Airbag inflator and an airbag apparatus

• US 6,234,521 B1
• Filed: 03/31/1997
• Issued: 05/22/2001
• Est. Priority Date: 04/08/1996
• Status: Expired due to Term

• Current Assignee: Daicel Chemical Industries Limited (Daicel Corporation)
• Original Assignee: Daicel Chemical Industries Limited (Daicel Corporation)
• Inventors: Ueda, Masayuki, Katsuda, Nobuyuki, Oda, Shingo
• Primary Examiner(s): CULBRETH, ERIC D
• Application Number:
  US08/829,314
• Time in Patent Office: 1,513 Days
• Field of Search: 280/741, 280/742, 280/737, 280/736
• US Class Current: 280/736
• CPC Class Codes: B01D 2275/105 Wound layers
• CPC Class Codes: B01D 2279/10 for air bags, e.g. inflators therefor
• CPC Class Codes: B01D 46/2411 Filter cartridges
• CPC Class Codes: B01D 46/4263 Means for active heating or cooling
• CPC Class Codes: B60R 21/2035 using modules containing inflator, bag and cover attachable to the steering wheel as a complete sub-unit steering wheel covers with tear lines B60R21/21656; assembling of modules B60R21/217
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder
• CPC Class Codes: B60R 21/33 Arrangements for non-electric triggering of inflation electrical circuits for triggering safety arrangements B60R21/01
• CPC Class Codes: C06D 5/06 by reaction of two or more solids

Abstract

An airbag inflator includes non-azide gas generating propellants, surrounding an ignition device, disposed inside a housing. The gas generating propellants are surrounded by a coolant/filter device having a pressure loss of 0.3×10⁻² to 1.5×10⁻² kg/cm² at a flow rate of 100 l/min/cm². A space is provided between an outer periphery of the coolant/filter device and the housing such that the combustion gas passes through the entire area of the coolant/filter device. The coolant/filter device is also surrounded by a swell suppressing layer which prevents the coolant/filter device from swelling due to a combustion of the gas generating propellants.

Claims

1. An inflator for an airbag, comprising:

a housing having a plurality of gas-discharge ports;

an ignition device installed in said housing;

a non-azide gas-generating material installed around said ignition device, said gas-generating material being a solid material ignitable by said igniter to produce combustion gas; and

a coolant-filter device installed around said gas-generating material, wherein

the total area of said gas-discharge ports per volume of combustion gas generated within said inflator is in the range of 0.5 to 2.50 cm²/mol.

2. An inflator of claim 1, wherein the maximum internal pressure in said inflator during operation is controlled in a range of 100-300 kg/cm².

3. An inflator according to claims 1 or 2, wherein the total area of said gas-discharge ports per unit volume of generated gas is 1.00-1.50 cm²/mol.

4. An inflator according to claim 1, wherein the maximum internal pressure during the operation is 130-180 kg/cm².

5. An inflator as in one of claims 1, 2 or 4, wherein each of said gas-discharge ports has an equivalent circle diameter of about 2-5 mm.

6. An inflator according to claims 1 or 2, wherein said plurality of gas-discharge ports that control the combustion of said gas-generating material are provided in at least one of said housing and a separation wall, separating said ignition device and said gas-generating material, in the direction in which a gas produced by said gas-generating material stored in said housing flows into an airbag.

7. An inflator according to claims 1 or 2, wherein said plurality of gas-discharge ports have one or two different areas.

8. An inflator according to claims 1 or 2, wherein a total of 12 to 24 gas-discharge ports are arranged in said housing or in a separation wall, separating said ignition device and said gas-generating material, in a circumferential direction.

9. An inflator of claim 8, wherein a total of 12 to 20 gas-discharge ports are arranged in said housing or in said separation wall.

10. An inflator according to claims 1 or 2, further comprising:

a moisture prevention seal tape which seals said gas-discharge ports.

11. An inflator of claim 10, wherein said seal tape is an aluminum tape having a width 2 to 3.5 times the diameter of said gas-discharge ports and a thickness of 25-80 μ

m.

12. An inflator of claim 10, wherein said seal tape ruptures in response to combustion of said gas-generating material without controlling the maximum internal pressure created in said housing by said generated gas.

13. An inflator according to claims 1 or 2, wherein an internal volume of the housing is 120 cc or less.

14. An inflator of claims 1 or 2, wherein said non-azide material has a linear combustion velocity of 30 mm/sec or less under a pressure of 70 kg/cm².

