| 摘要 |
PURPOSE:To improve the efficiency of a permanent magnet type direct drive motor at operating time by filling magnetic fluid in a gap between a stator and a movable element of the motor. CONSTITUTION:A permanent magnet type synchronous motor of direct drive type is composed of a stator 22 formed at a cylindrical frame 21, a rotational shaft 24 supported by bearings 23, and a rotor 26 having a permanent magnet 25. The stator 22 is formed of a core 22a and a winding 22b, and a gap 27 is formed between the stator 22 and the rotor 26. In this case, magnetic fluid 28 is filled in the gap 27. The fluid 28 is formed by mixing a dispersive material made of magnetic fine particles, a solvent and a surfactant. Magnetic fluid seals 29 for preventing the fluid from leaking are provided at both ends of the shaft 24. Thus, the fluid 28 reduces an air gap loss of a magnetic field, improves the efficiency at operating time and obtains a brake effect after the supply of the power is interrupted.
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