Inflator

• US 20030151241A1
• Filed: 11/27/2002
• Published: 08/14/2003
• Est. Priority Date: 11/30/2001
• Status: Active Grant

• Current Assignee: Daicel Chemical Industries Limited
• Original Assignee: Daicel Chemical Industries Limited
• Inventors: Matsuda, Naoki, Katsuda, Nobuyuki, Iwai, Yasunori
• Granted Patent: US 7,134,689 B2
• Time in Patent Office: Days
• US Class Current: 280/736
• 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 21/272 with means for increasing the pressure of the gas just before or during liberation, e.g. hybrid inflators
• CPC Class Codes: C06D 5/06 by reaction of two or more solids

Abstract

The present invention provides an inflator including pressurized gas, in which a discharge amount of combustion residues is suppressed.

High temperature combustion residues in combustion gas of a gas generating agent 36 remain in an inflator 10 and its discharging to the outside is suppressed due to the composition of the gas generating agent 36, a temperature difference between combustion gas and pressurized gas isolated from each other by a first rupturable plate 40, collision of the combustion gas to a wall surface 22a and the like.

Further, a compact inflator is also provided. That is, the present invention provides an inflator inflating an air bag with pressurized gas and combustion gas generated by combustion of the gas generating agent, in which the following requirements are satisfied: (1) pressurized gas contains an inert gas but it does not substantially contain oxygen;

(2) in the gas generating agent, a pressure is 0.8 or less;

(3) a mole ratio of an amount of pressurized gas and an amount of combustion gas generated of a gas generating agent is 1 to 10;

(4) a ratio of a mass of pressurized gas and a mass of a gas generating agent is 1 to 10;

(5) a mass of a gas generating agent is 1 to 30 g; and

(6) a charging pressure of pressurized gas is 30,000 to 67,000 kPa.

Claims

1. An inflator inflating an air bag with combustion gas generated by combustion of a gas generating agent and a pressurized medium, and comprising a means for making the combustion gas strike against one or at least two wall surfaces to have combustion residues in the combustion gas adhered to the one or at least two wall surfaces and a means for making the combustion gas contact with the pressurized medium to cool and solidify the combustion residues contained in the combustion gas due to a temperature difference, wherein a melting point of the combustion residues produced by combustion of the gas generating agent is not less than a discharging temperature of gas generated from the gas generating agent.

3. An inflator according to claim 1 or 2, comprising a pressurized medium chamber having an outer shell formed with a cylindrical pressurized medium chamber housing and charged with a pressurized medium, a gas generator connected to one end of the pressurized medium chamber and including an ignition means and a gas generating agent accommodated in a gas generator housing, and a diffuser portion which is connected to the other end of the pressurized medium chamber, wherein a first rupturable plate closes between the pressurized medium chamber and the gas generator, a second rupturable plate closes between the pressurized medium chamber and the diffuser portion, and further a cap having a gas ejecting hole provided on at least one of a side surface and an end surface thereof covers the first rupturable plate from the pressurized medium chamber side.

14. An inflator according to claim 3 or 4, wherein the cap has a flange portion formed by outwardly folding a peripheral edge portion of the opening and is fixed at the flange portion by crimping part of the gas generator housing.

15. An inflator according to claim 3 or 4, wherein the housing forming the pressurized medium chamber is symmetrical regarding the axial and radial directions.

16. An inflator according to claim 3 or 4, wherein a pressurized medium charging hole is formed in a side surface of the pressurized medium chamber housing, and the charging hole is closed by a pin after the pressurized medium is charged.

17. An inflator according to claim 16, wherein the pin protrudes into the pressurized medium chamber and the protruding portion thereof has such a length that combustion gas flow of the gas generating agent strikes against the protruding portion.

18. An inflator according to claim 3 or 4, wherein the as generator housing and the pressurized medium chamber housing are connected to each other by resistance-welding.

20. An inflator according to any one of claims 1, 2 and 4, wherein the gas generating agent includes 20 to 60 mass % of nitroguanidine and 80 to 40 mass % of an oxdizing agent.

21. An inflator according to any one of claims 1, 2 and 4, wherein the pressurized medium comprises argon and helium.

22. An inflator according to any one of claims 1, 2 and 4, wherein a ratio (A/B) of mole number (A) of the pressurized medium and a mole number (B) of a gas generated by combustion of the gas generating agent is 0.2 to 10.

