GB426242A - Improvements in electric motors, more particularly for clocks - Google Patents

Abstract

426,242. Alternating-current motors. HAYDON, A. W., 64, Ellsmere Avenue, Waterbury, Connecticut, U.S.A. July 2, 1934, No. 19500. Convention date, Aug. 9, 1933. [Class 35] Motors with unwound iron armatures.- In the field member of a single phase motor having two groups of polepieces, the angular displacement between polepieces of opposite polarity in the two groups is different and a single unwound rotor co-operates with all the polepieces. The motor is self starting and operates synchronously if the rotor is of hard steel, but otherwise as an induction motor. In the form shown the rotor consists of a ring of high hysteresis material 20 and the stator coil, which has a central core, is enclosed on one side by a disc having axial pole pieces 24, 25 and on the other side by a disc 22, shown in dotted lines, having shorter axial polepieces 26, 27. The polepieces 25, 26 co-operate to cause the motor to run at a twenty four pole speed after it has been brought up to that speed by the rotary field of the other set of polepieces. This other set comprises two sequences of four poles, the sequence being separated by the polepieces 25, 26 but the pitch of the second set corresponds to a twelve pole stator. Each sequence consists of two shaded poles 24 and two poles each consisting of a projection 27 on disc 22 and a radial polepiece 28 on a plate 23 which is placed alongside the disc 22 but separated therefrom by shading plates which lag the flux of polepieces 28.