Air bag-use gas generator and air bag device

• US 7,114,746 B2
• Filed: 12/27/2001
• Issued: 10/03/2006
• Est. Priority Date: 12/27/2000
• Status: Expired due to Term

• Current Assignee: Daicel Chemical Industries Limited
• Original Assignee: Daicel Chemical Industries Limited
• Inventors: Iwai, Yasunori, Miyaji, Katsuhito
• Primary Examiner(s): Fleming, Faye M.
• Application Number:
  US10/415,643
• Publication Number:
  US 20040051289A1
• Time in Patent Office: 1,741 Days
• Field of Search: 280/741, 280/740, 280/742, 280/736
• US Class Current: 280/741
• CPC Class Codes: B60R 21/26 characterised by the inflation fluid source or means to control inflation fluid flow arrangement or mounting thereof to the vehicle B60R21/20; blasting cartridges for producing gas under pressure in general F42B3/04; initiators or igniters therefor F42B3/10
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder

Abstract

A gas generator for an air bag having a simple structure, which is activated to apply as small an impact as possible to a vehicle occupant at the initial stage of activation and, thereafter, can reliably protect the vehicle occupant by rapidly increasing gas pressure, is provided. It is a gas generator for an air bag in which an inner cylindrical member is disposed in the housing to define an ignition means accommodating chamber and a combustion chamber, plural flame-transferring holes for communicating the both chambers with each other are formed on the circumferential surface of the inner cylindrical member, and the plural flame-transferring holes are formed at a distance of less than 30% of the axial length of the inner cylindrical member, from an end of the inner cylindrical member. A gas generator, which can use even a gas generating agent with less ignitability, and further can exhibit enough operation performance at the initial stage of activation even when using such a gas generating agent, is provided. It is a gas generator for an air bag in which an inner cylindrical member is disposed in the housing to define an ignition means accommodating chamber and a combustion chamber, and the central angle formed by the adjacent communicating portions which are formed on the circumferential surface of the inner cylindrical member is adjusted to be not more than 60 degrees.

Claims

1. A gas generator for an air bag comprising:

a housing having a gas discharging port;

a substantially cylindrical inner cylindrical member disposed in the housing, an ignition means accommodating chamber defined inside the inner cylindrical member, a combustion chamber defined outside the inner cylindrical member; and

plural flame-transferring holes formed in the circumferential surface of the inner cylindrical member to communicate the ignition means accommodating chamber with the combustion chamber, wherein

the plural flame-transferring holes are formed at a distance of less than 30% of the axial length of the inner cylindrical member, from an end of the inner cylindrical member,

the flame-transferring hole is formed to have the inner diameter of 1 to 4 mm, and

the flame-transferring holes are formed radially on the circumferential surface of the inner cylindrical member, and the central angle formed by the adjacent flame-transferring holes being not less than 60 degrees.

2. The gas generator for an air bag according to claim 1, wherein the plural flame-transferring holes are formed at a distance of less than 25% of the axial length of the inner cylindrical member, from an end of the inner cylindrical member.

3. The gas generator for an air bag according to claim 1 or 2, wherein an igniter, which is activated when an ignition electric current for activation is applied, is accommodated in one axial end side of the inner cylindrical member, and the plural flame-transferring holes are formed in the end being opposite, divided at the center of the axis of the inner cylindrical member.

4. The gas generator for an air bag according to claim 1, wherein the ignition means accommodating chamber accommodates an ignition means including an igniter which is activated when an ignition electric current is applied, the flame-transferring holes are for ejecting a flame generated by activation of the ignition means into the combustion chamber, and the flame-transferring holes eject a flame of a transfer charge with horizontal angle of more than 60 degrees, having the perpendicular axis as a center.

5. The gas generator for an air bag according to claim 1, wherein the ignition means accommodating chamber accommodates an ignition means including an igniter which is activated when an ignition electric current is applied, and the operation performance thereof is adjusted such that the tank pressure measured at 0.25×

T milliseconds is not more than 0.25×

P(kPa) when the maximum tank pressure is P(kPa), and a period of time from the start of rising of the tank pressure to the time when the maximum tank pressure P(kPa) has been reached is T milliseconds in tank combustion test.