15. A method of controlling the flow of gas from a gas generator to an airbag associated therewith, comprising:

providing an inflator housing;

placing a combustible non-azide gas-generating material in said housing;

providing a plurality of diffusion openings in communication with said gas-generating material and said airbag; and

correlating the total area of said diffusion openings and the characteristics of said gas-generating material such that said total area/volume of gas generated is in the range of 0.50 to 2.50 cm²/mol.

16. The method of claim 15, wherein said correlating step includes,

correlating the total area of said diffusion openings and the characteristics of said gas-generating material such that the maximum internal pressure in said housing created by said gas is in the range of 100 to 300 kg/cm².

17. The method according to claims 15 or 16, wherein said providing step includes,

setting said total area/volume of gas generated between 1.00 to 1.50 cm²/mol.

18. The method according to claim 15, wherein said correlating step includes,

correlating the total area of said diffusion openings and the characteristics of said gas-generating material such that the maximum internal pressure in said housing created by said gas is in the range of 130 to 180 kg/cm².

19. The method according to claims 15 or 16, wherein said diffusion opening providing step includes,

adjusting the size of said plurality of diffusion openings in the range of circle equivalent diameters of 2 to 5 mm.

20. The method according to claims 15 or 16, wherein said diffusion opening providing step includes,

providing said diffuser openings in at least one of a housing of said inflator and an inner wall provided in said inflator.

21. The method according to claims 15 or 16, wherein said diffusion opening providing step includes,

adjusting the size of said plurality of diffusion opening in groups with at least two respective circle equivalent diameters.

22. The method according to claims 15 or 16, wherein said diffusion opening providing step includes,

providing between 12 and 24 of said diffusion openings in an array in an circumference of said housing.

23. The method of claim 22, wherein said diffusion opening providing step includes,

providing between 12 and 20 of said diffusion openings in an array in the circumference of said housing.

24. The method according to claims 15 or 16, further comprising:

sealing the diffusion openings with a readily frangible moisture proof layer to preclude moisture deterioration of said gas-generating material.

25. The method of claim 24, wherein said sealing step includes,

preparing, as said moisture proof layer, an aluminum tape having a width 2 to 3.5 times the diameter of said gas-discharge ports and a thickness of 25-80 μ

m.

26. The method of claim 24, wherein said sealing step includes,

preparing, as said moisture proof layer, a material that ruptures in response to combustion of said gas-generating material without controlling the maximum internal pressure created in said housing by said generated gas.

27. The method according to claims 15 or 16, wherein said inflator housing providing step includes,

providing said housing with an internal volume of 130 cc or less when said inflator is used in a driver side airbag apparatus.

28. The method of claim 15, further comprising:

selecting the non-azide gas-generating material having a linear combustion velocity of 30 mm/ sec or less under a pressure of 70 kg/ cm².

29. A method of controlling internal pressures and quality of a predetermined amount of gas produced in a pyrotechnic airbag inflator housing, comprising:

providing a housing having a combustion chamber and an igniter associated with that chamber;

providing a non-azide combustible gas-generating material in said combustion chamber;

providing a coolant/filter structure surrounding said gas-generating material in said combustion chamber;

providing a plurality of gas discharge ports in said housing to convey generated gas toward an airbag at the exterior of said housing;

correlating the total open area of said plurality of discharge ports and the characteristics of said gas-generating material to control the maximum internal pressures generated in said housing by combustion of said gas-generating material; and

further correlating the characteristics of said coolant/filter structure with the characteristics of said gas-generating material for producing combustion contaminants, to effect entrapment of particulates of combustion in said coolant/filter structure to a predetermined degree.

30. The method of claim 29, wherein said non-azide combustible gas-generating material is selected from a solid material having a linear burning velocity of 30 mm/sec or less under a pressure of 70 kg/cm².

31. The method of claim 30, wherein the total open area of said plurality of discharge ports per volume of combustion gas generated within said inflator is in the range of 0.5 to 2.50 cm²/mol.

32. The method of claim 30, wherein the total open area of said discharge ports per volume of combustion gas generated within said inflator is in the range of 0.5 to 2.50 cm²/mol to control the maximum internal pressure generated in said housing is a range of 100 to 300 kg/cm².

33. The method as in any one of claims 29 to 32, wherein each of said discharge ports has a circle equivalent diameter of 2 to 5 mm.

