Seat belt tensioning mechanism - has electrically ignited explosive charge acting on spool in coiling direction

摘要

The seat belt tensioning mechanism is activated by a sensor assembly which in case of sudden deceleration of the vehicle emits an electric impulse which ignites an explosive charge. The gas pressure produced by the explosion drives the spool in coiling-on direction. Simultaneously a blocking mechanism is operated which provents the coiling-off of the belt. The mechanism comprises catch arm (7) working together with cam (3). The catch arm is provided with bore (10) closed up at the base by cover (12). The bore contains an explosive charge (11) which can be ignited by primer assembly (13) when it receives an electric impulse via wire (14) from a sensor assembly reacting to deceleration of the vehicle. The expanding gases following the ignition of the explosive charge act on surface (3a) of the rotary cam (3) which is set into rotation and spool (4) takes up any seat belt slack previously in exist tence. At the same time the catch arm (7) swings out in opposite direction than the rotation of the spool and moves into meshing position another catch on the other end of the spool axle.