Gas generator for air bag and air bag device

• US 20030132623A1
• Filed: 02/03/2003
• Published: 07/17/2003
• Est. Priority Date: 10/31/2000
• Status: Active Grant

• Current Assignee: Daicel Chemical Industries Limited
• Original Assignee: Daicel Chemical Industries Limited
• Inventors: Okuyama, Takashi, Ohji, Nobuyuki, Iwai, Yasunori, Katsuda, Nobuyuki, Yabuta, Mikio, Iwakiri, Toshiro, Nakashima, Yoshihiro, Miyaji, Katsuhito, Hatomoto, Atsushi
• Granted Patent: US 7,175,197 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 21/2644 using only solid reacting substances, e.g. pellets, powder

Abstract

The present invention provides a gas generator in which ignition and combustion performance of a gas generating agent and operation performance are enhanced. An inner cylindrical member 4 is disposed in a cylindrical housing 3, an annular first combustion chamber 5a is provided radially in the outside of the inner cylindrical member 4, and, in the combustion chamber 5a, a ratio (D/L) of its radial average distance (D) to its axial average length (L) is adjusted to be in the range of 0.2 to 2.0. The invention provides a gas generator for an air bag capable of reducing a size of the gas generator and easily and reliably adjusting a capacity of a combustion chamber which accommodates the gas generating agent, and also provides a retainer for such a gas generator. The invention provides a retainer which changes a flow of a gas ejected from a through-hole of an inner cylindrical member provided in the housing and has a cylindrical portion for collecting fluid and semifluid combustion products included in the gas, and provides a gas generator for an air bag using such a retainer. The invention provides a gas generator for an air bag comprising, in a housing having a gas discharging port, a inner cylindrical member having a cylindrical peripheral wall, and two combustion chambers defined by the inner cylindrical member, in which a gas generating agent to be ignited for generating a working gas is charged in the respective combustion chambers, and working gases generated in the respective combustion chambers pass through different flow-paths and reach the gas discharging port. The present invention further provides a gas generator for an air bag in which, in a housing having a gas discharging port, an inner cylindrical member having a cylindrical peripheral wall is disposed, two combustion chambers are defined by the inner cylindrical member, a gas generating agent which is burnt to generate a working gas is charged in each of the combustion chambers, and working gases generated in the respective combustion chambers pass through different flow-paths to reach a coolant means.

Claims

1. A gas generator for an air bag comprising, in a cylindrical housing having a gas discharging port, an inner cylindrical member disposed to define an inner space of the housing, an ignition means disposed inside the inner cylindrical member, and a first combustion chamber provided radially in the outside of the inner cylindrical member to accommodate a gas generating agent, wherein,

the first combustion chamber is adjusted such that a ratio (D/L) of its radial average distance (D)to its axial average length (L) is in the range of 0.2 to 2.0.

5. A gas generator for an air bag according to claim 1 or 3, wherein a retainer provided with a partition wall surface is disposed on an axial end of said first combustion chamber, and said partition wall surface limits the axial length of the first combustion chamber.

6. A gas generator for an air bag according to claim 1 or 4, wherein the housing limits an axial length of the first combustion chamber with an inner surface existing on the axial direction of the first combustion chamber.

7. A gas generator for an air bag according to any one of claims 1 to 6, wherein the inner cylindrical member is provided with a flame-transferring port for ejecting flames generated by actuation of the ignition means into the first combustion chamber, and the flame-transferring port is formed such that a distance L₁ from the center of the axial average length in the first combustion chamber to the center of the flame-transferring port is not more than ¼

of the axial average length L in the first combustion chamber.

8. A gas generator for an air bag according to any one of claims 1 to 7, wherein the first combustion chamber is formed annularly.

9. A gas generator for an air bag according to any one of claims 1 to 8, wherein the inside of the inner cylindrical member is further divided into an ignition means accommodating chamber and a second combustion chamber by a partition wall.

10. A gas generator for an air bag according to claim 9, wherein a gas generated by combustion of the gas generating agent accommodated in the second combustion chamber is not directly ejected into the first combustion chamber.