34. The method as in any one of claims 29 to 32, wherein the volume of said housing internally of said discharge ports is selected such that in combination with the combustion characteristics of said gas generating material the maximum internal pressure in the housing in maintained.

35. The method of claim 34, wherein said housing volume is 130 cc or less.

36. The method according to claims 29 or 30, wherein the total area of said discharge ports is 1.00 to 1.50 cm²/mol of gas generated in said housing to control the maximum internal pressure generated in said housing in a range of 100 to 300 kg/cm².

37. The method of claim 36, wherein each of said discharge ports has an equivalent circle diameter of 2 to 5 mm.

38. The method of claim 36, wherein said discharge ports are sized to include ports of at least two different size openings.

39. The method of claim 29, wherein the number of discharge ports is selected in the range of 12 to 20 and positioned circumferentially in the housing between the non-azide gas-generating material and an airbag mounted externally of the housing.

40. The method of claim 36, wherein the volume of said. housing internally of said discharge ports is selected such that the combustion characteristics of said gas-generating material the maximum internal pressure of the housing is maintained.

41. The method of claim 40, wherein each of said discharge ports has an equivalent circle diameter of 2 to 5 mm.

42. The method of claim 40, wherein said housing volume is 130 cc or less.

43. The method of claim 40, wherein each of said discharge ports has an equivalent circle diameter of 2 to 5 mm.

44. The method as in any one of claims 29 to 32, wherein said discharge ports are sized to include ports of at least two different size openings.

45. The method as in any one of claims 29 to 32, further comprising:

sealing said discharge ports with a frangible moisture blocking sealing tape having substantially no controlling effect on said maximum interval pressure range.

46. The method of claim 45, wherein said discharge ports are sized to include ports of at least two different size openings.

47. The method of claim 45, wherein said sealing tape is aluminum tape having a width of 2 to 3.5 times the diameter of said discharge ports and a thickness of 25 to 80 μ

m.

48. The method as in any one of claims 29 to 32, wherein the number of discharge ports is selected in the range of 12 to 20 and positioned circumferentially in the housing between the gas-generating material and an airbag mounted externally of the housing.

49. The method of claim 48, wherein said discharge ports are sized to include ports of at least two different size openings.

50. The method of claim 48, further comprising:

sealing said discharge port with a frangible moisture blocking sealing tape having substantially no controlling effect on said maximum interval pressure range.

51. The method of claim 50, wherein said discharge ports are sized to include ports of at least two different size openings.

52. The method of claim 50, wherein said sealing tape is aluminum tape having a width of 2 to 3.5 times the diameter of said discharge ports and a thickness of 25 to 80 μ

m.

53. The method of any one of claims 29 to 32, wherein said coolant/filter structure is provided with a pressure loss of 0.3×

10<sup>−

2</sup> to 1.5×

10<sup>−

2</sup> kg/cm² at a flow rate of 100 l/min/cm² at a normal temperature.

54. The method of claim 53, wherein each of said discharge ports has a circle equivalent diameter of 2 to 5 mm.

55. The method of claim 53, wherein the volume of said housing internally of said discharge ports is selected such that with the combustion characteristics of said non-azide gas-generating material the maximum internal pressure of the housing is maintained.

56. The method of claim 55, wherein said housing volume is 120 cc or less.

57. The method according to claims 29 or 30, wherein the total open area of said discharge ports per volume of combustion gas generated within said inflator is in the range of 1.00 to 1.50 cm²/mol to control the maximum internal pressure generated in said housing in a range of 100 to 300 kg/cm², and

wherein said coolant/filter structure is provided with a pressure loss of 0.3×

10<sup>−

2</sup> to 1.5×

10<sup>−

2</sup> kg/cm² at a flow rate of 100 l/min/cm² at a normal temperature.

58. The method as in any one of claims 29 to 32, wherein the housing has an outer wall containing said discharge ports;

and

further includes the step of providing a space between the coolant/filter structure and a circumferential wall to enhance the uniformity of flow of gas from said non-azide gas-generating material throughout the entire body of said coolant/filter device.

59. The method as in any one of claims 29 to 32, further comprising:

providing a peripheral space between the outer periphery of the said coolant/filter structure and the interior of a wall of said housing containing said plurality of discharge ports for enhancing the uniformity of flow through said coolant/filter device of combustion gas from said combustion chamber toward said discharge ports.

