GAS GENERATOR AND AIRBAG MODULE

• US 20130200600A1
• Filed: 09/27/2011
• Published: 08/08/2013
• Est. Priority Date: 10/15/2010
• Status: Active Grant

• Current Assignee: TRW Airbag Systems GmbH (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: TRW Airbag Systems GmbH (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Bierwirth, Sebastian, Hofmann, Achim, Neumayer, Hans-Peter, Spitzenberger, Dieter, Nuiding, Hannes, Schober, Thomas, Bommer, Josef, Breddermann, Tobias, Schwebel, Dietmar
• Granted Patent: US 9,452,729 B2
• Time in Patent Office: Days
• US Class Current: 280/740
• CPC Class Codes: B60R 2021/26011 using a filter through which the inflation gas passes
• CPC Class Codes: B60R 2021/26029 Ignitors
• CPC Class Codes: B60R 2021/2633 with a plurality of inflation levels
• CPC Class Codes: B60R 2021/2648 comprising a plurality of combustion chambers or sub-chambers
• CPC Class Codes: B60R 21/261 with means other than bag structure to diffuse or guide inflation fluid
• CPC Class Codes: B60R 21/263 using a variable source, e.g. plural stage or controlled output hybrid inflators B60R21/272
• CPC Class Codes: B60R 21/264 using instantaneous generation of gas, e.g. pyrotechnic B60R21/268 takes precedence
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder

Abstract

An inflator, especially for a protective device in a vehicle, includes a diffuser (10) which preferably forms a substantially rotation-symmetric external housing of the inflator with a closing member (12). The diffuser (10) includes more than 12, preferably more than 14, further preferably 23 discharge orifices (78) arranged in a row. Moreover, the inflator exhibits a plurality of further peculiarities.

Claims

1. An inflator, especially for a protective device in a vehicle, comprising a diffuser (10) preferably forming a substantially rotation-symmetric external housing of the inflator with a closing member (12), wherein the diffuser (10) includes more than 12, preferably more than 14, further preferably 23 discharge orifices (78) arranged in a row, wherein, preferably, the diffuser (10) includes only one single row of discharge orifices (78), which preferably are of circular shape.

2. The inflator according to claim 1, wherein the ratio of the outer circumference of the diffuser (10) in mm to the number n of the discharge orifices (78) in the row is less than 16.5, preferably less than 14.1, further preferably less than 9.85, further preferably is between 7.57 and 9.85, further preferably is between 8.20 and 8.96 and further preferably is approx. 8.56, and or wherein the diffuser (10)—

related to the central axis A of the diffuser (10)—

is surrounded ring-like by a fixation flange.

3. The inflator according to any one of the preceding claims, wherein the discharge orifices (78) have at least two, preferably three different flow cross-sections, the different flow cross-sections being defined by different diameters of the circular discharge orifices (78), and, preferably, wherein—

related to the central axis A of the diffuser (10)—

opposed discharge orifices (78) have equal flow cross-sections, and wherein, preferably, directly neighboring discharge orifices (78) have different flow cross-sections.

4. The inflator according to any one of the preceding claims, wherein the discharge orifices (78) have at least three different flow cross-sections and that in the row of the discharge orifices (78) at least partially a recurring sequence of the type of first flow cross-section→

second flow cross-section→

first flow cross-section→

third flow cross-section is provided, wherein further preferably the first flow cross-section is small, the second flow cross-section is medium and the third flow cross-section is large; and

wherein, further preferably,

the ratio of the outer circumference of the diffuser (10) in mm to the number of discharge orifices (78) having a small flow cross-section is less than 19.7, preferably ranges between 15.1 and 19.7 and further preferably is approx. 17.9; and

/or

wherein, further preferably, the ratio of the outer circumference of the diffuser (10) in mm to the number of discharge orifices (78) having the medium flow cross-section and/or to the number of discharge orifices (78) having the large flow cross-section is less than 39.4, preferably ranges between 28.2 and 39.4 and further preferably is approx. 32.8.

5. The inflator according to any one of the preceding claims, wherein the ratio of the total flow cross-section of all discharge orifices (78) of the row in mm² to the outer circumference of the diffuser (10) in mm is more than 110, preferably between 110 and 139 and further preferably is approx. 124;

and/or wherein the distances between neighboring discharge orifices (78) in the row are equal.

