Particulate removal in inflatable restraint system gas generators

• US 5,480,185 A
• Filed: 09/17/1993
• Issued: 01/02/1996
• Est. Priority Date: 12/14/1992
• Status: Expired due to Term

• Current Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Original Assignee: Morton International Incorporated (Autoliv Incorporated)
• Inventors: Lowe, William G., Smith, Bradley W., Rink, Linda M., Moore, Walter A.
• Primary Examiner(s): FERRITER, KARIN L
• Application Number:
  US08/123,311
• Time in Patent Office: 837 Days
• Field of Search: 280/737, 280/740, 280/741, 280/728 R, 280/736, 222/3
• US Class Current: 280/740
• CPC Class Codes: B60R 2021/26064 characterised by auto-ignition means
• 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
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder
• 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

An apparatus and a method for producing inflation gas for use in inflating a vehicle occupant restraint are provided wherein a filter housed within a chamber of the apparatus effects gas redirection and particulate removal from at least a portion of the hot gas released from a gas generating material-containing first chamber of the apparatus, forming a hot gas having a significantly reduced particulate content. The apparatus includes a diffuser having one or more controlling orifices and exit ports to provide for the passage of inflation gas therethrough into the vehicle occupant restraint. There is at least an approximately 180° cumulative change in gas direction between contacting the filter and the passage of the inflation gas into the diffuser.

Claims

1. An apparatus suitable for use in inflating a vehicle occupant restraint, comprising:

a container having a first chamber for storing a gas generating material and a second chamber useful in effecting gas redirection and for storing a supply of gas under pressure, the gas generating material when ignited producing a hot gas, the hot gas containing particulate of the gas generating material and byproducts thereof and being releasable from said first chamber into said second chamber by means of at least one gas exit nozzle, said second chamber housing a filter placed along the inner wall thereof opposite said gas exit nozzle, said filter being useful in effecting gas redirection and particulate removal from at least a portion of the hot gas released from said first chamber and impinging thereon forming an inflation gas for use in inflating the vehicle occupant restraint comprising hot gas having a significantly reduced particulate content; and

a diffuser having at least one controlling orifice for providing passage therein of at least a portion of the inflation gas from said container and at least one exit port for dispensing at least a portion of the inflation gas passing therein into the vehicle occupant restraint,

whereby there is at least an approximately 180°

cumulative change in gas direction between contacting the filter and the passage of the inflation gas into the diffuser.

2. The apparatus of claim 1 wherein said filter effects said particulate removal at least in part by means of particulate condensation.

3. The apparatus of claim 1 wherein said filter effects said particulate removal at least in part by means of particulate entrapment.

4. The apparatus of claim 1 wherein said filter comprises knitted metal wire.

5. The apparatus of claim 4 wherein said knitted metal wire comprises stainless steel.

6. The apparatus of claim 5 wherein said knitted stainless steel wire has a percent density in the range of 10 to 50 percent.

7. An apparatus suitable for use in inflating a vehicle occupant restraint, comprising:

an elongated cylindrical container having a first chamber for storing a gas generating material and a second chamber for storing a supply of gas under pressure and useful in effecting gas redirection, the gas generating material when ignited producing a hot gas, the hot gas containing particulate of the gas generating material and byproducts thereof, the hot gas being releasable from said first chamber into said second chamber by means of at least one gas exit nozzle, said second chamber housing a filter placed along the inner wall thereof opposite said gas exit nozzle, said filter being useful in effecting gas redirection and particulate removal from at least a portion of the hot gas released from said first chamber and impinging thereon forming a hot gas having a significantly reduced particulate content, whereby said filter effects said particulate removal at least in part by means of particulate condensation, wherein at least a portion of the significantly reduced particulate content hot gas mixing with the stored gas in said second chamber forming inflation gas for use in inflating the vehicle occupant restraint; and

a diffuser having at least one controlling orifice for providing passage therein of at least a portion of the inflation gas from said container and at least one exit port for dispensing at least a portion of the inflation gas passing therein into the vehicle occupant restraint,

whereby there is at least an approximately 180°

cumulative change in gas direction between impinging on said filter and the passage of the inflation gas into the diffuser.

