Dual level inflator

• US 6,168,200 B1
• Filed: 12/01/1998
• Issued: 01/02/2001
• Est. Priority Date: 12/01/1998
• Status: Expired due to Term

• Current Assignee: Arc Automotive Incorporated (The Jordan Co. LP)
• Original Assignee: Atlantic Research Corporation (L3Harris Technologies, Inc.)
• Inventors: Robbins, Richard K., DiGangi, Scott Joseph, Greist, Darton E. III
• Primary Examiner(s): Dickson, Paul N.
• Assistant Examiner(s): Fleming, Faye M.
• Application Number:
  US09/201,789
• Time in Patent Office: 763 Days
• Field of Search: 280/741, 280/736, 280/737, 102/530, 102/531
• US Class Current: 280/736
• CPC Class Codes: B60R 2021/2633 with a plurality of inflation levels
• CPC Class Codes: B60R 21/272 with means for increasing the pressure of the gas just before or during liberation, e.g. hybrid inflators

Abstract

A dual level inflator is provided for creating at least two different rates and levels of air bag inflation while optimizing cost effectiveness, size, safety and performance. The dual level inflator includes a unitized gas generator canister assembly including two canisters of gas generant material connected to a common base and positioned in a chamber formed in an inflator outer housing. The unitized assembly is easily transportable and mountable on the outer housing. Each canister of the unitized assembly includes apertures permitting direct communication between each canister cavity and the chamber of the outer housing. As a result, generant material positioned in each canister is directly exposed to the conditions in the outer housing chamber. The present assembly is advantageous in that it maximizes the internal volume available to the stored gas and, after the ignition of one canister and the inflation of the air bag, the remaining canister may be ignited without reinflating the air bag due to the previous depressurization of the chamber in combination with the selection of a generant material incapable of effectively burning in a low pressure environment, i.e. the directly connected chamber. The present dual inflator also includes seal means to prevent inadvertent ignition, and an arrangement by which the plurality of apertures formed in one canister are positioned relative to the apertures in the other canister to cause the gas flowing from one set of apertures to be sufficiently cooled by the inert gas in the chamber prior to reaching the apertures of the other canister thereby preventing inadvertent thermally induced ignition of the generant material in the remaining unfired canister.

Claims

1. An inflation device for inflating a vehicle safety restraint, comprising:

an outer housing including a chamber for containing a quantity of stored inert gas;

a unitized gas generator canister assembly mounted in said chamber and including a first generator canister containing a gas generant material, a second generator canister containing a gas generant material and positioned adjacent said first generator canister, and a common base connected to a first end of both said first and said second generator housings, said common base connected to said outer housing;

a first ignitor positioned adjacent said common base at said first end of said first generator canister for igniting said gas generant material in said first generator canister; and

a second ignitor positioned adjacent said common base at said first end of said second generator canister for igniting said gas generant material in said second generator canister;

each of said first generator canister and said second generator canister including a plurality of apertures exposing said generant material to the stored inert gas in said chamber to prevent an undesired pressure increase upon ignition of said gas generant material; and

ignition prevention means for preventing inadvertent ignition of said gas oenerant material in said second generator canister upon ignition and burning of said gas generant material in said first generator canister, said ignition prevention means including positioning said plurality of apertures in said first generator canister a sufficient distance from said plurality of apertures in said second generator canister to cause the gas flowing from said plurality of apertures of said first generator canister to be sufficiently cooled by the inert gas in said chamber prior to reaching said plurality of apertures of said second generator canister;

each of said first and said second generator canisters including a first side facing in a common first direction and a second side facing in a common second direction substantially opposite from said first direction, said plurality of apertures in said first generator canister being positioned on said first side thereof, said second side of said first generator canister being free from apertures, said plurality of apertures in said second generator canister being positioned on said second side thereof, said first side of said second generator canister being free from apertures.

2. The inflation device of claim 1, wherein each of said first and said second generator canisters are substantially cylindrically shaped, said common base including a mounting flange extending transversely outwardly from said first and said second generator canisters on two opposite sides of said unitized gas generator assembly, and said first and second generator canisters being disposed in abutting relation.

3. The inflation device of claim 1, wherein said outer housing includes a generally circular transverse cross-section, said common base being positioned within said chamber of said outer housing.

4. The inflation device of claim 1, wherein said outer housing includes an end cap mounted to close one end of said chamber and an outlet formed at an opposite end of said chamber, further including a burst disk positioned to close said outlet and adapted to fail upon the pressure in said chamber reaching a predetermined pressure level.

5. The inflation device of claim 4, wherein said first and said second igniters are mounted on said end cap.

6. The inflation device of claim 1 further comprising seal means between said first generator and said second generator to prevent hot gas from flowing therebetween.

