Heated gas inflator

• US 20060290108A1
• Filed: 06/23/2005
• Published: 12/28/2006
• Est. Priority Date: 06/23/2005
• Status: Active Grant

• Current Assignee: TRW Vehicle Safety Systems Incorporated (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: TRW Vehicle Safety Systems Incorporated (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Stevens, Halley O., O'Loughlin, John P.
• Granted Patent: US 7,380,820 B2
• Time in Patent Office: Days
• US Class Current: 280/728.1
• CPC Class Codes: B60R 2021/0018 Roll-over
• CPC Class Codes: B60R 21/264 using instantaneous generation of gas, e.g. pyrotechnic B60R21/268 takes precedence
• CPC Class Codes: C06D 5/00 Generation of pressure gas, e.g. for blasting cartridges, starting cartridges, rockets explosive compositions containing an oxidizer, fuels for rocket engines intended for reaction with an oxidant other than air C06B

Abstract

An inflator (40) for inflating an inflatable vehicle occupant protection device (14) includes structure that defines a chamber (220) and inflation fluid stored in the chamber. The inflation fluid includes in mixture a fuel gas, an oxidizer gas, and an inert gas mixture. The inflator (40) also includes an actuator for initiating a combustion reaction between the fuel gas and the oxidizer gas. The inert gas mixture includes at least two different inert gases and has a composition selected to produce desired performance characteristics of the inflator (40).

Claims

1. An inflator for inflating an inflatable vehicle occupant protection device, said inflator comprising:

structure defining a chamber;

inflation fluid stored in said chamber, said inflation fluid comprising in mixture a fuel gas, an oxidizer gas, and an inert gas mixture; and

actuatable means for initiating a combustion reaction between said fuel gas and said oxidizer gas;

said inert gas mixture comprising at least two different inert gases and having a composition selected to produce desired performance characteristics of the inflator.

2. The inflator recited in claim 1, wherein the selected composition gives said inert gas mixture a molecular weight that helps produce said desired performance characteristics of said inflator.

3. The inflator recited in claim 2, wherein the molecular weight resulting from the selected composition of said inert gas mixture helps produce a desired discharge mass flow rate of said inflator.

4. The inflator recited in claim 3, wherein the desired discharge mass flow rate is sufficient to deliver a volume of inflation fluid sufficient to inflate the inflatable vehicle occupant protection device to a predetermined pressure within a predetermined amount of time after actuation of the inflator.

5. The inflator recited in claim 1, wherein the selected composition gives said inert gas mixture a specific heat that helps produce said desired performance characteristics of said inflator.

6. The inflator recited in claim 5, wherein the specific heat resulting from the selected composition of said inert gas mixture helps produce a desired gas outlet temperature of said inflator.

7. The inflator recited in claim 6, wherein the desired gas outlet temperature is a temperature below which the inflatable vehicle occupant protection device will remain inflated above a predetermined pressure for a predetermined amount of time after actuation of the inflator.

8. The inflator recited in claim 5, wherein the specific heat provided by the selected composition of said inert gas mixture helps produce a desired inflator chamber pressure of said inflator.

9. The inflator recited in claim 1, wherein said performance characteristics of the inflator comprise at least one of a burst disk rupture time, a chamber pressure, a gas outlet temperature, and a discharge mass flow rate.

10. The inflator recited in claim 1, wherein said fuel gas makes up a fixed molar percentage of said inflation fluid, said oxidizer gas makes up a fixed molar percentage of said inflation fluid, and said inert gas mixture makes up a fixed molar percentage of said inflation fluid, the composition of said inert gas mixture being adjustable to produce said desired performance characteristics of the inflator without changing said fixed molar percentages of said fuel gas, said oxidizer gas, and said inert gas mixture.

11. The inflator recited in claim 10, wherein said fixed molar percentage of said fuel gas and said fixed molar percentage of said oxidizer gas are selected to produce a desired burst disk rupture time over a predetermined temperature band.

