Air bag with improved tear stitch

• US 20090033081A1
• Filed: 03/21/2008
• Published: 02/05/2009
• Est. Priority Date: 07/30/2007
• Status: Active Grant

• Current Assignee: TRW Vehicle Safety Systems Incorporated (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: TRW Vehicle Safety Systems Incorporated (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: FIischer, Kurt F., Rodriguez, Alberto, Kramer, Heather R., Klakulak, John
• Granted Patent: US 8,262,130 B2
• Time in Patent Office: Days
• US Class Current: 280/743.200
• CPC Class Codes: B60R 2021/23382 Internal tether means
• CPC Class Codes: B60R 2021/2395 comprising means to control the venting
• CPC Class Codes: B60R 21/233 comprising a plurality of individual compartments; comprising two or more bag-like members, one within the other B60R21/232 takes precedence
• CPC Class Codes: B60R 21/2338 Tethers
• CPC Class Codes: B60R 21/235 characterised by their material
• CPC Class Codes: B60R 21/239 characterised by their venting means

Abstract

An apparatus (10) for helping to protect an occupant (20) of a vehicle (12) includes an inflatable vehicle occupant protection device (14) having a deflated condition and an inflated condition. Tear stitching (200) interconnects portions (220 and 230) of the protection device (14) and is rupturable to permit the interconnected portions to move relative to each other. The tear stitching (200) includes a break point (210) and first and second segments (212) that extend away from the break point. The tear stitching (200) is arranged on the protection device (14) such that tension forces acting to rupture the tear stitching act primarily on the break point (210) so that the tear stitching ruptures first at the break point and then along the first and second segments (212) of the tear stitching.

Claims

1. An apparatus for helping to protect an occupant of a vehicle, the apparatus comprising:

an inflatable vehicle occupant protection device having a deflated condition and an inflated condition; and

tear stitching interconnecting portions of the protection device, the tear stitching being rupturable to permit the interconnected portions to move relative to each other, the tear stitching comprising a break point and first and second segments that extend away from the break point, the tear stitching being arranged on the protection device such that tension forces acting to rupture the tear stitching act primarily on the break point so that the tear stitching ruptures first at the break point and then along the first and second segments of the tear stitching.

2. The apparatus recited in claim 1, wherein the shape of the tear stitching effects the strength of the break point.

3. The apparatus recited in claim 1, wherein the tear stitching has an axis that extends through the break point and bisects the tear stitching, the tear stitching being arranged such that the axis extends substantially parallel to the tension forces acting to rupture the tear stitching.

4. The apparatus recited in claim 1, wherein the break point of the tear stitching comprises two or fewer stitches of the stitch line.

5. The apparatus recited in claim 1, wherein the tear stitching comprises a stitch thread and a bobbin thread, the bobbin thread having a tensile strength higher than a tensile strength of the stitch thread.

6. The apparatus recited in claim 1, wherein the interconnected portions of the protection device comprise a vent door and a panel of the protection device, the tear stitching being rupturable to permit the vent door to move relative to the panel.

7. The apparatus recited in claim 1, wherein the tear stitching interconnects portions of the protection device that when interconnected maintain the protection device in a first inflated condition with a first inflated volume, the tear stitching being rupturable to release the interconnected portions to allow the protection device to inflate to a second inflated condition with a second inflated volume, the second inflated volume being greater than the first inflated volume.

8. The apparatus recited in claim 7, wherein the tear stitching is configured to rupture in response to inflation fluid pressure in the protection device.

9. The apparatus recited in claim 1, further comprising a tether interconnecting portions of the protection device, the tear stitching maintaining the tether in a folded condition to shorten its effective length and maintain the protection device in a first inflated condition, the tear stitching being releasable in response to tension on the tether to allow the tether to unfold from the folded condition and lengthen to allow the protection device to inflate to a second inflated condition.

10. The apparatus recited in claim 1, wherein the interconnected portions comprise overlying first and second fabric portions, the tear stitching extending through the first and second fabric portions and interconnecting the portions, the second fabric portion being folded back to overlie the tear stitching and to form a fold, the fold being positioned adjacent the break point to help focus tension on the break point of the tear stitching.

11. The apparatus recited in claim 1, wherein the tear stitching comprises first and second stitch lines positioned next to each other, the first stitch line being adapted to rupture in response to initial deployment of the protection device, the second stitch line being adapted to rupture in response to deployment beyond the initial deployment of the protection device.

12. The apparatus recited in claim 11, wherein the second stitch line is adapted to rupture in response to unobstructed deployment and pressurization of the protection device.

13. The apparatus recited in claim 11, wherein each of the first and second stitch lines comprises a break point and first and second segments that extend away from the break point, the first stitch line having a configuration that is different than the second stitch line so that the rupture strength of the first stitch line is less than the rupture strength of the second stitch line.

14. The apparatus recited in claim 11, wherein the first line has a V-shaped configuration and the second stitch line has an arcuate configuration.

15. The apparatus recited in claim 11, wherein the first line has a first arcuate configuration and the second stitch line has a second arcuate configuration.

16. The apparatus recited in claim 11, wherein the first and second stitch lines comprise portions of a single line of stitching.

17. An apparatus for helping to protect an occupant of a vehicle, the apparatus comprising:

an inflatable vehicle occupant protection device having a deflated condition and an inflated condition; and

tear stitching interconnecting portions of the protection device, the tear stitching comprising first and second stitch lines positioned next to each other, the first stitch line being adapted to rupture in response to tension of a first magnitude exerted on the interconnected portions, the second stitch line being adapted to rupture in response to tension of a second magnitude, greater than the first magnitude, exerted on the interconnected portions.

18. The apparatus recited in claim 17, wherein the first stitch line is adapted to rupture in response to initial deployment of the protection device, the second stitch line maintaining the connection between the interconnected portions after initial deployment of the protection device and being adapted to rupture in response to deployment beyond the initial deployment of the protection device.

19. The apparatus recited in claim 17, wherein the first stitch line is adapted to rupture in response to initial deployment of the protection device and the second stitch line is adapted to rupture in response to unobstructed deployment and pressurization of the protection device.

20. The apparatus recited in claim 17, wherein each of the first and second stitch lines comprises a break point and first and second segments that extend away from the break point, the first stitch line having a configuration that is different than the second stitch line so that the rupture strength of the second stitch line is greater than the rupture strength of the first stitch line.

21. The apparatus recited in claim 17, wherein the first line has a V-shaped configuration and the second stitch line has an arc-shaped configuration.

22. The apparatus recited in claim 17, wherein the first line has a first arc-shaped configuration and the second stitch line has a second arc-shaped configuration.