Pyrotechnic linear inflator

• US 20050116454A1
• Filed: 11/12/2004
• Published: 06/02/2005
• Est. Priority Date: 11/13/2003
• Status: Active Grant

• Current Assignee: Automotive Systems Laboratory, Incorporated (Ningbo Junsheng Investment Group Co., Ltd.)
• Original Assignee: Automotive Systems Laboratory, Incorporated (Ningbo Junsheng Investment Group Co., Ltd.)
• Inventors: Stevens, Bruce A., Burns, Sean P., Quioc, Eduardo L., Newell, Jason, Dunham, Steven Maxwell-Gordon
• Granted Patent: US 7,192,055 B2
• Time in Patent Office: Days
• US Class Current: 280/741
• CPC Class Codes: B60R 2021/26041 of elongated shape
• CPC Class Codes: B60R 21/017 including arrangements for providing electric power to safety arrangements or their actuating means, e.g. to pyrotechnic fuses or electro-mechanic valves
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder
• CPC Class Codes: C06D 5/06 by reaction of two or more solids
• CPC Class Codes: F42B 3/04 for producing gas under pressure generators of inflation fluid especially adapted for vehicle air bags B60R21/26

Abstract

An airbag inflator (10) including an elongated outer housing (12) having an interior and one or more orifices (22) formed therealong to enable fluid communication between the outer housing interior and an exterior of the outer housing (12). The outer housing orifice(s) (22) open from the outer housing interior toward a first side (F) of the inflator. An elongated inner housing (14) is positioned in the outer housing interior. The inner housing (14) has an interior and one or more orifices (20) formed therealong to enable fluid communication between the inner housing interior and an exterior of the inner housing (14). The inner housing orifice(s) (20) open from the inner housing interior toward a second side (S) of the inflator. A quantity of a gas generant composition (16) extends along a portion of the interior of the inner housing (14). The gas generant (16) has a substantially “C”-shaped cross-section with a slot (24) extending along the length of the gas generant (16). The gas generant slot (24) is oriented facing the inner housing orifice(s) (20). A filter (15) is positioned intermediate the inner housing orifice(s) (20) and the outer housing orifice(s) (22) for filtering combustion products generated by combustion of the gas generant composition (16). An igniter (40) is operatively coupled to the gas generant composition (16) so as to enable fluid communication between the igniter (40) and the gas generant composition (16) upon activation of the inflator (10). The slotted, “C”-shaped cross section of the gas generant (16) provides a greater exposed gas generant surface area than would be achievable without the slot (24). This enhances the ignition and burning of the gas generant composition (16) upon inflator activation.

Claims

1. An inflator comprising:

an elongated outer housing having an interior and at least one orifice to enable fluid communication between the outer housing interior and an exterior of the outer housing, the at least one outer housing orifice opening from the outer housing interior toward a first side of the inflator;

an elongated inner housing positioned in the outer housing interior, the inner housing having an interior and at least one orifice to enable fluid communication between the inner housing interior and an exterior of the inner housing, the at least one inner housing orifice opening from the inner housing interior toward a second side of the inflator,

a quantity of a gas generant composition extending along at least a portion of the interior of the inner housing, the gas generant having a length and a substantially “

C”

-shaped cross-section with a slot extending along the length of the gas generant; and

an igniter operatively coupled to the gas generant composition, thereby initiating combustion of the gas generant composition upon activation of the inflator.

2. The inflator of claim 1 wherein the gas generant composition is formed into a unitary block.

3. The inflator of claim 1 wherein the inner housing has a longitudinal axis and the gas generant composition comprises a plurality of wafers stacked along the longitudinal axis.

4. The inflator of claim 1 wherein the inner housing is positioned coaxial with the outer housing.

5. The inflator of claim 1 wherein the substantially “

C”

-shaped cross-section defines an annular wall having an outer radius and an inner radius, and wherein the slot extends through the wall.

6. The inflator of claim 5 wherein the gas generant has an outer diameter and a ratio of length-to-outer diameter of at least 10:

1.

7. The inflator of claim 1 wherein the second side of the inflator is opposite the first side of the inflator.

8. The inflator of claim 1 wherein the gas generant composition is substantially coextensive with the inner housing.

9. The inflator of claim 1 wherein the slot is in communication with the at least one inner housing orifice.

10. The inflator of claim 1 wherein the inner housing includes a first end, a second end opposite the first end, and an aperture formed in the inner housing first end;

the outer housing includes a first end proximate the inner housing first end, a second end proximate the inner housing second end, and an aperture formed in the outer housing first end; and

a second filter is positioned intermediate the inner housing first end aperture and the outer housing first end aperture for filtering combustion products generated by combustion of the gas generant composition whereby, subsequent to activation of the inflator, inflation gases generated by combustion of the gas generant composition flow from the inner housing first end aperture through the second filter to exit the outer housing first end aperture.

