| 摘要 |
PURPOSE:To improve the stepping accuracy by providing n pieces of poles of stators opposed to a rotor for forming a permanent magnet having 2n pieces of pole teeth, and displacing the phase between stators by 1/2 of the pole pitch of the rotor. CONSTITUTION:A permanent magnet 7 which has 2n pieces of pole teeth and in which N- and S-poles are alternately magnetized radially at every other pole is inserted to a rotational shaft 1, and both ends are rotatably supported by bearings 5, 6 to form a rotor. A plurality pairs (two pairs in the drawing) of laminated stator groups 8, 9 and 10, 11 and exciting coils 12, 13 are provided on the inner periphery of a housing 2 to form stators. Each stator 8-11 has n pieces of pole teeth, and the pole teeth of the stators 8, 9 and 10, 11 are displaced by half of the pole teeth pitch P=2pi/n of the rotor. The toothed poles of the stators 9, 10 are displaced by P/4. Thus, the stepping accuracy is improved by about + or -2.5% in a simple structure to reduce the cost. |
