AIRBAG INFLATOR WITH ADAPTIVE FLOW ORIFICE

• US 20030209894A1
• Filed: 05/10/2002
• Published: 11/13/2003
• Est. Priority Date: 05/10/2002
• Status: Active Grant

• Current Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Original Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Inventors: Roueche, Clark, Larsen, Alan R.
• Granted Patent: US 6,655,712 B1
• Time in Patent Office: Days
• US Class Current: 280/736
• CPC Class Codes: B60R 2021/26094 characterised by fluid flow controlling valves
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder

Abstract

An inflator device having a chamber wherein a pressure dependant gas generant reacts to produce inflation gas and at least one orifice allowing the gas to pass and inflate an airbag. The at least one orifice is defined at least in part by a shape memory alloy having an austenite finishing temperature (T_f). The at least one orifice has a first fluid flow through area (A₁) when at a temperature less than T_f and a second fluid flow through area (A₂) when at a temperature greater than T_f. The second fluid flow through area (A₂) is less than the first fluid flow through area (A₁).

Claims

1. In an inflator device having at least one orifice wherethrough inflation gas can pass, an improvement comprising:

the at least one orifice at least in part defined by a shape memory alloy material having an austenite finishing temperature (T_f), wherein the at least one orifice defines a first fluid flow through area (A₁) when at a temperature less than T_f and a second fluid flow through area (A₂) when at a temperature greater than T_f, where A₂<

A₁.

2. The improvement of claim 1 wherein the inflator device comprises a plurality of orifices wherethrough inflation gas can pass and wherein at least several of the plurality of orifices are at least in part defined by the shape memory alloy material.

3. The improvement of claim 1 wherein the inflator device comprises a chamber wherein a supply of a combustible gas generant material is burned to produce the inflation gas.

4. The improvement of claim 3 wherein the combustible gas generant material has a burn rate which is pressure dependent.

5. The improvement of claim 4 wherein the pressure dependency of the burn rate of the combustible gas generant material, as represented by n in the burn rate expression:

r_b=k(P)ⁿ

where, r_b is the burn rate of the gas generant material, k is a constant, P is the combustion pressure, and n is the slope of a linear regression line drawn through a log-log plot of burn rate versus pressure,

is at least about 0.4 at 1000 psi.

6. The improvement of claim 1 wherein the at least one orifice is additionally at least in part defined by at least one opening formed in the inflator device and wherein the shape memory alloy material forms a restrictor disposed adjacent the at least one opening.

7. The improvement of claim 6 wherein the restrictor comprises an opening aligned with the at least one orifice.

8. The improvement of claim 7 wherein the restrictor opening has a first cross sectional area (a₁) when the shape memory alloy material is at a temperature less than T_f and a second cross sectional area (a₂) when the shape memory alloy is at a temperature greater than T_f.

9. The improvement of claim 8 wherein the shape memory alloy material of the restrictor is punched to form the restrictor opening having the second cross sectional area (a₂) and wherein the restrictor opening in the shape memory alloy material of the restrictor is subsequently extruded to have the first cross sectional area (a₁).

10. The improvement of claim 1 wherein the shape memory alloy material has an austenite finishing temperature (T_f) of at least 90°

C.

11. The improvement of claim 10 wherein the shape memory alloy material comprises an alloy including nickel and titanium.

12. The improvement of claim 1 wherein the shape memory alloy material comprises a ternary alloy comprising copper, aluminum and nickel.

13. The improvement of claim 1 wherein the shape memory alloy material comprises a ternary alloy comprising copper, aluminum and bromine.

14. The improvement of claim 1 wherein the shape memory alloy material comprises a ternary alloy comprising iron, manganese and silicon.

15. The improvement of claim 1 wherein the shape memory alloy material has an austenite finishing temperature (T_f) of greater than 107°

C.

16. The improvement of claim 1 wherein the at least one orifice comprises a circular shape.

17. The improvement of claim 1 wherein the at least one orifice is an orifice wherethrough inflation gas exits the inflator device.

18. The improvement of claim 1 wherein the at least one orifice is an orifice internally within the inflator device.

19. An airbag inflator device comprising:

a first chamber wherein a supply of a combustible gas generant material reacts to produce gas and

an orifice assembly in fluid communication with the first chamber and defining at least one of orifice wherethrough at least a portion of the produced gas can pass, the orifice assembly comprising at least one inflator device opening and a restrictor disposed adjacent the at least one inflator device opening, the restrictor at least in part defined by a shape memory alloy material having an austenite finishing temperature (T_f) whereby the at least one orifice defines a first fluid flow through area (A₁) when at a temperature less than T_f and a second fluid flow through area (A₂) when at a temperature greater than T_f, where A₂<

A₁.

