| 摘要 |
PURPOSE:To increase an output on high load and the number of revolutions on low load by providing a pole piece being higher in permeability than a permanent magnet between a yoke and a part of permanent magnets of stator formed of the yoke and permanent magnets placed within said yoke. CONSTITUTION:Within a cylindrical yoke 7 forming a stator, a plurality of permanent magnets 8 are secured so that their magnetic poles are reversed alternately. A pole piece 9 being higher in permeability than a permanent magnet 8 is fitted between the yoke 7 and a part of the permanent magnets 8. The pole piece 9 is radially thick at its magnetizing end 10 and becomes gradually thinner toward its demagnetizing end 11. Therefore, the magnetic gap between the pole piece 9 and an armature core 3 is the narrowest at the magnetizing end 10 and becomes wider toward the demagnetizing side. In this manner, a magnetic flux is increased to raise on output torque on high load when this machine is started and the number of revolutions is augmented on low load. This DC machine is suitable for an automobile starter.
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