Gas generator for an air bag

• US 20050206144A1
• Filed: 02/24/2005
• Published: 09/22/2005
• Est. Priority Date: 02/27/2004
• Status: Active Grant

• Current Assignee: Daicel Chemical Industries Limited
• Original Assignee: Daicel Chemical Industries Limited
• Inventors: Matsuda, Naoki, Iwai, Yasunori, Numoto, Kenji, Hirooka, Masato
• Granted Patent: US 7,413,216 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

A gas generator for an airbag producing no malfunction is provided.

When the first combustion gas generated in the first combustion chamber 30 enters the filter chamber 50, most of the gas is discharged through the gas discharge port 52, however, part of the combustion gas flows into the second through hole 62. This combustion gas flows through the vent hole 76 into the second combustion chamber 40 after changes its flow direction by the gas-flow inhibiting member 80 inside the second cap member 75. At this time, the temperature of the gas is lowered, so that the second gas generating agent 43 is never burnt.

Claims

1. A gas generator for an airbag, comprising two combinations of an ignition means and a combustion chamber including a gas generating agent, the two ignition means capable of being activated separately from each other with a time lag,

the gas generator having a structure such that part of the combustion gas possibly flows from a gas discharge passage into the other combustion chamber in a procedure where one of the ignition means is activated first, the gas generating agent in one of the combustion chambers is ignited and burnt first to generate a combustion gas and the combustion gas flows in the gas discharge passage and is discharged from a gas discharge port to inflate an air bag,

at least one flame-transferring preventing means being provided at a given position in the passage where the combustion gas flows from the gas discharge passage into the other combustion chamber for obstructing direct advance of the combustion gas flow.

2. The gas generator for an air bag according to claim 1, wherein the flame-transferring preventing means comprises a combination of a cap member and a gas-flow inhibiting member arranged in the interior of the cap member,

the cap member comprises a ceiling surface and a side surface having a plurality of vent holes, the opposite side of the ceiling surface comprises an opening portion, and

the gas-flow inhibiting member is arranged such that, when a combustion gas flows from the gas discharge passage and enters the cap member through the opening portion of the cap member, the direction of the combustion gas is changed by the gas-flow inhibiting member and then the gas flow enters, through the vent holes of the side surface, the other combustion chamber (second combustion chamber) in which combustion is started with delay.

3. The gas generator for an airbag according to claim 1 or 2, wherein the flame-transferring preventing means comprises a seal tape, and by the seal tape, the combustion gas flow is prevented from entering the other combustion chamber in which combustion is started with delay.

4. The gas generator for an airbag according to claim 1 or 2, wherein the flame-transferring preventing means comprise a wire mesh or coolant/filter, the combustion gas flow flows, through the wire mesh or coolant/filter, into the other combustion chamber in which combustion is started with delay.

5. The gas generator for an airbag according to claim 1 or 2, wherein the gas discharge passage itself has a structure for obstructing the direct advance of the combustion gas flow.

6. The gas generator for an airbag according to claim 1, wherein a coolant/filter is arranged, separately to the flame-transferring preventing means, in the gas discharge passage that leads to the gas discharge port, and when part of the combustion gas flows into the other combustion chamber, the combustion gas always passes through the coolant/filter to enter the other combustion chamber because of the action of the flame-transferring means for obstructing a direct advance of the combustion gas flow.

7. A gas generator for an airbag, comprising a first ignition means and a first combustion chamber accommodating a first gas generating agent in one end side of a cylindrical housing, and a second ignition means and a second combustion chamber accommodating a second gas generating agent in the other end side of a cylindrical housing,

a first partition wall having a first through hole and a second partition wall having a second through hole defining a separated space between the first combustion chamber and the second combustion chamber, a space formed between the first partition wall and the second partition wall including a filter chamber provided with a cylindrical filter,

the cylindrical housing having a gas discharge port provided in the surface directly facing the cylindrical filter,

a cap member being provided as a flame-transferring preventing means in the second combustion chamber,

the cap member having a ceiling surface and a side surface having a plurality of vent holes, provided with an opening portion in the opposite side of the ceiling surface, the cap member covering the second through hole from the opening portion side, being fixed onto the second partition wall.

