| 摘要 |
PURPOSE:To exactly self-start a brushless motor by providing a coil piece pitch of an armature core different from the pole pitch of a rotor magnet and providing a specific variation in the thickness of the pole of the rotor magnet and the thickness of the armature core. CONSTITUTION:Coils 4-7 of the first phase and coils 8-11 of the second phase having approx. 30 deg. of mechanical angle of coil side pitch are provided, for example, around an armature core 3, magnetic pole forming magnets 14-17 of 8 poles are, for instance, provided, and a pair of north and south poles per one magnet are formed. The magnets 14-17 are so formed that the size in thickness of the north and south poles is gradually decreased from the adjacent point of the respective poles toward the peripheral direction. Thus, both the back and forth paths of the respective coils 4-11 may not face the magnetic neutral point of the poles of the rotor. Since the generated torques are different between the outward path and the return path, appreheusion of causing self-start failure can be eliminated. |
