Air bag module

• US 6,425,601 B1
• Filed: 06/08/2000
• Issued: 07/30/2002
• Est. Priority Date: 06/03/1996
• Status: Expired due to Term

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Universal Propulsion Company Incorporated (Rtx Corporation)
• Inventors: Lewis, Donald J.
• Primary Examiner(s): English, Peter C.
• Application Number:
  US09/590,037
• Time in Patent Office: 782 Days
• Field of Search: 280/737, 280/736, 280/741, 280/730.1, 280/730.2, 280/728.2, 280/743.1, 280/728.1, 280/735
• US Class Current: 280/728.2
• CPC Class Codes: B60R 2021/01006 Mounting of electrical components in vehicles
• CPC Class Codes: B60R 21/01 Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents electrical circuits for transmission of signals between steering wheel and the vehicle itself B60R16/027; for electrically actuating belt retractor locking means B60R22/343
• CPC Class Codes: B60R 21/207 in vehicle seats
• 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 21/23138 specially adapted for side protection B60R21/23184, B60R21/232 take precedence
• CPC Class Codes: B60R 21/237 characterised by the way they are folded
• CPC Class Codes: B60R 21/272 with means for increasing the pressure of the gas just before or during liberation, e.g. hybrid inflators

Abstract

The present invention is a self-contained air bag module and to a method of protecting an occupant of a vehicle in a collision involving the vehicle using the self-contained air bag module of the invention. The self-contained air bag module of the invention has an air bag having an interior volume in fluid communication with a high thermal efficiency inflator, the high thermal efficiency inflator having an initiator, and adapted for producing a sufficient quantity of a gaseous product to substantially inflate the air bag; and an impact detector in electrical or mechanical communication with the initiator. The high thermal efficiency inflator contains a pyrotechnic material in an amount sufficient to produce at least about 10 mole percent of the inflation gas, and a pressurized gas is present in an amount sufficient to produce up to about 90 mole percent of the inflation gas. The storage pressure of the gas is sufficiently high to produce an aerodynamic drag on burning pyrotechnic material passing through the gas, thereby slowing the burning pyrotechnic material, where the drag produced on the burning pyrotechnic material and the distance between the stored pyrotechnic material and the inner surface of the housing of the inflator are sufficiently great that, upon combustion of the pyrotechnic material, contact between a sufficient amount of the burning pyrotechnic material and the inner surface of the housing is prevented to allow at least about 90 percent of the heat produced by the combustion of the pyrotechnic material to be transferred to the inflation gas, so that no more than about 10 percent of the heat is transferred to the housing, resulting in a thermal efficiency of the high thermal efficiency inflator of at least about 90 percent.

Claims

1. A self-contained air bag module, comprising:

an air bag having an interior volume in fluid communication with a high thermal efficiency inflator, the high thermal efficiency inflator having an initiator, and adapted for producing a sufficient quantity of a gaseous product to substantially inflate the air bag; and

an impact detector in electrical or mechanical communication with the initiator;

wherein the high thermal efficiency inflator comprises;

a housing having an inner surface, and defining an interior volume, the housing containing a pressurized gas at a first pressure in the interior volume;

a pyrotechnic material for producing heat upon combustion, having a bum rate that is accelerated at the first pressure in comparison to the burn rate at a pressure of one atmosphere, the pyrotechnic material stored within the interior volume of the housing at a distance from the inner surface of the housing, wherein the stored pyrotechnic material is subjected to the first pressure of the pressurized gas, wherein the pyrotechnic material in and of itself is substantially free of thermal contact with the housing before the combustion thereof;

an ignitor for initiating combustion of the pyrotechnic material upon receipt of an initiation signal; and

means for maintaining the pressurized gas at the first pressure within the interior volume, and to open when the gas attains a predetermined second, higher pressure upon heating of the pressurized gas by combustion of the pyrotechnic material to allow an inflation gas to pass from the housing;

wherein

the pyrotechnic material is present in an amount sufficient to produce at least about 10 mole percent of the inflation gas, and the pressurized gas is present in an amount sufficient to produce up to about 90 mole percent of the inflation gas; and

wherein the first pressure of the gas is sufficiently high to produce an aerodynamic drag on burning pyrotechnic material passing through the gas, thereby slowing the burning pyrotechnic material;

wherein

the drag produced on the burning pyrotechnic material and the distance between the stored pyrotechnic material and the inner surface of the housing are sufficiently great that, upon combustion of the pyrotechnic material, contact between a sufficient amount of the burning pyrotechnic material and the inner surface of the housing is prevented to allow at least about 90 percent of the heat produced by the combustion of the pyrotechnic material to be transferred to the inflation gas, so that no more than about 10 percent of the heat is transferred to the housing, resulting in a thermal efficiency of the high thermal efficiency inflator of at least about 90 percent.

