| 摘要 |
PROBLEM TO BE SOLVED: To prevent generation of a fluctuation force of an armature. SOLUTION: A speed switching type motor has a stator 11 for forming field magnetic flux, an armature 14 having a coil wiring material 19 wound therearound, a commutator 20 in which the coil wiring material 19 is connected to a plurality of segments 23 radially disposed with a slit 25 sandwiched, a first brush 32 and a second brush 33 sliding on the commutator 20 at positions separated by 180 degrees in the circumferential direction, and a third brush 34 sliding on the commutator 20 at a position deviated from both the brushes 32, 33 in the circumferential direction. Dummy segments 26 not conductive to the coil wiring material 19 are disposed in each of slits 25 of the commutator 20. Since a period of forming a closed circuit of the coil wiring material due to shortage between segments of the third brush can be shortened, a phenomenon in which imbalance generated in the rotation magnetic field of the armature causes a brake torque to be imposed on the armature can be prevented, and thus, the fluctuation force of the armature can be prevented. COPYRIGHT: (C)2008,JPO&INPIT
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