Patent ID: 6798102
Filing Date: 2004-09-28
Classification: E05F,E05Y,F16D,F16H,H02K

Abstract:
A motor comprising:a motor main body that includes a rotatable shaft, which is driven to rotate upon energization of the motor main body; a speed reducing unit that is connected to the motor main body and includes a worm shaft and an output shaft, wherein the worm shaft is rotatably supported in coaxial relationship to the rotatable shaft, and the speed reducing unit transmits rotation of the worm shaft to the output shaft after reducing a rotational speed of the worm shaft; and a clutch that is arranged between the rotatable shaft and the worm shaft, wherein the clutch includes: a driving-side rotator that rotates integrally with the rotatable shaft; a driven-side rotator that rotates integrally with the worm shaft; a spring support that includes an inner peripheral surface and is non-rotatably arranged; and a coil spring that includes: a spring main body that is received in the spring support and is helically wound, wherein the spring main body includes first and second ends; first and second driving-side engaging portions that are provided in the first and second ends, respectively, of the spring main body and are engageable with the driving-side rotator in a corresponding rotational direction for winding the spring main body and thus for reducing an outer diameter of the spring main body; and first and second driven-side engaging portions that are provided in the first and second ends, respectively, of the spring main body and are engageable with the driven-side rotator in a corresponding rotational direction for unwinding the spring main body and thus for increasing the outer diameter of the spring main body, wherein: when the driving-side rotator is rotated by the rotatable shaft upon energization of the motor main body, the spring main body is wound to decrease the outer diameter of the spring main body, so that rotation of the driving-side rotator is transmitted to the driven-side rotator through the coil spring; and when the driven-side rotator is rotated by an external mechanical rotational force generated outside the motor, the spring main body is unwound to increase the outer diameter of the spring main body, so that a frictional force between an outer peripheral surface of the spring main body and the inner peripheral surface of the spring support is increased to lock the output shaft.