Gas generator, method for the production thereof and module having a gas generator

• US 9,139,156 B2
• Filed: 09/29/2009
• Issued: 09/22/2015
• Est. Priority Date: 09/30/2008
• 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, Fuerstenberger, Franz, Nuiding, Hannes, Leier, Dieter, Schoenhuber, Georg, Friedrich, Joerg
• Primary Examiner(s): Ilan, Ruth
• Application Number:
  US12/997,615
• Publication Number:
  US 20110101651A1
• Time in Patent Office: 2,184 Days
• Field of Search: 280/728.2, 280/736, 280/740, 280/741, 102/530, 102/202.12, 102/202.14
• US Class Current: 1/1
• CPC Class Codes: B01D 2279/10 for air bags, e.g. inflators therefor
• CPC Class Codes: B01D 39/12 of wire gauze; of knitted wire; of expanded metal
• CPC Class Codes: B60R 2021/26029 Ignitors
• CPC Class Codes: B60R 2021/26076 characterised by casing
• 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
• CPC Class Codes: F42B 3/04 for producing gas under pressure generators of inflation fluid especially adapted for vehicle air bags B60R21/26

Abstract

An inflator as well as a method of manufacturing an inflator, a module including an inflator and an airbag module. In an inflator, especially for a protective device in a vehicle, comprising plural components a sealant is applied in the area of abutting components, especially a sealant which adheres to both abutting components.

Claims

1. An inflator (10) for a protective device in a vehicle, comprising:

a housing;

at least one igniter; and

a base that connects the at least one igniter to the housing,

wherein the base is at least partially injection molded around the at least one igniter and the housing to interconnect the base, the housing, and the at least one igniter, the inflator further comprising a sealant applied in an area where the base abuts the housing.

2. An inflator (10) according to claim 1, wherein the abutting base and housing form at least part of the outer inflator surface.

3. An inflator (10) according to claim 1, wherein the base (32) is made of plastic.

4. An inflator (10) according to claim 3, wherein the base (32) embeds portions of the at least one igniter (28), the at least one igniter (28) being pre-fabricated.

5. An inflator (10) according to claim 3, wherein the base (32) forms an igniter plug receipt (38).

6. An inflator (10) according to claim 1, wherein the housing is made of metal.

7. An inflator (10) according to claim 6, wherein the base is injection-molded to the edge of an orifice (26) in the housing in order to close the orifice (26).

8. An inflator (10) according to claim 1, wherein the sealant (42) is applied to the transitional edge of the abutting base and housing from outside the inflator (10).

9. An inflator (10) according to claim 1, wherein the sealant (42) is introduced into a recess (54) provided at the transition of the base and the housing.

10. An inflator (10) according to claim 1, wherein in the application state the sealant (42) is liquid and/or is an acrylate adhesive.

11. An inflator (10) according to claim 1, wherein the sealant (42) can be applied in liquid state and can subsequently be hardened by UV light.

12. An inflator (10) according to claim 1, wherein the sealant (42) features at least one of the following properties:

Breaking strength according to ISO 527 [MPa] 2-4;

Rupture elongation according to ISO 527 [%] 200-400;

Viscosity at 23°

C. according to Brookfield Sp/U and 3/100 [mPas] 400-800;

Glass transition temperature (rheometer) [°

C.] 10-30;

Thermal expansion coefficient at 30-140°

C. [ppm/K] 150-350;

Density at 23°

C. [g/cm³] 0.6-1.5;

Water absorption according to ISO 62, 24 h at 23°

C. [%] 0.9-1.7.

13. An inflator (10) according to claim 1, wherein the sealant (42) contains a fluorescent dye, and/or a dye deviating from the plastic material of the part to which the sealant (42) is attached.

14. A method for checking the density of an inflator (10) according to claim 13 by making use of a camera, wherein a sealing bead formed by the sealant (42) is irradiated with UV light to measure the density of the sealing bead.

15. An inflator (10) according to claim 1, further comprising an annular filter (76) disposed upstream of discharge orifices (78) which has two axial ends, the filter being outwardly bent at one of its axial ends (80, 82).

16. An inflator (10) according to claim 15, wherein the filter (76) has the same thickness in the bent portion as in a central portion which is adjacent to the bent portion.

17. An inflator (10) according to claim 15, wherein a filter wall, viewed in the axial cross-section, extends substantially in an S-shape between the ends.

18. An inflator (10) according to claim 15, wherein the bent portion is adjacent to an upright edge (20) in a corner portion of the inflator (10) formed by a circumferential wall (16) and a bottom.

19. An inflator (10) according to claim 15, wherein the filter (76) is positioned axially braced in the inflator (10) and/or is made of a wire mesh of wires having substantially equal cross-sections.

