| 摘要 |
PURPOSE: To reduce magnetic leakage from the driving shaft of a permanent- magnet rotor when shaft is made of a magnetic material by putting a roller yoke on the driving shaft and intercepting a magnetic circuit at, at least, one location between the driving shaft and the bearing. CONSTITUTION: In a brushless motor 1, a magnetic rotating shaft 7 rotatably supported by a bearing 5 and the magnetic rotating shaft 12 of a rotor 8 provided with magnetic pieces 11 for field in a rotor yoke 10 are coupled with each other in the inside diameter section of a nonmagnetic sleeve 15. The rotating shaft 12, the sleeve 15, and the rotating shaft 7 transmit the rotational force of the rotor 8 to the outside, at the same time, the shafts 12 and 7 maintain a constant interval in the sleeve 15 and inhibits the transmission of leak magnetic fluxes from the rotor 8. Therefore, the effective magnetic fluxes are increased and the efficiency of the motor 1 is improved. At the same time, higher torques can be transmitted due to the magnetic materials used for the shafts 7 and 12. |