11. A gas generator for an air bag according to claim 9 or 10, wherein the retainer limits the axial average length of the first combustion chamber and defines a flow-space of a gas oppositely to the first combustion chamber, and the inner cylindrical member is formed with a communication hole capable of making the second combustion chamber and the flow-space of gas communicate with each other.

12. A gas generator for an air bag according to any one of claims 1 to 11, wherein the gas generating agent accommodated in the first combustion chamber includes fuel and oxidizing agent, and the oxidizing agent is basic metal nitrate.

13. A gas generator for an air bag according to claim 12, wherein the fuel is guanidine derivatives or a mixture thereof.

51. An air bag apparatus comprising:

a gas generator for an air bag,

an impact sensor for detecting an impact to actuate the gas generator,

the air bag which introduces gas generated in the gas generator to expand, and

a module case for accommodating the air bag, wherein

the gas generator for the air bag is the one in any one of claims 1 to 50.

2. A gas generator for an air bag comprising, in a cylindrical housing having a gas discharging port, an inner cylindrical member disposed to define an inner space of the housing, an ignition means disposed inside the inner cylindrical member, and a first combustion chamber provided radially in the outside of the inner cylindrical member to accommodate a gas generating agent, wherein,

a retainer provided with a partition wall surface is disposed on an axial end of said first combustion chamber, and said partition wall surface limits an axial length of the first combustion chamber.

3. A gas generator for an air bag comprising, in a cylindrical housing having a gas discharging port, an inner cylindrical member disposed to define an inner space of the housing, an ignition means disposed inside the inner cylindrical member, and a first combustion chamber provided radially in the outside of the inner cylindrical member to accommodate a gas generating agent, wherein,

said housing limits an axial length of said first combustion chamber with an inner surface existing in the axial direction of the first combustion chamber.

4. A gas generator for an air bag comprising, in a cylindrical housing comprising a diffuser shell which has a cylindrical shape with a top and has a gas discharging port, and a closure shell which has a cylindrical shape with a bottom and forms an inner space together with the diffuser shell, an inner cylindrical member disposed to define the inner space of the housing, an ignition means disposed inside the inner cylindrical member, and a first combustion chamber accommodating a gas generating agent provided radially in the outside of the inner cylindrical member, wherein

said inner cylindrical member is provided with a flame-transferring port for ejecting flames generated by actuation of the ignition means into the first combustion chamber, and the flame-transferring port is formed such that a distance L₁ from the center of the axial average length measured from the closure shell-inner bottom surface in the first combustion chamber to the center of the flame-transferring port is not more than ¼

of the axial average length L in the first combustion chamber.

14. A retainer used for a gas generator for an air bag comprising, in a cylindrical housing having a gas discharging port, an inner cylindrical member having a cylindrical peripheral wall provided with a through-hole, and at least either of an ignition means and a gas generating agent is disposed inside the inner cylindrical member, wherein

the retainer includes a cylindrical portion which is positioned with a distance from an outer peripheral surface of the cylindrical peripheral wall and faces the outer peripheral surface, and a flange-shaped partition wall portion integrally formed together with the cylindrical portion, and at least either of the cylindrical portion and the partition wall portion changes a flow of a gas ejected from the through-hole formed in the cylindrical peripheral wall and collects combustion products other than gaseous material included in the gas.

15. A retainer according to claim 14, wherein the cylindrical portion is formed into a size and shape capable of covering at least a communication hole of the inner cylindrical member.

16. A retainer according to claim 14 or 15, wherein part of the cylindrical portion is formed into a size and shape capable of fitting outwardly the cylindrical peripheral wall of the inner cylindrical member.

17. A retainer according to any one of claims 14 to 16 used for a gas generator for an air bag which accommodates annular coolant means for purifying or cooling a gas generated by combustion of a gas generating agent stored in a housing, wherein

all or part of the cylindrical portion is formed into a shape and size capable of fitting to at least one of an inner peripheral surface and an outer peripheral surface of the coolant means and an inner peripheral surface of a housing peripheral wall.

18. A retainer according to any one of claims 14 to 17, wherein an end opening of the cylindrical portion is integrally formed with a engaging portion which engages a cylindrical peripheral wall of an inner cylindrical member in an inwardly directed flange-like shape.