6. The inflator according to any one of the preceding claims, wherein the row of the discharge orifices (78) extends in circumferential direction with respect to a central axis A of the diffuser (10) and has a beginning with a first discharge orifice (78a) and an end with a last discharge orifice (78b), the distance between the first discharge orifice (78a) and the last discharge orifice (78b) being larger, preferably twice as large as the distance between neighboring discharge orifices (78) in the row;

wherein, further preferably, a joint of a tamping strip (84) is arranged between the beginning and the end of the row.

7. The inflator according to any one of the preceding claims, wherein the row includes n discharge orifices (78) and extends in circumferential direction with respect to the central axis A of the diffuser, the row having a beginning with a first discharge orifice (78a) and an end with a last discharge orifice (78b) and the angular distance between neighboring discharge orifices (78) amounting to 360°

/(n+1).

8. Inflator, especially for a protective device in a vehicle and preferably according to any one of the preceding claims, characterized by a fuel canister (58) filled with fuel including a fuel canister bottom (66) and a fuel canister opening (64) opposed to the fuel canister bottom (66) which is closed by means of a combustion chamber component (60).

9. The inflator according to claim 8, wherein the combustion chamber component is a combustion chamber sleeve (60) which preferably encloses at least partially a combustion chamber (56) associated with a particular activating stage of the inflator, wherein the combustion chamber sleeve (60) exhibits a combustion chamber sleeve opening or an open side and a combustion chamber sleeve bottom (72) opposed thereto which covers the fuel canister opening (64), wherein preferably a second fill member (76) preferably connected to the combustion chamber sleeve bottom (72) is arranged at the combustion chamber sleeve bottom (72);

and/or wherein further preferably

at least part of a side wall (62) of the fuel canister (58) extending between the fuel canister opening (64) and the fuel canister bottom (66) is directly opposed to at least part of a side wall (102) of the combustion chamber sleeve (60) extending between the combustion chamber sleeve orifice or the open side of the combustion chamber sleeve (60) and the combustion chamber sleeve bottom (72).

10. The inflator according to any one of the preceding claims, wherein the fuel canister (58) and the combustion chamber sleeve (60) are two open substantially cylindrical sleeves which are inserted into each other at opposed orientation so that an inner or outer shell of the fuel canister (58) and an outer or inner shell of the combustion chamber sleeve (60) substantially cover each other over the entire axial length of the shells, the combustion chamber sleeve (60) being preferably slipped onto the outside of the fuel canister (58).

11. The inflator according to any one of the preceding claims, wherein in the fuel canister bottom (66) a central fuel canister bottom opening (68) is formed for receiving a support component, especially an igniter carrier (32);

wherein, preferably, the fuel canister bottom opening (68) is formed by a preferably bent, inner edge portion (70) extending from the fuel canister bottom (66) into the interior of the fuel canister (58).

12. The inflator according to any one of the preceding claims, wherein plural holes (106) are formed in the fuel canister bottom (66), and/or wherein the combustion chamber sleeve (60) is free of holes, apart from the combustion chamber sleeve orifice or the open side, and/or wherein the combustion chamber sleeve (60) is slipped onto an igniter carrier (32).

13. Inflator, especially for a protective device in a vehicle and preferably according to any one of the preceding claims, comprising a combustion chamber sleeve (60) which at least partially encloses a combustion chamber (56) filled with fuel, wherein the combustion chamber sleeve (60) is designed such that it changes its shape by pressure formed during combustion of the fuel so as to release a discharge orifice (112) leading out of the combustion chamber (56), preferably into a further combustion chamber (44) of the inflator, for a combustion gas formed during combustion of the fuel.

14. Inflator, especially for a protective device in a vehicle and preferably according to any one of the preceding claims, comprising a combustion chamber sleeve (60) which at least partially encloses a combustion chamber (56) filled with fuel, wherein the combustion chamber sleeve (60) is designed such that it changes its position and/or shape by pressure formed during combustion of the fuel so as to release a discharge orifice (112) leading out of the combustion chamber (56), preferably into a further combustion chamber (44) of the inflator, for a combustion gas formed during combustion of the fuel. 31;

wherein the combustion chamber sleeve (60) is attached to a support component of the inflator, especially an igniter carrier (32), and the discharge orifice (112) is formed by the fact that the combustion chamber sleeve (60) detaches at least partially from the supporting component so that a discharge gap (112) is formed between the combustion chamber sleeve (60) and the supporting component; and

wherein—

related to a central axis C of the combustion chamber sleeve (60)—

the discharge gap (112) is formed to be not completely circumferential or at least not to have a constant width, wherein the discharge gap (112) has its largest width in an area facing away from a filter (46) disposed outside the combustion chamber (56) and/or having the largest possible distance from the filter (46).

