Patent ID: 6343758
Filing Date: 2002-02-05
Classification: B60R

Abstract:
A pretensioner for use in a vehicle having a webbing retractor, the webbing retractor including webbing and a winding shaft for winding the webbing, and being for use with a gas generating agent, the pretensioner comprising:a cylinder having an inner wall, the cylinder being for receiving gas therein from a gas generating agent when the vehicle is in a state of emergency; a piston movably provided inside said cylinder for rotating the winding shaft in a direction for winding the webbing due to piston movement inside said cylinder caused by gas pressure; a sealing member formed from an elastic material in an arcuate shape, and provided proximate a bottom surface of said piston for sealing a gap between said piston and the inner wall of said cylinder due to said sealing member being pressed against the bottom surface of said piston by gas pressure; and a cylindrical protruding seal holding portion having an upper wall portion and an external periphery formed integrally with the bottom surface of said piston, said sealing member extending arcuately around the external periphery of said seal holding portion, and said sealing member including a side wall portion proximate the inner wall of said cylinder, wherein said sealing member includes a discontinuity and said piston includes a bottom surface side and a top surface side, wherein the discontinuity defines a path of fluid communication from the bottom surface side of said piston to the top surface side of said piston.