8. The gas generator for an airbag according to claim 7, wherein the flame-transferring preventing means comprises a combination of a cap member and a cylindrical gas-flow inhibiting member arranged in the interior of the cap member,

a cylindrical gas-flow inhibiting member is concentrically provided inside the cap member to have one end opening portion facing the second through hole and the other end opening portion facing the ceiling surface of the cap member, and

when the combustion gas flows through the second through hole into the cap member, the direction thereof is changed by the gas-flow inhibiting member, and then the gas flow enters the second combustion chamber through the vent holes in the side surface.

9. The gas generator for an airbag according to claim 7 or 8, wherein the flame-transferring preventing means comprises a seal tape, and the vent holes of the cap member are closed by the seal tape.

10. The gas generator for an airbag according to claim 7 or 8, wherein the flame-transferring preventing means comprises a wire mesh arranged between the side surface of the cap member and the side surface of the gas-flow inhibiting member, the combustion gas is caused to flow into the other combustion chamber in which the initiation of combustion is delayed after passing through the above wire mesh.

11. The gas generator for an airbag according to claim 7 or 8, wherein the flame-transferring preventing means comprises a coolant/filter disposed between the ceiling surface of the cap member and the other end opening portion of the gas-flow inhibiting member, the combustion gas is caused to flow through the coolant/filter into the other combustion chamber in which the initiation of combustion is delayed.

12. The gas generator for an airbag according to claim 7 or 8, wherein a covering member, which prevent the direct advancement of the combustion gas flow to the second through hole, is provided on the second partition wall surface inside the filter chamber.

13. The gas generator for an airbag according to claim 7 or 8, wherein no part of the first through hole directly faces any part of the second through hole in the axial direction.

14. A gas generator for an airbag, comprising a first ignition means and a first combustion chamber accommodating a first gas generating agent in one end side of a cylindrical housing, and a second ignition means and a second combustion chamber accommodating a second gas generating agent in the other end side of a cylindrical housing,

a first partition wall having a first through hole and a second partition wall having a second through hole defining a separated space between the first combustion chamber and the second combustion chamber, a space formed between the first partition wall and the second partition wall including a filter chamber provided with a cylindrical filter,

the cylindrical housing having a gas discharge port provided in the surface directly facing the cylindrical filter, wherein

at least one gas flow diversion members being disposed in the filter chamber to forcibly make the combustion gas flow enter the cylindrical filter when the combustion gas generated in the first combustion chamber flows into the filter chamber from the first through hole.

15. The gas generator for an airbag according to claim 14, wherein the gas flow diversion member comprises a ceiling surface and a circumferential surface having a plurality of vent holes, and an opening portion is provided in the opposite side of the ceiling surface,

a single gas flow diversion member is arranged such that a gap corresponding to a passage for gas flow is secured between the second through hole and ceiling surface, the circumferential surface abuts against the inner circumferential surface of the cylindrical filter and the diversion member covers the first through hole at the opening portion side and is fixed to the first partition wall.

16. The gas generator for an airbag according to claim 14, wherein two gas flow diversion members is provided,

among these, a first gas flow diversion member, which comprises a ceiling surface, a circumferential surface having a plurality of vent holes and a opening portion provided in the opposite side of the ceiling portion, is arranged such that the circumferential surface abuts against the inner circumferential surface of the cylindrical filter and the diversion member covers the first through hole at the opening portion side and is fixed to the first partition wall,

a second gas flow diversion member, which comprises a ceiling surface, a circumferential surface having a plurality of vent holes and a opening portion provided in the opposite side of the ceiling portion, is arranged such that the circumferential surface abuts against the inner circumferential surface of the cylindrical filter and the diversion member covers the second through hole at the opening portion side and is fixed to the second partition wall, and

the ceiling surface of the first gas flow diversion member and the ceiling surface of the second gas flow diversion member are arranged to abut against each other.

17. The gas generator for an airbag according to claim 14 or 15, wherein a cap member corresponding to a flame-transferring preventing means is further arranged in the second combustion chamber, and this cap member, which comprises a ceiling surface, a side surface having a plurality of vent holes and an opening portion provided in the opposite side of the ceiling surface, covers the second through hole at the opening portion side and is fixed to the second partition wall.