Dual stage air bag inflator with secondary propellant cap

• US 6,701,849 B2
• Filed: 04/10/2001
• Issued: 03/09/2004
• Est. Priority Date: 03/05/1999
• Status: Expired due to Term

• Current Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: McFarland, Eric R., Mika, Darin P.
• Primary Examiner(s): TUDOR, HAROLD JAY
• Application Number:
  US09/829,696
• Publication Number:
  US 20020144621A1
• Time in Patent Office: 1,064 Days
• Field of Search: 102/530, 102/531, 280/736, 280/741, 280/742
• US Class Current: 102/530
• 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

An inflator (10) for inflating an inflatable device includes a housing (20). A primary propellant (240) in a primary chamber (200) in the housing (20) is ignitable to provide inflation fluid to inflate the inflatable device. A secondary propellant (250) in a secondary chamber (180) in the housing (20) is ignitable to provide inflation fluid to inflate the inflatable device. The inflator (10) includes initiator means (130, 154) for selectively igniting either the primary propellant (240) alone or both of the primary and secondary propellants (240, 250). The inflator (10) also includes a secondary propellant cap (260) for closing the secondary chamber (180) and for maintaining the secondary propellant (250) in the secondary chamber. The secondary propellant cap (260) has a first position blocking flow of combustion products of the first propellant (240) into the secondary chamber (180) when only the primary propellant is ignited. The secondary propellant cap (260) is movable by combustion products of the secondary propellant (250) when ignited from the first position to a second position enabling flow of inflation fluid out of the secondary chamber (180) to inflate the inflatable device.

Claims

1. An inflator for providing inflation fluid for inflating an inflatable vehicle occupant protection device, said inflator comprising:

a housing;

a primary propellant in a primary chamber in said housing and ignitable to provide inflation fluid to inflate the inflatable device;

a secondary propellant in a secondary chamber in said housing and ignitable to provide inflation fluid to inflate the inflatable device;

initiator means for selectively igniting either said primary propellant alone or both of said primary and secondary propellants; and

a secondary propellant cap having a generally kidney-shaped configuration for closing said secondary chamber and for maintaining said secondary propellant in said secondary chamber;

said secondary propellant cap having a first position blocking flow of combustion products of said primary propellant into said secondary chamber when only said primary propellant is ignited;

said secondary propellant cap being movable by combustion products of said secondary propellant when ignited from the first position to a second position enabling flow of inflation fluid out of said secondary chamber to inflate the inflatable device.

2. An inflator as set forth in claim 1, wherein said secondary propellant cap when in the first position is pressed into an opening in a housing portion of said inflator and upon ignition of said secondary propellant pops free of the housing portion.

3. An inflator for providing inflation fluid for inflating an inflatable vehicle occupant protection device, said inflator comprising:

a housing;

a primary propellant in a primary chamber in said housing and ignitable to provide inflation fluid to inflate the inflatable device;

a secondary propellant in a secondary chamber in said housing and ignitable to provide inflation fluid to inflate the inflatable device;

a housing portion at least partially defining said primary chamber and said secondary chamber;

initiator means for selectively igniting either said primary propellant alone or both of said primary and secondary propellants; and

a secondary propellant cap for closing said secondary chamber and for maintaining said secondary propellant in said secondary chamber;

said secondary propellant cap being movable from a first position to a second position by combustion products of said secondary propellant, when said secondary propellant is ignited;

said secondary propellant cap, in the first position, being pressed into an opening in said housing portion and blocking flow of combustion products of said primary propellant into said secondary chamber when only said primary propellant is ignited;

said secondary propellant cap, in the second position, being completely separated from said housing portion and enabling flow of inflation fluid out of said secondary chamber through said opening in said housing portion to inflate the inflatable device.

4. An inflator as set forth in claim 3 wherein said housing has a fluid passage for directing flow of inflation fluid out of said housing to the inflatable device, said housing deforming due to the pressure of inflation fluid in said housing upon actuation of one or both of said primary and secondary propellants, the flow area of said fluid passage increasing due to deformation of said housing and varying in accordance with the pressure of inflation fluid in said housing.