2. An inflator inflating an air bag with combustion gas generated by combustion of a gas generating agent and a pressurized medium, and comprising a means for changing a flowing direction of the combustion gas to have combustion residues in the combustion gas adhered to one or at least two wall surfaces and a means for making the combustion gas contact with the pressurized medium to cool and solidify the combustion residues contained in combustion gas due to a temperature difference, wherein a melting point of the combustion residues produced by combustion of the gas generating agent is not less than a discharging temperature of gas generated from the gas generating agent.

4. An inflator comprising a pressurized medium chamber having an outer shell formed with a cylindrical pressurized medium chamber housing and charged with a pressurized medium, a gas generator connected to one end of the pressurized medium chamber and including an ignition means and a gas generating agent accommodated in a gas generator housing, and a diffuser portion which is connected to the other end of the pressurized medium chamber, wherein a first rupturable plate closes between the pressurized medium chamber and the gas generator, a second rupturable plate closes between

the pressurized medium chamber and the diffuser portion, a cap having a gas ejecting hole covers the first rupturable plate from the pressurized medium chamber side and further, at least one selected from the following requirements (a), (b) and (c) is provided:

(a) an inner wall surface of the pressurized medium chamber housing is rough;

(b) the gas ejecting hole is oriented so that combustion gas ejected from the gas ejecting hole does not strike against an inner wall surface of a pressurized medium chamber housing by airline distance; and

(c) a barrier member is disposed in the vicinity of the gas ejecting hole, and combustion gas ejected from the gas ejecting hole moves after it strikes against the barrier member.

5. An inflator according to claim 4, wherein, in the requirement (a), the inner wall surface of the pressurized medium chamber housing has a groove formed continuously or discontinuously in the circumferentical direction.

6. An inflator according to claim 5, wherein a depth of the groove is not less than 0.2 mm.

7. An inflator according to claim 4, wherein, in the requirement (b), the gas ejecting hole is provided on a side surface of the cap and is opened towards the gas generator.

8. An inflator according to claim 4, wherein, in the requirement (b), the gas ejecting hole is provided on an side surface of the cap, and a member for circumferentially restricting an ejecting direction of combustion gas from the gas ejecting hole is provided.

9. An inflator according to claim 4, wherein, in the requirement (b), the gas ejecting hole is provided on an end surface of the cap, and a member for circumferentially restricting an ejecting direction of combustion gas from the gas ejecting hole is provided.

10. An inflator according to claim 4, wherein, in the requirement (c), the barrier member is cylindrical one end side thereof is closed integrally with the end surface of the cap, the other end thereof is opened and a side surface thereof is formed to face the gas ejecting hole provided in the side surface of the cap with a gap, and combustion gas moves from the opening after it strikes against a side surface inner wall of the cylindrical member.

11. An inflator according to claim 4, wherein, in the requirement (c), the barrier member is disk-shaped, integrated with the end surface of the cap and extended from the end surface of the cap towards an inner wall surface of the pressurized medium chamber housing, and after combustion gas ejected from the gas ejecting hole provided in the side surface of the cap strikes against a peripheral edge portion of the barrier member, the combustion gas moves from a gap between the inner wall surface of the pressurized medium chamber housing and the peripheral edge portion of the barrier member.

12. An inflator according to claim 4, wherein, in the requirement (c), the barrier member is disk-shaped, integrated with the end surface of the cap and extended from the end surface of the cap towards an inner wall surface of the pressurized medium chamber housing so that a peripheral edge portion thereof abuts on the inner wall surface, a gas passing port is provided in the peripheral edge portion of the barrier member and a member for circumferentially restricting an ejecting direction of gas from the gas passing port is provided, and combustion gas ejected from the gas ejecting hole provided in the side surface of the cap is ejected from the gas passing port.

13. An inflator according to claim 4, which is provided with the requirements (a) and (b), the requirements (a) and (c) the requirements (b) and (c), or the requirements (a), (b) and (c).

19. An inflator according to claim 4, wherein, in the gas generating agent, a melting point of combustion residues produced by combustion of the gas generating agent is not less than a discharging temperature of a gas generated from the gas generating agent.

23. An inflator inflating an air bag with combustion gas generated by combustion of a gas generating agent and a pressurized medium, and comprising a pressurized gas chamber having an outer shell formed with a cylindrical pressurized gas chamber housing and charged with a pressurized gas, a gas generator connected to the pressurized gas chamber and including an ignition means and a gas generating agent accommodated in a gas generator housing, and a diffuser portion connected to a portion other than the pressurized gas chamber, wherein a first rupturable plate closes between the pressurized gas chamber and the gas generator, a second rupturable plate closes between the pressurized gas chamber and the diffuser portion, wherein the diffuser portion is a cap having a plurality of gas discharging holes through which gas passes and at least one of pieces generated by breaking the first and the second rupturable plates and a residues contained in combustion gas produced by combustion of the gas generating agent is prevented from flowing outside the inflator.

