Gas generator for vehicle occupant restraint system

• US 5,443,286 A
• Filed: 08/13/1993
• Issued: 08/22/1995
• Est. Priority Date: 10/09/1992
• Status: Expired due to Fees

• Current Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Original Assignee: Morton International Incorporated (Autoliv Incorporated)
• Inventors: Erickson, James D., Cunningham, Donald J.
• Primary Examiner(s): FERRITER, KARIN L
• Application Number:
  US08/106,291
• Time in Patent Office: 739 Days
• Field of Search: 280/736, 280/741, 102/530, 102/531, 102/202.5, 60/256, 422/164, 422/165, 422/166
• US Class Current: 280/741
• CPC Class Codes: B60R 2021/26029 Ignitors
• CPC Class Codes: B60R 2021/26064 characterised by auto-ignition means
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder

Abstract

A gas generator for vehicle occupant restraint systems comprises an elongated housing having gas outlet openings, a sealed, rupturable gas generant cartridge positioned within the housing, and pyrotechnic gas generant contained in the cartridge in the form of a plurality of wafers having openings defining a central passage. An igniter capsule mounted at one end of the housing has an exit opening juxtaposed the sealed gas generant cartridge and the central passage of the gas generant therein. The igniter capsule contains ignitor material, and an initiator and initiator charge. The initiator ignites the ignitor material which expels a fireball of hot combustion products from the capsules exit opening, rupturing the sealed cartridge and igniting the gas generant charge to produce gas for inflating an air bag. A rupturable seal is provided over the exit opening of the ignitor capsule and a nozzle directs hot combustion products to the gas generant cartridge. The initiator charge is auto ignitor material for operating the gas generator if it is exposed to fire. The ignitor capsule comprises overlapping metal parts, and is mounted as a closure of the elongated housing. The gas generant cartridge is placed in the housing surrounded by filtering and cooling screens. One end of the rupturable gas generant cartridge adjacent the ignitor capsule outlet is scored for rupturing inwardly to admit the ignitor fireball. The cartridge contains wraps of filter screen to provide structural rigidity, and additional filter and cooling materials surround the cartridge.

Claims

1. A gas generator for a vehicle occupant restraint system, comprising:

an elongated cylindrical housing having a length at least two times greater than its diameter and having gas outlet openings formed therethrough;

a pyrotechnic gas generant material contained within the housing, the gas generant material defining a single open elongated central passage therein;

an igniter capsule containing substantially all of the igniter material for igniting the pyrotechnic gas generant and having means for igniting the igniter material, the igniter capsule positioned adjacent the pyrotechnic gas generant material and defining a single exit opening adjacent the .open central passage formed in the gas generant material, the exit opening being of substantially the same diameter or smaller than the open central passage formed in the gas generant material;

whereby ignition and burning of the igniter material causes an expulsion of hot igniter material, combustion products from the igniter capsule into and along the length of the open central passage in the gas generant material, thereby igniting the gas generant material along the length of the open central passage.

41. A gas generator as defined in claim 1 and further comprising a sealed cylindrical cartridge containing the gas generant material.

42. A gas generator as defined in claim 41 wherein the sealed cylindrical cartridge has an end wall adjacent the igniter capsule, the end wall having a weakened rupturable entry portion positioned between the exit opening of the igniter capsule and the single elongated central passage of the gas generant material.

2. A gas generator for a vehicle occupant restraint system, comprising:

a housing having gas outlet openings formed therethrough;

a pyrotechnic gas generant material contained within the housing, the gas generant material defining an elongated central passage therein;

an igniter capsule containing igniter material and having means for igniting the igniter material, the igniter capsule positioned adjacent the pyrotechnic gas generant material and defining an exit opening adjacent the central passage formed in the gas generant material, the exit opening defined by the igniter capsule comprising a nozzle extending therefrom and directing hot combustion products from the igniter capsule into the central passage in the gas generant material;

whereby ignition and burning of the igniter material causes an expulsion of hot combustion products from the igniter capsule into the central passage in the gas generant material, thereby igniting the gas generant material along the length of the central passage.

