Gas generator with propellant stored under pressure

Abstract

A gas generator comprising: - a gas chamber (10) with a first orifice (21) having a first passage surface, - a main cover (51) closing the first orifice (21), - pressurized gases stored in the gas chamber (10), - a pyrotechnic chamber (30) arranged within the gas chamber (10), - an ignition device (40), characterized in that the gas generator comprises at least one partition wall (33) of the gas chamber (10) with at least one second orifice (22) having a second passage surface smaller than the first passage surface, and in that the pyrotechnic chamber (30) is arranged between the partition wall (33) and the first orifice (21). Figure for the abbreviation: Fig. 1

Description

Title of the invention: Gas generator with propellant stored under pressure Technical field of the invention

[0001] The present invention relates generally to a gas generator for automotive safety applications. In particular, the invention relates to a gas generator comprising a pressurized gas reservoir and propellant stored in the pressurized gas reservoir. State of the art

[0002] Gas generators capable of storing propellant directly in a pressurized gas reservoir are known in the prior art. However, such a system may exhibit high internal pressures during operation (propellant combustion generates hot combustion gases and can increase the pressure of the gases already present in the gas reservoir) and / or may be difficult to operate, particularly if gases must be supplied to the system over a long period of time (propellant combustion is typically accelerated when pressure increases). Documents EP1846272A2 or JP2001191889A illustrate such gas generators. Description of the invention

[0003] One object of the present invention is to address the disadvantages of the prior art mentioned above and in particular, first of all, to provide a gas generator with propellant stored directly in a pressurized gas reservoir without exhibiting high internal pressures during operation and / or which allows gas to be supplied to the system over a large period of time and / or which allows the initial aggressiveness to be limited.

[0004] To this end, a first aspect of the invention relates to a gas generator comprising: - a gas chamber with a first opening presenting a first passage surface and arranged to allow drainage of the gas chamber, - a main cover, sealing the first opening, - pressurized gases stored in the gas chamber, - a pyrotechnic chamber, arranged within the gas chamber, - propellant, stored in the pyrotechnic chamber. - an ignition device arranged to trigger combustion of the propellant, characterized in that the gas generator may comprise at least one partition wall of the gas chamber with at least one second orifice which may have a second passage surface smaller than the first passage surface, and in that the pyrotechnic chamber can be arranged between the bulkhead and the first orifice. The bulkhead separates the gas chamber into an upstream and a downstream section (which contains the pressurized propellant), and the second orifice limits pressure increases in the upstream section, even during propellant combustion. Furthermore, the small surface area of ​​the second orifice allows for a longer emptying time in the upstream section of the gas chamber. Consequently, the upstream section of the gas chamber experiences less pressure increase than a prior art generator and / or the total emptying time is longer compared to a prior art gas generator and / or the initial gas flow rate is lower than a prior art generator due to the independent, staggered, or sequential control of the upstream section (which contains only gases) and the downstream section (which contains propellant and pressurized gases).Indeed, at the start of operation, the gases from the combustion of the propellant can cause the seal to rupture and may need to be drained first.

[0005] According to one embodiment, the pyrotechnic chamber may comprise: - a first pyrotechnic chamber containing an initial propellant charge - a second pyrotechnic chamber containing a second propellant charge and the gas generator may include at least one pyrotechnic passage between the first and second pyrotechnic chambers. Such an (optional) implementation allows for fine-tuning of the pyrotechnic operation: sequential ignition of the two pyrotechnic chambers can be planned, or preferential ignition of one of the charges; specific and / or differentiated containment of the pyrotechnic chambers and / or different propellant charges (in mass and / or shape and / or material) can be provided...

[0006] According to one embodiment, the pyrotechnic passage may comprise: - a third opening between the first pyrotechnic chamber and the second pyrotechnic chamber, sealed by an intermediate cover, - A fourth opening between the first and second pyrotechnic chambers, left open by the intermediate cover. Closing the third opening, while leaving the fourth open, further increases the possibilities for fine-tuning the operation. A specific containment of the first pyrotechnic chamber can be achieved with the third opening closed for rapid ignition, and the fourth opening can be used to allow, facilitate, or trigger sympathetic ignition of the second pyrotechnic chamber once the propellant in the first pyrotechnic chamber has been properly ignited.

