TRANSMISSION RATIO VARIABLE DEVICE

PROBLEM TO BE SOLVED: To provide a transmission ratio variable device which suppresses the relative rotation of a motor shaft and a lock holder when locked, which stabilizes quality and facilitates manufacturing. SOLUTION: The transmission ratio variable device includes a lock device 51 composed of the lock holder 52 arranged integrally with the motor shaft 30 and a lock arm restricting the rotation of the lock holder 52 by engaging with the engaging groove 56 of the lock holder 52, and a torque limit ring 57 restricting and allowing the relative rotation of the motor shaft 30 and the lock holder 52 based on frictional resistance. Also, the lock holder 52 includes an inner tube 81 contacting the torque limit ring 57, an outer tube 82 formed with the engaging grooves 56, and a damper 83 elastically connecting the inner tube 81 and the outer tube 82, and is constructed so that the angle over which the inner tube 81 and the outer tube 82 can rotate relative to each other is restricted to a predetermined angle or less. COPYRIGHT: (C)2011,JPO&INPIT