| 摘要 |
PROBLEM TO BE SOLVED: To provide a stepping motor in which the play of a rotor can be suppressed, by applying an energizing force to the rotor in both cases where the working temperature is higher and lower than a normal temperature. SOLUTION: In a stepping motor 12, the shaft section 20 of a rotor 13 is inserted into the inner race 17a of a ball bearing 17, and the outer race 17b of the bearing 17 is inserted into a frame 15 which supports a stator 14. In addition, the coefficients of expansion of the bush 22 of the shaft section 20 and the cylindrical wall section 15a of the frame 15 are made larger than that of the bearing 17. A wave washer 24 is provided on the inside of the ball bearing 17 in the thrusting direction, and presses the rotor 13 in the direction shown by the arrow A. Another wave washer 25 is further provided on the outside of the bearing 17 in the thrust direction, and energizes a frame 3 in the direction shown by the arrow B.
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