| 摘要 |
A seat belt retractor is formed of a frame, a reel rotationally supported by the frame for winding a seat belt, a reel urging device connected to the reel for urging the reel in a seat belt winding direction, a locking device provided between the frame and the reel for allowing the reel to rotate freely in a normal state and preventing the reel to rotate in a belt unwinding direction when necessary, and a belt tension control mechanism for controlling a belt tension of the seat belt. The belt tension control mechanism includes a motor, and a power transmission path situated between the motor and the reel and actuated by the motor. The power transmission path has an OFF-state in which a rotational torque of the motor is not transmitted between the motor and the reel, and an ON-state in which the rotational torque is transmitted between the motor and the reel. A power transmission path switching mechanism selectively switches the power transmission path between the ON-state and the OFF-state. The belt tension control mechanism is simplified by reducing the number of the components.
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