Single phase stepping motor

Abstract

A single phase stepping motor, particularly for clocks, with a rotor with several pole teeth, of which each pole tooth comprises a main pole and an auxiliary pole formed on the latter, and with a stator, the latter being made of two stator parts connected with one another via a bridge part, the latter carrying the excitation winding, of which each stator part on its free end transfers into an equal or smaller number (in comparison to the rotor pole number) of stator pole teeth, the stator pole teeth being directed towards the face side of the rotor, as well as a permanent magnetic circuit arranged between the stator pole teeth by means of which circuit the rest position of the rotor is determined with the unexcited condition of the stator. Each auxiliary pole comprises a projection extending in the circumferential direction in the area of the edge of the rotor and the permanent magnetic circuit comprises at least one permanent magnet, the latter being arranged beyond the circumference of the rotor and extending with its pole axis approximately tangential to the rotor such that a part of the magnetic lines of force close across the circumferential edge zone of a main pole and auxiliary pole of the rotor.