Assembly and method for the moderation of inflator output

• US 5,678,857 A
• Filed: 02/23/1996
• Issued: 10/21/1997
• Est. Priority Date: 02/23/1996
• Status: Expired due to Fees

• Current Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Original Assignee: Morton International Incorporated (Autoliv Incorporated)
• Inventors: Johnson, Darrin L., Rink, Linda M.
• Primary Examiner(s): Johnson, Brian L.
• Assistant Examiner(s): English, Peter C.
• Application Number:
  US08/606,261
• Time in Patent Office: 606 Days
• Field of Search: 280/728.2, 280/740, 280/742, 280/736, 280/737, 280/741, 280/732, 280/730.1, 280/728.1
• US Class Current: 280/740
• CPC Class Codes: B60R 21/201 Packaging straps or envelopes for inflatable members
• CPC Class Codes: B60R 21/2171 specially adapted for elongated cylindrical or bottle-like inflators with a symmetry axis perpendicular to the main direction of bag deployment, e.g. extruded reaction canisters B60R21/2176 takes precedence
• CPC Class Codes: B60R 21/26 characterised by the inflation fluid source or means to control inflation fluid flow arrangement or mounting thereof to the vehicle B60R21/20; blasting cartridges for producing gas under pressure in general F42B3/04; initiators or igniters therefor F42B3/10
• CPC Class Codes: B60R 21/261 with means other than bag structure to diffuse or guide inflation fluid

Abstract

An inflatable restraint system assembly and method of operation are provided wherein a compliance chamber pressure vessel formed about the gas exit area of an inflator appropriately and desirably moderates the inflation gas output from the inflator into an associated inflatable device such as inflatable vehicle occupant restraint. The invention has particular utility for use in conjunction with high mass flow rate inflators.

Claims

1. A combination comprising:

an airbag inflator having an exit area defined by at least one exit opening wherethrough, upon actuation of said inflator, gas for the inflation of an airbag is exhausted, and

a compliance chamber defined by a pressure vessel adapted to withstand an internal pressure of at least about 200 psi and formed about the inflator exit area, said compliance chamber having an exit area formed by at least one exit orifice wherethrough the gas for the inflation of the airbag is discharged to the airbag,

wherein the maximum gaseous mass flow rate through the compliance chamber exit area being no more than about 300% of the average gaseous mass flow rate through the compliance chamber exit area and, during the first 10 milliseconds after the inflator begins exhausting gas, the total mass flow through the compliance chamber exit area is at least 20 percent less than the total mass flow through the inflator exit area.

2. The combination of claim 1 wherein said airbag inflator has a maximum gaseous mass flow rate through the inflator exit area of at least about 300% of the average gaseous mass flow rate through the inflator exit area.

3. The combination of claim 2 wherein said airbag inflator satisfies at least one of the following performance characteristics:

a) the mass exiting said airbag inflator over the first 5 milliseconds after said inflator begins exhausting gas is greater than 15% of the total mass exiting said inflator and

b) the mass exiting said airbag inflator over the first 10 milliseconds after said inflator begins exhausting gas is greater than 30% of the total mass exiting said inflator.

4. The combination of claim 3 wherein the mass exiting said airbag inflator over the first 5 milliseconds after said inflator begins exhausting gas is greater than 25% of the total mass exiting said inflator.

5. The combination of claim 3 wherein the mass exiting said airbag inflator over the first 10 milliseconds after said inflator begins exhausting gas is greater than 40% of the total mass exiting said inflator.

6. The combination of claim 1 wherein said airbag inflator is elongated and cylindrically shaped.

7. The combination of claim 1 wherein the pressure vessel of said compliance chamber is elongated and cylindrically shaped.

8. The combination of claim 1 wherein said airbag inflator utilizes a fuel material in the form of a fluid for the production of the inflation gas.

9. The combination of claim 1 wherein a free volume is formed between said airbag inflator and said pressure vessel, the free volume being in surrounding relation with said airbag inflator.

10. The combination of claim 1 wherein said airbag inflator is only partially received within said pressure vessel.

11. The combination of claim 1 wherein said airbag inflator has a maximum mass flow rate through the inflator exit area which occurs within 5 milliseconds after said airbag inflator begins exhausting gas.

