A SEAT-BELT PRE-TENSIONER

摘要

A pretensioner for a safety-belt includes an elongate housing (1) defining a chamber (2) and a unit (3) for movement along the housing. The unit has an end element in the form of a piston (4) which is provided with balls (5) received in a groove (6) which enables the piston to move only in one direction. The piston is connected by a resilient spring (7) to a connector element (8) of a form corresponding to that of a piston (4). The connector element is connected (12) to one end of a wire (11) which is connected to part of a safety-belt. A peg (17) maintains the spring (7) compressed. When the pretensioner is actuating gas from a gas generator it is applied to the piston (4) moving the whole unit (3) within the housing whilst braking the peg (17). At the end of the movement the piston (4) cannot move back towards its initial position. Any subsequent slack appearing within the safety-belt is taken up by expansion of the spring (7). Once the spring has expanded, the connector (8) cannot move back towards its initial position.