3. A gas generator as defined in claim 2 and further comprising a rupturable seal positioned on one of the exit opening of the igniter capsule or the nozzle, which seal ruptures upon burning of the igniter material and consequent build up of pressure in the igniter capsule, thereby permitting the expulsion of hot combustion products from the igniter capsule into the central passage of the gas generant material.

4. A gas generator as defined in claim 3 wherein the seal is an integral, break-away end wall of the nozzle.

5. A gas generator as defined in claim 2 wherein the nozzle and the central passage in the gas generant material are aligned.

6. A gas generator as defined in claim 5 wherein the gas generant is provided in a plurality of annular wafers having aligned central openings defining the central passage.

7. A gas generator as defined in claim 6 wherein the wafers are longitudinally spaced apart.

8. A gas generator as defined in claim 7 and further comprising a sealed cartridge containing the gas generant material, the sealed cartridge having a rupturable entry opening juxtaposed the nozzle outlet of the igniter capsule and covering the central passage in the gas generant material.

9. A gas generator as defined in claim 8 wherein the rupturable entry portion of the cartridge wall includes a recess offsetting the rupturable entry portion inwardly and the nozzle extends into the recess.

10. A gas generator as defined in claim 2 wherein the gas generant is provided in a plurality of annular wafers having aligned central openings defining the central passage.

11. A gas generator as defined in claim 10 wherein the wafers are incrementally longitudinally spaced apart by spacers integral with the wafers.

12. A gas generator as defined in claim 11 and further comprising a sealed cartridge containing the gas generant material, the sealed cartridge having a rupturable entry opening juxtaposed the exit opening of the igniter capsule and covering the central passage in the gas generant material.

13. A gas generator as defined in claim 12 wherein the rupturable entry portion of the cartridge wall includes a recess offsetting the rupturable entry portion inwardly, and the exit opening of the igniter capsule comprises a nozzle received in the offset recess.

14. A gas generator as defined in claim 2 wherein the means for igniting the igniter material is an initiator charge comprised of auto ignition material for igniting in fire conditions below the temperature at which the housing loses structural integrity.

15. A gas generator for a vehicle occupant restraint system, comprising:

an elongated housing having gas outlet openings defined therethrough, the housing having a tubular side wall, a first end and end wall, and a second end;

pyrotechnic gas generant material contained within the housing and extending from adjacent the first end and end wall toward the second end, the gas generant material including a plurality of annular wafers with aligned central openings defining an elongated central passage aligned with the axis of the elongated housing;

an igniter capsule including a base and cap secured together and containing igniter material therein, the base of the capsule forming a portion of the closure of the second end wall of the elongated housing, the base including a skirt extending from the periphery thereof, the cap having a generally hemispherical configuration and being placed against the periphery of the base within the skirt, and the skirt roll crimped over the cap, the cap defining an exit opening from the igniter cartridge and further including a nozzle extending from the exit opening toward the central opening in the wafers of pyrotechnic gas generant material, the igniter capsule having an initiator and associated initiator charge directed toward the igniter material;

whereby, when operated, the initiator sets off the initiator charge and resultingly the igniter material, and the igniter material thereafter causes an expulsion of hot combustion products from the igniter capsule into the central passage of pyrotechnic gas generant material for igniting it along the length of the central passage.

16. A gas generator as defined in claim 15 wherein the exit opening is covered by a rupturable seal, which ruptures to release hot combustion products from the igniter capsule.

17. A gas generator as defined in claim 15 wherein the nozzle includes an integral break-away end wall which breaks away to release hot combustion products from the igniter capsule.

18. A gas generator as defined in claim 15 wherein the elongated housing has inwardly projecting nubs spaced from the second end thereof, the capsule is mounted in the second end of the housing in engagement with the numbs, and the second end of the housing wall is roll crimped inwardly to secure the capsule with the housing.

24. A gas generator as defined in claim 15 and further comprising a sealed cartridge containing the pyrotechnic gas generant material.

25. A gas generator as defined in claim 24 and further comprising a filter and cooling means positioned between the sealed cartridge and the gas outlet openings of the housing.