15. Inflator, especially for a protective device in a vehicle and preferably according to any one of the preceding claims, comprising a combustion chamber sleeve (60) which at least partially encloses a combustion chamber (56) filled with fuel, wherein the combustion chamber sleeve (60) is designed such that it changes its position and/or shape by pressure formed during combustion of the fuel so as to release a discharge orifice (112) leading out of the combustion chamber (56), preferably into a further combustion chamber (44) of the inflator, for a combustion gas formed during combustion of the fuel, wherein the combustion chamber sleeve (60) is slipped onto a fuel canister (58) filled with fuel and having a fuel canister bottom (66) including one or more holes (106) through which the combustion gas flows to the discharge orifice (112);

wherein, preferably, the hole or holes (106) in the fuel canister bottom (66) is/are formed as late as by the pressure developed during combustion of the fuel and tearing of the fuel canister bottom (66) caused thereby.

16. The inflator according to any of the preceding claims, wherein before the combustion of the fuel the combustion chamber sleeve (60) has no discharge orifice;

and/or wherein due to the pressure the combustion chamber sleeve (60) moves toward a ceiling portion (14) of a diffuser (10) of the inflator, wherein the movement is preferably restricted by the ceiling portion (14), wherein, preferably, the combustion chamber sleeve (60) is partly supported on the ceiling portion (14) of the diffuser (10), preferably already prior to activation of the inflator, and a tilting and/or an uneven deformation of the combustion chamber sleeve (60) is caused by the pressure.

17. Inflator, especially for a protective device in a vehicle and preferably according to any one of the preceding claims, comprising an igniter sleeve (38) which at least partially encloses an igniter (34) and an igniter chamber (42) especially filled with a booster charge and is adjacent to a first combustion chamber (44) especially filled with fuel, wherein the igniter sleeve (38)—

related to a central axis B of the igniter sleeve (38)—

has overflow orifices (98) unevenly distributed in circumferential direction.

18. The inflator according to claim 17, wherein the igniter sleeve (38) includes a marker (92) distant from its central axis B or extending non-symmetrically from the central axis B which indicates the predetermined orientation of the igniter sleeve (38) and/or wherein the igniter sleeve (38) includes a nose or a recess as marker (92) and/or wherein the igniter sleeve (38) has a configuration which is adapted to a configuration of a neighboring component of the inflator such that mounting of the igniter sleeve (38) in the inflator is possible at the predetermined orientation only, wherein preferably,

the igniter sleeve (38) offset with respect to a central axis A of a diffuser and a bottom (40) of the igniter sleeve (38) is opposed to a ceiling portion (14) of the diffuser (10), wherein the igniter sleeve bottom (40) has a slant adapted to a curvature of the ceiling portion (14) of the diffuser (10) such that the igniter sleeve (38) fits below the ceiling portion (14) of the diffuser (10) at the predetermined orientation only, and/or wherein preferably,

the igniter sleeve (38) is radially tapered in axial direction toward a bottom (40) of the igniter sleeve (38).

19. The inflator according to any one of the preceding claims, wherein the overflow orifices (98) in circumferential direction define a maximum angular range a that extends to both sides of a connecting line x between the central axis B of the igniter sleeve (38) and the portion of the filter (46) maximally distant from the central axis B, wherein the angular range α

is preferably obtuse and preferably ranges between 90° and

135°

, further preferably between 100° and

120° and

further preferably is approx. 110°

.

20. The inflator according to any of the preceding claims, wherein the angular range a includes areas in which a distance from the filter (46) not blocked by components of the inflator is maximal and/or wherein the angular range a encloses a combustion chamber component which is arranged in the first combustion chamber, especially a combustion chamber sleeve (60) which surrounds a second combustion chamber (56) which in turn is at least partially surrounded by the first combustion chamber (44).