24. An inflator according to claim 23, wherein a cap which has a plurality of gas discharging holes through which gas passes and prevents at least one of pieces generated by breaking the first rupturable plate and combustion residues of the gas generating agent from flowing outside the inflator is disposed inside the pressurized gas chamber to cover the first rupturable plate from the pressurized gas chamber.

25. An inflator according to claim 23 or 24, wherein a cap which has a plurality of gas discharging holes through which gas passes and prevents at least one of pieces generated by breaking the first rupturable plate and combustion residues of the gas generating agent from flowing outside the inflator is disposed inside the pressurized gas chamber to cover the second rupturable plate from the pressurized gas chamber.

26. An inflator according to claim 23 or 24, wherein the cap comprises a cylindrical member having one end opened and the other end closed, and has a plurality of gas discharging holes on at least a peripheral surface thereof.

27. An inflator according to claim 23 or 24, wherein, in the cap, that the relationship between a distance L from a closed end surface of the cap to a gas discharging hole nearest to the closed end surface and a diameter D of the rupturable plate satisfies the following formula:

L≧

D/2.

28. An inflator according to claim 27, wherein the distance L is 3 to 8 mm.

29. An inflator according to claim 23 or 24, wherein diameters of a plurality of the gas discharging holes in the cap are 0.5 to 2 mm.

30. An inflator according to claim 23 or 24, wherein a total opening area of a plurality of the gas discharging holes in the cap is 20 to 1000 mm².

31. An inflator according to claim 23 or 24, wherein the cap is disposed such that the axial direction of the cap and the axial direction of the pressurized gas chamber housing coincide with each other.

32. An inflator according to claim 23 or 24, comprising a means for changing the flow direction of the combustion gas by the cap, making combustion residues included in the combustion gas adhere to one or at least two portions of the wall surface, further making the combustion gas contact with the pressurized gas to cool and solidify the combustion residues contained in the combustion gas due to a temperature difference, wherein a melting point of the combustion residues produced due to combustion of the gas generating agent is not less than a discharging temperature of a gas generated from the gas generating agent.

33. An inflator according to claim 24, further provided with at lease one selected from the following requirements (a) to (c):

(a) an inner wall surface of the pressurized gas chamber housing is rough;

(b) the gas ejecting hole in the cap is oriented so that combustion gas ejected from the gas ejecting hole does not strike against an inner wall surface of a pressurized gas chamber housing by airline distance; and

(c) a barrier member is disposed in the vicinity of the gas ejecting hole, and combustion gas ejected from the gas ejecting hole moves after it strikes against the barrier member.

34. An inflator according to claim 33, wherein, in the requirement (a), the inner wall surface of the pressurized gas chamber housing has a groove formed continuously or discontinuously in the circumferentical direction.

35. An inflator according to claim 33, wherein a depth of the groove is not less than 0.2 mm.

36. An inflator according to claim 33, wherein, in the requirement (b), the gas ejecting hole is provided on a side surface of the cap and is opened towards the gas generator.

37. An inflator according to claim 33, wherein, in the requirement (b), the gas ejecting hole is provided on an side surface of the cap, and a member for circumferentially restricting an ejecting direction of combustion gas from the gas ejecting hole is provided.

38. An inflator according to claim 33, wherein, in the requirement (b), the ejecting hole is provided on an end surface of the cap, and a member for circumferentially restricting an ejecting direction of combustion gas from the gas ejecting hole is provided.

39. An inflator according to claim 33, wherein, in the requirement (c), the barrier member is cylindrical, one end side thereof is closed integrally with the end surface of the cap, the other end thereof is opened and a side surface thereof is formed to face the gas ejecting hole provided in the side surface of the cap with a gap, and combustion gas moves from the opening after it strikes against a side surface inner wall of the cylindrical member.

40. An inflator according to claim 33, wherein, in the requirement (c), the barrier member is disk-shaped, integrated with the end surface of the cap and extended from the end surface of the cap towards an inner wall surface of the pressurized gas chamber housing, and after combustion gas ejected from the gas ejecting hole provided in the side surface of the cap strikes against a peripheral edge portion of the barrier member, the combustion gas moves from a gap between the inner wall surface of the pressurized gas chamber housing and the peripheral edge portion of the barrier member.

