Abstract: Provided is a pretensioner that can be easily and accurately assembled and manufactured, a seat belt retractor, and a seat belt apparatus provided with the seat belt retractor. A pretensioner has at least a gas generator for generating gas in the event of an emergency, a case, a pipe mounted to the case, a predetermined number of drive transmission members that are movably provided in the pipe and moved by receiving gas pressure to transmit force for rotating the spool in the seat-belt retracting direction, a piston that is movably provided in the pipe and moved by receiving gas pressure to push the drive transmission members, a ring gear that is at least rotatably provided in the case, has, on the outer periphery thereof, a plurality of pressed portions pressed by the drive transmission members, and rotates the spool by the pressing force, and an elastic member attached to the gas generator side of the piston.

Abstract: [Object] To provide a retractor that is manufacturable at a much lower cost by making a pretensioner operate more effectively, by minimizing the length of a pipe so that a weight reduction is realized effectively, and by easing the restriction for the shape of a guide member. [Solution] A pipe 17 in which a plurality of balls as force transmitting members are provided includes an attaching portion 17c as a projection provided at one end portion 17a thereof. A guide member 18 having a guide surface 18c that guides the balls has attaching grooves 18 as recesses. The attaching portion 17c is fitted into the attaching grooves 18, whereby the pipe 17 is attached around the outer circumference thereof to the guide member 18 attached to a frame. Since the guide member 18 is provided on the outer circumference of the pipe 17, the pipe 17 can be shortened.

Abstract: To allow a seat belt retractor to be easily assembled and to be made compact while effectively operating a pretensioner and an energy absorbing mechanism. A plurality of balls 20 rotate a ring gear 25 by gas generated in the event of an emergency. Since internal teeth 25a are meshed with external teeth 26a, a pinion 26 is rotated by the rotation of the ring gear 25, and a spool retracts a seat belt. After pressing the ring gear 25, the balls 20 separate from the ring gear 25 and are stored in an arc-shaped passage 33. Since the seat belt is then withdrawn, the pinion 26 and the ring gear 25 rotate in a seat-belt withdrawing direction. In this case, some of the balls 20 in contact with the ring gear 25 are returned by the ring gear 25. Therefore, the ring gear 25 more smoothly rotates because the influence of the balls 20 is suppressed.

Abstract: To effectively operate a pretensioner using a plurality of balls and an energy absorption mechanism, to simplify the structure of an exhaust passage in the pretensioner, and to facilitate the working process of the exhaust passage. A pretensioner 15 includes a plurality of balls 20 serving as force transmission members and a piston 21 in a pipe 17. A piston body 21a of the piston 21 includes a shaft portion 21c and a substantially hemispherical head portion 21d. The piston body 21a is provided with an exhaust hole 21e extending in the axial direction and exhaust grooves 21f communicating with the exhaust hole 21e that define an exhaust passage. The exhaust grooves 21f prevent the exhaust hole 21e from being closed even if the head portion 21d of the piston 21 contacts the ball 20. Since the exhaust hole 21e and the exhaust grooves 21f are simply provided in the piston body 21a formed as a single member, the structure of the exhaust passage is simple, and working of the exhaust passage is easy.

Abstract: [Object] To provide a retractor that is manufacturable at a much lower cost by making a pretensioner operate more effectively, by minimizing the length of a pipe so that a weight reduction is realized effectively, and by easing the restriction for the shape of a guide member. [Solution] A pipe 17 in which a plurality of balls as force transmitting members are provided includes an attaching portion 17c as a projection provided at one end portion 17a thereof. A guide member 18 having a guide surface 18c that guides the balls has attaching grooves 18 as recesses. The attaching portion 17c is fitted into the attaching grooves 18, whereby the pipe 17 is attached around the outer circumference thereof to the guide member 18 attached to a frame. Since the guide member 18 is provided on the outer circumference of the pipe 17, the pipe 17 can be shortened.

Abstract: To allow a seat belt retractor to be easily assembled and to be made compact while effectively operating a pretensioner and an energy absorbing mechanism. A plurality of balls 20 rotate a ring gear 25 by gas generated in the event of an emergency. Since internal teeth 25a are meshed with external teeth 26a, a pinion 26 is rotated by the rotation of the ring gear 25, and a spool retracts a seat belt. After pressing the ring gear 25, the balls 20 separate from the ring gear 25 and are stored in an arc-shaped passage 33. Since the seat belt is then withdrawn, the pinion 26 and the ring gear 25 rotate in a seat-belt withdrawing direction. In this case, some of the balls 20 in contact with the ring gear 25 are returned by the ring gear 25. Therefore, the ring gear 25 more smoothly rotates because the influence of the balls 20 is suppressed.

Abstract: To effectively operate a pretensioner using a plurality of balls and an energy absorption mechanism, to simplify the structure of an exhaust passage in the pretensioner, and to facilitate the working process of the exhaust passage. A pretensioner 15 includes a plurality of balls 20 serving as force transmission members and a piston 21 in a pipe 17. A piston body 21a of the piston 21 includes a shaft portion 21c and a substantially hemispherical head portion 21d. The piston body 21a is provided with an exhaust hole 21e extending in the axial direction and exhaust grooves 21f communicating with the exhaust hole 21e that define an exhaust passage. The exhaust grooves 21f prevent the exhaust hole 21e from being closed even if the head portion 21d of the piston 21 contacts the ball 20. Since the exhaust hole 21e and the exhaust grooves 21f are simply provided in the piston body 21a formed as a single member, the structure of the exhaust passage is simple, and working of the exhaust passage is easy.

Abstract: A seat belt retractor including a spool for winding up a seat belt; and a locking mechanism having a locking member that rotates together with the spool in the normal state, but is prevented from rotating in a belt withdrawing direction in the event of an emergency, generating a rotational difference relative to the spool. The spool further including an energy absorbing pin that is disposed on the spool and the locking member to limit the load applied to the seat belt when the rotational difference is generated between the spool and the locking member. The energy absorbing pin has a shaft portion that is fitted in a hole of the spool and a head portion that is in contact with the locking member. The head portion comprises a curved contact surface to be in contact with the locking member.