20. An inflator (10) according to claim 15, wherein the filter (76) is laterally spaced apart from the discharge orifices (78) provided in the housing (12) of the inflator (10).

21. An inflator (10) according to claim 15, wherein the filter (76) is tapered toward an axial end (80, 82), opposed to the bent end.

22. An inflator (10) according to claim 15, wherein the filter (76) is adjacent to inflator parts at its axial ends (80, 82) and the radially innermost contacting position of the bent end is located radially further outward at the associated inflator part than the radially outermost contacting position of the opposed axial end (80, 82) at the associated inflator part.

23. An inflator (10) according to claim 15, wherein the filter (76) is formed of wires having different thicknesses.

24. An inflator (10) according to claim 23, wherein the filter (76) has a tapered axial end (82) in the area of which the filter (76) has a larger length of thinner wires related to the volume than in the adjacent portion in the entire residual area.

25. An inflator (10) according to claim 1, further comprising the at least one igniter (28) as a pre-fabricated component, and a combustion chamber (56) which is filled at least partly with pyrotechnic material (58) adapted to be ignited via at least one overflow orifice (66), characterized in that, after activating the at least one igniter (28) for igniting the pyrotechnic material (58), the overflow orifice (66) is movable relative to the combustion chamber (56).

26. An inflator (10) according to claim 25, wherein the overflow orifice (66) is provided in a movable wall.

27. An inflator (10) according to claim 26, further comprising an intermediate chamber (62) receiving a boosting charge (64) which is adjacent to the at least one igniter (28) and which is separated from the combustion chamber (56) by a cap (60), wherein the cap (60) is provided with the overflow orifice (66) and is arranged in the inflator (10) such that it is movable by activating the at least one igniter (28).

28. An inflator (10) according to claim 27, wherein in the non-activated state of the inflator (10) the cap (60) is adjacent at the end face to an elastic component (70), the component having a recess (72) into which the cap (60) projects.

29. An inflator (10) according to claim 28, wherein the elastic component (70) can be compressed by the movement of the cap (60).

30. An inflator (10) according to claim 28, wherein the elastic component (70) is a filter made of mesh, and that the elastic component (70) is adjacent to the inside of an end face of the inflator (10).

31. An inflator (10) according to claim 27, wherein the cap (60) has at least one lateral overflow orifice (66).

32. An inflator (10) according to claim 25, wherein the cap (60) forms the only partition between the intermediate chamber (62) and a combustion chamber (56) at least partly filled with pyrotechnic material (58).

33. An inflator (10) according to claim 1, wherein the at least one igniter (28) is a pre-fabricated component, and further comprising an intermediate chamber (62) receiving a boosting charge (64) which is adjacent to the at least one igniter (28) and which is confined by a cap (60), wherein the cap (60) is pushed onto the base (32) with its igniter-side open end.

34. An inflator (10) according to claim 33, wherein the cap (60) is pressed with the base (32) or is placed onto the latter while forming a press-fit.

35. An inflator (10) according to claim 33, wherein the cap (60) is attached to the base (32) such that it is movable by activating the at least one igniter (28).

36. An inflator (10) according to claim 33, wherein the base (32) is formed by injection-molding around the at least one igniter (28) and is provided for fixing the at least one igniter (28) at the inflator (10).

37. An inflator (10) according to claim 1, wherein the housing (12) has a central axis, and the at least one igniter (28) is embedded in the base (32), the housing (12) or a part connected to the housing (12) featuring a recess (34) into which the base (32) extends and portions of a wall forming the recess (34) being bent inwardly and an outwardly extending bulge (48) being formed distant from the opening of the recess (34).

38. An inflator (10) according to claim 37, wherein the recess extends in ring shape relative to the central axis.

39. An inflator (10) according to claim 37, wherein adjacent to the recess the wall forming the recess (34) has the same wall thickness as in the bent portion.

40. An inflator (10) according to claim 37, wherein, viewed axially, the recess (34) is S-shaped, wherein the opening portion of the wall forming the recess (34) extends outwardly.

41. An inflator (10) according to claim 1, wherein the housing (12) has a central axis, and the at least one igniter (28) is embedded in the base (32), wherein the housing (12) or a part connected to the housing (12) exhibits a recess (34) into which the base (32) extends, and wherein a wall forming the recess (34) exhibits a bottom portion (50) having an orifice (26) through which the base (32) extends, the bottom portion (50) having at least one projection (52) and/or a recess (54) at its opposed outsides in the area in which the base (32) contacts the bottom portion (50).