[0007] According to one embodiment: - the third orifice may have a third passage surface, - the fourth orifice may have a fourth passage surface smaller than the third passage surface.

[0008] According to one embodiment, the second pyrotechnic chamber can be arranged between the partition wall and the first pyrotechnic chamber. In other words, the two pyrotechnic chambers are arranged on the same side of the partition wall that supports the second opening.

[0009] According to one embodiment, the second pyrotechnic chamber may comprise a wall formed, preferably directly, by the partition wall. The number of internal components is limited as much as possible.

[0010] According to one embodiment, the second pyrotechnic chamber may include a drainage channel opening into the first pyrotechnic chamber.

[0011] According to one embodiment, the drainage channel may have an outlet sealed by the intermediate operculum. The third orifice may be one end of the drainage channel.

[0012] According to one embodiment, the ignition device can be arranged on a side wall of the gas chamber, preferably in a direction perpendicular to an axial direction of the gas chamber. Such an arrangement makes it possible to reduce the size and / or connection of the gas generator.

[0013] According to one embodiment, the gas generator may include a sealing element, such as a sheath, separate from the ignition device and arranged between the ignition device and the gases stored under pressure. The sealing element may typically be welded to the gas chamber, and the ignition device may be crimped onto the sealing element.

[0014] According to one embodiment, the sealing element may open, preferably directly, into the pyrotechnic chamber. Ignition is facilitated.

[0015] According to one embodiment, the sealing element can open into the first pyrotechnic chamber.

[0016] According to one embodiment, the sealing element can form a mechanical stop for an intermediate wall separating the first pyrotechnic chamber from the second pyrotechnic chamber.

[0017] According to one embodiment, the pyrotechnic chamber can be formed by a pyrotechnic box arranged within the gas chamber. Such a pyrotechnic box can be designed to contain, at least partially and / or at least temporarily, the combustion gases so as to limit the stresses applied to the gas chamber and / or the walls of the gas chamber.

[0018] According to one embodiment, the pyrotechnic housing may include the partition wall.

[0019] According to one embodiment, the pyrotechnic casing may comprise a case or basket with a lateral surface, and the lateral surface may have a peripheral portion tightly mounted in the gas chamber, preferably with the ignition device arranged between the first orifice and the peripheral portion tightly mounted in the gas chamber. Such a negative-clearance mounting creates a seal that limits pressure increases in the upstream part of the gas chamber.

[0020] According to one embodiment, the gas generator may include a gas diffuser arranged to diffuse gases towards a safety cushion; the first orifice may open into the gas diffuser. Such a diffuser makes it possible to contain / calm / redirect / reduce the pressure of the gases that drain from the first orifice before they enter an airbag.

[0021] According to one embodiment, the gas generator may comprise a secondary gas chamber with a first secondary orifice having a first secondary flow surface and gases stored under pressure. The gas chamber and the secondary gas chamber may have similar and / or equal shapes and / or volumes, or not.

[0022] According to one embodiment, the secondary gas chamber may include a secondary pyrotechnic chamber, preferably partitioned into a first secondary pyrotechnic chamber and a second secondary pyrotechnic chamber. The pyrotechnic chamber and the secondary pyrotechnic chamber may have similar and / or equal shapes and / or volumes, or not.

[0023] According to one embodiment, the gas generator may include at least one secondary partition wall of the secondary gas chamber with at least one second secondary orifice which may have a second secondary passage surface smaller than the first secondary passage surface, and the secondary pyrotechnic chamber may be arranged between the secondary partition wall and the first secondary orifice.

