Gas generator for vehicle occupant restraint system

Claims

We claim:

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.

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.

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.

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.

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.

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.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to gas generators, or inflators, using pyrotechnic gas generant for inflating air bags which are part of a vehicle occupant restraint system.

2. Description of Prior Art

Gas bags, which are more commonly referred to as air bags, are mounted within vehicles in positions to deploy in the event of a crash and to cushion an occupant from the effects of the crash. It is well known in the art to inflate air bags by gas generators using a combustible solid gas generant charge.

A typical gas generator for a passenger side air bag includes a cylindrical housing having openings therein for release of gas, a gas generant charge deployed along the interior length of the housing in pellet or wafer form, and a cooling and filtering structure surrounding the combustible gas generant charge in order to filter out hot or burning particles and cool the gas produced by the gas generant charge. Ignition of the gas generant charge is achieved by an igniter tube extending through the gas generant charge along the axis of the charge and the housing. The tube typically contains rapid detonation cord, or fuse, and igniter powder. An electric initiator and charge, or squib, is mounted at one end of the housing and lights the fuse. The fuse in turn sets off the igniter powder, which bursts the igniter tube and lights the gas generant charge.

Although it is a requirement that a gas generator produce gas very quickly so that the air bag deploys in time to provide occupant protection, there are also disadvantages in deploying the air bag too quickly. In particular, an overly rapid deployment of the air bag can injure an out-of-position occupant, especially a child. Thus, it is preferable that the initial deployment of the air bag be somewhat retarded, in order to avoid such an injury.

Most proposals for controlling the rate of initial gas generation have involved dividing the inflators into two stages. This is sometimes accomplished by dividing the single inflator housing into two chambers or compartments, each of which contain combustible gas generant material and providing a delay between ignition in the two chambers.

All of the foregoing has led to more complexity and cost in the manufacture of gas generators for air bags. As such gas generators are more widely used in vehicles, there is a need for more economical construction and ease of assembly, with due regard for controlled delivery of inflation gases to protect an out-of-position occupant.

SUMMARY OF THE INVENTION

An object of the invention herein is to provide an improved gas generator for vehicle occupant restraint systems which features simplicity and efficiency in the construction thereof that enables economic manufacture and assembly.

Another object of the invention is to provide an improved gas generator having an igniter capsule for mounting in the housing.

A further object of the invention is to provide an improved gas generator with a combustible gas generant provided in a sealed cartridge subassembly which facilitates shipping and handling of the gas generant prior to assembly of the generator and simplifies the assembly process itself.

An additional object of the invention is to provide an improved gas generator where the igniter and combustible gas generant are provided in separate, sealed subassemblies which are adjacently positioned in a housing and reliably cooperate to produce gas for inflating the air bag of a vehicle occupant restraint system.

Yet another object of the invention is to provide an improved gas generator for vehicle occupant restraint systems which has a single stage of combustible gas generant and provides controlled delivery of gas for inflating an air bag with due regard for the possibility of an out-of-position passenger.

A still further object of the invention is to provide an improved gas generator wherein an igniter and combustible gas generant are cooperative to achieve relatively uniform and even ignition of the gas generant.

In accomplishing these and other objects of the invention, there is provided a gas generator for vehicle occupant restraint systems which comprises an elongated housing having gas outlet openings formed along at least a portion of the length thereof, a pyrotechnic gas generant material contained within the housing, and an igniter capsule mounted to the housing. The igniter capsule has an outlet opening to the interior of the housing and juxtaposed the gas generant material therein, igniter material confined in the capsule, and an initiator for ignition of the igniter material. Operation of the initiator ignites the igniter material which burns rapidly and expels a fireball of hot products of combustion from the igniter capsule opening into contact with the pyrotechnic gas generant material, which is thereby ignited to produce gas for inflating the air bag of a vehicle occupant restraint system.

According to some aspects of the invention, the gas generant is provided in a cylindrical configuration with a central axial passage and the fireball is expelled into and along the central passage, thereby igniting the gas generant substantially evenly along the length of the housing. Further, the gas generant is provided in annular wafers having central openings, the wafers being stacked to achieve the cylindrical configuration of the gas generant and the central passage thereof.

According to certain aspects of the invention, a rupturable seal is provided over the outlet of the igniter capsule, and a nozzle extends from the outlet for directing the hot products of combustion toward the gas generant charge, and when the gas generant has a central passage, into that passage. Further features of the invention include providing an auto igniter for setting off the igniter material to operate the gas generator if it is exposed to fire, and positioning the auto igniter between the initiator and the igniter material whereby the auto igniter is also used as the initiator charge in the normal operation of the gas generator.

According to further aspects of the invention, the igniter capsule is formed of two overlapped metal parts, the igniter capsule is positioned at the open end of the elongated housing, and the end of the housing wall is rolled over the igniter capsule to mount and retain it.

According to additional aspects of the invention, the pyrotechnic gas generant charge is sealed in a rupturable cartridge. The gas generant cartridge is placed in the housing surrounded by filtering and cooling screens. One end of the gas generant cartridge is positioned adjacent the outlet of the igniter capsule and the gas generant cartridge has a scored or otherwise weakened entry wall which ruptures inwardly to admit the igniter fireball. When the gas generant is annular wafers, they are sealed in a generally cylindrical cartridge scored to admit the igniter fireball into the central passage defined by the gas generant.

According to other features of the invention, the gas generant cartridge is generally cylindrical and formed of a sheet of aluminum having a lapped, adhesively-sealed seam. End caps close the cartridge, and the end cap adjacent the igniter capsule has a scored or otherwise weakened portion for admitting the igniter fireball. The cartridge is alternately deep drawn with one end cap.

The gas generant charge is provided with a selected surface area to volume ratio to burn somewhat progressively and, in cooperation with the remaining structure of the gas generator, provide a delivery of gas for inflating the air bag of a vehicle occupant restraint system consistent with protecting an out-of-position passenger.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

With this summary of the invention, a detailed description follows with reference being made to the accompanying drawings which form a part of the specification, of which:

FIG. 1 is a side elevation view, partially in longitudinal section, of a gas generator for a vehicle occupant restraint system, according to the invention herein;

FIG. 2 is a longitudinal sectional view of the open end of the gas generator of FIG. 1, showing the housing and the igniter capsule thereof, during mounting of the igniter capsule;

FIG. 3 is an end view of the gas generator of FIG. 1;

FIG. 4 is a cross sectional view of the gas generator of FIG. 1, taken along the lines 4--4 of FIG. 1;

FIG. 5 is a perspective view, partially cut away, of the gas generant cartridge of the gas generator of FIG. 1;

FIG. 6 is a side elevation view, partially in longitudinal section, of a gas generator for a vehicle occupant restraint system, employing an alternative configuration of gas generant material, according to the invention herein;

FIG. 7 is an enlarged sectional view of a portion of the gas generator of FIG. 6;

FIG. 8 is an enlarged view of the nozzle of the igniter capsule of the gas generator