20. The airbag inflator device of claim 19 wherein the inflator device comprises a plurality of orifices wherethrough inflation gas can pass and wherein at least several of the plurality of orifices are at least in part defined by the shape memory alloy material.

21. The airbag inflator device of claim 19 wherein the combustible gas generant material has a burn rate pressure dependency, represented by n in the burn rate expression:

r_b=k(P)ⁿ

where, r_b is the burn rate of the gas generant material, k is a constant, P is the combustion pressure, and n is the slope of a linear regression line drawn through a log-log plot of burn rate versus pressure,

of at least about 0.4 at 1000 psi.

22. The airbag inflator device of claim 19 wherein the restrictor comprises an opening aligned with the at least one orifice.

23. The airbag inflator device of claim 22 wherein the restrictor opening has a first cross sectional area (a₁) when the shape memory alloy material is at a temperature less than T_f and a second cross sectional area (a₂) when the shape memory alloy is at a temperature greater than T_f.

24. The airbag inflator device of claim 23 wherein the shape memory alloy material of the restrictor is punched to form the restrictor opening having the second cross sectional area (a₂) and wherein the restrictor opening in the shape memory alloy material of the restrictor is subsequently extruded to have the first cross sectional area (a₁).

25. The airbag inflator device of claim 19 wherein the shape memory alloy material has an austenite finishing temperature (T_f) of at least 90°

C.

26. The airbag inflator device of claim 19 wherein the shape memory alloy material has an austenite finishing temperature (T_f) of greater than 107°

C.

27. The improvement of claim 19 wherein the at least one orifice is an orifice wherethrough the produced gas exits the inflator device.

28. The improvement of claim 19 wherein the at least one orifice is an orifice internally within the inflator device and wherethrough the produced gas exits the first chamber.

29. A self-regulating inflation gas rate flow inflator device comprising:

a first chamber wherein a supply of a combustible gas generant material having a burn rate which is pressure dependent is burned to form a product gas and

at least one orifice wherethrough at least a portion of the product gas can pass, the at least one orifice at least in part defined by a shape memory alloy material comprises a ternary alloy comprising copper, aluminum and one of nickel and bromine, the shape memory alloy having an austenite finishing temperature (T_f) of at least 90°

C., wherein the at least one orifice defines a first fluid flow through area (A₁) when at a temperature less than T_f and a second fluid flow through area (A₂) when at a temperature greater than T_f, where A₂<

A₁.

30. The device of claim 29 wherein the inflator device comprises a plurality of orifices wherethrough inflation gas can pass and wherein at least several of the plurality of orifices are at least in part defined by the shape memory alloy material.

31. The device of claim 29 wherein the pressure dependency of the burn rate of the combustible gas generant material, as represented by n in the burn rate expression:

r_b=k(P)ⁿ

where, r_b is the burn rate of the gas generant material, k is a constant, P is the combustion pressure, and n is the slope of a linear regression line drawn through a log-log plot of burn rate versus pressure,

is at least about 0.4 at 1000 psi.

32. The device of claim 29 wherein the at least one orifice is additionally at least in part defined by at least one opening formed in the inflator device and wherein the shape memory alloy material forms a restrictor disposed adjacent the at least one opening.

33. The device of claim 32 wherein the restrictor comprises an opening aligned with the at least one orifice.

34. The device of claim 33 wherein the restrictor opening has a first cross sectional area (a₁) when the shape memory alloy material is at a temperature less than T_f and a second cross sectional area (a₂) when the shape memory alloy is at a temperature greater than T_f.

35. The device of claim 34 wherein the shape memory alloy material of the restrictor is punched to form the restrictor opening having the second cross sectional area (a₂) and wherein the restrictor opening in the shape memory alloy material of the restrictor is subsequently extruded to have the first cross sectional area (a₁).

36. The improvement of claim 29 wherein the at least one orifice is an orifice wherethrough inflation gas exits the inflator device.

37. The improvement of claim 29 wherein the at least one orifice is an orifice internally within the inflator device.