41. An inflator according to claim 33, wherein, in the requirement (c), the barrier member is disk-shaped, integrated with the end surface of the cap and extended from the end surface of the cap towards an inner wall surface of the pressurized gas chamber housing so that a peripheral edge portion thereof abuts on the inner wall surface, a gas passing port is provided in the peripheral edge portion of the barrier member and a member for circumferentially restricting an ejecting direction of gas from the gas passing port is provided, and combustion gas ejected from the gas ejecting hole provided in the side surface of the cap is ejected from the gas passing port.

42. An inflator according to claim 33, which is provided with the requirements (a) and (b), the requirements (a) and (c), the requirements (b) and (c), or the requirements (a), (b) and (c).

43. An inflator according to claim 33 or 24, wherein the cap has a flange portion formed by outwardly folding a peripheral edge portion of the opening and is fixed at the flange portion by crimping part of the gas generator housing.

44. An inflator according to claim 23 or 24, wherein the housing forming the pressurized gas chamber is symmetrical regarding the axial and radial directions.

45. An inflator according to claim 23 or 24, wherein a pressurized gas charging hole is formed in a side surface of the pressurized gas chamber housing, and the charging hole is closed by a pin after the pressurized gas is charged.

46. An inflator according to claim 45, wherein the pin protrudes into the pressurized gas chamber and the protruding portion thereof has such a length that combustion gas flow of the gas generating agent strikes against the protruding portion.

47. An inflator according to claim 23 or 24, wherein the gas generator housing and the pressurized gas chamber housing are connected to each other by resistance-welding.

48. An inflator according to claim 23 or 24, wherein, in the gas generating agent, a melting point of combustion residues produced by combustion of the gas generating agent is not less than a discharging temperature of a gas generated from the gas generating agent.

49. An inflator according to claim 23 or 24, wherein the gas generating agent includes 20 to 60 mass % of nitroguanidine and 80 to 40 mass % of an oxidizing agent.

50. An inflator according to claim 23 or 24, wherein the pressurized gas comprises argon and helium.

51. An inflator according to claim 23 or 24, wherein a ratio (A/B) of mole number (A) of the pressurized gas and a mole number (B) of a gas generated by combustion of the gas generating agent is 0.2 to 10.

52. An inflator inflating an air bag with pressurized gas and combustion gas generated by combustion of a gas generating agent, which is provided with the following requirements (1) to (6):

(1) pressurized gas contains an inert gas but it does not substantially contain oxygen;

(2) in the gas generating agent, a pressure index obtained by the following formula;

rb=α

Pⁿ (in the formula, rb;

burning velocity, α

;

coefficient, P;

pressure, and n;

pressure index) is 0.8 or less;

(3) a ratio A1/A2 of an amount (mole number) of pressurized gas (A1) and an amount (mole number) of gas generated by combustion of a gas generating agent (A2) is 1 to 20;

(4) a ratio B1/B2 of a mass (B1) of pressurized gas (B1) and a mass (B2) of a gas generating agent is 1 to 20;

(5) a mass of a gas generating agent is 0.5 to 30 g; and

(6) a charging pressure of pressurized gas is 30,000 to 67,000 kPa.

53. An inflator according to claim 52, wherein, in the requirement (2), a combustion flame temperature of the gas generating agent is not more than 3000°

C.

54. An inflator according to claim 52, wherein, in the requirement (2), the gas generating agent is a non-azide gas generating agent.

55. An inflator according to claim 52 or 53, which is further provided with the requirement (7) such that a ratio A1/C of an amount (mole numbers)(A1) of the pressurized gas and a total surface area (cm²) (C) of the gas generating agent is 0.004 to 0.05 mole/cm².

56. An inflator according to claim 52 or 53, which is further provided with the requirement (8) such that a ratio C/E of a total surface area (cm²) (C) of the gas generating agent and a total area (cm²) (E) of the gas discharging hole is 0.5 to 4.

57. An inflator according to claim 52 or 53, wherein the inflator has a pressurized gas chamber having an outer shell formed by a cylindrical pressurized gas chamber housing and charged with pressurized gas, and an outer diameter of the pressurized gas chamber housing is preferably not more than 40 mm.

58. An inflator according to claim 52 or 53, wherein the inflator has a pressurized gas chamber having an outer shell formed by a cylindrical pressurized gas chamber housing and charged with pressurized gas, and a ratio (L/D) of an outer diameter (D) and a length (L) of the pressurized gas chamber housing is preferably 1 to 10.

59. An inflator according to claim 52 or 53, wherein the inflator has a pressurized gas chamber having an outer shell formed by a cylindrical pressurized gas chamber housing and charged with pressurized gas, and the pressurized gas chamber housing is symmetrical regarding the axial and radial directions.