21. Inflator, especially for a protective device in a vehicle and preferably according to any one of the preceding claims, comprising an igniter sleeve (38) which at least partially encloses an igniter (34) and an igniter chamber (42) especially filled with a booster charge and is adjacent to a first combustion chamber (44) associated with a first activating stage of the inflator, as well as a combustion chamber sleeve (60) which at least partially encloses a second combustion chamber (56) filled with fuel and associated with a second activating stage of the inflator, wherein both sleeves (38, 60) are juxtaposed and are preferably differently offset with respect to a central axis A of the inflator, and/or wherein

the distance between a central axis B of the igniter sleeve (38) and a central axis C of the combustion chamber sleeve (60) is between 22.5 and 27.5 mm, preferably between 23.5 and 26.5 mm and further preferably is approx. 25 mm and/or wherein the ratio of the minimum inner diameter c of the combustion chamber sleeve to the minimum inner diameter d of the igniter sleeve is between 1.64 and 2.63, preferably between 1.83 and 2.32 and further preferably is approx. 2.06, and/or wherein—

related to a central axis A of the inflator—

the first combustion chamber (44) is radially confined at least partially by an at least partly circumferential filter (46), the ratio of the inner diameter f of the filter (46) to the minimum inner diameter d of the igniter sleeve (38) ranging between 3.19 and 4.76, preferably between 3.50 and 4.27 and further preferably being approx. 3.85.

22. Inflator, especially for a protective device in a vehicle and preferably according to any one of the preceding claims, comprising an igniter sleeve (38) which at least partially encloses an igniter (34) and an igniter chamber (42) especially filled with a booster charge and is adjacent to a first combustion chamber (44) associated with a first activating stage of the inflator, as well as a combustion chamber sleeve (60) which at least partially encloses a second combustion chamber (56) filled with fuel and associated with a second activating stage of the inflator, wherein the combustion chamber sleeve (60) is adjacent to the first combustion chamber (44) which—

related to a central axis A of the inflator—

is radially confined at least partially by an at least partly circumferential filter (46), the ratio of the inner diameter f of the filter to the minimum inner diameter c of the combustion chamber sleeve (60) ranging between 1.66 and 2.11, preferably between 1.76 and 1.99 and further preferably being approx. 1.87; and

/or wherein

the ratio of the outer diameter a of the inflator to the minimum inner diameter d of the igniter sleeve (38) is between 4.09 and 5.98, preferably between 4.46 and 5.39 and further preferably is approx. 4.89; and

/or wherein

the ratio of the outer diameter a of the inflator to the minimum inner diameter c of the combustion chamber sleeve (60) is between 2.13 and 2.66, preferably between 2.24 and 2.50 and further preferably is approx. 2.38.

23. Inflator, especially for a protective device in a vehicle and preferably according to any one of the preceding claims, comprising an igniter sleeve (38) which at least partially encloses an igniter (34) and an igniter chamber (42) especially filled with a booster charge and is adjacent to a first combustion chamber (44) associated with a first activating stage of the inflator, as well as a combustion chamber sleeve (60) which at least partially encloses a second combustion chamber (56) filled with fuel and associated with a second activating stage of the inflator, wherein the axial distance of an open side of the igniter sleeve (38) from a bottom (20) of a closing member (12) of the inflator is unequal to the axial distance of an open side of the combustion chamber sleeve (60) from the bottom (20) of the closing member (12), the distance of the igniter sleeve (38) preferably being larger;

and/or wherein the igniter sleeve (38) and the combustion chamber sleeve (60) are attached to a first igniter carrier (30) or to a second igniter carrier (32), wherein the axial height of the contact area between the igniter sleeve (38) and the first igniter carrier (30) is larger than the axial height of the contact area between the combustion chamber sleeve (60) and the second igniter carrier (32); and

/or wherein

both the igniter sleeve (38) is raised by the pressure developed during combustion of the booster charge and the combustion chamber sleeve (60) is raised by the pressure developed during combustion of the fuel, preferably in the direction of the ceiling portion (14) of a diffuser (10) of the inflator, wherein by raising the combustion chamber sleeve (60) a discharge orifice, preferably in the form of a discharge gap (112) is released which leads out of the combustion chamber sleeve (60), whereas no discharge orifice is released by raising the igniter sleeve (38).

24. Inflator, especially for a protective device in a vehicle and preferably according to any one of the preceding claims, comprising a filter (46) and a combustion chamber component at least partially enclosing a combustion chamber (56), especially a combustion chamber sleeve (60), wherein the filter (46) extends in a ring-shaped manner about the combustion chamber (56) and, at a position of its ring-shaped extension, includes a critical filter portion (120) which is closer to the combustion chamber component than the remaining filter areas situated at its ring-shaped extension, wherein the critical filter portion (120) has a reduced thickness compared to areas of the filter that are adjacent to the critical filter portion (120).

