Abstract: An adaptive load limiting seat belt retractor particularly adapted for motor vehicle applications. The retractor provides multiple levels of load limiting through the use of a pair of internal torsion bar elements. The torsion bar elements control the tension force on the seat belt webbing during an impact in a manner which provides desirable crash management characteristics. The retractor can be switched between high and low load limiting modes through activation of a pyrotechnic pretensioner. When the pyrotechnic pretensioner is not activated, the retractor provides a low load level characteristic. Pretensioner activation switches the retractor into a high load level operating condition. A high load limiting level is provided when the pretensioner is not activated if the spindle rotation exceeds a limited level in the low load limiting condition.

Abstract: A seat belt retractor for use in seat belt restraint systems. The retractor incorporates dual rotopretensioner units and adaptive load limiting characteristics. Preferably, the rotopretensioners are positioned on opposite ends of a retractor spool for driving the spool for pretensioning rotation. A first pretensioner may be activated alone to provide pretensioning rotation. In one embodiment of the invention, if the second pretensioner is not activated, the system will be engaged to provide a given belt load limiting characteristic. A second rotopretensioner may be fired either after the first pretensioner is fired to increase pay-in capacity or to activate a different load limiting characteristic for the retractor.

Abstract: An adaptive load limiting seat belt retractor particularly adapted for motor vehicle applications. The retractor provides multiple levels of load limiting through the use of a pair of internal torsion bar elements. The torsion bar elements control the tension force on the seat belt webbing during an impact in a manner which provides desirable crash management characteristics. The retractor can be switched between high and low load limiting modes through activation of a pyrotechnic pretensioner. When the pyrotechnic pretensioner is not activated, the retractor provides a low load level characteristic. Pretensioner activation switches the retractor into a high load level operating condition. A high load limiting level is provided when the pretensioner is not activated if the spindle rotation exceeds a limited level in the low load limiting condition.