Patent ID: 6065704
Filing Date: 2000-05-23
Classification: B60R

Abstract:
A seat belt tensioner having a reel for mounting one end of a seat belt and being rotatable to extend and retract the seat belt, a pressure chamber, and a piston having screw threads connecting to the reel, said piston being mounted for movement through the chamber in response to activation of a pyrotechnic device, which exerts a force on the piston, to rotate the reel to retract the seat belt, characterized by having a normally-closed vent for said chamber, a plurality of pyrotechnic devices which may be selectively activated to vary the magnitude and duration of said force, a first and second of said devices being selectively separately operable to produce different forces of different durations on said piston, and a third of said devices being selectively operable to open said vent to reduce the forces on said piston.