19. A retainer according to any one of claims 14 to 18 used for a gas generator for an air bag in which a first combustion chamber for accommodating the gas generating agent is provided radially in the outside of the inner cylindrical member wherein,

the partition wall portion is formed into a shape and size capable of defining at least an axial end of the first combustion chamber.

20. A gas generator for an air bag comprising, in a cylindrical housing having a gas discharging port, an inner cylindrical member having a cylindrical peripheral wall provided with a through-hole, at least either of an ignition means and a gas generating agent disposed in the inner cylindrical member, and a retainer, which has a cylindrical portion surrounding part of the inner cylindrical member and a flange-shaped partition wall portion integrally formed on the cylindrical portion, disposed outside the inner cylindrical member, wherein

a cylindrical portion of the retainer is positioned with a distance from an outer peripheral surface of the cylindrical peripheral wall and faces the outer peripheral surface, and at least one of the cylindrical portion and the peripheral wall changes flow of a gas ejected from a through-hole formed in the cylindrical peripheral wall of the inner cylindrical member and collects combustion products other than gaseous material included in the gas.

21. A gas generator for an air bag according to claim 20, wherein the cylindrical portion of the retainer exists at a horizontally projected position of a through-hole provided on cylindrical peripheral wall of the inner cylindrical member.

22. A gas generator for an air bag according to claim 20 or 21, wherein the cylindrical portion of the retainer faces the communication hole of the inner cylindrical member without closing the communication hole.

23. A gas generator for an air bag according to any one of claims 20 to 22, wherein part of the cylindrical portion of the retainer is fitted outwardly to the cylindrical peripheral wall of the inner cylindrical member.

24. A gas generator for an air bag according to any one of claims 20 to 23, wherein an annular coolant means for purifying or cooling a gas generated by combustion of the gas generating agent stored in the housing is accommodated in the housing, and all or part of the cylindrical portion of the retainer is fitted to at least one of an inner peripheral surface and an outer peripheral surface of the coolant means and an inner peripheral surface of a housing peripheral wall.

25. A gas generator for an air bag according to any one of claims 20 to 24, wherein an end opening of the cylindrical portion is integrally formed with a engaging portion which engages a cylindrical peripheral wall of an inner cylindrical member in an inwardly directed flange-like shape.

26. A gas generator for an air bag according to claim 25, wherein the housing comprises a diffuser shell having a gas discharging port and a closure shell forming an inner space together with the diffuser shell, the inner cylindrical member includes a step-notch formed by stepwisely notching an outer peripheral surface of the inner cylindrical member in the closure shell side, and a engaging portion of the retainer engages the notch.

27. A gas generator for an air bag according to any one of claims 20 to 26, wherein a first combustion chamber for accommodating the gas generating agent is provided radially in the outside of the inner cylindrical member, and a peripheral wall of the retainer is formed into a shape and size capable of defining at least an axial end of the first combustion chamber and is provided on the axial end of the first combustion chamber.

28. A gas generator for an air bag according to claim 27, wherein, in the retainer, the partition wall portion receives combustion pressure of the first gas generating agent accommodated in the first combustion chamber, and thereby the engaging portion is pushed against a step-notched portion of the inner cylindrical member.

29. A gas generator for an air bag according to any one of claims 20 to 28, wherein, inside the inner cylindrical member, an ignition means accommodating chamber and a second combustion chamber are defined adjacent to each other in the axial direction by a partition wall, and a communication hole of the inner cylindrical member is open at the second combustion chamber.

30. A gas generator for an air bag according to any one of claims 20 to 29, wherein the inside the inner cylindrical member is further divided into an ignition means accommodating chamber and a second combustion chamber by a partition wall, and the retainer collects combustion products other than gaseous material generated by combustion of the second gas generating agent.

31. A gas generator for an air bag according to any one of claims 20 to 30, wherein the gas generating agent accommodated in the first combustion chamber includes fuel and oxidizing agent, the oxidizing agent is basic metal nitrate.

32. A gas generator for an air bag according to claim 31, wherein the fuel is guanidine derivatives or a mixture thereof.