25. The inflator according to any one of the preceding claims, wherein between the combustion chamber component (60) and the critical filter portion (120) a gap (122) is formed, and/or

wherein the material of which the filter (46) is made is compressed more highly in the critical filter portion (120) than in the adjacent areas;

and/or wherein

the combustion chamber component (60) has an increased material thickness at least in the area opposed to the critical filter portion (120); and

/or

wherein the filter (46) extends along a circumferential wall (16, 22) of the inflator surrounding a chamber (44) of the inflator in which the combustion chamber component (60) is disposed; and

/or wherein

the combustion chamber component (60) extends over a larger axial height than the filter (46), the combustion chamber component (60) substantially exhibiting an increased material thickness only in the axial area in which also the filter (46) extends.

26. The inflator according to any one of the preceding claims, wherein the ratio of the minimum thickness j of the critical filter portion (120) to the thickness of the adjacent areas of the filter (46) is between 0.43 and 0.93, preferably between 0.53 and 0.78 and further preferably is approx. 0.65, and/or wherein

the ratio of the minimum thickness j of the critical filter portion (120) to the maximum width (h) of the gap (122) is between 1.17 and 2.85, preferably between 1.50 and 2.23 and further preferably is approx. 1.83;

and/or wherein

the inflator is closed at a first axial end face by a diffuser (10) having a substantially axially extending circumferential wall (16), wherein the filter (46) extends in axial direction beyond the circumferential wall (16).

27. The inflator, especially for a protective device in a vehicle and preferably according to any one of the preceding claims, comprising a circumferential wall (16, 22) which especially surrounds a combustion chamber (44) and a filter (46) which extends at least partially along the wall (16, 22), wherein the wall (16, 22) has at least one supporting portion (124) which constitutes an axial support for the filter (46) and is preferably integrally formed with the wall (16. 22), and wherein either plural supporting portions (124) are formed by preferably embossed beads, which beads, preferably, are spaced apart from each other in circumferential direction, and/or wherein a supporting portion (124) is formed by a completely circumferential, preferably embossed bead.

28. Inflator, especially for a protective device in a vehicle and preferably according to any one of the preceding claims, comprising a first combustion chamber (44) filled with fuel which is associated with a first activating stage of the inflator and is closed on one side by a lid, especially a diffuser (10), wherein a first fill member (52;

82), preferably made of silicone, is disposed between the fuel and the lid,

wherein the first fill member (52;

82) has at least one preferably circular recess (116, 118) into which a sleeve, especially an igniter sleeve (38) associated with the first activating stage of the inflator or a combustion chamber sleeve (60) associated with a second activating stage of the inflator projects, and wherein

the first fill member (52;

82) has two recesses (116, 118) of different size, wherein the igniter sleeve (38) preferably projects into the smaller recess (116) and the combustion chamber sleeve (60) preferably projects into the larger recess (118), wherein preferably,

the ratio of the diameter of the larger recess (118) to the diameter of the smaller recess (116) is between 1.52 and 2.25, preferably between 1.67 and 2.03 and further preferably is approx. 1.84, and/or wherein,

the first fill member (82) is designed in at least two parts, wherein preferably, each of the two partial members (114) has the shape of a double half moon.

29. The inflator, especially for a protective device in a vehicle and preferably according to any one of the preceding claims, comprising a radially projecting generator flange (18)—

related to a central axis A of the inflator—

for mounting the inflator to a support, wherein the generator flange (18) is substantially rectangular, wherein

the ratio of the length l to the width b of the rectangle ranges between 1.12 and 1.31, preferably between 1.16 and 1.27 and further preferably is approx. 1.21, and/or wherein

the ratio of the length l of the rectangle to the outer diameter a of the external housing ranges between 1.24 and 1.48, preferably between 1.30 and 1.42 and further preferably is approx. 1.36, and/or wherein

the ratio of the width b of the rectangle to the outer diameter a of the external housing is between 1.01 and 1.23, preferably between 1.06 and 1.17 and further preferably is approx. 1.12.

30. The inflator, especially for a protective device in a vehicle and preferably according to any one of the preceding claims, comprising an igniter unit (26, 28), wherein the igniter unit (26, 28) has a marker (90), wherein, preferably, the marker (90) is a milled slot, and/or wherein the marker (90) sets a predetermined orientation of connecting pins of the igniter unit (26, 28).

31. The inflator according to any one of the previous claims, wherein the igniter unit (26, 28) is a pre-assembled unit having an igniter carrier (30, 32) and an igniter (34, 36) held therein which is preferably adapted to be inserted in a bottom orifice (24) of a closing member (12) of the inflator.

