| 摘要 |
A direct current motor is comprised of an armature, magnets arranged to face each other through the armature, a commutator and brushes. The armature has a core and a plurality of coils wound on the core. Each magnet has a main part and an extension extending form the main part. The main part has an angular interval which corresponds to an interval of winding each coil, so that the extension is positioned outside the coil in the circumferential direction. During the commutation period of the coil, that is, during shorting of the coil by the brush, the amount of magnetic flux passing through the coil is changed by the extension of the magnet. Thus, an induction voltage is generated in the coil to counteract to a reactance voltage of the coil.
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