60. An inflator according to claim 52 or 53, wherein the inflator has a pressurized gas chamber having an outer shell formed by a cylindrical pressurized gas chamber housing and charged with pressurized gas, and the pressurized gas chamber housing is symmetrical regarding the axial and radial directions and both ends thereof are reduced in diameter.

61. An inflator according to claim 52 or 53, wherein the inflator has a pressurized gas chamber having an outer shell formed by a cylindrical pressurized gas chamber housing and charged with pressurized gas, a pressurized gas charging hole is formed in a side surface of the pressurized gas chamber housing, and the gas charging hole is closed by a pin after the pressurized gas is charged.

62. An inflator according to claim 61, wherein the pin is protruding into the pressurized gas chamber housing and a protruding portion thereof has such a length that combustion gas flow strikes against the protruding portion.

63. An inflator according to claim 52, comprising a pressurized gas chamber having an outer shell formed by a cylindrical pressurized gas chamber housing and charged with pressurized gas, a gas generator having an outer shell formed by a gas generator housing and including an ignition means and a gas generating agent inside the housing, and a diffuser portion,

wherein the gas generator housing is connected to one end of the pressurized gas chamber housing and the diffuser portion is connected to the other end of the pressurized gas housing, and

a first rupturable plate closes between the pressurized gas chamber and the gas generator and a second rupturable plate closes between the pressurized gas chamber and the diffuser portion.

64. An inflator according to claim 63, wherein a cap having a gas ejecting hole provided in at least one of a side surface and an end surface thereof covers the first repturable plate from the pressurized gas chamber side.

65. An inflator according to claims 63 or 64, wherein the gas generator housing and the pressurized gas chamber housing, and the diffuser portion and the pressurized gas chamber housing are connected by resistance-welding.

66. An inflator according to claim 63 or 64, wherein the outer diameters of the pressurized gas chamber housing, the gas generator housing and the diffuser portion are equal or approximate to one another.

74. An air bag system provided with an actuation-signal outputting means comprising an impact sensor and a control unit, and a module case accommodating an inflator according to claim 52 and an air bag.

67. An inflator inflating an airbag with pressurized gas, wherein the pressurized gas is charged in a pressurized gas chamber having an outer shell formed by a cylindrical pressurized gas chamber housing,

the pressurized gas chamber housing is symmetrical regarding the axial and radial directions and both ends thereof are reduced in diameter.

68. An inflator according to claim 67, using combustion gas obtained by combustion of a gas generating agent together with pressurized gas as a inflating means for an air bag, and comprising a pressurized gas chamber having an outer shell formed by a cylindrical pressurized gas chamber housing and charged with pressurized gas, a gas generator for generating combustion gas, and a diffuser portion having a gas discharging hole, wherein the pressurized gas chamber housing is symmetrical regarding the axial and radial directions and both ends thereof are reduced in diameter.

69. An inflator according to claim 68, wherein the gas generator has an outer shell formed by a gas generator housing and including an ignition means and a gas generating agent inside the housing,

the gas generator housing is connected to one end of the pressurized gas chamber housing and the diffuser portion is connected to the other end of the pressurized gas housing, and

a first rupturable plate closes between the pressurized gas chamber and the gas generator and a second rupturable plate closes between the pressurized gas chamber and the diffuser portion.

70. An inflator according to claim 68, wherein one or both of a set of the gas generator housing and the pressurized gas chamber housing, and a set of the diffuser portion and the pressurized gas chamber housing are connected by resistance-welding.

71. An inflator according to claim 67, substantially using only pressurized gas as an inflating means for an air bag, and comprising a pressurized gas chamber having an outer shell formed by a cylindrical pressurized gas chamber housing and charged with pressurized gas, and a diffuser portion connected to the pressurized gas chamber and having a gas discharging hole, wherein a rupturable plate closes between the pressurized gas chamber and the diffuser portion and an igniter which is a rupturing means for the rupturable plate is accommodated in the diffuser portion, and

the pressurized gas chamber housing is symmetrical regarding the axial and radial directions and both ends thereof are reduced in diameter.

72. An inflator according to claim 71, wherein a cylindrical gas discharging port connected to the gas discharging hole of the diffuser portion is provided, the gas discharging port is mounted to coincide with the axial direction of the pressurized gas chamber housing, and the pressurized gas discharged from the gas discharging hole passes through the gas discharging port and is discharged from an opening provided in the gas discharging port to inflate the air bag.

73. An inflator according to claim 71, wherein the diffuser portion and the pressurized gas chamber housing are connected to each other by resistance-welding.