| 摘要 |
PROBLEM TO BE SOLVED: To suppress striking sound attributed to a gap in a circumferential direction between a rotor and a gear and to suppress a low frequency vibration generated during a low rotational speed and low load torque.SOLUTION: A plurality of groove parts 7a, 7b extending in a radial direction is provided at one end of a rotor 7 whose the other end is in contact with a piezo-electric element. At an end face facing the rotor 7 of a gear 8, a plurality of engaging parts (a cylindrical projection part 85 and block parts 83, 84) for respectively engaging with the plurality of groove parts 7a, 7b is provided. At each of the engaging parts, a plurality of beam parts 81A, 81B having a spring property each one end of which is in contact with corresponding one inner wall among the plurality of groove parts 7a, 7b is provided. |
