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Electronic seat belt tensioning system

  • US 5,558,370 A
  • Filed: 03/30/1995
  • Issued: 09/24/1996
  • Est. Priority Date: 03/30/1995
  • Status: Expired due to Term
First Claim
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1. A method of controlling the tension of a vehicle seat belt comprising the steps of:

  • detecting deployment of said seat belt from a wound condition to an unwound condition;

    determining the amount of seat belt which is unwound;

    activating a winding means to incrementally rewind the seat belt until a first predetermined tensive force is exhibited by the seat belt on a vehicle occupant;

    deactivating the winding means to substantially release the first predetermined tensive force exhibited by the seat belt on the occupant to place the seat belt in a substantially tensionless state;

    continuously monitoring the amount of seat belt unwound while in the tensionless state;

    comparing the monitored amount of seat belt unwound to a predetermined pay out value;

    generating an out-of-position alarm if the monitored amount exceeds the predetermined pay out value;

    continuously monitoring vehicle acceleration;

    determining whether the vehicle acceleration has exceeded a first threshold value;

    if the first threshold value is exceeded, activating the winding means to rewind the seat belt until a second predetermined tensive force is exhibited on the occupant;

    deactivating the winding means to release the second predetermined tensive force exhibited by the seat belt if the vehicle acceleration falls back below the first threshold value;

    determining whether the vehicle acceleration has exceeded a second threshold value greater than the first threshold value;

    triggering a pretensioner means if the second threshold value has been exceeded, said pretensioner means rewinding said seat belt with a third predetermined tensive force greater than the second predetermined force generated by the winding means.

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