Patent ID: 6585295
Filing Date: 2003-07-01
Classification: B60R

Abstract:
A device for pretensioning and force-limiting a safety belt web joined to a reel mechanism in a vehicle, the device comprising:a cylinder, a piston displaceable in the cylinder and having a piston rod, the piston rod joined to one side of the piston and extending through an opening in a first end wall of the cylinder, a motion-transmitting element acting between the piston rod and the reel mechanism, said element achieving rotation of the reel mechanism in a winding-up direction of the belt web upon displacement of the piston in one direction, a pyrotechnic charge causing, when detonated, a pressure increase in a cylinder chamber between the piston and a second end wall of the cylinder whereby the piston is displaced in said one direction, wherein the motion-transmitting element is joined to a ring gear of a planetary gear set so that displacement of the piston in the cylinder results in rotation of the ring gear, wherein the planetary gear set is so disposed and coupled to the reel mechanism that the gear ratio between the ring gear and the reel mechanism is about 1:1 upon rotation of the ring gear in the winding-up direction of the web, wherein the planetary gear set is so structured that the gear ratio between the ring gear and the reel mechanism is higher when rotating in an opposite direction, whereby a return movement of the piston over a certain distance in the cylinder corresponds to a several times longer feed-out of the web from the reel mechanism.