| 摘要 |
PURPOSE:To prevent the cracks of a magnet and to prevent the stop of operation due to the peel-off of the magnet by engaging the engaging parts of the permanent magnet with the positioning projections provided in a yoke and providing a magnet cover comprising a nonmagnetic material in the inside of the yoke and the permanent magnet. CONSTITUTION:The projections 2, which are protruded from the outer periphery of the cylindrical yoke 1 to the inner side, are provided. Small holes are perforated at the center of the arc shaped magnet 3, thereby the engaging parts 3a are formed. The engaging parts 3a of the magnet 3 are engaged with the projections 2 of the yoke 1. The first contacting part 4a has a cylindrical wall whose outer diameter is approximately equal to the inner diameter of the arc shaped magnet 3. The second contacting part 4b has the cylindrical wall whose outer diameter is approximately equal to the inner diameter of the yoke 1. The magnet cover 4, which comprises a nonmagnetic material and is provided with said contacting parts 4a and 4b, is provided in the inside of the magnet 3 and the yoke 1, so that the surface of the step 4c is contacted with the bottom surface of the magnet 3. The open end of the contacting part 4a of the magnet cover 4 is fixed to the magnet 3. |