[0024] According to one embodiment, the gas generator may include at least a second operculum closing the second orifice. Description of the figures

[0025] Other features and advantages of the present invention will become more apparent upon reading the following detailed description of an embodiment of the invention given by way of non-limiting example and illustrated by the accompanying drawings, in which:

[0026] [Fig-1] represents a cross-sectional view of a gas generator according to the invention;

[0027] [Fig.2] represents a cross-sectional view of an alternative gas generator of the [Fig.l].

[0028] Detailed description of embodiment(s)

[0029] Figure [1] represents a gas generator comprising: - a gas chamber 10 with a first orifice 21 presenting a first passage surface and arranged to allow emptying of the gas chamber 10, - a main cover 51, sealing the first orifice 21, - pressurized gases stored in the gas chamber 10, - a pyrotechnic chamber 30, arranged in the gas chamber 10, and comprising a first pyrotechnic chamber PI containing a first propellant charge and a second pyrotechnic chamber P2 containing a second propellant charge, - an ignition device 40 arranged to trigger combustion of the first propellant charge, - a secondary gas chamber 10' with a first secondary orifice 21' with a first secondary passage surface, - a secondary main operculum 51', sealing the first secondary orifice 21', - gases stored under pressure in the secondary gas chamber 10', - a secondary pyrotechnic chamber 30' arranged within the secondary gas chamber 10', and comprising a first secondary pyrotechnic chamber PI' containing a first secondary propellant charge and a second secondary pyrotechnic chamber P2' containing a second secondary propellant charge, - a secondary ignition device 40' arranged to trigger combustion of the first secondary propellant charge - a diffuser 60, with a filter 65, interposed between the gas chamber 10 and the secondary gas chamber 10'.

[0030] With regard to the structure of the gas chamber 10 or the secondary gas chamber 10', an assembly of two parts can be provided: a chamber bottom 11 or a secondary chamber bottom 11' respectively, and a closing wall or a secondary closing wall 12' respectively, the parts being able to be welded together for example, by inertia welding for example.

[0031] The gas chamber 10 or the secondary gas chamber 10' can contain gases under pressure (for example, a mixture of inert gases, such as a mixture of argon and helium, but other gases and / or mixtures may be used, and reactive gases, such as oxygen and / or hydrogen, may be used). A storage pressure of between 30 and 60 MPa may be used, for example. The gas chamber 10 and the secondary gas chamber 10' are closed respectively by a plug 14 or a secondary plug 14'.

[0032] Regarding the structure of the pyrotechnic chamber 30 or the pyro chamber According to the 30' technique, an assembly of several parts is possible: a basket 31 or a secondary basket 31' can respectively receive a cup 32 or a secondary cup 32' with a perforated central chimney and be closed by a partition wall 33 or a secondary partition wall 33'. The cup 32 forms a partition of the pyrotechnic chamber 30 into a first pyrotechnic chamber P1 containing a first propellant charge and a second pyrotechnic chamber P2 containing a second propellant charge. Similarly, the secondary cup 32' forms a partition of the secondary pyrotechnic chamber 30' into a first secondary pyrotechnic chamber P1' containing a first secondary propellant charge and a second secondary pyrotechnic chamber P2' containing a second secondary propellant charge.

[0033] For the first propellant loading and / or the second propellant loading and / or the first secondary propellant loading and / or the second secondary propellant loading, a bulk loading, such as pellets, with a diameter ranging from 3 mm to 10 mm and a thickness ranging from 0.5 mm to 4.5 mm, may be used. However, a propellant block and / or ignition relays with powder may also be used.

[0034] It can be noted that the cup 32 and the secondary cup 32' include a central perforated chimney, which acts as a drainage channel for the combustion gases. Furthermore, in the state of [Fig. 1] where the gas generator has not yet operated, the base or downstream end of the central chimney of the cup 32 forms a third orifice 23 closed by an intermediate operculum 52. Finally, the presence of several fourth orifices 24 in the cup 32 can be noted, left free by the intermediate operculum 52. Similarly, the central chimney of the secondary cup 32' forms a third secondary orifice 23' closed by a secondary intermediate operculum 52', which leaves several fourth secondary orifices 24' free. In the given example, the third orifice 23 has a third surface, and the fourth orifices 24 together have a fourth surface, smaller than the third surface.