8. The apparatus of claim 7 wherein said filter effects said particulate removal at least in part by means of particulate entrapment.

9. The apparatus of claim 7 wherein said filter comprises knitted metal wire.

10. The apparatus of claim 9 wherein said knitted metal wire comprises stainless steel.

11. The apparatus of claim 10 wherein said knitted stainless steel wire has a percent density in the range of 10 to 50 percent.

12. A hybrid inflator for an air bag comprising,

a storage chamber for storing inflation gas under high pressure, said storage chamber being formed by a hollow cylindrical sleeve that is closed at one end by a fill plug means and open at an opposite end,

a pyrotechnic heater closing said opposite end of said sleeve, said pyrotechnic heater being recessed into said sleeve and including a combustion chamber having a pyrotechnic charge therein, a nozzle orifice, a solid plug means abutting a shoulder adjacent said nozzle orifice, and a first diaphragm,

a diffuser having a plurality of orifices for dispensing inflation gas from said storage chamber uniformly into an air bag, and

a second diaphragm,

said storage chamber being sealed from said diffuser by said second diaphragm and being further sealed from said combustion chamber by said first diaphragm backed up by said solid plug means against the high pressure of the inflation gas stored in said storage chamber,

whereby as the pressure in the combustion chamber rises and exceeds the pressure of the stored inflation gas in said storage chamber upon ignition of said pyrotechnic charge, said solid plug is unseated with said first diaphragm subsequently rupturing when the pressure in said combustion chamber exceeds the pressure in the storage chamber, and hot gas from the burning pyrotechnic charge heats the stored inflation gas in said storage chamber causing a rapid pressure rise therein so that when the pressure in said storage chamber exceeds the structural capability of said second diaphragm, rupture of the latter occurs allowing the heated gas to vent through said diffuser orifices in an air bag,

said inflator further including impingement filter material placed on the inner wall of said fill plug means opposite the nozzle orifice of said pyrotechnic heater.

13. The hybrid inflator of claim 12 wherein said filter material effects filtering by means of condensation thereon of liquid phase particles entrained the hot gas impinging thereon.

14. A method for producing inflation gas in an apparatus suitable for use in inflating a vehicle occupant restraint and comprising a container having a first chamber for storing a gas generating material and a second chamber useful in effecting gas redirection and for storing a supply of gas under pressure, said method comprising the steps of:

igniting the gas generating material stored in the first chamber to produce a hot gas, the hot gas containing particulate of the gas generating material and byproducts thereof,

releasing the hot gas from the first chamber into the second chamber by means of at least one gas exit nozzle and whereby at least a portion of the released hot gas impinges onto a filter placed along the inner wall of the second chamber opposite the gas exit nozzle;

effecting gas redirection and particulate removal from at least a portion of the released hot gas by means of a filter secured to an inner wall of the second chamber opposite the gas exit nozzle of the first chamber to form an inflation gas for use in inflating the vehicle occupant restraint comprising hot gas having a significantly reduced particulate content; and

passing the inflation gas by means of a diffuser having at least one controlling orifice for providing passage therein of at least a portion of the inflation gas and at least one exit port for dispensing at least a portion of the inflation gas passing therein into the vehicle occupant restraint;

whereby there is at least an approximately 180°

cumulative change in gas direction between impinging onto the filter and the passage of the inflation gas into the diffuser.

15. The method of claim 14 wherein said particulate removal comprises condensation of liquid phase particulate on said filter.

16. The method of claim 14 wherein said particulate removal comprises entrapment of particulate on said filter.

17. The method of claim 14 wherein said filter forms a body and said effecting gas redirection and particulate removal comprises impinging the particulate-containing hot gas onto the filter with at least a portion of the hot gas progressing into the filter body with said particulate removal comprising condensation of liquid phase particulate and entrapment of particulate on the filter.