Vehicle restraint system cushion with sacrificial tear seam
AssigneeMorton International, Inc.
InventorsScott A. Meyer, Timothy M. Martersteck
Life of this patent
Estimating the term…
Abstract
An inflatable air bag cushion for use in a vehicle restraint system that reduces the load experienced on the peripheral seam of a driver or passenger air bag to reduce or prevent combing of the cushion fabric. A sacrificial stitched seam 26 is sewn inboard of the standard peripheral seam 20 on the cushion. Upon inflation, the sacrificial seam tears at a predetermined cushion pressure slightly lower than the maximum. The outer stitched seam, composed of a stronger thread, survives throughout the cushion deployment. The final load experienced by the outer stitched seam and adjacent fabric is reduced. As a result, lower strength fabrics may be utilized which will reduce overall cushion costs.
Claims10
An inflatable impact protection air bag cushion having a back panel made of a fabric with a marginal edge and a central portion fastened to a vehicle at a location which provides inflation gas to an opening in the back panel from an inflator in the event of a collision, said air bag also having a front panel made of a fabric with a marginal edge that is joined to the back panel marginal edge by a main seam while the bag is turned inside out with stitches of threads having a strength sufficiently high to cause the cushion fabric to comb at said stitches due to normal maximum inflation gas pressure;
- a sacrificial seam formed to be coextensive with the main seam and having a strength which causes said sacrificial seam to tear during inflation just prior to the time when the maximum inflation gas pressure reaches the main seam;
- and
- said sacrificial seam being located between said opening and said main seam to be subjected to the maximum inflation gas pressure before said pressure reaches said main seam, said sacrificial seam being spaced generally parallel with the main seam and at a distance from the main seam that is sufficiently small so as not to substantially influence deployment while reducing the final load due to the normal maximum inflation gas pressure the main seam and adjacent fabric experience by an amount sufficient to prevent combing.
An inflator impact protection cushion including;
- an air bag adapted to be fastened to a vehicle and provided with an opening for receiving inflation gas from an inflator, said air bag being comprised of front and back panels of cushion fabric having marginal edges that are secured by a main seam;
- the cushion fabric strength and the force on the main seam due to deploying inflation pressure being so selected that cushion fabric will at least partially fail at the main seam during normal inflation deployment;
- and
- a sacrificial seam in the same cushion fabric having a strength that is selected to fail during deployment just prior to full inflation of said cushion, said sacrificial seam being sized and positioned to add an incremental volume to the air bag cushion that is effective to prevent said failure at said main seam and a slight delay before full inflation pressure reaches the main seam.
A method of making an inflatable impact protection air bag cushion comprising:
- providing front and back panels of cushion fabric having peripheral mating edges;
- joining the panels together via a main seam which surrounds at least a portion of the air bag, said seam being formed of stitches of thread whose strength is such that with full deployment gas pressure, the main seam tends to result in combing where the cushion fabric begins tearing adjacent to seam stitches;
- and
- reducing the combing of the cushion fabric by forming a sacrificial seam that is weaker than the main seam so that said sacrificial seam will fail at a predetermined pressure less than full deployment pressure, said sacrificial seam being closely positioned along side of said main seam and of a sufficient length to delay the time when the full deployment pressure reaches the main seam whereby the final load experienced by the main seam and adjacent fabric is reduced, without otherwise influencing directional deployment of the air bag cushion.
Dependencies are inferred from the claim text.