[0035] Support components can be provided in the pyrotechnic chamber to hold the pyrotechnic charges in place and limit vibrations, movements, and displacements. Typically, these components can be made of foam and / or fabric and / or fibers, and / or are compressible. Thus: - the first pyrotechnic chamber PI may include a first 34mm shimming disc, and / or - the second pyrotechnic chamber P2 may include a second 35mm beveling disc, and / or - the first secondary pyrotechnic chamber PI' may include a first secondary shim disc 34", and / or - the second secondary pyrotechnic chamber P2' may include a second secondary 35' shimming disc.

[0036] The ignition device 40 is fixed to the gas chamber 10 and typically comprises an electro-pyrotechnic igniter overmolded in a metal igniter support. However, other configurations are possible (for example, an igniter crimped onto the igniter support). A sealing element 45 is welded directly onto the gas chamber 10, and the ignition device 40 is crimped into the sealing element 45. The sealing element 45 is, for example, an elongated metal part, for example made of stamped sheet metal, with a weak point (for example, punched grooves) at its end. The sealing element 45, via a lateral hole in the basket 31, opens directly into the first pyrotechnic chamber PL. In this embodiment, the structure of the secondary ignition device 40' and the secondary sealing element 45' is identical, but different arrangements and / or structures are possible.

[0037] The gas generator of [Fig. 1] has an elongated axial shape, with the diffuser 60 positioned in the middle, between the gas chamber 10 and the secondary gas chamber 10'. Studs 15 are welded to allow for robust mounting in a safety module, at 90° to the axial direction of the gas generator, as are the ignition device 40 and the secondary ignition device 40'. This structure allows for a simple safety module design and robust coupling with the airbag. It should also be noted that the main orifice 21 and the secondary main orifice 21' are opposite each other, but other arrangements are possible.

[0038] The pyrotechnic chamber 30 (specifically via an annular clamping portion of the basket 31) is tightly mounted in the gas chamber 10 with the sealing element 45 located between the annular clamping portion and the first orifice 21. Taking into account the partition wall 33, this arrangement has the effect of partitioning the gas chamber 10 into an upstream portion AM containing only pressurized gases, and a downstream portion containing pressurized gases and pressurized propellant. It should be noted that the partition wall 33 has secondary orifices 22 which connect the upstream portion AM of the gas chamber 10 with the pyrotechnic chamber 30 and, more importantly, with the first orifice 21. In other words, in order to drain via the main orifice 21, the gases stored in the upstream portion AM of the gas chamber 10 must pass primarily through the secondary orifices 22 of the partition wall 33.In the given example, the first orifice 21 has a first surface, and the second orifices 22 together have a second surface, smaller than the first surface.

[0039] The operation of the gas generator in [Fig. 1] will be described. If necessary, a trigger signal is sent to the ignition device 40 to initiate the operation of the gas generator.

[0040] The electro-pyrotechnic igniter of the ignition device 40, under the effect of this triggering signal, will ignite, and the pressure in the sealing element 45 will rapidly rise, causing it to open. Hot gases and hot particles are projected directly into the first pyrotechnic chamber PI to ignite the first propellant charge.

[0041] Due to the presence of the main seal 51 and the intermediate seal 52, the first pyrotechnic chamber PI is well confined, which ensures a rapid, homogeneous, and efficient ignition of the first propellant charge, so that the pressure in the first pyrotechnic chamber PI will rapidly increase. It follows that once the first propellant charge is ignited, the following actions can occur simultaneously, almost simultaneously, or at different times, in any order: - the main operculum 51 can rupture, - the intermediate operculum 52 can rupture, - hot gases and hot particles can be projected into the second pyrotechnic chamber P2 through the fourth orifices 24.