12. The inflator recited in claim 11, wherein said burst disk rupture time is within 3 milliseconds after actuation of said inflator.

13. The inflator recited in claim 11, wherein said predetermined temperature band is −

30°

C. to +85°

C.

14. The inflator recited in claim 1, wherein the composition of said inert gas mixture is selected to help control the amount of heat transferred to said inflation fluid from said combustion reaction.

15. The inflator recited in claim 1, wherein said inert gases are selected from the group consisting of helium, argon, nitrogen, neon, krypton, xenon, and radon.

16. The inflator recited in claim 1, wherein said inert gases include helium and at least one other inert gas selected from the group consisting of argon, nitrogen, neon, krypton, xenon, and radon.

17. The inflator recited in claim 1, further comprising a burst disk for blocking inflation fluid flow out of said chamber, said combustion reaction adding heat to said inflation fluid which pressurizes said inflation fluid and causes said burst disk to rupture and release said inflation fluid to flow out of said chamber.

18. The inflator recited in claim 1, wherein said fuel gas comprises at least one of hydrogen and a hydrocarbon selected from the group consisting of methane, ethane, propane, an alcohol, and an ether.

19. The inflator recited in claim 1, wherein said oxidizer gas comprises at least one of oxygen and air.

20. The inflator recited in claim 1, wherein said inflation fluid comprises 5-15 molar % hydrogen, 4-25 molar % oxygen, up to 90 molar % helium and up to 90 molar % argon. Within these ranges, the inflation fluid composition may include 40-88 molar % helium and up to 3-20 molar % argon.

21. The inflator recited in claim 1, wherein said inflation fluid comprises 5-15 molar % hydrogen, 4-25 molar % oxygen, 40-88 molar % helium, and 3-20 molar % argon.

22. The inflator recited in claim 1, wherein said inflation fluid is stored in said inflator at up to about 10,000 psig.

23. A method for producing an inflator for inflating an inflatable vehicle occupant protection device, said method comprising the steps of:

providing a structure defining a chamber for receiving pressurized inflation fluid;

providing inflation fluid for storage in said chamber, said inflation fluid comprising in mixture a fuel gas, an oxidizer gas, and an inert gas mixture comprising at least two different inert gases; and

selecting the composition of said inert gas mixture to produce desired performance characteristics of the inflator.

24. The method recited in claim 23, further comprising the step of providing actuatable means for initiating a combustion reaction between said fuel gas and said oxidizer gas.

25. The method recited in claim 23, wherein said step of selecting the composition of said inert gas mixture comprises the step of selecting a composition of said inert gas mixture that results in a molecular weight of said inert gas mixture that helps produce said desired performance characteristics of the inflator.

26. The method recited in claim 23, wherein said step of selecting the composition of said inert gas mixture comprises the step of selecting a composition of said inert gas mixture that helps produce a desired discharge mass flow rate of the inflator.

27. The method recited in claim 23, wherein said step of selecting the composition of said inert gas mixture comprises the step of selecting a composition of said inert gas mixture that results in a specific heat of said inert gas mixture that helps produce said desired performance characteristics of the inflator.

28. The method recited in claim 27, wherein said step of selecting the composition of said inert gas mixture comprises the step of selecting a composition of said inert gas mixture that helps produce a desired gas outlet temperature of the inflator.

29. The method recited in claim 23, wherein said step of providing inflation fluid comprises the steps of:

providing said fuel gas as a fixed molar percentage of said inflation fluid;

providing said oxidizer gas as a fixed molar percentage of said inflation fluid;

providing said inert gas mixture as a fixed molar percentage of said inflation fluid; and

adjusting the composition of said inert gas mixture to produce said desired performance characteristics of the inflator without changing said fixed molar percentages of said fuel gas, said oxidizer gas, and said inert gas mixture.

30. The method recited in claim 23, wherein said step of selecting the composition of said inert gas mixture comprises the step of selecting the composition of said inert gas mixture to help control the amount of heat transferred to said inflation fluid from said combustion reaction.