19. A gas generator for a vehicle occupant restraint system, comprising:

an elongated housing having gas outlet openings defined therethrough, the housing having a tubular side wall, a first end and end wall, and a second end;

pyrotechnic gas generant adjacent contained within the housing and extending from adjacent the first end and end wall toward the second end, the gas generant material including a plurality of annular wafers with aligned central openings defining an elongated central passage aligned with the axis of the elongated housing;

an igniter capsule mounted at the second end of the housing, the igniter capsule including a base and a cap secured together and containing igniter material therein, the base of the capsule forming at least a portion of a second end wall of the elongated housing, the igniter capsule having an initiator and associated initiator charge directed toward the igniter material and the igniter capsule defining an outlet opening juxtaposed the central opening in the wafers of pyrotechnic gas generant material contained within the housing, and including a nozzle extending from the exit opening toward the central opening of the pyrotechnic gas generant material, the nozzle including an integral break-away end wall which breaks away to release hot combustion products from the igniter capsule, whereby, when operated, the initiator sets off the initiator charge and resultingly the igniter material, and the igniter material thereafter causes an expulsion of hot combustion products from the igniter capsule into the central passage of pyrotechnic gas generant material for igniting it along the length of the central passage.

20. A gas generator as defined in claim 19 wherein the capsule is positioned within the tubular side wall of the housing near the second end thereof, and the housing wall adjacent the second end is formed inwardly over the capsule to close the housing and secure the capsule therein.

21. A gas generator as defined in claim 20 wherein the capsule is axially positioned within the tubular housing by engagement with inwardly projecting nubs formed thereon.

22. A gas generator as defined in claim 20 wherein the initiator is an electrically operable initiator mounted in an opening in the base of the capsule, the initiator having terminals exposed on the exterior of the housing and capsule.

23. A gas generator as defined in claim 22 wherein the initiator charge is auto ignition material for igniting the igniting material in fire conditions below the temperature at which the housing loses its structural integrity.

26. A gas generator for a vehicle occupant restraint system, comprising:

an elongated cylindrical housing having a length at least two times greater than its diameter and having gas outlet openings formed therethrough, the housing having a tubular side wall, a first end and end wall, and a second end;

pyrotechnic gas generant material contained within the housing and extending from adjacent the first end and end wall toward the second end, the gas generant material including a plurality of annular wafers with aligned central openings defining an elongated open central passage aligned with the axis of the elongated housing;

an igniter capsule mounted at the second end of the housing and containing substantially all the igniter material for igniting the pyrotechnic gas generant material, the igniter capsule having an initiator and associated initiator charge directed toward the igniter material and the igniter capsule defining an outlet opening including a nozzle juxtaposed the central opening in the wafers of pyrotechnic gas generant material contained within the housing;

a sealed cartridge containing the pyrotechnic gas generant material, the sealed cartridge having an end wall adjacent the outlet of the nozzle extending from the igniter capsule and covering the central opening of the pyrotechnic gas generant material, and the cartridge end wall having a rupturable entry portion against which the nozzle directs hot combustion products from the igniter capsule,

whereby, when operated, the initiator sets off the initiator charge and resultingly the igniter material, and the igniter material thereafter causes an expulsion of hot combustion products from the igniter capsule through the rupturable entry portion of the sealed cartridge into the open central passage of pyrotechnic gas generant material for igniting it along the length of the central passage.

27. A gas generator as defined in claim 26 wherein the rupturable entry portion of the cartridge wall includes a recess offsetting the rupturable entry portion inwardly, and the nozzle is received in the offset recess.

28. A gas generator as defined in claim 27 and further comprising a filter and cooling means positioned between the sealed cartridge and the gas outlet openings of the housing.

