| 摘要 |
A DC motor having a rotor which rotates about an axis and a stator. The motor comprises at least two coils adapted to be energized for current to flow therethrough, each coil having a first current path portion through which current flows in a first direction and a second current path portion through which current flows in a second, opposite direction. A magnetic flux generator includes at least one pair of circumferentially disposed magnetic poles for generating flux of alternating magnetic field polarity in a rotary path about the axis, the magnetic flux linking each coil such that if a coil is energized throughout a region of magnetic flux of predetermined polarity, a rotational torque of predetermined direction is produced through a range having an electrical angle greater than 180 DEG . A circuit alternately energizes the coils for current to flow through each energized coil for a duration substantially equal to an electrical angle of 180 DEG when the energized coil is within the range of the torque of predetermined direction. In one embodiment, each coil is wound toroidally on a toroidal core, and the coils are separated by an electrical angle of 180 DEG . In this embodiment, one magnetic polarity of the magnetic flux is asymmetric with respect to the other magnetic polarity thereof. In another embodiment, the first and second current path portions are disposed on substantially the same cylindrical surface concentric about the axis, and the first and second current path portions are separated from each other by an electrical angle less than 180 DEG .
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