Patent ID: 8746803

Claim:
A seat belt retractor comprising at least a frame; a seat belt; a spool that is rotatably supported by the frame and around which the seat belt is refracted; a locking mechanism that is provided on the frame and locks the rotation of the spool in a seat-belt-withdrawal direction in times of emergency; and a pretensioner that is provided on the frame and is activated in the times of emergency in such a manner as to rotate the spool in a seat-belt-retracting direction, wherein the pretensioner includes at least a case that is provided on the frame; a pipe having an open end portion at one end portion thereof; a specific number of force transmitting members that are movably provided in the pipe and transmit a force for rotating the spool in the seat-belt-retracting direction; a gas generator that is provided on a side of the pipe at another end and generates a gas in the times of emergency; a piston that is movably provided in the pipe and pushes the force transmitting members when moved by a pressure of the gas; a ring gear that is at least rotatably provided in the case and has a plurality of internal teeth on an inner circumference thereof and a plurality of pushing portions on an outer circumference thereof, the pushing portions being pushed by the force transmitting members; a pinion that is provided on a spool-side member in the case and has external teeth meshable with the internal teeth of the ring gear, the pinion causing the spool to rotate; and a guide member that is provided on the frame and guides the force transmitting members coming out of the open end portion of the pipe, and wherein the open end portion of the pipe has a projection on an outer circumference thereof formed integrally with the pipe, the guide member has a recess, and the projection of the pipe is fitted into the recess of the guide member, whereby the outer circumference of the open end portion of the pipe is attached to the guide member, wherein the projection of the pipe is in the form of a flange-shaped projection, the guide member has an anchoring portion, the recess has a pair of attaching grooves facing parallel to each other and each having an open end on the same side thereof, the anchoring portion has a fitting hole, and the fitting hole is separated from a guide surface of the guide member by the attaching grooves; the outer circumference of the open end portion of the pipe is attached to the guide member by fitting the flange-shaped projection of the pipe into the attaching grooves from the open end side of the attaching grooves and fitting the pipe into the fitting hole of the anchoring portion of the guide member; wherein an inner circumferential surface of the open end portion of the pipe and the guide surface of the guide member are flush with or substantially flush with each other.