2. The self-contained air bag module of claim 1, wherein the pyrotechnic material is located within the housing in a frangible container that ruptures upon combustion of the pyrotechnic material.

3. The self-contained air bag module of claim 1, wherein the pyrotechnic material is located within the housing in a container formed from a combustible material that burns upon combustion of the pyrotechnic material.

4. The self-contained air bag module of claim 3, wherein the combustible material is deep draw steel, aluminum or a combination of palladium and aluminum.

5. The self-contained air bag module of claim 1, wherein the pyrotechnic material is located within the housing in a container comprising a plug formed from a frangible or combustible material, such that, upon combustion of the pyrotechnic material, the plug ruptures or burns, allowing particles of burning pyrotechnic material to pass through the pressurized gas, transferring heat to the pressurized gas.

6. The self-contained air bag module of claim 5, wherein the container defines a plurality of apertures or pores.

7. The self-contained air bag module of claim 1, wherein the pyrotechnic material is located within the housing in a porous container defining a plurality of apertures or pores, wherein the apertures or pores are of a sufficient size and a sufficient number to allow combusting particles to pass into the interior volume from the porous container through the pores, thereby heating the pressurized gas.

8. The self-contained air bag module of claim 1, wherein the pyrotechnic material is stored within the housing in the form of an extruded stick of the material.

9. The self-contained air bag module of claim 1, wherein the distance between the stored pyrotechnic material and the inner surface of the housing is at least about 0.25 inch.

10. The self-contained air bag module of claim 9, wherein the distance between the stored pyrotechnic material and the inner surface of the housing is at least about 0.5 inch.

11. The self-contained air bag module of claim 1, wherein the first pressure is at least about 4,000 psi.

12. The self-contained air bag module of claim 11, wherein the first pressure is from about 5,000 to about 7,000 psi.

13. The self-contained air bag module of claim 12, wherein the first pressure is about 6,000 psi.

14. The self-contained air bag module of claim 1, wherein the first pressure is sufficiently high and the pyrotechnic material is present in an amount sufficient to produce a peak operational pressure in the inflation gas of from about 12,000 psi to about 20,000 psi.

15. The self-contained air bag module of claim 14, wherein the peak operational pressure of the inflation gas is from about 15,000 psi to about 17,000 psi.

16. The self-contained air bag module of claim 15, wherein the peak operational pressure of the inflation gas is about 16,000 psi.

17. The self-contained air bag module of claim 1, wherein the second pressure is from about 7,000 to about 11,000 psi.

18. The self-contained air bag module of claim 1, wherein the second pressure ranges from about 8,000 to about 10,000 psi.

19. The self-contained air bag module of claim 1, wherein the pyrotechnic material is present in an amount sufficient to produce from about 40 to about 60 mole percent of the inflation gas.

20. The self-contained air bag module of claim 1, wherein the pyrotechnic material is a microporous, solvent processed propellant.

21. The self-contained air bag module of claim 20, wherein the pyrotechnic material has a porosity of at least about 20 percent.

22. The self-contained air bag module of claim 20, wherein the pyrotechnic material comprises ammonium nitrate oxidizer and an energizer.

23. The self-contained air bag module of claim 22, wherein the energizer comprises at least one of RDX, HMX, CL-20, TNX, NQ, NTO, TAGN, PETN, TATB, and TNAZ.

24. The self-contained air bag module of claim 22, wherein the pyrotechnic material comprises ammonium nitrate, RDX, and a cellulose acetate binder.

25. The self-contained air bag module of claim 24, wherein the pyrotechnic material comprises about 60 weight percent ammonium nitrate, about 36 weight percent RDX, and about 4 weight percent cellulose acetate binder, and has a burn rate of 20,000 m/s.

26. The self-contained air bag module of claim 20, wherein the pyrotechnic material is in the form of an extruded stick, a fine powder, flakes, granules, or particles.

27. The self-contained air bag module of claim 1, wherein the ignitor is a pyrotechnic squib.

28. The self-contained air bag module of claim 27, wherein the pyrotechnic squib comprises a pair of connector pins electrically connected by a bridge wire, coated with or in thermal contact with a first firing compound, wherein the first firing compound is subjected to the pressure of the pressurized gas.

29. The self-contained air bag module of claim 1, wherein the pressurized gas is a chemically inert gas having a thermal conductivity of no more than about 250 W/cm·

°

C. at 25°

C.

30. The self-contained air bag module of claim 29, wherein the pressurized gas is argon, or a mixture containing argon.

31. The self-contained air bag module of claim 1, wherein the housing is formed from a material having a thermal conductivity at 25°

C. of less than about 1 Watts/cm·

°

C.