[0042] Preferably, the fourth orifices 24 can be positioned or sized to ensure that hot gases and hot particles enter or penetrate the second pyrotechnic chamber P2 through the fourth orifices 24 before the rupture of the main flap 51, so as to guarantee the ignition of the second propellant charge by the combustion of the first propellant charge. Thus, the sequence is as follows: ignition of the first propellant charge, passage of hot gases and hot particles into the second pyrotechnic chamber P2 to guarantee the ignition of the second propellant charge, and opening of the main flap 51 and the intermediate flap 52; the opening of the intermediate flap 52 being achieved or caused by the combustion of the second propellant charge.

[0043] Once the first propellant charge is ignited and the main port 51 is opened, gases from the gas chamber 10 can drain into the diffuser 60 and pass through the filter 65 to inflate an airbag. It should be noted that the basket 31 has a bottom that is detached or offset from the bottom of the chamber 11, which ensures that the first gases to escape from the gas chamber 10, and thus cause the airbag to inflate, are cold gases, followed by combustion gases from the first propellant charge.

[0044] Once the second propellant charge is ignited and the intermediate gate 52 is opened, combustion gases from the second propellant charge can drain through the first orifice 51 (via the chimney of the cup 32 and the first pyrotechnic chamber PI) as well as through the fourth orifice 24 and participate in the inflation of the airbag.

[0045] When the combustion pressure in the pyrotechnic chamber decreases, it can be noted that the pressurized gases present in the upstream part AM of the gas chamber 10 can drain through the first orifice 51 (via the second orifices 22, the chimney of the cup 32 and the first pyrotechnic chamber PI) and participate in the inflation of the airbag.

[0046] With the structure of the gas generator in [Fig. 1], the following points can be noted: - The presence of the pyrotechnic chamber 30 (including the basket 30 and the partition wall 33) helps to limit the pressure increase experienced by the gas chamber 10, and in particular by its outer wall. Indeed, when the sealing device 45 is opened, and / or during ignition, the wall of the basket 31 and / or the partition wall 33 attenuate or limit the propagation of pressure waves in the rest of the gas chamber 10. - The larger surface area of ​​the first orifice 21 compared to the total surface area of ​​the second orifices 22 helps to limit the aggressiveness of the gas discharge from the gas chamber 10, particularly by reducing the rate of gas discharge from the upstream section AM. It can also be considered that the ability to adjust the total operating time is improved. - The partition of the pyrotechnic chamber 30 increases the options / possibilities for adjusting propellant combustion and ensures better ignition of the first pyrotechnic chamber. This latter point is further enhanced by the presence of the intermediate port 52. The fourth ports 24 allow for rapid ignition of the second propellant charge, which nevertheless remains confined by the presence of the intermediate port 52. - the tightening (no play assembly) of the pyrotechnic chamber 30 in the bottom of chamber 11, by an annular portion in contact of the basket 31 with the bottom of chamber 11 guarantees the efficiency of the emptying of the gases from the upstream part AM through the second orifices 22.

[0047] With regard to the secondary gas chamber 10', the operation is the same, and it is possible to plan to trigger the secondary ignition device 40' simultaneously or with a time delay (ahead or behind) with the triggering of the ignition device 40.

[0048] Figure 2 represents an alternative to the gas generator of Figure 1. The generator of Figure 2 includes, in particular: - a gas chamber 110 with a first orifice 121 presenting a first passage surface arranged to allow drainage of the gas chamber 110, - a main cover 151, closing the first orifice 121, - of pressurized gases stored in the gas chamber 110, - a pyrotechnic chamber 130, arranged in the gas chamber 110, formed in particular by a basket 131, a chimney 132 and a partition wall 133, - a propellant charge, housed in the pyrotechnic chamber 130, - an ignition device 140 arranged to trigger combustion of the first propellant charge, - a secondary gas chamber 110' with a first secondary orifice 121' with a first secondary passage surface, - a secondary main operculum 151', sealing the first secondary orifice 121', - gases stored under pressure in the secondary gas chamber 110', - a diffuser 60, with a filter 65, interposed between the gas chamber 10 and the secondary gas chamber 10' and also housing a support mechanism 161, - 115 studs to fix the gas generator to a support or in a safety module.

