| 摘要 |
A clutch is arranged between a rotatable shaft and a worm shaft in a motor. The clutch includes a driving-side rotator connected to the rotatable shaft, a driven-side rotator connected to the worm shaft, a spring support and a coil spring arranged in the spring support. When the driving-side rotator is rotated upon energization of the motor, the coil spring is wound by the driving-side rotator to reduce an outer diameter of the coil spring, so that the rotation of the driving-side rotator is transmitted to the driven-side rotator and the worm shaft. When the driven-side rotator is rotated by an external mechanical force, the coil spring is unwound by the driven-side rotator to increase the outer diameter of the coil spring, so that a frictional force between the spring support and the coil spring is increased to restrain rotation of the driven-side rotator. |
