Synchronous electric motor

摘要

A small two-phase motor having first and second field coils which each cooperate with a long, thin cylindrical rotor. The rotor is provided with only a single pair of nonsalient rotor poles and has a length to diameter ratio which advantageously is at least about 2.5. A stator pole piece assembly is in magnetic flux relationship with the rotor and includes first and second sets of salient stator poles which respectively cooperate with the first and second field coils. There are only two salient stator poles in each set, and the stator poles are angularly spaced apart by approximately ninety electrical degrees. In some embodiments one of the stator poles in the first set and one of the stator poles in the second set extend in opposite directions parallel to the rotor axis from a single tubular member which forms a part of the pole piece assembly.