Piston drive for tightening a vehicle safety belt

摘要

The invention relates to a piston drive for tightening a vehicle safety belt with a piston-like drive member (3) arranged in a guide tube (2), a drive means (7) for producing a propellant gas which drives the drive member (3) by expanding in a pressure and expansion chamber defined by the drive member (3), a movement transmitting system (4, 11) connecting the drive member (3) and the safety belt to be tightened, and with a discharge system with a release or rupture element (26, 40) which opens a discharge orifice (37) in the drive member (3) during a return movement of the drive member (3) advanced by the propellant gas, the propellant gas under pressure in the pressure and expansion chamber (18, 38) issuing through this discharge orifice (37). <IMAGE>