| 摘要 |
PURPOSE:To reduce noise of rotor by arranging each pole of a permanent magnet to be secured to a rotor body such that the border thereof in the rotary direction inclines from one axial direction toward the other axial direction. CONSTITUTION:In a permanent magnet 23, opposite end sides 23a, 23b in the rotary direction are arranged in parallel each other and inclining against the axis of a rotor shaft 4. A magnetism detecting element 11 detects magnetism and supplies exciting current to a specific coil. At this time, a portion of N or S pole is facing with that pole and the N or S pole faces entirely with that pole as the rotation proceeds. Consequently, the magnetic force functioning between the permanent magnet 23 of rotor 21 and the pole 6 of stator 5, when the rotor rotates, has an approximately sinusoidal waveform. By such arrangement, deformation or vibration of the rotor body is suppressed and noise can be reduced. Each pole of the permanent magnet has the border in the rotary direction inclining from one axial direction toward the other axial direction. |