5. An inflator as set forth in claim 4 further comprising a flow control member for defining a control passage located between said primary propellant and said fluid passage, the flow area of said control passage varying in accordance with the pressure of inflation fluid in said housing upon actuation of one or both of said primary and secondary propellants.

6. An inflator as set forth in claim 4 wherein said housing portion is a one-piece igniter housing.

7. An inflator as set forth in claim 3 wherein said secondary propellant cap has a generally kidney-shaped configuration.

8. An inflator as set forth in claim 3 wherein said secondary propellant chamber is encircled by said primary propellant chamber.

9. An inflator as set forth in claim 3 wherein said initiator means comprises a primary initiator and a primary ignition material for igniting said primary propellant, and wherein said initiator means comprises only a secondary initiator for igniting said secondary propellant.

10. An inflator as set forth in claim 3 wherein said secondary propellant cap has first and second opposite major side surfaces, said first major side surface being exposed to said secondary propellant in said secondary chamber, said second major side surface being exposed to the fluid pressure of said primary chamber.

11. An apparatus for providing inflation fluid for inflating an inflatable vehicle occupant protection device, the apparatus comprising:

a housing having a plurality of exit openings for enabling flow of inflation fluid out of the inflator;

primary and secondary combustion chambers located within the housing, a first inflation fluid source located in the primary combustion chamber and actuatable to effect flow of inflation fluid through the plurality of exit openings, a second inflation fluid source located in the secondary combustion chamber and actuatable to effect flow of inflation fluid through the primary combustion chamber and through the plurality of exit openings, the secondary combustion chamber including an open top which enables inflation fluid resulting from actuation of the second inflation fluid source to exit the second combustion chamber;

the first inflation fluid source and the second inflation fluid source comprising solid pyrotechnic material which, when ignited, generates inflation fluid;

a first initiator associated with the primary combustion chamber for, when energized, actuating the first inflation fluid source;

a second initiator associated with the secondary combustion chamber for, when energized, actuating the second inflation fluid source;

a cap closing the open top of the secondary combustion chamber, the cap preventing inflation fluid resulting from actuation of only the first inflation fluid source from entering the secondary combustion chamber, inflation fluid resulting from actuation of the second inflation fluid source removing the cap from at least a portion of the open top of the secondary combustion chamber to form a passage for enabling inflation fluid resulting from actuation of the second inflation fluid source to exit the secondary combustion chamber, the passage extending from the secondary combustion chamber to the primary combustion chamber, a gap that is formed between opposing surface portions of the secondary combustion chamber and the cap when the cap is removed from at least a portion of the open top of the secondary combustion chamber defining the passage in its entirety and inflation fluid exiting the secondary combustion chamber flowing through only the gap; and

a flow control member that extends over the secondary combustion chamber and at least a portion of the primary combustion chamber for controlling flow of inflation fluid toward the exit openings, the cap contacting the flow control member when the cap is lifted from the open top of the secondary combustion chamber.

12. An apparatus for providing inflation fluid for inflating an inflatable vehicle occupant protection device, the apparatus comprising:

a housing having a plurality of exit openings for enabling flow of inflation fluid out of the inflator;

primary and secondary combustion chambers located within the housing, a first inflation fluid source located in the primary combustion chamber and actuatable to effect flow of inflation fluid through the plurality of exit openings, a second inflation fluid source located in the secondary combustion chamber and actuatable to effect flow of inflation fluid through the primary combustion chamber and through the plurality of exit openings, the secondary combustion chamber including an open top which enables inflation fluid resulting from actuation of the second inflation fluid source to exit the second combustion chamber;

the first inflation fluid source and the second inflation fluid source comprising solid pyrotechnic material which, when ignited, generates inflation fluid;

a first initiator associated with the primary combustion chamber for, when energized, actuating the first inflation fluid source;

a second initiator associated with the secondary combustion chamber for, when energized, actuating the second inflation fluid source;

a cap closing the open top of the secondary combustion chamber, the cap preventing inflation fluid resulting from actuation of only the first inflation fluid source from entering the secondary combustion chamber, inflation fluid resulting from actuation of the second inflation fluid source removing the cap from at least a portion of the open top of the secondary combustion chamber to form a passage for enabling inflation fluid resulting from actuation of the second inflation fluid source to exit the secondary combustion chamber, the passage extending from the secondary combustion chamber to the primary combustion chamber, a gap that is formed between opposing surface portions of the secondary combustion chamber and the cap when the cap is removed from at least a portion of the open top of the secondary combustion chamber defining the passage in its entirety and inflation fluid exiting the secondary combustion chamber flowing through only the gap;

