| 摘要 |
A permanently magnetic stator for a DC dynamo electric machine which is adapted to define an extremely large air gap between pole pieces disposed face to face with a non-magnetic or substantially non-magnetic columnar solid body rotor. Two main permanent magnets, rectangular in cross section, are disposed opposite to each other on the inside of a square-shaped stator yoke to set up a double-pole magnetic field in the air gap. The pole pieces are plate-like and respectively mounted on the opposed surfaces of the main magnets so that the magnetic field along the center line of the air gap defined between the pole pieces is parallel to leakage magnetic fields formed on both sides of the extremely large air gap between the main magnets. Blocking magnets, each producing a magnetic field reverse in direction but equal in intensity to each leakage magnetic field, are mounted opposite to each other on the inside of the yoke between the main magnets, thereby cancelling the leakage magnetic fields and ensuring a strong magnetic field in the extremely large air gap.
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