| 摘要 |
PURPOSE:To detect magnetizing position accurately by altering the field generated from an exciter for magnetizing the inner peripheral part, the end face part, and the side face part, thereby producing a rectangular magnetizing wave having mountains and troughs. CONSTITUTION:A plastic magnet 18 for brushless motor is molded using a metal mold equipped with an exciter 11 for exciting only the side face part 13 and the inner peripheral part 14 at the time of molding. When the field generated from the exciter 11 is altered, a rectangular magnetizing waveform is produced. In other words, the waveform 19 of flux from each pole comprising an annular plastic magnet 18 has more than one mountains 21 and troughs 22 wherein the difference of flux density between the mountain 21 and the trough 22 is within 30% and the rising/ falling waveform 19 from N to S poles or from S to N poles is within 10 deg.. The flux establishes a closed magnetic path 15 in the body of the plastic magnet 18. This constitution enhances flux density and allows accurate detection of magnetizing position and stabilized rotation of rotor. |
