| 摘要 |
PROBLEM TO BE SOLVED: To prevent vibration and noise or the like of a speed switching motor. SOLUTION: The speed switching motor has a stator 11 for forming a field magnetic flux, an armature 14 having a coil wire 19 wound therearound, a commutator 20 in which the coil wire 19 is connected to a plurality of segments 23 annularly arrayed while sandwiching each insulating part 25, a first brush 32 and a second brush 33 that are brought into sliding contact with the commutator 20 at positions apart by 180 degrees in the circumferential direction, and a third brush 34 brought into sliding contact with the commutator 20 at a position deviated from the brushes 32, 33 in the circumferential direction. Wide insulating parts 25A and narrow insulating parts 25B are arrayed in the commutator 20 at prescribed intervals. A non-conductive dummy segment 26 is arranged in each of the wide insulating parts 25A. It is possible to reduce a closed circuit formation period of the coil wire due to a short-circuit of the segments of the third brush. Therefore, it is possible to prevent vibration and noise or the like by suppressing a whirling force of the armature. COPYRIGHT: (C)2008,JPO&INPIT
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