7. A dual level inflation device for inflating a vehicle safety restraint, comprising:

an outer housing including a chamber for containing a quantity of stored inert gas and an outlet for directing pressurized gas into the vehicle safety restraint;

a first generator canister mounted in said chamber, said first generator canister including a first canister wall forming a cavity containing gas generant material and at least one first aperture formed in said first canister wall to permit open communication between said cavity and said chamber, said gas generant material in said first generator canister exposed to the stored inert gas to prevent an undesired pressure increase in said cavity upon ignition of said generant material;

a second generator canister mounted in said chamber, said second generator canister including a second canister wall forming a cavity containing gas generant material and at least one second aperture formed in said second canister wall to permit open communication between said cavity and said chamber, said gas generant material in said second generator canister exposed to the stored inert gas to prevent an undesired pressure increase in said cavity upon ignition of said generant material; and

at least one igniter for igniting said generant material in said first and said second generator canisters;

ignition prevention means for preventing inadvertent ignition of said generant material in said second generator canister upon ignition and burning of said generant material in said first generator canister, said ignition prevention means including positioning said at least one first aperture a sufficient distance from said at least one second aperture to cause the gas flowing from said at least one first aperture to be sufficiently cooled by the inert gas in said chamber prior to reaching said at least one second aperture;

said first and said second generator canisters including a first side facing in a common first direction and a second side facing in a common second direction substantially opposite from said first direction, said ignition prevention means including said at least one first aperture being positioned on said first side of said first generator canister, said second side of said first generator canister being free from apertures, said at least one second aperture being positioned on said second side of said second generator canister, and said first side of said second generator canister being free from apertures.

8. The inflation device of claim 7, wherein said gas generant material in at least one of said first and said second generator canisters is of a type incapable of burning effectively under low pressure.

9. The inflation device of claim 8, wherein each of said first and said second generator canisters include a booster charge mounted in said cavity between said at least one ignitor and said gas generant material, each of said at least one first aperture and said at least one second aperture including a booster aperture positioned adjacent one of said booster charge and said at least one ignitor.

10. The inflation device of claim 9, wherein each of said at least one first aperture and said at least one second aperture includes a plurality of apertures extending substantially longitudinally along said first and said second generator canisters.

11. The inflation device of claim 10, wherein said plurality of apertures includes two rows of apertures.

12. The inflation device of claim 8, wherein said first generator canister contains a first predetermined quantity of gas generant material and said second generator canister contains a second predetermined quantity of gas generant material less than said first predetermined quantity.

13. A dual level inflation device for inflating a vehicle safety restraint, comprising:

an outer housing including a chamber for containing a quantity of inert gas at a first predetermined pressure level and an outlet for directing pressurized gas into the vehicle safety restraint;

a burst disk positioned to close said outlet and adapted to fail upon the pressure in said chamber reaching a second predetermined pressure level greater than said first predetermined pressure level;

a first generator canister mounted in said chamber and including a cavity containing gas generant material and at least one first aperture formed in said first generator canister to permit open communication between said cavity and said chamber;

a second generator canister mounted in said chamber and including a cavity containing gas generant material and at least one second aperture formed in said second generator canister to permit open communication between said cavity and said chamber;

at least one igniter for igniting said generant material in said first and said second generator canisters;

an ignition prevention means for preventing inadvertent ignition of said gas generant material in said second generator canister upon ignition and burning of said gas generant material in said first generator canister, said ignition prevention means including positioning said at least one first aperture a sufficient distance from said at least one second aperture to cause the gas flowing from said at least one first aperture to be sufficiently cooled by the inert gas in said chamber prior to reaching said at least one second aperture;

each of said first and said second generator canisters including a first side facing in a common first direction and a second side facing in a common second direction substantially opposite from said first direction, said ignition prevention means including said at least one first aperture being positioned on said first side of said first generator canister, said second side of said first generator canister being free from apertures, said at least one second aperture being positioned on said second side of said second generator canister, and said first side of said second generator canister being free from apertures.

14. The inflation device of claim 13, wherein said outer housing includes an end cap mounted to close one end of said chamber and an outlet formed at an opposite end of said chamber, further including a burst disk positioned to close said outlet and adapted to fail upon the pressure in said chamber reaching a predetermined pressure level.

15. The inflation device of claim 13, wherein said at least one igniter includes a first ignitor mounted on said end cap adjacent one end of said first generator canister for igniting said generant material in said first generator canister and a second ignitor mounted on said end cap adjacent one end of said second generator canister for igniting said generant material in said second generator canister.

16. The inflation device of claim 13, wherein said gas generant material in said first generator and said second generator canisters are continually exposed to the stored inert gas to prevent an undesired pressure increase in said respective cavity upon ignition of said generant material, each of said at least one first aperture and said at least one second aperture includes a plurality of apertures extending substantially longitudinally along said first and said second generator canisters, wherein said gas generant material in at least one of said first and said second generator canisters is of a type incapable of burning effectively under low pressure.