29. A gas generator for a vehicle occupant restraint system, comprising:

an elongated cylindrical housing having a length at least two times its diameter and having gas outlet openings defined therein;

an elongated sealed cylindrical cartridge containing a plurality of wafers of pyrotechnic gas generant material, the wafers having aligned central openings forming an open central passage, the cartridge having a tubular side wall rupturable to release gas produced by the pyrotechnic gas generant material, when ignited, the cartridge further having end walls with at least one of the end walls including a rupturable entry portion adjacent the central passage defined through the wafers of gas generant material, the sealed gas generant cartridge being received within the elongated cylindrical housing and extending substantially its entire length; and

an igniter charge deployed outside and adjacent the rupturable entry end wall portion of the sealed gas generant cartridge juxtaposed the central passage in the gas generant wafers, the igniter charge being substantially all igniter material for the gas generant and means for igniting the igniter charge;

whereby, when ignited, the igniter charge produces hot combustion products which rupture the entry portion of the cartridge end wall, and enter the open central passage of the wafers of pyrotechnic gas generant material therein to ignite them.

30. A gas generator as defined in claim 29 and further comprising a filter and cooling means positioned between the sealed cartridge and the gas outlet openings of the housing.

31. A gas generator as defined in claim 30 wherein the sealed gas generant cartridge is formed of metal, and wherein the end wall on which the rupturable entry portion is formed is thicker than the tubular side wall.

32. A gas generator as defined in claim 31 wherein the rupturable entry portion of the end wall comprises scoring.

33. A gas generator as defined in claim 32 wherein the scoring is in the configuration of a cruciform.

34. A gas generator as defined in claim 32 wherein the tubular side wall of the gas generant cartridge comprises a roll sheet of aluminum having an overlapped sealed seam, and the end walls of the gas generant cartridge are end caps having skirts which fit over the tubular side wall and are sealed thereto.

35. A gas generator as defined in claim 32 wherein the tubular side wall and one end wall of the gas generant cartridge are deep-drawn aluminum, and the other applied to the end is an end cap including the scoring.

36. A gas generator as defined in claim 35 wherein the sealed gas generator cartridge includes at least one wrap of filter screen deployed inside and adjacent to the tubular side wall, the filter screen providing additional rigidity to the sealed gas generant cartridge.

37. A gas generator as defined in claim 29 wherein the sealed gas generator cartridge includes at least one wrap of filter screen deployed inside and adjacent to the tubular side wall, the filter screen providing additional rigidity to the sealed gas generant cartridge.

38. A gas generator as defined in claim 37 wherein the sealed gas generant cartridge is formed in metal, the end wall on which the rupturable entry portion is formed is thicker than the tubular side wall, and the rupturable entry portion is a weakened portion of the end wall.

39. A gas generator as defined in claim 38 wherein the rupturable entry portion of the end wall comprises scoring.

40. A gas generator for a vehicle occupant restraint system, comprising:

an elongated cylindrical housing having a tubular side wall, a first end and end wall and a second end;

a plurality of gas outlet opening defined in the tubular wall of the cylindrical housing, the gas outlet openings being deployed in diametrically opposed groups;

a tubular filter and cooling assembly received in the housing extending from the first end wall and positioned adjacent the tubular side wall, the tubular filter and cooling assembly having plural layers of filter material including screening;

a cylindrical sealed gas generant cartridge received in the housing within the tubular filter and cooling assembly, the gas generant cartridge having a rupturable tubular side wall and a end cap stronger than the tubular sidewall, the end cap having a weakened rupturable entry wall portion facing the second end of the housing;

a pyrotechnic gas generant material contained within the cartridge, the gas generant material including a plurality of wafers of gas generant having aligned openings forming a central passage, one end of which is adjacent the rupturable entry wall portion of the cartridge;

an igniter capsule including a base mounted at and closing the second end of the housing;

the igniter capsule base defining an opening receiving and mounting an electrically operable initiator with terminals thereof exposed on the exterior of the housing;

an initiator charge mounted adjacent the initiator for ignition thereby;

igniter powder contained within the igniter capsule adjacent the initiator charge for ignition thereby;

the initiator capsule further including a cap cooperating with the base to contain the igniter material, the cap having a rupturably sealed exit opening defined by a nozzle directed at the rupturable entry wall portion of the gas generant cartridge and the central passage of the gas generant material therein.