Inflator having an ignition nozzle

• US 20060174794A1
• Filed: 02/10/2005
• Published: 08/10/2006
• Est. Priority Date: 02/10/2005
• 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., Johnson, Darrin L., Cook, Fred J.
• Granted Patent: US 7,703,395 B2
• Time in Patent Office: Days
• US Class Current: 102/530
• CPC Class Codes: B60R 21/264 using instantaneous generation of gas, e.g. pyrotechnic B60R21/268 takes precedence
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder

Abstract

An inflator (10) includes a container (12) having a chamber (120). An exit opening (48) is provided in the container (12) and is connected to the chamber (120). A substance (122, 180) is stored in the chamber (120) and is responsive to heat for providing inflation fluid. An igniter (130) is associated with the container (12) and is actuatable to provide combustion products for heating the substance (122, 180). A nozzle (80) is interposed between the igniter (130) and the chamber (120). A passage (90) extends from the igniter (130) and through the nozzle (80). The passage (90) includes a divergent portion (110) for focusing a flow of combustion products from the igniter (130) into the chamber (120).

Claims

1. An inflator comprising:

a container having a chamber, an exit opening provided in the container and connecting to the chamber;

a substance stored in the chamber, the substance being responsive to heat for providing inflation fluid;

an igniter associated with the container and actuatable to provide combustion products for heating the substance; and

a nozzle interposed between the igniter and the chamber, a passage extending from the igniter and through the nozzle, the passage including a divergent portion for focusing a flow of combustion products from the igniter into the chamber.

2. The inflator of claim 1 wherein a nozzle opening connects the divergent portion of the passage and the chamber, the combustion products having a pressure at the nozzle opening that is approximately equal to a pressure within the chamber adjacent the nozzle opening.

3. The inflator of claim 2 wherein the passage also includes a convergent portion that is located immediately upstream of the divergent portion, the flow of combustion products being accelerated in the convergent portion of the passage.

4. The inflator of claim 3 wherein a throat of the passage separates the convergent and divergent portions, the flow of combustion products reaching the speed of sound at the throat and forming a region of supersonic flow within the divergent portion of the passage immediately downstream of the throat.

5. The inflator of claim 4 wherein the region of supersonic flow terminates within the chamber, the region of supersonic flow terminating with a shock pattern.

6. The inflator of claim 5 wherein the substance stored in the chamber for providing inflation fluid when heated is a solid propellant, the combustion products from the igniter igniting the solid propellant so as to provide inflation fluid.

7. The inflation of claim 6 wherein the shock pattern acts to pulverize some of the solid propellant so as to aid in the ignition of the solid propellant.

8. The inflator of claim 6 wherein a rupturable material extends over the nozzle opening that connects the divergent portion of the passage and the chamber, the rupturable material preventing the solid propellant from entering the passage, the flow of combustion products from the igniter rupturing the rupturable material.

9. The inflator of claim 2 wherein the substance stored in the chamber for providing inflation fluid when heated is a stored gas under pressure, a burst disk being located in the passage for isolating the igniter from pressure of the stored gas.

10. The inflator of claim 9 wherein the stored gas under pressure is a combustible mixture of gases, combustion products from the igniter igniting the combustible mixture of gases.

11. The inflator of claim 1 wherein the inflator includes an igniter endcap for supporting the igniter, the nozzle being formed as one piece with the igniter endcap and not from separate pieces secured together, the passage extending through the igniter endcap and the nozzle and being formed by a single, uninterrupted surface.

12. The inflator of claim 11 wherein the passage also includes a convergent portion that is located immediately upstream of the divergent portion, the flow of combustion products being accelerated in the convergent portion of the nozzle.

13. The inflator of claim 12 wherein a throat of the passage separates the convergent and divergent portions, the flow of combustion products reaching the speed of sound at the throat and forming a region of supersonic flow within the divergent portion of the passage immediately downstream of the throat, the region of supersonic flow terminating with one of a shock wave or a shock pattern.

14. The inflator of claim 1 wherein an igniter endcap and a diffuser endcap form opposite ends of the container, the igniter endcap supporting the igniter and the diffuser endcap including the exit opening through which inflation fluid may exit the chamber, the nozzle being associated with the igniter endcap and focusing the flow of combustion products toward the diffuser endcap.