| 摘要 |
A pyrotechnic pretensioner for a vehicle safety restraint comprising means for tensioning belt webbing, a cable (3) for actuating the tensioning means, a piston (7) slidably movable within a cylinder (8) and attached to one end of the cable (3), a reservoir of force (9) for driving the piston along the cylinder to pull the cable and tension the webbing, and a locking means (10) which allows free movement of the piston in the cylinder in a webbing tensioning direction and operates to engage the piston (7) with the cylinder (8) in response to movement of the cable in a webbing loosening direction, wherein the internal surface of the cylinder has a tooth profile cooperating with the piston locking means (10) and the piston has a circumferential radially extending resilient sealing member (11, 12) for cooperating with the tooth profile to seal the spaces between teeth. There are two sealing O-rings (11, 12) spaced apart by an odd number of 1/2 pitches of the cylinder teeth which are preferably of saw tooth profile. |