12. The combination of claim 11 wherein said airbag inflator has a maximum mass flow rate through the inflator exit area which occurs within 2 milliseconds after said airbag inflator begins exhausting gas.

13. An airbag module subassembly comprising:

an inflator having an exit area defined by at least one exit opening wherethrough, upon actuation of said inflator, gas for the inflation of an airbag is exhausted, said inflator having;

a) a maximum gaseous mass flow rate through the inflator exit area of at least about 300% of the average gaseous mass flow rate through the inflator exit area, and

b) the maximum mass flow rate through the inflator exit area occurs within 5 milliseconds after the inflator begins exhausting gas, and

a one-piece reaction canister structure body part including first and second opposite side walls and a bridging portion joining said first and second opposite side walls wherein the bridging portion at least in part defines a pressure vessel adapted to withstand an internal pressure of at least about 200 psi, wherein at least the bridging portion and said inflator cooperate to define a compliance chamber about the inflator exit area, said compliance chamber having an exit area formed by at least one exit orifice wherethrough the gas for the inflation of the airbag is discharged to the airbag, said compliance chamber having;

a) a maximum gaseous mass flow rate through the compliance chamber exit area of no more than about 300% of the average gaseous mass flow rate through the compliance chamber exit area, and

b) less than about 15% of the total mass exiting through the compliance chamber exit area exits within the first 5 milliseconds after the inflator begins exhausting gas.

14. The airbag module subassembly of claim 13 wherein the maximum mass flow rate through the inflator exit area occurs within 2 milliseconds after said airbag inflator begins exhausting gas.

15. The airbag module subassembly of claim 13 wherein the compliance chamber pressure vessel is adapted to withstand an internal pressure of at least about 500 psi.

16. The airbag module subassembly of claim 13 wherein said one-piece reaction canister structure body part is fabricated by a continuous extrusion of an extrudable material.

17. The airbag module subassembly of claim 13 wherein said one-piece reaction canister structure body part is fabricated of aluminum.

18. A method for the operation of an airbag inflator having an exit area defined by at least one exit opening wherethrough, upon actuation of the inflator, gas for the inflation of an airbag is exhausted, said method comprising the steps of:

exhausting gas for the inflation of the airbag through the inflator exit area and into a pressure vessel defining a compliance chamber about the inflator exit area, the compliance chamber pressure vessel being adapted to withstand an internal pressure of at least about 200 psi and having an exit area formed by at least one exit orifice, and

discharging airbag inflation gas from the compliance chamber and into the airbag through the compliance chamber exit area at a maximum gaseous mass flow rate of no more than about 300% of the average gaseous mass flow rate through the compliance chamber exit area,

wherein during the first 10 milliseconds after the inflator begins said exhausting of gas, the total mass flow through the compliance chamber exit area is least 20 percent less than the total mass flow through the inflator exit area.

19. The method of claim 18 wherein the maximum rate of said exhausting is at least about 300% of the average rate of said exhausting.

20. The method of claim 18 wherein at least one of the following performance characteristics is satisfied:

a) the mass exiting the airbag inflator over the first 5 milliseconds after the inflator begins said exhausting is greater than 15% of the total mass exiting the inflator and

b) the mass exiting the airbag inflator over the first 10 milliseconds after the inflator begins said exhausting is greater than 30% of the total mass exiting the inflator.

21. The method of claim 18 wherein the mass exiting the airbag inflator over the first 5 milliseconds after the inflator begins said exhausting is greater than 25% of the total mass exiting the inflator.

22. The method of claim 18 wherein the mass exiting the airbag inflator over the first 10 milliseconds after the inflator begins said exhausting is greater than 40% of the total mass exiting the inflator.

23. The method of claim 18 wherein the maximum mass flow rate of said exhausting occurs within 5 milliseconds after the airbag inflator begins said exhausting.

24. The method of claim 18 wherein the maximum mass flow rate of said exhausting occurs within 2 milliseconds after the airbag inflator begins said exhausting.