until it is stopped by the bottom of the base part 60, so that the tip 41 pierces the seal cover 20. The adjustment nozzle 13 comprises a central boss to prevent interference with the tip 41 when the opening piston 40 is in the Figure 2 opening position.

[0104] It can thus be noted that the fumes produced by the electric pyrotechnic igniter 50 are sufficient to generate a thrust on the opening piston, which is greater than the retaining force exerted by the engagement of the boss 521 in the groove 42. It can be noted that said separation is preferably elastic and / or reversible, and / or occurs without involving plastic deformation and / or without causing material to flake off from the associated parts. This allows the retaining member to be used as a locking member.

[0105] It can also be noted that the safety shell 53, with its perforated distal wall, traps the fragments that can flake off from the electric pyrotechnic igniter 50 (fragments of the plastic insulating cap, fragments of the metal casing, or fragments of the pyrotechnic material), and also avoids the expansion of the charge cartridge of the electric pyrotechnic igniter 50 during operation from preventing the opening piston 40 from moving, so that the space between the safety shell 53 and the opening piston 40 or the base part 60 (in particular the exposed part of the central bore of the opening piston 40 and of the internal bore of the base part 60) remains relatively clean and / or free of solid particles that could affect the movement of the opening piston 40.

[0106] Thus, the opening piston 40 slides in the base part 60 under the guidance of its lateral wall, and this guidance remains effective after operation, thanks to the filtering effect provided by the safety shell, so that it is possible to guarantee that the opening piston will return to the rest position Figure 2 after it has reached the opening position. This return of the opening piston 40 allows the release of the vent 11, to ensure good repeatability of the passage of the gas stored in the gas chamber 10 from one gas generator to another.

[0107] Thus, as shown in Figure 4 , the opening piston 40 can return, as in the example shown in Figure 4 , to the rest position Figure 1 . However, it can be provided that the opening piston is prevented from returning in the triggering position, which will be set between the rest position Figure 1 and the opening position Figure 3 .

[0108] The opening piston, which has returned to the rest position, is then locked in this rest position by the groove 42 of the containment boss 521. As in the case before operation Figure 2 , after operation, when the opening piston 40 is in the rest position Figure 4When the opening piston 40 is in the rest position, the recess 42 accommodates the boss 521. Since the inlet diameter of the central hole of the opening piston 40 is smaller than the diameter of the boss 521, the opening piston 40 cannot move freely and it can be considered that:

[0109] - the boss 521 forms a locking element of the opening piston 40 for fixing the opening piston 40 in the rest position, or

[0110] - the recess 42 forms a locking element of the opening piston 40 for fixing the opening piston 40 in the rest position, or

[0111] - the boss 521 forms a first locking element of the opening piston 40 (identical to the first fixing element 71) and the recess 42 forms a second locking element of the opening piston 40 (identical to the second fixing element 72) for fixing the opening piston 40 in the rest position.

[0112] Therefore, the opening piston 40 is firmly locked in the rest position after the operation, so that the expansion gas can be released reproducibly into the diffusion hole 61 of the base member 60, as indicated by the arrow in Figure 4 .

[0113] In general, the following can be noted:

[0114] - the opening piston 40 is fixed in the rest position before the operation, allowing to ensure that the movement to the opening position always starts from the same position, thus improving the reproducibility,

[0115] - the filtering or barrier function provided by the safety shell 53 ensures a reproducible and reliable return of the opening piston, it can also be noted that the debris ejected from the gas generator can be less without the need to provide sealing gaskets (which would also not favor the free movement of the opening piston 40),

[0116] - the return of the opening piston 40 after the opening of the sealing cover allows a reproducible flow of the gas of the gas chamber 10 and always through the same passage cross section,

[0117] - the regulation nozzle 13 can be easily adjusted to regulate the flow according to the needs of different applications,

[0118] without the need to change the opening mechanism,

[0119] - the locking of the opening piston 40 in the return, trigger or rest position, by eliminating any risk of kick, oscillation, reciprocation of the opening piston 40 when the gas chamber 10 is completely emptied, helps to further improve the reproducibility of the operation.

[0120] In the example of Figure 4 , the locking element (or elements) is (are) identical to the fixing element (or elements), but different parts or members can be considered.

