| 摘要 |
PURPOSE:To detect the speed of rotation and a rotational position with excellent responsiveness by a construction wherein a magnetism-sensitive element fixed on a bias magnet is provided on the stator side of a rotary electric machine and a magnetic rotary disc having a plurality of ear pieces facing said magnetism- sensitive element is provided on the rotor side of the machine. CONSTITUTION:A magnetism-sensitive element 15 is provided on the stator 3 side, while a magnetic rotary disc 18 is fitted on the rotor yoke 10 side. The element 15 is fixed on a bias magnet 16, and the magnet 16 is fitted to a printed circuit board 17, while the board 17 is retained by a stator 3. The disc 18 is formed of a thin iron plate, has a plurality of ear pieces 19 cut and raised in the periphery, and is fixed to a yoke 10. The element 15 is fixed at a position opposite to ear pieces 19 and with a prescribed gap therefrom, while the gap is devised not to be affected by the leakage flux of a rotor magnet 9. By this construction, electric signals of eight cycles are obtained intermittently in one rotation from eight ear pieces 19, for instance, and the speed of rotation and a rotational position can be detected with excellent response. The disc 18 can be used also as an air cooling fan. |