32. Inflator, especially for a protective device in a vehicle and preferably according to any one of the preceding claims, comprising a diffuser (10) forming a preferably substantially rotation-symmetric external housing of the inflator with a closing member (12), wherein at least in portions the wall thickness of the closing member (12) is larger than that of the diffuser (10), wherein, preferably, the closing member (12) has a substantially plane bottom (20) in which preferably at least one opening (24) for receiving an igniter carrier (30, 32) is formed and that at least the bottom (20) has a larger wall thickness than the diffuser (10).

33. Inflator, especially for a protective device in a vehicle and preferably according to any one of the preceding claims, comprising a combustion chamber component at least partially enclosing a combustion chamber (56), especially a combustion chamber sleeve (60), and a diffuser (10) including a ceiling portion (14), wherein the combustion chamber component (60) contacts the ceiling portion (14) of the diffuser (10) in a non-activated state of the inflator at least at one point (110), and wherein—

related to a central axis A of the diffuser—

the axial distance g between the combustion chamber component and the ceiling portion (14) is varying such that the maximum distance g between the combustion chamber component (60) and the ceiling portion (14) of the diffuser (10) is between 2.3 and 3.7 mm, preferably between 2.7 and 3.3 mm and further preferably is approx. 3.0 mm.

34. The inflator according to any one of the preceding claims, characterized by an igniter sleeve (38) offset with respect to the central axis A of the diffuser whose axial distance i from the ceiling portion (14) of the diffuser (10) is varying such that the maximum distance i between the igniter sleeve (38) and the ceiling portion (14) of the diffuser (10) is between 2.1 and 3.5 mm, preferably between 2.5 and 3.1 mm and further preferably amounts to approx. 2.8 mm.

35. Inflator, especially for a protective device in a vehicle and preferably according to any one of the preceding claims, comprising a first combustion chamber (44) associated with a first activating stage of the inflator and a second combustion chamber (56) associated with a second activating stage of the inflator, wherein the second combustion chamber (56) is surrounded at least partially by the first combustion chamber (44) and has a smaller volume than the first combustion chamber (44), wherein

the ratio of the volume of the first combustion chamber (44) to the volume of the second combustion chamber (56) is between 2.07 and 3.78, preferably between 2.41 and 3.21 and further preferably amounts to approx. 2.82, and/or wherein

the ratio of the volume of the first combustion chamber (44) to the volume of an igniter sleeve (38) at least partially surrounded by the first combustion chamber (44) is between 9.00 and 35.0, preferably between 11.6 and 22.0 and further preferably amounts to approx. 15.5, and/or wherein

the ratio of the outer diameter a of an external housing of the inflator to the height h₁ of the external housing is between 1.38 and 1.78 and further preferably is approx. 1.57, and/or wherein

the construction height of the inflator, especially the axial height h₁ of an external housing of the inflator, is between 30 and 50 mm and preferably is approx. 40 mm, in particular 42 mm.

36. Inflator, especially for a protective device in a vehicle and preferably according to any one of the preceding claims, comprising a first combustion chamber (44) associated with a first activating stage of the inflator and a second combustion chamber (56) associated with a second activating stage of the inflator, wherein the second combustion chamber (56) is surrounded at least partially by the first combustion chamber (44) and has a smaller volume than the first combustion chamber (44), wherein the ratio of the volume of the first combustion chamber (44) to the volume of the second combustion chamber (56) is between 2.34 and 3.27, preferably between 2.54 and 3.00 and further preferably amounts to approx. 2.76, and/or, wherein

the ratio of the volume of the first combustion chamber (44) to the volume of an igniter sleeve (38) at least partially surrounded by the first combustion chamber (44) ranges between 13.5 and 31.0, preferably between 16.0 and 24.0 and further preferably amounts to approx. 19.3, and/or wherein

the ratio of the outer diameter a of an external housing of the inflator to the height h₁ of the external housing ranges between 0.94 and 1.16 and further preferably amounts to approx. 1.05, and/or wherein

the construction height of the inflator, especially the axial height h₁ of an external housing of the inflator, ranges between 50 and 70 mm and preferably amounts to approx. 60 mm.

37. An airbag module for a vehicle comprising an airbag having a volume of 40 to 60 liters, characterized by an inflator according to any one of the claims 1 to 36.

38. An airbag module for a vehicle comprising an airbag having a volume of 60 to 135 liters, characterized by an inflator according to any one of the claims 1 to 36.