11. The inflator of claim 10 further including an aperture formed in the second end of the inner housing, an aperture formed in the second end of the outer housing, and a third filter positioned intermediate the inner housing second end aperture and the outer housing second end aperture for filtering combustion products generated by combustion of the gas generant composition whereby, subsequent to activation of the inflator, inflation gases generated by combustion of the gas generant composition flow from the inner housing second end aperture through the third filter to exit the outer housing second end aperture.

12. The inflator of claim 11 wherein the igniter is positioned intermediate the inner housing first end and the inner housing second end.

13. The inflator of claim 10 wherein the igniter is positioned proximate the second end of the inner housing.

14. The inflator of claim 1 further comprising a filter positioned intermediate the at least one inner housing orifice and the at least one outer housing orifice for filtering combustion products generated by combustion of the gas generant composition.

15. The inflator of claim 1, wherein a direction of flow of inflation gas exiting the at least one outer housing orifice is angularly spaced apart approximately 180 degrees from a direction of flow of inflation gas exiting the at least one inner housing orifice.

16. The inflator of claim 1 wherein the igniter is threadedly received within the outer housing

17. An airbag system comprising the inflator of claim 1 and at least one airbag coupled to the inflator airbag thereby providing fluid communication between the inflator and an interior of the airbag upon activation of the inflator.

18. The airbag system of claim 17 wherein the inflator comprises:

an inner housing enclosing the gas generant strip, the inner housing having at least one orifice to enable fluid communication between the gas generant strip and an exterior of the inner housing;

an outer housing enclosing the inner housing to form a cavity therebetween, the outer housing having at least one orifice to enable fluid communication between the inner housing and an exterior of the outer housing; and

a filter positioned in the cavity for filtering combustion products generated by combustion of the gas generant strip.

19. The airbag system of claim 18 further comprising a crash event sensor in communication with the igniter, the crash event sensor including a known crash sensor algorithm that signals activation of the airbag system in the event of a collision.

20. The airbag system of claim 17 wherein the at least one airbag is a side curtain airbag.

21. The airbag system of claim 17 wherein the at least one airbag is a head curtain airbag.

22. A vehicle occupant restraint system including the inflator of claim 1.

23. The inflator of claim 1 wherein the gas generant composition is a gas generant strip comprising a unitary, longitudinal block having a slot extending along a length thereof, and a substantially “

C”

-shaped cross-section.

24. A vehicle occupant restraint system comprising an airbag system having at least one airbag and an inflator coupled to the airbag so as to enable fluid communication with an interior of the airbag upon activation of the inflator, the inflator comprising:

a gas generant strip comprising a unitary, longitudinal block having a slot extending along a length thereof, and a substantially “

C”

-shaped cross-section;

a housing structure enclosing the gas generant strip; and

an igniter operatively coupled to the gas generant strip so as to enable fluid communication between the igniter and the gas generant strip upon activation of the inflator.

25. The vehicle occupant restraint system of claim 24 further comprising a safety belt assembly including a housing and a safety belt extending from the housing.

26. The vehicle occupant restraint system of claim 24 wherein the housing structure comprises:

an inner housing enclosing the gas generant strip, the inner housing having at least one orifice to enable fluid communication between the gas generant strip and an exterior of the inner housing;

an outer housing enclosing the inner housing to form a cavity therebetween, the outer housing having at least one orifice to enable fluid communication between the inner housing and an exterior of the outer housing; and

a filter positioned in the cavity for filtering combustion products generated by combustion of the gas generant strip.

27. The vehicle occupant restraint system of claim 24 further comprising a crash event sensor in communication with the airbag system, the crash event sensor including a crash sensor algorithm that signals activation of the airbag system in the event of a collision.

28. A gas generant strip for use in an inflator, comprising a unitary, longitudinal block having a slot extending along a length thereof, and a substantially “

C”

-shaped cross-section.

29. The gas generant strip of claim 28 wherein the “

C”

-shaped cross-section defines an annular wall having an outer radius and an inner radius, and wherein the slot is formed through the wall.

30. The gas generant strip of claim 29 wherein a total outer surface area A of the gas generant block is approximated by the relation:

A=L(X(r_o+r_i)+2(r_o−

r_i))+X(r_o²−

r_i²)

where;

L=the length of the gas generant block;

r_o=the outer radius of the wall;

r_i=the inner radius of the wall; and

X=an arc length occupied by the wall, in radians.