Airbag inflator and an airbag apparatus

• US 6,196,581 B1
• Filed: 12/30/1998
• Issued: 03/06/2001
• Est. Priority Date: 04/08/1996
• Status: Expired due to Term

• Current Assignee: Daicel Chemical Industries Limited
• Original Assignee: Daicel Chemical Industries Limited
• Inventors: Ueda, Masayuki, Katsuda, Nobuyuki, Oda, Shingo
• Primary Examiner(s): CULBRETH, ERIC D
• Application Number:
  US09/222,960
• Time in Patent Office: 797 Days
• Field of Search: 280/741, 280/736, 280/742, 552/67, 555/25, 555/26
• US Class Current: 280/736
• CPC Class Codes: B01D 2275/105 Wound layers
• CPC Class Codes: B01D 2279/10 for air bags, e.g. inflators therefor
• CPC Class Codes: B01D 46/2411 Filter cartridges
• CPC Class Codes: B01D 46/4263 Means for active heating or cooling
• CPC Class Codes: B60R 21/2035 using modules containing inflator, bag and cover attachable to the steering wheel as a complete sub-unit steering wheel covers with tear lines B60R21/21656; assembling of modules B60R21/217
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder
• CPC Class Codes: B60R 21/33 Arrangements for non-electric triggering of inflation electrical circuits for triggering safety arrangements B60R21/01
• CPC Class Codes: C06D 5/06 by reaction of two or more solids

Abstract

An airbag inflator includes non-azide gas generating propellants, surrounding an ignition device, disposed inside a housing. The gas generating propellants are surrounded by a coolant/filter device having a pressure loss of 0.3×10⁻² to 1.5×10⁻² kg/cm² at a flow rate of 100 l/min/cm². A space is provided between an outer periphery of the coolant/filter device and the housing such that the combustion gas passes through the entire area of the coolant/filter device. The coolant/filter device is also surrounded by a swell suppressing layer which prevents the coolant/filter device from swelling due to a combustion of the gas generating propellants.

Claims

1. An inflator for an airbag, comprising:

a housing having gas-discharge ports;

an ignition device provided within said housing;

a gas-generating material provided around said ignition device, said gas generating material being ignited by said ignition device to produce a combustion gas; and

a coolant/filter device provided around said gas-generating material and adapted to at least one of cool and filter the combustion gas, said coolant-filter device being made of metal meshes and having a bulk density of 3.0-5.0 g/cm³.

2. The inflator of claim 1, wherein said gas generating material is a solid non-azide gas generating material.

3. The inflator of claim 1, wherein said coolant/filter device has a substantially annular configuration and made of stainless steel metal meshes compressed in both radial and axial directions to provide the bulk density before providing the coolant/filter within said housing.

4. The inflator of claim 1, wherein said coolant/filter device is formed of flat-plaited metal meshes laminated in a radial direction.

5. The inflator of claim 1 wherein the metal meshes have a wire diameter of 0.3-0.6 mm.

6. The inflator of claim 1, further comprising:

an inner cylinder disposed in said housing, said inner cylinder defining an ignition device accommodating chamber for installing said ignition device therein, and

a combustion chamber for storing said gas-generating material and said coolant/filter device.

7. The inflator of claim 1, wherein said coolant/filter device is obtained by forming stainless steel meshes into a cylinder, repetitively folding one end portion of the cylinder outwardly to form an annular multi-layer body, and compressing the multi-layer body in both axial and radial directions in a die.

8. The inflator of claim 1, wherein said coolant/filter device is obtained by forming stainless steel meshes into a cylinder, pressing the cylinder in a radial direction to form a plate member, rolling the plate member into a multi-layer cylinder body, and compressing the multi-layer cylinder body in both axial and radial directions in a die.

9. The inflator of claim 1, wherein said coolant/filter device includes metal meshes of a wire diameter of 0.3 to 0.6 mm, and has at an inside thereof a layer of a thickness of 1.5 to 2.0 mm made of metal meshes of a wire diameter of 0.5 to 0.6 mm.

10. The inflator of claim 1, wherein said coolant/filter device is obtained by laminating flat-plaited metal meshes of a wire diameter of 0.3 to 0.6 mm in a radial direction and compressing them in radial and axial directions.

11. The inflator of claim 1, wherein an outer periphery of said coolant/filter device includes a swell suppressing layer for preventing said coolant/filter device from swelling when the combustion gas passes therethrough.

