Gas generator with cooling device

• US 6,196,583 B1
• Filed: 12/15/1999
• Issued: 03/06/2001
• Est. Priority Date: 06/20/1997
• Status: Expired due to Fees

• Current Assignee: TRW Airbag Systems GmbH & Co., KG
• Original Assignee: TRW Airbag Systems GmbH & Co., KG
• Inventors: Fink, Martin, Leifheit, Markus, Tieu, Anh-Dung, Hinterberger, Christof, Lindner, Markus, Laucht, Horst, Ruckdeschel, Rolf, Winterhalder, Marc
• Primary Examiner(s): Rice, Kenneth R.
• Application Number:
  US09/445,899
• Time in Patent Office: 447 Days
• Field of Search: 280/736, 280/741, 280/742
• US Class Current: 280/736
• CPC Class Codes: B60R 2021/26017 a cooling agent being added to the inflation fluid
• CPC Class Codes: B60R 21/264 using instantaneous generation of gas, e.g. pyrotechnic B60R21/268 takes precedence
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder

Abstract

The present invention relates to an inflator for a safety device, in particular for a vehicle occupant restraint system, comprising a housing (1, 15; 22, 23), a combustion chamber formed in the housing and including a solid propellant (6) for generating hot gas, and a coolant (13) introduced into a predetermined flow path of the hot gas. The inflator in accordance with the invention is characterized in that the flow path of the hot gas passes through a nozzle (10) comprising a pitot zone (20) in which the hot gas emerging from the combustion chamber (21) has a high static pressure, and comprising a nozzle neck (19) in which the hot gas builds up a high dynamic pressure, and in that the coolant (13) is arranged in a sleeve-shaped reservoir (11) extending from the pitot zone (20) at least in part into the nozzle neck (19). The inflator in accordance with the invention permits an effective reduction in the exhaust gas temperature of the generated hot gas.

Claims

1. An inflator, in particular for passive vehicle occupant restraint systems, comprising a housing (1, 15;

22, 23), a combustion chamber (21) formed in said housing and including solid propellant (6) for generating hot gas, and a coolant (13) introduced into a predetermined flow path of the hot gas, characterized in that the flow path of the hot gas passes through a nozzle (10) comprising a pitot zone (20) in which the hot gas emerging from said combustion chamber (21) has a high static pressure, and comprising a nozzle neck (19) in which the hot gas builds up a high dynamic pressure, and that said coolant (13) is arranged in a sleeve-shaped reservoir (11) extending from said pitot zone (20) at least in part into said nozzle neck (19).

2. The inflator as set forth in claim 1, characterized in that said reservoir (11) is provided in the region of said pitot zone (20) of said nozzle (10) with pressure-relief ports (12).

3. The inflator as set forth in claim 1, characterized in that said reservoir (11) is provided in the region of said nozzle neck (19) with one or more openings (14).

4. The inflator as set forth in claim 3, characterized in that said openings (14) are set back relative to the downstream end of said nozzle neck (19) and in the upper end of said nozzle neck (19) a mixing zone (18) for the hot gas and said coolant (13) is configured.

5. The inflator as set forth in any of the claim 1, characterized in that said housing (1, 5) is configured tubular and consists essentially of an upper housing part (1) and a lower housing part (15).

6. The inflator as set forth in claim 5, characterized in that said nozzle (10) is arranged in said upper housing part (1) and coaxially to said combustion chamber (21) formed in said lower housing part (15).

7. The inflator as set forth in claim 5, characterized in that the wall of said upper housing part (1) locates said nozzle (10) centered.

8. The inflator as set forth in claim 5, characterized in that said combustion chamber (21) is separated from said nozzle (10) by a perforated plate (8) having bore holes (9) for the exit of the hot gas towards said nozzle (10).

9. The inflator as set forth in claim 8, characterized in that said sleeve-shaped reservoir (11) for said coolant (13) is centrally secured to said perforated plate (8) and is arranged coaxially to said nozzle (10).

10. The inflator as set forth in claim 1, characterized in that said housing (22, 23) comprises a pot-shaped lower housing part (23) and a cover-like upper housing part (22).

11. The inflator as set forth in claim 10, characterized in that arranged in the middle of said upper housing part (22) are an igniter (2) and a sleeve (5) which in the region of said igniter (2) is filled with a pyrotechnical booster charge (3).

12. The inflator as set forth in claim 10, characterized in that said coolant (13) is located on the side of said sleeve (5) opposite said igniter (2) and is separated from said pyrotechnical booster charge (3) by a pressure plate (25).

13. The inflator as set forth in claim 1, characterized in that said combustion chamber (21) annularly surrounds said sleeve (5).

14. The inflator as set forth in claim 10, characterized in that said nozzle (10) is located press-mounted in the middle of a nozzle plate (26) pressed into place in said lower housing part (23), said nozzle (10) being located opposite said sleeve (5).

15. The inflator as set forth in claim 1, characterized in that said solid propellant (6) is present in the form of pellets, rings or compacts.

16. The inflator as set forth in claim 1, characterized in that said coolant (13) in said reservoir (11) is enclosed in a burstable sleeve.