| 摘要 |
PURPOSE:To obtain a large distance between a position detecting permanent magnet and a magnetic sensor by a method wherein magnetic paths are formed around the magnet and the magnetic sensor is provided in the magnetic paths. CONSTITUTION:A position detecting permanent magnet 7, a yoke 8 made of soft magnetic material and a fixing member 9 which is made of nonmagnetic material and holds magnet 7 and the yoke 8 are provided on the rotor shaft 6 of a permanent rotor. The position detecting permanent magnet 7 is ring- shaped and as mang permanent magnets 7 as the number of the poles of the permanent magnet rotor are magnetized along the thickness direction. The yoke 8 is ring-shaped and has the size equal to the size of the permanent magnet 7. The permanent magnet 7, the yoke 8 and the fixing member 9 are brought into contact tightly with each other and bonded to each other with adhesive. Therefore, magnetic paths are formed on the rear side, i.e., the rotor core side, of the permanent magnet 7. The assembly on the rotor core is so performed as to have the magnetic paths of the rotor agree with the poles on the end surface of the permanent magnet 7 facing a magnetic sensor. With this constitution, a high flux density can be obtained at the magnetic sensor part. |