[0049] The gas chamber 110 is formed by the assembly of a chamber bottom 111 and a closing wall 112, a plug 114 allows the gas chamber 110 to be closed. Similarly, the secondary gas chamber 110' is formed by the assembly of a secondary chamber bottom 111' and a secondary closing wall 112', a secondary plug 114' allows the secondary gas chamber 110' to be closed.

[0050] The structure of the gas chamber 110 is similar to the structure of the gas chamber 10 of the gas generator in [Fig. 1]. However, the secondary gas chamber 110' does not have an ignition device, and a support mechanism 161 is provided in the diffuser 160 to support the secondary main cover 151' or the part of the bottom of the secondary chamber 111' to which the secondary main cover 151' is welded, and to be retracted by the action of the gases in the gas chamber 110 when it is opened.

[0051] The pressurized gases stored in the gas chamber 110 or in the secondary gas chamber 110', the ignition device 140 and the sealing element 135 meet the same characteristics as for the gas generator of [Fig.1].

[0052] The gas generator of [Fig.2] differs from the gas generator of [Fig.1] in particular with regard to: - of the pyrotechnic chamber 130 and of the gas chamber 110, which is not partitioned, - of the secondary gas chamber 110' which does not contain pressurized propellant, - of the secondary gas chamber 110' which does not include an independently controllable opening device and whose opening is dependent on the opening of the gas chamber 110. It should be kept in mind that these differences may be independent of each other, and that it might be possible to consider bringing only some of these differences to the gas generator of [Fig.1].

[0053] As regards the pyrotechnic chamber 130, in the embodiment shown, it is composed of three distinct parts: a drainage channel, i.e., a chimney 132 which can form a drainage element, a basket 131, and a partition wall 133. The basket 131 forms an external wall of the pyrotechnic chamber 130 and contains the propellant. The chimney 132 forms an internal tube within the pyrotechnic chamber 130 and has a base that mates with the basket 131 at its end opposite the first orifice 151. The partition wall 133 mates (here by crimping) with the basket 131 at its end opposite the first orifice 151 to close the basket 131. The structure of the pyrotechnic chamber 130 is shown here in three parts, but other embodiments are possible.

[0054] It can be noted that the chimney 132 has orifices only in its upstream part (at its end opposite the first orifice 151), and that the partition wall 133 has a second orifice 122, opposite the channel formed by the chimney 132. Finally, the pyrotechnic chamber 130 includes a compensator 135 (a piece of foam or compressible fabric) intended to ensure optimal packing of the propellant.

[0055] As with the generator of [Fig.1], the second orifice 122 has a second surface that is lower than the first surface of the first orifice 121.

[0056] Thus, the emptying when the gas chamber 110 is opened and the combustion of the propellant in the pyrotechnic chamber 130 is essentially controlled by the size of the first orifice 121, and the emptying of the upstream part AM of the gas chamber 110 is restricted or limited or even shifted by the second orifice 122.

[0057] Furthermore, the pyrotechnic chamber 130 with its walls surrounding the propellant and with the ignition device 140 which opens directly into the propellant charge makes it possible to limit or contain the pressure and overpressure waves or to act as a shield, which makes it possible to reduce the stresses applied to the walls of the gas chamber 110 (the bottom of the chamber 111 and / or the closing wall 112). Industrial application

[0058] A gas generator according to the present invention, and its manufacture, are capable of industrial application.

[0059] It will be understood that various modifications and / or improvements obvious to a person skilled in the art can be made to the different embodiments of the invention described in this description without departing from the scope of the invention. In particular, it may be noted that the detailed description mentions: - a single first orifice or a single first secondary orifice: we could foresee several first orifices or several first secondary orifices; - several second orifices or several secondary second orifices: one could foresee a single second orifice or a single secondary second orifice; - a single third orifice or a single secondary third orifice: we could foresee several third orifices or several secondary third orifices; - several fourth orifices or several secondary fourth orifices: one could foresee a single fourth orifice or a single secondary fourth orifice.