33. A gas generator for an air bag comprising, in a housing having a gas discharging port, an inner cylindrical member having a cylindrical peripheral wall, two combustion chambers defined by the inner cylindrical member, wherein

gas generating agents to be burnt for generating a working gas are charged in the respective combustion chambers, and

working gases generated in the respective combustion chambers pass through different flow-paths and reach the gas discharging port.

35. A gas generator for an air bag according to claim 33 or 34, which further comprises an ignition means to ignite a gas generating agent, and the ignition means is accommodated inside the inner cylindrical member.

36. A gas generator for an air bag according to any one of claims 33 to 35, wherein a working gas generated in one of the combustion chambers passes through a flow-space divided from the other combustion chamber and does not pass through the other combustion chamber.

37. A gas generator for an air bag according to any one of claims 33 to 36, wherein working gases generated in the respective combustion chambers pass through different coolant means to reach the gas discharging port.

38. A gas generator for an air bag according to any one of claims 33 to 37, wherein working gases generated in the respective combustion chambers reach different gas discharging ports respectively provided in the corresponding combustion chambers.

39. A gas generator for an air bag according to any one of claims 33 to 38, wherein one or both of the gas discharging port and coolant means are provided independently of each other, in correspondence with each combustion chambers defined in the housing.

40. A gas generator for an air bag according to any one of claims 33 to 39, wherein all or part of one of the two combustion chambers is defined in the housing by being surrounded by the other combustion chamber.

41. A gas generator for an air bag according to any one of claims 33 to 40, wherein the coolant means is formed cylindrically, and either or both of the two combustion chambers are adjacent to the inside of the coolant means.

42. A gas generator for an air bag according to any one of claims 33 to 41, wherein a working gas generated in one of the two combustion chambers passes through a flow-space which can communicate with said combustion chamber to reach the gas discharging port.

43. A gas generator for an air bag according to any one of claims 33 to 42, wherein a working gas generated in one of the two combustion chambers passes through a flow-space which can communicate with said combustion chamber to reach the gas discharging port, and the flow-space is defined in the housing to pass through the other combustion chamber or to be adjacent to the other combustion chamber.

44. A gas generator for an air bag according to any one of claims 36, 42 and 43, wherein the flow-space communicating with one of the two combustion chambers is defined in the housing by the retainer defining an end of the other combustion chamber.

45. A gas generator for an air bag according to any one of claims 42 to 44, wherein a seal tape closes between the flow-space and the combustion chamber which can communicate with the flow-space, and the seal tape is ruptured only by pressure of the combustion chamber which can communicate with the flow-space.

46. A gas generator for an air bag according to any one of claims 42 to 45, wherein one of the two combustion chambers and the flow-path can communicate with each other through the communication hole, and the communication hole is sealed by a seal tape, and the seal tape is provided in a position where combustion flames of the gas generating agent accommodated in the other combustion chamber does not touch the seal tape.

47. A gas generator for an air bag according to claim 46, wherein the seal tape is made of aluminum and having a metal layer thickness of 10 to 100 mm.

48. A gas generator for an air bag according to any one of claims 33 to 47, wherein one of the two combustion chambers is provided inside the inner cylindrical member disposed in the gas generator, and the other combustion chamber is provided radially in the outside of the inner cylindrical member.

49. A gas generator for an air bag according to claim 48, wherein the combustion chamber defined inside the inner cylindrical member and the other combustion chamber are provided concentrically to be adjacent in the radial direction.

50. A gas generator for an air bag according to any one of claims 33 to 49, wherein an interior of the inner cylindrical member is divided into two chambers which are adjacent to each other in the axial direction by a partition wall which expands radially, one of the two chambers defined inside the inner cylindrical member closer to the gas discharging port is a combustion chamber, and the other chamber is an ignition means accommodating chamber for accommodating the ignition means.

34. A gas generator for an air bag comprising, in a housing having a gas discharging port, an inner cylindrical member having a cylindrical peripheral wall and two combustion chambers defined by the inner cylindrical member, wherein

gas generating agents to be burnt for generating a working gas are charged in the respective combustion chambers, and

a working gas generated in one of the combustion chambers reaches the gas discharging port without passing through the other combustion chamber.