Multi-stage gas generator with thermal uncoupling of the propellant charges

• US 6,314,888 B1
• Filed: 05/18/1999
• Issued: 11/13/2001
• Est. Priority Date: 05/19/1998
• Status: Active Grant

• Current Assignee: TRW Airbag Systems GmbH & Co., KG
• Original Assignee: TRW Airbag Systems GmbH & Co., KG
• Inventors: Schropp, Roland, Müller, Werner
• Primary Examiner(s): TUDOR, HAROLD JAY
• Application Number:
  US09/314,476
• Time in Patent Office: 910 Days
• Field of Search: 102/530, 102/531, 280/736, 280/741
• US Class Current: 102/530
• CPC Class Codes: B60R 2021/2607 characterised by heating or heat insulating means, e.g. for use under extreme temperatures
• 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
• CPC Class Codes: B60R 22/4628 characterised by fluid actuators, e.g. pyrotechnic gas generators actuating a cable B60R22/4619

Abstract

A multi-stage gas generator comprises a housing with an outer wall and also inner walls, at least two combustion chambers filled with at least one propellant charge, one igniter each associated with a propellant charge for the independent activation of each propellant charge, and at least one thermal insulation arrangement between the propellant charges. The arrangement reduces a transport of thermal energy, generated on the ignition of a propellant charge, to the other non-ignited propellant charge to such a high extent that the non-ignited propellant charge remains below its autogenous ignition temperature. Instead of or additionally to the thermal arrangement a cooling arrangement may be provided.

Claims

1. A multi-stage gas generator, comprising:

an outer housing with a cylinder outer wall centered on an axis,

at least spaced apart first and second combustion chambers in said housing, each combustion chamber being filled with a propellant charge;

each one of said combustion chambers having an associated igniter for the independent activation of each propellant charge; and

first and second filter housings centered on said axis and located between said first and second combustion chambers;

said first filter housing having a first filter chamber containing a first cylindrical filter centered on said axis, a first wall permitting first gas flow into the first filter chamber from said first combustion chamber, a second wall spaced from said second filter housing, and first gas flow openings for directing said first gas flow radially from said first filter chamber, said first gas flow being directed radially through said first cylindrical filter;

said second filter housing having a second filter chamber containing a second cylindrical filter centered on said axis, a third wall permitting second gas flow from said second combustion chamber into said second filter chamber, a fourth wall spaced from said second wall, and second gas flow openings for directing said second gas flow radially from said second filter chamber, said second gas flow being directed radially through said second cylindrical filter;

at least one thermal insulation arrangement between said second and fourth walls, which arrangement reduces a transport of thermal energy, to the other non-ignited propellant charge such that said non-ignited propellant charge remains below its autogenous ignition temperature, and where said first and second filter housings are arranged between said combustion chambers in a manner that gas is prevented from flowing from one filter chamber to the other filter chamber.

2. The multi-stage gas generator according to claim 1, wherein said gas generator is a tubular gas generator with two combustion chambers arranged at opposite ends of said tube.

3. The multi-stage gas generator according to claim 1, wherein the thermal insulation arrangement comprises at least one of the following means:

insulating material;

gas; and

vacuum.

4. The multi-stage gas generator according to claim 1, wherein said insulating material consists of one of plastic or ceramic.

5. The multi-stage gas generator according to claim 1, wherein said outer housing has protruding cooling ribs.

6. A multi-stage gas generator, comprising:

a housing with an outer wall and also inner walls;

at least two combustion chambers filled with a propellant charge;

one igniter associated with each one of said combustion chambers for the independent activation of each propellant charge; and

at least one thermal insulation arrangement between said propellant charges, which arrangement reduces a transport of thermal energy, generated on the ignition of a propellant charge, to the other non-ignited propellant charge to such a high extent that said non-ignited propellant charge remains below its autogenous ignition temperature, wherein each combustion chamber has its own filter chamber, and wherein said filter chambers are arranged between said combustion chambers and are spaced apart by said thermal insulation arrangement wherein an intermediate space between said two filter chambers has a vacuum.

7. A multi-stage gas generator, with a housing with external and also internal walls, at least two combustion chambers filled with a propellant charge, one igniter associated with each one of said combustion chambers for the independent activation of each propellant charge, and at least one cooling arrangement which at least partially surrounds said housing adjacent at least one of said combustion chambers, said cooling arrangement reducing a transport of thermal energy, generated on the ignition of a propellant charge, to the other non-ignited propellant charge to such a high extent that said non-ignited propellant charge remains below its autogenous ignition temperature, wherein said cooling arrangement includes cooling ribs protruding from said external wall.

8. The multi-stage gas generator according to claim 7, wherein at least one thermal insulation arrangement between said propellant charges is provided.

9. The multi-stage gap generator according to claim 7, wherein said gas generator is a tubular gas generator with said two combustion chambers arranged at opposite ends of said tube.

10. The multi-stage gas generator according to claim 9, wherein the thermal arrangement comprises at least one of the following means:

insulating material;

gas; and

vacuum.