an annular filter that encircles the secondary combustion chamber and filters inflation fluid resulting from actuation of the first and second inflation fluid sources; and

a flow control member that extends over the secondary combustion chamber and at least a portion of the filter, the flow control member helping to position the filter between the secondary combustion chamber and the exit openings and directing inflation fluid resulting from actuation of at least the second inflation fluid source toward the filter.

13. An inflator for providing inflation fluid for inflating an inflatable vehicle occupant protection device, the inflator comprising:

a housing;

primary and secondary propellant chambers located within the housing, the secondary propellant chamber including a side wall and an open top;

a primary propellant in the primary propellant chamber being ignitable to provide inflation fluid to inflate the inflatable device;

a secondary propellant in the secondary propellant chamber being ignitable to provide inflation fluid to inflate the inflatable device;

first initiator means for igniting the primary propellant and secondary initiator means for igniting the secondary propellant;

a cap for covering the open top of the secondary propellant chamber and preventing flow of inflation fluid resulting from ignition of the primary propellant into the secondary propellant chamber when only the primary propellant is ignited, the cap including a surface which is in engagement with the side wall of the secondary propellant chamber when the cap is covering the open top of the secondary propellant chamber, inflation fluid resulting from ignition of the secondary propellant moving the surface of the cap away from and out of engagement with at least a portion of the side wall of the secondary propellant chamber so as to remove the cap from covering at least part of the open top of the secondary propellant chamber and creating a flow passage for enabling flow of inflation fluid out of the secondary propellant chamber, inflation fluid flowing out of the secondary propellant chamber flowing through only the flow passage created during removal of the cap; and

a flow control member that extends over the secondary propellant chamber and at least a portion of the primary propellant chamber for controlling flow of inflation fluid within the housing, the cap contacting the flow control member when the cap is dislodged from the side wall of the secondary propellant chamber.

14. An inflator for providing inflation fluid for inflating an inflatable vehicle occupant protection device, the inflator comprising:

a housing;

primary and secondary propellant chambers located within the housing, the secondary propellant chamber including a side wall and an open top;

a primary propellant in the primary propellant chamber being ignitable to provide inflation fluid to inflate the inflatable device;

a secondary propellant in the secondary propellant chamber being ignitable to provide inflation fluid to inflate the inflatable device;

first initiator means for igniting the primary propellant and secondary initiator means for igniting the secondary propellant;

a cap for covering the open top of the secondary propellant chamber and preventing flow of inflation fluid resulting from ignition of the primary propellant into the secondary propellant chamber when only the primary propellant is ignited, the cap including a surface which is in engagement with the side wall of the secondary propellant chamber when the cap is covering the open top of the secondary propellant chamber, inflation fluid resulting from ignition of the secondary propellant moving the surface of the cap away from and out of engagement with at least a portion of the side wall of the secondary propellant chamber so as to remove the cap from covering at least part of the open top of the secondary propellant chamber and creating a flow passage for enabling flow of inflation fluid out of the secondary propellant chamber, inflation fluid flowing out of the secondary propellant chamber flowing through only the flow passage created during removal of the cap;

an annular filter that encircles the secondary propellant chamber and filters inflation fluid resulting from actuation of the first and second propellants; and

a flow control member that extends over the secondary propellant chamber and at least a portion of the filter, the flow control member helping to position the filter within the housing and directing inflation fluid resulting from actuation of the first and second propellants toward the filter.

