Filter for airbag inflator using variable expanded metal

• US 20090295132A1
• Filed: 05/27/2008
• Published: 12/03/2009
• Est. Priority Date: 05/27/2008
• Status: Active Grant

• Current Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Original Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Inventors: Jackson, Scott, Smith, Kevin, Smith, Gary, Lang, Gregory J., Lewis, Robert E.
• Granted Patent: US 7,823,919 B2
• Time in Patent Office: Days
• US Class Current: 280/736
• CPC Class Codes: B01D 39/12 of wire gauze; of knitted wire; of expanded metal
• CPC Class Codes: B60R 2021/26011 using a filter through which the inflation gas passes
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder

Abstract

An airbag inflator that includes a pyrotechnic material capable of producing a quantity of gas during deployment. The inflator also includes a filter. The filter may be an expanded metal filter that is wrapped about the pyrotechnic material. When this filter is wrapped about the pyrotechnic material, the filter forms a plurality of layers having holes that are a different size. This filter also includes a first set of barriers and a second set of barriers that are positioned exterior of the first set of barriers, the second set of barriers being offset from the first set of barriers. Gas passing through the filter will encounter the first set of barriers, be re-directed, encounter the second set of barriers, be re-directed, and then flow out of the filter.

Claims

1. An inflator comprising:

a pyrotechnic material for producing a quantity of gas during deployment; and

an expanded metal filter wrapped about the pyrotechnic material, wherein when the filter is wrapped about the pyrotechnic material, the filter forms a plurality of layers and at least two layers have holes that are a different size.

2. An inflator as in claim 1 wherein the flow of the gas through different size holes ensures that the gas flow is not constant and operates to filter and cool the gas.

3. An inflator as in claim 1 wherein the holes of different sizes are produced by piercing the metal filter to form holes of consistent size and then expanding the holes into a slit having the desired size.

4. An inflator as in claim 1 wherein the filter is tuned such that it does not affect the internal combustion pressure of the inflator.

5. An inflator as in claim 1 wherein the filter is a single sheet of material.

6. An inflator as in claim 1 wherein the filter further comprises a first barrier.

7. An inflator as in claim 6 wherein the filter further comprises a second barrier that is positioned exterior of the first barrier, the second barrier being offset from the first barrier.

8. An inflator as in claim 7 wherein the gas passing through the filter will encounter the first barrier, be re-directed, encounter the second barrier, be re-directed, and then flow out of the filter.

9. An inflator as in claim 8 wherein the redirection of the gas by the first barrier causes particulates to collect on the first barrier and the redirection of the gas by the second barrier causes particulates to collect on the second set of barriers.

10. An inflator as in claim 7 wherein the first and second set of barriers are areas of the expanded metal filter without holes.

11. An inflator comprising:

a pyrotechnic material for producing a quantity of gas during deployment; and

a filter wrapped about the pyrotechnic material, the filter comprising a plurality of layers, the filter further comprising a first set of barriers and a second set of barriers that are positioned exterior of the first set of barriers, the second set of barriers being offset from the first set of barriers, the gas passing through the filter will encounter the first set of barriers, be re-directed, contact the second set of barriers, be re-directed, and then flow out of the filter.

12. An inflator as in claim 11 wherein the redirection of the gas by the first set of barriers causes particulates to collect on the first set of barriers and the redirection of the gas by the second set of barriers causes particulates to collect on the second set of barriers.

13. An inflator as in claim 11 wherein the filter comprises an expanded metal filter wrapped about the pyrotechnic material, wherein when the filter is wrapped about the pyrotechnic material, the filter forms a plurality of layers and at least two of the layers have holes that are a different size.

14. An inflator as in claim 13 wherein the flow of the gas through different size holes ensures that the gas flow is not constant and operates to filter and cool the gas.

15. An inflator as in claim 13 wherein the holes of different sizes are produced by piercing the metal filter to form holes of consistent size and then expanding the holes into a slit having the desired size.

16. An inflator as in claim 13 wherein adjacent holes have different sizes.

17. An inflator as in claim 13 wherein the holes are formed by having slits of different sizes and then expanding the slits.

18. An expanded metal filter for use in an airbag inflator comprising a plurality of layers for wrapping about a pyrotechnic material, wherein when the filter is wrapped about the pyrotechnic material, at least two layers have holes that are a different size.

19. A filter as in claim 18 wherein the filter further comprising a first set of barriers and a second set of barriers that are positioned exterior of the first set of barriers, the second set of barriers being offset from the first set of barriers, the gas passing through the filter will encounter the first set of barriers, be re-directed, contact the second set of barriers, be re-directed, and then flow out of the filter.