60. The method of claim 59, wherein both the coolant/filter device and the peripheral space provided are annular in shape and are substantially coextensive at the outer periphery of said coolant/filter device.

61. The method of claim 60, wherein the radial extent of said peripheral space is in the range of 1.0 to 4.0 mm.

62. The method of claim 61, wherein the radial cross-sectional area S_t of said peripheral space is equal to or greater than the total areas A_t of the gas discharge ports for controlling the maximum internal pressure in said housing.

64. The method of claim 62, wherein the ratio S_t/A_t is in the range of 2-5.

65. The method of claim 60, wherein said maximum internal pressure in said housing is in the range of 130 to 180 kg/cm².

66. The method of claim 65, wherein the radial extent of said annular peripheral space is 1.0 to 4.0 mm.

67. The method of claim 65, wherein the radial cross-sectional area S_t of said peripheral space is equal to or greater than the total areas A_t of the gas discharge ports for controlling the maximum internal pressure in said housing.

68. The method of claim 29, wherein a total weight of combustion particles discharged from said discharge ports is 2 g or less.

69. The method of claim 29, wherein an internal pressure of the airbag inflator, at a time when said non-azide solid gas-generating material is generating a combustion gas, is a function of said total open area A_t of the gas discharge ports.

63. The method of claim 63, wherein the ratio S_t/A_t is in the range of 1-10.

70. A method of maximizing the gas output of an airbag inflator while minimizing the physical size thereof, comprising:

forming an inflator housing having an internal volume of no greater than 130 cc; and

charging said housing with a solid non-azide gas-generating material having a decomposition initiation temperature of 330°

C. or lower and a combustion temperature of 2000°

K. or higher.

71. The method of claim 70, further comprising:

providing said non-azide solid gas-generating material with a linear burning velocity of no greater than 30 mm/sec under a pressure of 70 kg/cm².

72. The method of claims 70 or 71, wherein said forming step includes,

selecting the inflator housing capacity in the range of 60 to 130 cc and the amount of non-azide solid gas-generating material in the range of 20 to 50 g.

73. An airbag apparatus, comprising:

an airbag inflator including,

a housing having a plurality of gas-discharge ports,

an ignition device installed in said housing,

a non-azide gas-generating material installed around said ignition device, said gas-generating material being a solid material ignitable by said igniter to produce combustion gas, and

a coolant/filter device installed around said gas-generating material, wherein

the total area of said gas-discharge ports per volume of combustion gas generated within said inflator is in the range of 0.5 to 2.50 cm²/mol;

an impact sensor for detecting an impact and outputting an impact detection signal;

a control unit for receiving the impact detection signal and outputting a drive signal to the ignition device of said airbag inflator;

an airbag to be inflated by admitting a gas thereto generated by said airbag inflator; and

a module case for accommodating said airbag.

74. An airbag inflator for inflating airbags, comprising:

a housing having a plurality of gas discharge ports having a total open area A_t;

an ignition device installed in the housing;

a non-azide solid gas-generating material having a given surface area A installed in the housing and ignitable by the ignition device to produce a combustion gas; and

a coolant/filter device accommodating the solid gas-generating material and adapted to cool the combustion gas and arrest combustion contaminant particulates from said gas;

wherein the ratio A/A_t of the total surface area A of the solid gas-generating material to the sum A_t of open areas of the gas discharge ports is equal to or greater than 100.

75. The airbag inflator of claim 74, wherein said the ratio A/A_t is 100-300 for a driver side airbag.

76. The airbag inflator of claim 74, wherein the ratio A/A_t is 250-3600 for an airbag for use for side collision protection.

77. An airbag inflator according to claim 74, wherein the non-azide solid gas-generating material has a linear burning velocity of 5-30 mm/sec under a pressure of 70 kg/cm².

78. An airbag inflator according to claim 74, wherein the non-azide solid gas-generating material has a linear burning velocity of 5-15 mm/sec under the pressure of 70 kg/cm².

79. an airbag inflator according to claims 77 or 78, wherein the housing has an inner volume of 60-130 cc.

80. an airbag inflator according to claim 74, wherein the housing has an inner volume of 60-130 cc.

81. An airbag inflator as in any one of claims 77 to 80, wherein the amount of the non-azide solid gas-generating material therein is 20-50 g.

82. An airbag inflator according to claim 74, wherein the amount of the non-azide solid gas-generating material therein is 20-50 g.

