GB875125A - Improvements in permanent magnet type electric motors or generators - Google Patents

Abstract

875,125. Electric motors and generators. M. & E. PROJECTS Ltd., and HITCHCOCK, S. I. Sept. 26, 1957 [July 2, 1956], No. 20440/56. Class 35. [Also in Group XXXVII] In an electric motor whose rotor and stator respectively include one or more permanent magnets 5, 7 and a number of pole pieces each carrying a field winding 3, such as disclosed in Specification 547,668, there are connected in series with the windings and in parallel with each other two contact breakers periodical opening of whose contact points 18, 20 is produced by rotation of the rotor, each fixed contact point 20 being resiliently mounted by an associated spring 21 so that it can be depressed in response to engagement by the moving contact point 18, and such fixed contact point 20 and spring 21 being adjustable by a cam 28 and lever 30 towards or away from the opposite moving contact point to vary the length of time the contacts are closed. As shown, the moving contact points 18 are driven from a rotor half-shaft 11 via spur gear-wheels 14, 15, eccentrics 16, and connecting rods 17 slidable in bearings 19; the mechanism is mounted on an electrically insulating disc 35 angularly adjustable about the half-shaft axis by a hand-operated lever 36 which thereby varies the motor speed and direction of rotation. Also, by relative angular adjustment of the two driven gear-wheels 15 relative to the driving gear-wheel 14, the two contact pairs can be made to close either simultaneously or in sequence to provide a further operational adjustment. The rotor shown comprises two halves 4 separated by an aluminium distance piece 8 and containing an axially magnetized central multiple or single magnet 5 together with smaller magnets 7 in four spaced arms. The invention alternatively is applicable to a generator having a wound armature rotor co-operating with the pole pieces of one or more permanent magnets forming a stator.