12. The inflator of claim 11, wherein said swell suppressing layer is a metal mesh layer formed on an outer peripheral surface of said coolant/filter device and has a pressure loss being smaller than the coolant/filter device.

13. The inflator of claim 11, wherein said swell suppressing layer includes a perforated cylinder fitted over an outer peripheral surface of said coolant/filter device.

14. The inflator of claim 1, further comprising:

a space defined in an outer side of said coolant/filter device within said housing, said space being a continuous space adjacent to the gas discharge ports and arranged such that the combustion gas passes an entire portion of said coolant/filter device.

15. The inflator according to claim 14, wherein a radial cross-section of said annular space St is equal to or greater than a total open area of the gas discharge ports At.

16. The inflator of claim 15, wherein a ratio of the area St to the sum of area At, St/At, is between 1 and 10.

17. The inflator of claim 16, wherein a ratio of the area St to the sum of area At, St/At, is between 2 and 5.

18. The inflator of claim 1, wherein said gas generating material is a non-azide gas generating material including an organic nitrogen compound.

19. A coolant/filter device used in an air bag inflator for producing a combustion gas to inflate an air bag, said coolant/filter device confining a gas generating material in an inflator housing and adapted to cool and filter the combustion gas, comprising:

metal meshes radially laminated in an annular configuration and compressed in both radial and axial directions to provide a predetermined bulk density at least prior to being placed in the inflator housing.

20. The coolant/filter device of claim 19, wherein the desired bulk density of said coolant/filter device is 3.0-5.0 g/cm³.

21. The coolant/filter device of claim 19, wherein said coolant/filter device is formed of flat-plaited metal meshes including metal wires laminated in an radial direction.

22. The coolant/filter device of claim 19, wherein said metal meshes have a diameter of 0.3-0.6 mm.

23. A method of forming an annular coolant/filter device for an air bag inflator for at least one of cooling a combustion gas produced by a combustion of a gas generating material provided within an inflator housing and filtering combustion particulates contained in the combustion gas, comprising:

providing a sheet of metal meshes;

forming said sheet into a cylinder;

repetitively folding one end of said cylinder outwardly toward an opposite end thereof to form an annular multi-layer body; and

compressing said multi-layer body in a forming die in both radial and axial directions to provide a predetermined bulk density.

24. The method of claim 23, wherein the predetermined bulk density imparted to said coolant/filter device is from 3.0 to 5.0 g/cm³.

25. The method of claim 23, wherein said metal meshes are formed of stainless steel wires having a diameter of 0.3 to 0.6 mm.

26. The method of claim 23, further comprising:

providing an external swell suppressing layer on an outer periphery of said coolant/filter device in order to prevent said coolant/filter device from swelling when the combustion gas passes therethrough.

27. The method of claim 26, wherein said external swell suppressing layer is a perforated cylinder which fits around said annular coolant/filter device.

28. A method of forming an annular coolant/filter device for an air bag inflator for at least one of cooling a combustion gas produced by a combustion of a gas generating material provided within an inflator housing and filtering combustion particulates in the combustion gas, comprising:

rolling a plate member made of metal meshes into a first multi-layer cylindrical body; and

compressing said first multi-layer cylindrical body in a forming die in radial and axial directions to impart desired bulk density.

29. The method of claim 28, further comprising:

forming at least a first metal mesh cylinder formed of metal wire having diameters of 0.3 to 0.6 mm;

forming at least a second metal mesh cylinder formed of metal wire having diameters of 0.5 to 0.6 mm; and

fitting at least the second metal mesh cylinder to an inside of the first metal mesh cylinder to define an inner layer of the annular coolant/filter device.

30. The method of claim 28, further comprising:

repetitively folding one end of the first multi-layer cylindrical body and toward the other end thereof to form a second multi-layer cylindrical body.

31. The method of claim 28, wherein the desired bulk density imparted to said coolant/filter device is from 3.0 to 5.0 g/cm³.

32. The method of claim 28, wherein said metal meshes are formed of stainless steel wires having a diameter of 0.3 to 0.6 mm.

33. The method of claim 28, further comprising:

providing an external swell suppressing layer on an outer periphery of said coolant/filter device to prevent said coolant/filter device from swelling when the combustion gas passes therethrough.

34. The method of claim 33, wherein said external swell suppressing layer is a perforated cylinder fitted around said annular coolant/filter device.

35. The method of claim 28, further comprising:

forming the metal meshes into a cylinder prior to the compressing step; and

pressing said cylinder in a radial direction to form said plate member.