| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve operability by so specifying measurement of an inner yoke that an axial clearance exists between a rotor and the inner yoke on an outer periphery of a rotary shaft, and arranging a ring-like permanent magnet in the clearance. SOLUTION: An isotropic annular permanent magnet 8 is arranged between an inner surface of a rotor 4 and an axially inner end of an inner yoke 6, on an outer periphery of a hollow rotary shaft 1. In assembling, first, a sub-assembly is inserted which is composed of the hollow rotary shaft 1, a gear 2, a plate spring 3a, and an armature 3. Next, a sub-assembly is inserted, which is sequentially composed of the rotor 4, a permanent magnet 8, the inner yoke 6, an outer yoke 5 and an excitation coil 7. It is possible to omit steps such as position alignment, adhesion and removal of excessive adhesive. A manufacturing cost can thus be reduced.</p> |