15. An apparatus for providing inflation fluid for inflating an inflatable vehicle occupant protection device, the apparatus comprising:

a housing having a plurality of exit openings for enabling flow of inflation fluid out of the inflator;

primary and secondary combustion chambers located within the housing, a first inflation fluid source located in the primary combustion chamber and actuatable to effect flow of inflation fluid through the plurality of exit openings, a second inflation fluid source located in the secondary combustion chamber and actuatable to effect flow of inflation fluid through the primary combustion chamber and through the plurality of exit openings, the secondary combustion chamber including an open top which enables inflation fluid resulting from actuation of the second inflation fluid source to exit the second combustion chamber, a perimeter of the secondary combustion chamber being defined by an interior surface;

the first inflation fluid source and the second inflation fluid source comprising solid pyrotechnic material which, when ignited, generates inflation fluid;

a first initiator associated with the primary combustion chamber for, when energized, actuating the first inflation fluid source;

a second initiator associated with the secondary combustion chamber for, when energized, actuating the second inflation fluid source; and

a cap including structure for engaging the interior surface of the secondary combustion chamber to secure the cap in a first condition closing the open top of the secondary combustion chamber, the cap, when in the first condition, preventing inflation fluid resulting from actuation of only the first inflation fluid source from entering the secondary combustion chamber, inflation fluid resulting from actuation of the second inflation fluid source moving the cap from the first condition closing the open top of the secondary combustion chamber to a second condition in which the cap is completely separated from at least a portion of the perimeter of the secondary combustion chamber so as to form a gap having opposite boundaries defined by the cap and the portion of the perimeter of the secondary combustion chamber from which the cap is completely separated, inflation fluid resulting from actuation of the second inflation fluid source flowing through only the gap as the inflation fluid flows to the primary combustion chamber.

16. The apparatus as set forth in claim 15 wherein the secondary combustion chamber includes a side wall, the side wall including the interior surface and an upper end of the interior surface of the side wall defining the open top of the secondary combustion chamber, the structure of the cap, when in the first condition closing the open top of the secondary combustion chamber, being in abutting engagement with and sealing against the interior surface of the side wall.

17. The apparatus as set forth in claim 16 wherein the cap is press fit against the interior surface of the side wall of the secondary combustion chamber so that the inflation fluid within the secondary combustion chamber must reach a predetermined pressure to dislodge the cap from the side wall.

18. The apparatus as set forth in claim 15 further including an annular filter that encircles the secondary combustion chamber and filters inflation fluid resulting from actuation of the first and second inflation fluid sources.

19. An apparatus for providing inflation fluid for inflating an inflatable vehicle occupant protection device, the apparatus comprising:

a housing having a plurality of exit openings for enabling flow of inflation fluid out of the inflator;

primary and secondary combustion chambers located within the housing, a first inflation fluid source located in the primary combustion chamber and actuatable to effect flow of inflation fluid through the plurality of exit openings, a second inflation fluid source located in the secondary combustion chamber and actuatable to effect flow of inflation fluid through the primary combustion chamber and through the plurality of exit openings, the secondary combustion chamber being defined by a wall that defines an open top of the second combustion chamber;

the first inflation fluid source and the second inflation fluid source comprising solid pyrotechnic material which, when ignited, generates inflation fluid;

a first initiator associated with the primary combustion chamber for, when energized, actuating the first inflation fluid source;

a second initiator associated with the secondary combustion chamber for, when energized, actuating the second inflation fluid source; and

a cap associated with the secondary combustion chamber, the cap being a structure which has no holes that extend through the structure for conducting inflation fluid through the cap, the cap having a first position in which the cap is located on the wall of the secondary combustion chamber preventing inflation fluid resulting from actuation of only the first inflation fluid source from entering the secondary combustion chamber, inflation fluid resulting from actuation of the second inflation fluid source moving the cap from the first position to a second position, at least a portion of the cap being spaced away from the wall of the secondary combustion chamber when the cap is in the second position so as to enable inflation fluid flow from the secondary combustion chamber to the primary combustion chamber, a gap being defined between the portion of the cap that is spaced away from the wall and the wall of the secondary combustion chamber, inflation fluid resulting from actuation of the second inflation fluid source flowing through only the gap prior to entering the primary combustion chamber.

20. The apparatus as set forth in claim 19 wherein the cap is press fit against the wall of the secondary combustion chamber so that the inflation fluid resulting in actuation of the second inflation fluid source must reach a predetermined pressure to dislodge the cap from the wall.

21. The apparatus as set forth in claim 19 further including an annular filter that encircles the secondary combustion chamber and filters inflation fluid resulting from actuation of the first and second inflation fluid sources.