6. The gas generator for an air bag according to claim 1, wherein the ignition means accommodating chamber accommodates an ignition means, including an igniter which is activated when an ignition electric current is applied, and the operation performance thereof is adjusted such that the tank pressure measured at 0.80×

T milliseconds is not less than 0.70×

P(kPa) when the maximum tank pressure is P(kPa), and a period of time from the start of rising of the tank pressure to the time when the maximum tank pressure P(kPa) has been reached is T milliseconds in tank combustion test.

7. The gas generator for an air bag according to claim 1, wherein the ignition means accommodating chamber accommodates an ignition means including an igniter which is activated when an ignition electric current is applied, the combustion chamber accommodates a gas generating agent ignited and burnt by activation of the ignition means to generate a combustion gas, and the pressure inside the housing reaches its maximum at 10 to 20 milliseconds after the ignition electric current is applied.

8. The gas generator for an air bag according to claim 1, wherein the ignition means accommodating chamber accommodates an ignition means including an igniter which is activated when an ignition electric current is applied, the plural flame-transferring holes are formed to eject a flame generated by activation of the ignition means into the combustion chamber, and both of an elevation angle and a depression angle of a ejected flame are adjusted to 45 degrees.

9. An air bag apparatus comprising a gas generator, an impact sensor detecting an impact to activate the gas generator, an air bag introducing a gas generated in the gas generator to inflate, and a module case accommodating the gas generator, wherein the gas generator for an air bag is a gas generator according to claim 1.

21. The gas generator for an air bag according to any one of claim 1, 10, 12, 13 and 18, wherein, the central angle formed by the adjacent communicating portions or flame-transferring holes is 90 degrees or higher.

22. The gas generator for an air bag according to any one of claim 1, 10, 12, 13 and 18, further comprising a deflecting member which has a cylindrical portion and which is disposed circumferentially between said combustion chamber and said discharge port.

23. A method for obtaining an S-shaped tank curve from a gas generator during a tank combustion test, comprising:

providing the gas generator of any one of claims 1, 10, 12 and 18;

activating the ignition means by applying an ignition electric current; and

setting parameters of the gas generator such that the tank pressure the tank pressure measured at 0.25×

T (milliseconds) is not more than 0.25×

P(kPa) and the tank pressure measured at 0.80×

T (milliseconds) is not less than 0.70×

P(kPa),

wherein P represents the maximum tank pressure (kPa), and T represents a period of time from the start of rising of the tank pressure to the time when the maximum tank pressure P(kPa) has been reached (milliseconds) in tank combustion test.

24. A method for obtaining an S-shaped tank curve meeting parameters that the tank pressure the tank pressure measured at 0.25×

T (milliseconds) is not more than 0.25×

P(kPa) and the tank pressure measured at 0.80×

T (milliseconds) is not less than 0.70×

P(kPa) during a tank combustion test from a gas generator, comprising;

providing the gas generator of any one of claims 1, 10, 12, 13 and 18; and

activating the ignition means by applying an ignition electric current.

25. A method to inflate an air bag, comprising:

providing the gas generator of any one of claims 1, 10, 12 and 18;

activating the ignition means by applying an ignition electric current; and

setting parameters of the gas generator such that the tank pressure the tank pressure measured at 0.25×

T (milliseconds) is not more than 0.25×

P(kPa) and the tank pressure measured at 0.80×

T (milliseconds) is not less than 0.70×

P(kPa),

wherein P represents the maximum tank pressure (kPa), and T represents a period of time from the start of rising of the tank pressure to the time when the maximum tank pressure P(kPa) has been reached (milliseconds) in tank combustion test.

10. A gas generator for an air bag comprising:

a housing having a gas discharging port;

a substantially cylindrical inner cylindrical member disposed in the housing;

an ignition means accommodating chamber for accommodating a ignition means defined inside the inner cylindrical member;

a combustion chamber for accommodating gas generating agent defined outside the inner cylindrical member; and

plural communicating portions circumferentially formed on the circumferential surface of the inner cylindrical member to communicate the ignition means accommodating chamber with the combustion chamber, wherein

the central angle formed by the adjacent communicating portions is not less than 60 degrees,

the communicating portion comprises at least one flame-transferring hole radially penetrating the inner cylindrical member, and

the flame-transferring hole is formed to have the inner diameter of 1 to 4mm.