42. An inflator (10) according to claim 41, wherein the edge of the orifice (26) at an outside has a convex projection, the projection (52) being formed by a circumferential bead.

43. An inflator (10) according to claim 41, wherein the bottom portion (50) has an annularly circumferential indentation (54) at the outside opposed to the projection (52) in the area of the projection (52).

44. An inflator (10) according to claim 41, wherein at each of the outsides at least one projection (52) and/or at least one indentation (54) is formed in the area in which the base (32) contacts the same, wherein the at least one projection (52) and/or the at least one indentation (54) extend annularly around the orifice (26) and/or wherein the indentation (54) formed in the outside facing the at least one igniter (28) is disposed radially inside the indentation formed at the opposed outside.

45. An inflator (10) according to claim 1, wherein the base (32) is formed by injection-molding around at least portions of a wall forming an indentation (54) and/or is formed of plastic material.

46. An inflator (10) according to claim 1, wherein the housing (12) has at its outer circumference a flange (24), wherein the flange (24) has an asymmetric shape so as to ensure a definite mounting position at least in the twisting direction when fastening the inflator (10).

47. An inflator (10) according to claim 46, wherein in the flange (24) at least one notch is provided as mounting positioning means (86).

48. An inflator (10) according to claim 46, wherein plural notches are provided which are disposed at different angular distances along the periphery of the flange (24).

49. An inflator (10) according to claim 46, wherein as mounting positioning means (86) a positioning orifice is provided in the flange (24).

50. A module comprising an inflator (10) according to claim 46, wherein a holding element (92) is provided having a counter piece engaging with a mounting positioning means (86) of the flange (24).

51. A module according to claim 50, wherein the counter piece includes at least one projection formed at the holding element (92).

52. A module according to claim 50, wherein the holding element (92) has at least one fastening bolt (102), wherein the fastening bolt (102) contacts the outer periphery of the flange (24).

53. A module according to claim 52, wherein the fastening bolt (102) does not contact the flange (24) in the area of the mounting positioning means (86).

54. A module according to claim 50, wherein an airbag (96) is provided having an inlet orifice (98), wherein the edge of the inlet orifice (98) is clamped between the flange (24) and the holding element (92).

55. An inflator (10) according to claim 1, further comprising a combustion chamber (56) filled at least partly with pyrotechnic material (58) which is confined by combustion chamber walls, wherein all combustion chamber walls are made of the same metal.

56. An inflator (10) according to claim 55, wherein the combustion chamber walls are formed by plural interconnected parts, said parts being load-bearing parts.

57. An inflator (10) according to claim 55, wherein the combustion chamber (56) is an annular chamber.

58. An inflator (10) according to claim 55, wherein the axial height of the inflator (10) is less than its diameter.

59. An inflator (10) according to claim 1, further comprising a combustion chamber (56) disposed inside the housing (12) and containing pyrotechnic, gas generating material (58), the wall thickness of the components of the housing (12) being 2.0 mm or less.

60. An inflator (10) according to claim 59, wherein the housing comprises a diffuser (14) and a closing member (18).

61. An inflator (10) according to claim 60, wherein the diffuser (14) and the closing member (18) are fixed to each other by a single connection defining the strength, the connection being a circumferential weld (22) between the diffuser (14) and the closing member (18).

62. An inflator (10) according to claim 60, wherein the wall thickness of the diffuser (14) is not more than 1.5 mm.

63. An inflator (10) according to claim 60, wherein the wall thickness of the closing member (18) is not more than 1.9 mm.

64. An inflator (10) according to claim 59, wherein upon activation a maximum pressure in the combustion chamber of 300 bars is produced.

65. An inflator (10) according to claim 1, wherein a combustion chamber (56) provided in the inflator (10) has a toroidal shape.

66. An inflator (10) according to claim 1, further comprising a combustion chamber (56) disposed inside the housing (12) which contains pyrotechnic gas generating material (58), wherein the ratio of the maximum combustion chamber pressure occurring upon activation of the inflator (10) to the wall thickness of the housing (12) is more than 150 bars/mm and less than 220 bars/mm.

67. An inflator (10) according to claim 1, further comprising plural discharge orifices (78) provided on the housing (12) and a combustion chamber (56) disposed inside the housing (12) containing pyrotechnic gas generating material (58), wherein the ratio of the entire discharge area of the inflator (10) to the minimum and/or maximum wall thickness of the components of the external housing (12) is more than 34 mm.

68. An inflator (10) according to claim 1, wherein the housing (12) has a diffuser (14) including a substantially cylindrical circumferential wall (16) and comprising a combustion chamber (56) disposed inside the housing (12) and containing pyrotechnic gas generating material (58), wherein the ratio of the diameter of the diffuser (14) to the minimum wall thickness of the external housing (12) is between 35 and 45.