Claims

Demands

1. A gas generator comprising: - a gas chamber (10; 110) with a first orifice (21; 121) having a first passage surface and arranged to allow emptying of the gas chamber (10; 110), - a main cover (51; 151) closing the first orifice (21; 121), - pressurized gases stored in the gas chamber (10; 110), - a pyrotechnic chamber (30; 130) arranged in the gas chamber (10; 110), - propellant stored in the pyrotechnic chamber (30; 130), - an ignition device (40; 140) arranged to trigger combustion of the propellant, characterized in that the gas generator comprises at least one partition wall (33; 133) of the gas chamber (10; 110) with at least a second orifice (22; 122) having a second passage surface smaller than the first passage surface, and in that the pyrotechnic chamber (30; 130) is arranged between the partition wall (33;133) and the first orifice (21; 121), the gas generator comprising a sealing element (45; 145), such as a sheath, separate from the ignition device (40; 140) and arranged between the ignition device (40; 140) and the gases stored under pressure.;

2. Gas generator according to claim 1, in which the pyrotechnic chamber (30) comprises: - a first pyrotechnic chamber (PI) containing a first propellant charge, - a second pyrotechnic chamber (P2) containing a second propellant charge, and in which the gas generator comprises at least one pyrotechnic passage between the first pyrotechnic chamber (PI) and the second pyrotechnic chamber (P2).

3. Gas generator according to claim 2, wherein the pyrotechnic passage comprises: - a third orifice (23) between the first pyrotechnic chamber (PI) and the second pyrotechnic chamber (P2), closed by an intermediate operculum (52; 152), - a fourth orifice (24) between the first pyrotechnic chamber (PI) and the second pyrotechnic chamber (P2), left free by the intermediate operculum (52; 152).

4. Gas generator according to claim 3, wherein: - the third orifice (23) has a third passage surface, - the fourth orifice (24) has a fourth passage surface smaller than the third passage surface.

5. Gas generator according to any one of claims 2 to 4, wherein the second pyrotechnic chamber (P2) is arranged between the partition wall (33) and the first pyrotechnic chamber (PI).

6. Gas generator according to any one of claims 2 to 5, wherein the second pyrotechnic chamber (P2) comprises a wall formed by the partition wall (33).

7. Gas generator according to any one of claims 2 to 6, wherein the second pyrotechnic chamber (P2) includes a drainage channel opening into the first pyrotechnic chamber (PI).

8. Gas generator according to claim 7 in its dependence on claim 3, wherein the drainage channel has an outlet closed by the intermediate operculum (52; 152).

9. Gas generator according to any one of claims 1 to 8, wherein the ignition device (40; 140) is arranged on a side wall of the gas chamber (10; 110), preferably in a direction perpendicular to an axial direction of the gas chamber (10; 110).

10. Gas generator according to any one of claims 1 to 9, wherein the sealing element (45; 145) opens into the pyrotechnic chamber (30; 130).

11. Gas generator according to claim 10 in its dependence on any one of claims 2 to 8, wherein the sealing member (45) opens into the first pyrotechnic chamber (PI).

12. Gas generator according to any one of claims 1 to 11, wherein the pyrotechnic chamber (30; 130) is formed by a pyrotechnic casing arranged in the gas chamber (10; 110).

13. Gas generator according to claim 12, wherein the pyrotechnic housing includes the partition wall (33; 133).

14. A gas generator according to any one of claims 12 to 13, wherein the pyrotechnic casing comprises a case or basket with a lateral surface, and wherein the lateral surface has a peripheral portion tightly mounted in the gas chamber (10; 110), preferably with the ignition device (40; 140) arranged between the first orifice (21; 121) and the peripheral portion tightly mounted in the gas chamber (10; 110).