32. The self-contained air bag module of claim 31, wherein at least a portion of the housing is formed from at least one material selected from the group consisting of low thermal conductivity metal, ceramic, epoxy, fiber glass, and nylon.

33. The self-contained air bag module of claim 1, wherein the impact detector comprises an actuating arm configured and adapted to move at least one switch arm upon impact, thereby initiating a timing circuit and charging a capacitor with current from a battery, such that when the charged capacitor is discharged after a preset period of time, operation of the inflator is initiated.

34. The self-contained air bag module of claim 1, further comprising a compartment containing the air bag, wherein the compartment is configured and adapted for attachment to an interior portion of a vehicle to provide protection for an occupant of the vehicle.

35. The self-contained air bag module of claim 34, wherein the compartment comprises at least one flap or door that pivots open to allow inflation of the air bag.

36. The self-contained air bag module of claim 34, wherein the air bag comprises a body portion having an interior volume, a first end, a second end, and a length, a first flap attached to the first end, and having an interior volume in fluid communication with the interior volume of the body portion, a second flap attached to the second end, and having an interior volume in fluid communication with the interior volume of the body portion, and a root portion, extending along the length of the body portion, in fluid communication with the interior volume of the body portion and the inflator;

wherein, for storage in the compartment, the first flap and the second flap are folded across the body portion, and the air bag is spirally wound in a tight roll that unwinds during inflation.

37. A method of protecting an occupant of a vehicle in a collision involving the vehicle, the method comprising:

providing a self-contained air bag module, comprising;

an air bag in fluid communication with a high thermal efficiency inflator, having an initiator, and adapted for producing a sufficient quantity of a gaseous product to substantially inflate the air bag, wherein the inflator is in fluid communication with the air bag; and

an impact detector in electrical or mechanical communication with the initiator;

wherein the high thermal efficiency inflator comprises;

a housing having an inner surface, and defining an interior volume, the housing containing a pressurized gas at a first pressure in the interior volume;

a pyrotechnic material for producing heat upon combustion, having a burn rate that is accelerated at the first pressure in comparison to the burn rate at a pressure of one atmosphere, the pyrotechnic material stored within the interior volume of the housing at a distance from the inner surface of the housing, wherein the stored pyrotechnic material is subjected to the first pressure of the pressurized gas, wherein the pyrotechnic material in and of itself is substantially free of thermal contact with the housing before the combustion thereof;

an ignitor for initiating combustion of—

the pyrotechnic material upon receipt of an initiation signal; and

means for maintaining the pressurized gas at the first pressure within the interior volume, and to open when the gas attains a predetermined second, higher pressure upon heating of the pressurized gas by combustion of the pyrotechnic material to allow an inflation gas to pass from the housing;

wherein

the pyrotechnic material is present in an amount sufficient to produce at least about 10 mole percent of the inflation gas, and the pressurized gas is present in an amount sufficient to produce up to about 90 mole percent of the inflation gas; and

wherein

the first pressure of the gas is sufficiently high to produce an aerodynamic drag on burning pyrotechnic material passing through the gas, thereby slowing the burning pyrotechnic material;

wherein

the drag produced on the burning pyrotechnic material and the distance between the stored pyrotechnic material and the inner surface of the housing are sufficiently great that, upon combustion of the pyrotechnic material, contact between a sufficient amount of the burning pyrotechnic material and the inner surface of the housing is prevented to allow at least about 90 percent of the heat produced by the combustion of the pyrotechnic material to be transferred to the inflation gas, so that no more than about 10 percent of the heat is transferred to the housing, resulting in a thermal efficiency of the high thermal efficiency inflator of at least about 90 percent; and

detecting the collision with the impact detector, thereby initiating operation of the inflator, and inflating the air bag to protect the occupant.

38. The method of claim 37, further comprising initiating operation of the inflator by moving at least one switch arm with an actuating lever that moves upon impact of the vehicle;

thereby causing a voltage to be applied by a source of electrical power through a diode to a timing circuit start terminal, and charging a capacitor;

producing a series of pulses with the timing circuit after a preset time, triggering a transistor having a collector into a state of conductivity at the same frequency as the pulses, producing a voltage on the collector of the transistor; and

using the voltage to discharge the capacitor through the ignitor to fire the ignitor, and initiate operation of the inflator.

39. The method of claim 37, further comprising providing the pressurized gas at a first pressure sufficiently high to produce an aerodynamic drag on burning pyrotechnic material passing through the gas, thereby slowing the burning pyrotechnic material, such that the drag produced on the burning pyrotechnic material and the distance between the stored pyrotechnic material'"'"'s location and the inner surface of the housing prevent contact between at least 50 percent of the burning pyrotechnic material and the housing.