69. An inflator (10) according to claim 1, wherein the housing (12) has a diffuser (14) including a substantially cylindrical circumferential wall (16) and comprising a combustion chamber (56) disposed inside the housing (12) and containing pyrotechnic gas generating material (58), wherein the ratio of the diameter of the diffuser (14) to the maximum axial height of the inflator (10) is 1.8+0.1.

70. An inflator (10) according to claim 1, wherein the housing (12) includes a flange (24) at its outer periphery, wherein the flange (24) is circumferential in a closed manner and is planar and/or that the flange (24) is formed to be free of screwing orifices.

71. An inflator (10) according to claim 1, wherein the housing (12) has a flange (24) at its outer periphery, wherein the flange (24) is circumferential and is planar, and/or that the flange (24) exhibits an annular clamping surface for an airbag (96) having a width ranging from 8 to 11% of the maximum diameter of the housing (12).

72. An inflator (10) for a protective device in a vehicle according to claim 1, wherein the housing (12) has a flange (24) at its outer periphery, wherein the flange (24) is circumferential and planar, and/or in that the flange (24) exhibits an annular clamping surface for an airbag (96) having a width ranging from 5.5 to 7.5 mm.

73. An airbag module (90) comprising an inflator (10) according to claim 1, the airbag module (90) further comprising a flange (24) at the outer periphery of the housing (12), an airbag (96) having an inlet orifice (98) defined by an orifice edge (100), and comprising a clamping element (104) opposed to the flange (24) for clamping the orifice edge (100) between itself and the flange (24), wherein the orifice edge (100) is clamped by such force and the clamping surface is designed such that the lateral displacing force produced by a maximum pressure in the airbag (96) at the orifice edge (100) is between 10 and 80% less than the frictional force generated by the clamping force between the orifice edge (100) and the flange (24) and the clamping element (104).

74. An airbag module (90) comprising an inflator (10) according to claim 1, the airbag module (90) further comprising a flange (24) at the outer periphery, an airbag (96) having an inlet orifice (98) defined by an orifice edge (100), and comprising a clamping element (104) opposed to the flange (24) for clamping the orifice edge (100) between itself and the flange (24), wherein the clamped portion of the orifice edge (100) the inflator (10) has one or more recesses for circumferential positioning.

75. An inflator (10) according to claim 1, wherein the housing (12) has a diffuser (14) including a substantially cylindrical circumferential wall (16) including plural discharge orifices (78) and a closing member (18) which is welded with the diffuser (14), wherein the diffuser (14) and the closing member (18) are in the form of a shell and wherein the discharge orifices (78) are covered at the inside of the diffuser (14) by a tamping (84) in the form of a tamping film, and the tamping (84) is spaced apart from the inner edge of the closing member (18), a weld (22) being disposed between the diffuser (14) and the closing member (18).

76. An inflator (10) according to claim 75, wherein the spacing between the tamping (84) and the inner edge of the closing member (18) is between 3 and 5.5 mm.

77. An inflator (10) according to claim 75, wherein the closing member (18) has a circumferential upright edge at which it is welded to the diffuser (14) and the smallest distance of the weld (22) from the tamping (84) is at least between 3 and 5.5 mm.

78. An inflator (10) according to claim 1, wherein the at least one igniter (28) has an igniter cap (36) containing a plastic material and is at least partially surrounded by plastic injection molding, wherein the material of the igniter cap (36) and the material of the plastic injection molding are selected such that the igniter cap (36) melts at least partially with the plastic injection molding during injection molding.

79. An inflator (10) according to claim 78, wherein the igniter cap (36) and the plastic injection molding consist of the same material.

80. An inflator (10) according to claim 78, wherein the plastic material contains glass fibers.

81. An inflator (10) according to claim 80, wherein the share of glass fibers is approximately 30% volume.

82. An inflator (10) according to claim 1, wherein the housing (12) and the at least one igniter (28) are connected by means of the plastic injection molding.

83. An inflator (10) according to claim 82, wherein the housing (12) has an orifice (26) and the plastic injection molding is molded to the edge of the orifice (26) for closing the housing (12) to the outside.

84. An inflator (10) for a protective device in a vehicle, comprising:

a housing;

at least one igniter; and

a base that connects the at least one igniter to the housing, the base including a portion over which an open end of a boosting charge-containing cap is positioned to attach the cap to the base,

wherein the base is at least partially injection molded around the at least one igniter and the housing to interconnect the base, the housing, and the at least one igniter, the inflator further comprising a sealant applied in an area where the base abuts the housing.