| 摘要 |
A device for winding up a vehicle seat belt in the event of a vehicle impact comprises a hollow winding drum rotatably mounted in a casing coaxially surrounding a threaded central axle which is rotationally fast with the casing. An annular piston inserted between the drum and axle is axially movable by the pressure generated by combustion gases issuing from a pyrotechnic charge detonated by a signal from an impact detector, to rotate the drum and wind up the belt, the piston being keyed for rotation with the drum and for helical movement relative to the axle. Under normal conditions the drum is free to rotate to wind up and unwind the belt, but a mechanism is automatically actuated upon impact to prevent or oppose rotation of the drum in an unwinding direction. |
