| 摘要 |
<p>A self-starting electric motor including a thin, cylindrical, nonsalient pole rotor having only a single pair of rotor poles. First and second field coils are coaxially disposed around the rotor in axially spaced relationship with each other and are enclosed by a housing of magnetic material. The housing also encloses a stator pole piece assembly having first and second sets of salient stator poles which respectively cooperate with the first and second coils. The stator poles are angularly spaced around the rotor with a uniform radial air gap therebetween. When two-phase current is applied to the coils, the rotor begins rotating and reaches synchronous speed substantially instantaneously. At least one and preferably each of the salient stator poles of the machine subtends an angle of at least about one hundred and twenty electrical degrees with respect to the axis of rotation of the rotor. Advantageously there are only two salient stator poles in each of the first and second sets, and the stator poles in the respective sets are angularly spaced apart by approximately ninety electrical degrees. The rotor of the machine is extremely thin and has a length to diameter ratio of at least about 2.5 to 1. In one embodiment, one of the stator poles in the first set and one of the stator poles in the second set are in integral one-piece relationship with each other. These poles advantageously are fabricated from a single tubular member. The entire pole piece assembly thus may comprise only three component parts.</p> |
