| 摘要 |
PROBLEM TO BE SOLVED: To prevent cracking caused by variation of environment even if a rotating pole and a permanent magnet for speed detection are produced through injection molding by resin molding the part of rotor where a permanent magnet is formed. SOLUTION: A permanent magnet 57 is injection molded in the vicinity of circumferential edge 54 of a rotor supporting board 51. The permanent magnet 57 extends to the underside of index magnet holding part 56. A notch or a resin insertion hole is made in the circumferential edge of a flange 55 and when the permanent magnet 57 is injection molded, it is extended above the circumferential edge 54 to form a part of holding protrusion 58. Consequently, the permanent magnet 57 is secured rigidly to the rotor supporting board 51. Furthermore, a plurality of anchor recesses 62 are made in the vicinity of circumferential edge 54 and the permanent magnet 57 is secured stably without causing a rotating pole to float from the rotor supporting board 51 by the anchor effect of anchor recesses 62. |