11. The gas generator for an air bag according to claim 10, wherein the communicating portion comprises at least two flame-transferring holes radially penetrating in the inner cylindrical member.

12. A gas generator for an air bag comprising;

a housing having a gas discharging port;

a substantially cylindrical inner cylindrical member disposed in the housing;

an ignition means accommodating chamber for accommodating an ignition means defined inside the inner cylindrical member;

a combustion chamber for accommodating a gas generating agent defined outside the inner cylindrical member, and

plural flame-transferring holes for ejecting a flame generated by activation of the ignition means into the combustion chamber, wherein

the plural flame-transferring holes are formed on the circumferential surface of the inner cylindrical member, and the flame-transferring holes eject a flame, generated by activation of the ignition means into the combustion chamber, at 45 degree of elevation angle and depression angle,

the flame-transferring hole is formed to have the inner diameter of 1 to 4mm, and

the flame-transferring holes are radially formed on the circumferential surface of the inner cylindrical member, and the central angle formed by the adjacent communicating portions being not less than 60 degrees.

13. A gas generator for an air bag comprising:

a housing having a gas discharging port;

a substantially cylindrical inner cylindrical member disposed in the housing;

an ignition means accommodating chamber for accommodating an ignition means defined inside the inner cylindrical member;

a combustion chamber for accommodating a gas generating agent defined outside the inner cylindrical member; and

plural flame-transferring holes for ejecting a flame generated by activation of the ignition means into a first combustion chamber, wherein

the plural flame-transferring holes are formed on the circumferential surface of the inner cylindrical member, and the flame-transferring holes are formed at a distance of 30% to 70% of the axial length of the inner cylindrical member, from an end of the inner cylindrical member, the flame-transferring holes being formed on the circumferential surface of the inner cylindrical member, and the central angle formed by the adjacent flame-transferring holes being not less than 60 degrees.

14. The gas generator for an air bag according to claim 13, wherein the plural flame-transferring holes are formed at a distance of 40% to 60% of the axial length of the inner cylindrical member, from an end of the inner cylindrical member.

15. The gas generator for an air bag according to claim 13 or 14, wherein an igniter which is activated when an ignition electric current for activation is applied in one axial end side of the inner cylindrical member, and the plural flame-transferring holes are formed in the end being opposite, divided with respect to the axial center of the inner cylindrical member.

16. The gas generator for an air bag according to claim 13, wherein the ignition means accommodating chamber accommodates an ignition means including an igniter which is activated when an ignition electric current is applied, the plural flame-transferring holes ejecting a flame generated by activation of the ignition means into the combustion chamber are circumferentially formed on the circumferential surface of the inner cylindrical member, and the horizontal angle of an ejecting flame from the flame-transferring holes is adjusted to not less than 60 degrees having, as the center, the axis perpendicular to the center of the flame-transferring holes.

17. The gas generator for an air bag according to claim 13, wherein the ignition means accommodating chamber accommodates an ignition means including an igniter which is activated when an ignition electric current is applied, the combustion chamber accommodates a gas generating agent ignited and burnt by activation of the ignition means to generate a combustion gas, and the pressure inside the housing reaches its maximum at 5 to 20 milliseconds after the ignition electric current is applied.

18. A gas generator for an air bag comprising;

a housing having a gas discharging port;

a substantially cylindrical inner cylindrical member disposed in the housing;

an ignition means accommodating chamber for accommodating an ignition means defined inside the inner cylindrical member; and

a combustion chamber for accommodating a gas generating agent defined outside the inner cylindrical member, and

plural communicating portions circumferentially formed on the circumferential surface of the inner cylindrical member to communicate the ignition means accommodating chamber with the combustion chamber, wherein

the central angle formed by the adjacent communicating portions is not more than 60 degrees.

19. The gas generator for an air bag according to claim 18, wherein the communicating portion comprises one or at least two flame-transferring holes radially penetrating in the inner cylindrical member.

20. The gas generator for an air bag according to claim 19, wherein the communicating portion comprises one flame-transferring hole radially penetrating in the inner cylindrical member, and the flame-transferring hole is formed to have the inner diameter of 1 to 4mm.