[0121] exist Figure 2 In the example shown, grooves 42 and bosses 521 are shown, but flexible lugs, tight-fitting elements, tongues, or any other type of elastic, reversible securing and / or locking device may also be provided, preferably without plastic or irreversible deformation or the risk of parts falling out or breaking, especially during operation. Furthermore, the securing and / or locking elements may extend over 360°, or in sections or at points.

[0122] Industrial applications

[0123] The gas generator and its manufacture shown in the present invention are easy to apply in industry.

[0124] It will be apparent to those skilled in the art that various modifications and improvements can be made to the various embodiments of the invention described in this specification without departing from the scope of the invention.

Claims

1. A gas generator for a user protection device, the gas generator comprising: - a gas chamber (10), including a bleed port (11), - a sealing cover plate (20) closing the discharge opening (11), - an expansion gas (30) stored under pressure in the gas chamber (10) closed by the sealing cover (20) and used to deploy the protection device after the sealing cover (20) is opened, an opening piston (40) arranged to move between a rest position and an open position, wherein the movement of the opening piston (40) from the rest position to the open position causes the sealing cover plate (20) to open, - a pyrotechnic device arranged to move the opening piston (40) from the rest position to the opening position, Characterized in that the gas generator comprises: - at least one fixing element of the opening piston (40) for fixing the opening piston (40) in a rest position at least before the pyrotechnic device is triggered, and / or - at least one locking element of the opening piston (40) for locking the opening piston (40) in a rest position or a triggered position (arranged between the opening position and the rest position) after the pyrotechnic device has been triggered.

2. The gas generator according to claim 1, wherein the fixing element of the opening piston (40) is a mechanical fixing element, and / or the locking element of the opening piston (40) is a mechanical locking element.

3. The gas generator according to claim 1 , comprising at least one reference component adjacent to the opening piston ( 40 ), such as an igniter support ( 52 ), Furthermore, the fixing member of the opening piston (40) and / or the locking member of the opening piston (40) include: - at least one male protrusion, such as a rib, provided on one of the opening piston (40) and the reference member, and / or - At least one female complementary shape, such as a groove (43), is provided on the other of said opening piston (40) and said reference member.

4. A gas generator according to claim 3, wherein at least one of the male protrusion and the female complementary shape portion includes a joint portion that engages with the other of the male protrusion and the female complementary shape portion, and the joint portion includes an inclined surface that is inclined less than 35° and preferably less than 20° relative to the travel direction of the opening piston (40).

5. The gas generator according to any one of claims 3 or 4, wherein the male protrusion and the female complementary shape: - is asymmetrical along the direction of travel of the opening piston (40), and / or - Continuous or discontinuous or segmented in a direction transverse to the direction of travel of the opening piston (40).

6. A gas generator according to any one of claims 1 to 5, wherein the opening piston (40) includes a guide side wall, and the guide side wall is configured to ensure that the opening piston (40) is guided in the gas generator when the opening piston moves between the rest position and the open position, and in the direction of movement of the opening piston (40) between the rest position and the open position, the guide length of the guide side wall is smaller than the characteristic dimension of the opening piston (40) in the transverse direction of movement of the opening piston (40) between the rest position and the open position.

7. The gas generator according to claim 6, wherein a gap exists between the guide wall and the gas generator at a radius less than or equal to 0.075 mm, advantageously less than or equal to 0.05 mm.

8. The gas generator according to any one of claims 6 or 7, wherein the guide wall is free of a fixing element for the opening piston (40) and / or a locking element and / or a sealing device for the opening piston (40).

9. A gas generator according to any one of claims 1 to 8, wherein the pyrotechnic device comprises an electropyrotechnic igniter (50), and wherein the gas generator comprises a containment vessel (53) arranged around the electropyrotechnic igniter (50) and / or at least partially between the opening piston (40) and the electropyrotechnic igniter (50).

10. The gas generator according to claim 9, wherein the containment vessel (53) comprises a filter portion at least partially arranged between the opening piston (40) and the electropyrotechnic igniter (50).

11. The gas generator according to any one of claims 9 or 10, wherein the electropyrotechnic igniter (50) comprises: - pyrotechnic materials, - a charging box containing pyrotechnic material and for opening the lid after the pyrotechnic material has been ignited, - An electrically insulating cover, for example a plastic cover, which covers the charging box.

12. A user protection device comprising at least one gas generator according to any one of claims 1 to 11.

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