GB667209A - Improvements relating to electromagnetically-operated driving mechanisms - Google Patents

Abstract

667,209. Non-ratchet electromagnetic stepby-step drive. SIEMENS BROS. & CO., Ltd. July 21, 1950 [July 22, 1949]. No. 19393/49. Class 40 (iv). [Also in Group XXXV] A step-by-step motor, e.g. for use to drive a stepping switch in automatic telephone systems, has an unwound polarized rotor which. advances both upon stator energization and de-energization. The rotor is made up of two members 1, 2 separated from each other by a short gap. The member 1. comprises a permanent magnet 4 and two iron plates 5 each of which has two opposite limbs, with bent-over ends 7. The other rotor member 2 consists of an iron plate 8 having four equally spaced limbs with bent over ends 12 which, together with the other bent-over ends 7, form an eight-pole combination having the pole-pieces equally spaced and interdigitated. The stator has a pole-piece 15 and two pole-pieces 16 which are joined to the stator core by a yoke 17. The stator pole-pieces receive successive magnetizations of opposite polarity from successively excited stator coils 20, 21, the current in either of which depends upon the position of a change-over contact actuated by a cam. When a supply switch is closed a current flows in one of the stator coils so as to produce such a polarity as to repulse a permanently polarized pole-piece 7 and, at the same time, a pole-piece 12 which has a side extension, pointing towards the stator pole-piece is attracted towards the latter. The next step of advance is made when the supply switch a is open, i.e. no stator energization. In this case the torque produced is due to the attraction between each stator pole-piece and that pole-piece 7 which has its side extension pointing towards this stator pole-piece at the time of de-energization.