83. An airbag inflator of claim 74, wherein the total area of said plurality of gas discharge ports per volume of combustion gas generated within said inflator is in the range of 0.5 to 2.50 cm²/mol.

84. An airbag inflator of claim 74, wherein the maximum internal pressure in said inflator is controlled thereby in a range of 100-300 kg/cm².

85. An airbag inflator according to claim 74, wherein the non-azide gas-generating material is a solid non-azide material ignitable by said igniter to produce combustion gas.

86. An airbag inflator according to claim 74, wherein the quantity of combustion particulates contained in said gas discharged from said gas discharge ports is an amount of not larger than 2 g.

87. An airbag inflator according to claim 74, wherein said inflator is attached to a steering wheel.

88. An airbag inflator according to claim 74, wherein said inflator is installed in a passenger side dashboard.

89. An airbag apparatus, comprising:

an airbag inflator including,

a housing having a plurality of gas discharge ports having a total open area A_t,

an ignition device installed in the housing,

a non-azide solid gas-generating material having a known surface area A installed in the housing and ignitable by the ignition device to produce a combustion gas, and

a coolant/filter device accommodating the solid gas-generating material and adapted to cool the combustion gas and arrest combustion contaminant particulates from said gas,

wherein the ratio A/A_t of the total surface area A of the solid gas-generating material to the sum A_t of open areas of the gas discharge ports is equal to or greater than 100;

an impact sensor for detecting an impact and outputting an impact detection signal;

a control unit for receiving the impact detection signal and outputting a drive signal to the ignition device of said airbag inflator;

an airbag to be inflated by admitting a gas thereto generated by said airbag inflator; and

a module case for accommodating said airbag.

90. An airbag apparatus according to claim 89, wherein the non-azide solid gas-generating material has a linear burning velocity of 5-30 mm/sec under a pressure of 70 kg/cm².

91. An airbag apparatus according to claim 89, wherein the solid gas-generating material has a linear burning velocity of 5-15 mm/sec under a pressure of 70 kg/cm².

92. An airbag apparatus according to claim 90 or 91, wherein the housing has an inner volume of 60-130 cc.

93. An airbag apparatus according to claim 89, wherein the housing has an inner volume of 60-130 cc.

94. An airbag apparatus as in any one of claims 90 to 93, wherein an amount of the non-azide solid gas-generating material therein is 20-50 g.

95. An airbag apparatus according to claim 89, wherein an amount of the non-azide solid gas-generating material therein is 20-50 g.

96. An airbag apparatus of claim 89, wherein the total area of said plurality of gas discharge ports per volume of combustion gas generated within said inflator is in the range of 0.5 to 2.50 cm²/mol.

97. An airbag apparatus of claim 96, wherein the maximum internal pressure in said inflator is controlled thereby in a range of 100-300 kg/cm².

98. An airbag apparatus of claim 89, wherein the non-azide gas-generating material is a solid non-azide material ignitable by said igniter to produce combustion gas.

99. An airbag apparatus of claim 89, wherein the quantity of combustion particulates contained in said gas discharged from said gas discharge ports is an amount of not larger than 2 g.

100. An airbag apparatus of claim 89, wherein said inflator is attached to a steering wheel.

101. An airbag apparatus of claim 89, wherein said inflator is installed in a passenger side dashboard.

102. A method of inflating an airbag, comprising:

providing a housing having a plurality of gas discharge ports having a total open area A_t;

installing an ignition device in the housing;

installing a non-azide solid gas-generating material having a surface area A in the housing, said non-azide solid gas-generating material being ignitable by the ignition device to produce a combustion gas;

providing a coolant/filter device which accommodates the solid gas-generating material and adapted to cool the combustion gas and arrest combustion contaminant particulates from said gas; and

setting the ratio A/A_t of the total surface area A of the solid gas-generating material to the sum A_t of open areas of the gas discharge ports to be equal to or greater than 100.

103. An airbag inflator for inflating airbags, comprising:

a housing having a plurality of gas discharge ports having a total open are A_t;

an ignition device installed in the housing;

a non-azide solid gas-generating material having a surface area A installed in the housing an ignitable by the ignition device to produce a combustion gas; and

a coolant/filter device accommodating the solid gas-generating material and adapted to cool the combustion gas and arrest combustion contaminant particulates from said gas;

wherein the ratio A/A_t of the total surface area A of the solid gas-generating material to the sum A_t of open areas of the gas discharge ports is 80-240 for an airbag for a front passenger seat.