GB771297A - Improvements in or relating to electric motors - Google Patents

Abstract

771,297. A.C. commutator machines. BRUNT, C. H. Sept. 13, 1955, No. 26122/55. Class 35. The speed of a shaft 6 is continuously variable between low and high values when driven by a repulsion motor comprising armatures 7, 8, with commutators 9, 10, having short-circuited brushes mounted on rings which are angularly adjustable through 90 degrees for the same direction of rotation, or through 120 degrees if the motor is to be reversible. The armatures are mounted on the common shaft, and field windings 16, 18, co-operate with the armatures 7, 8, respectively, these field windings being connected to a three-phase supply by placing winding 16 across two phases, and the winding 18 across one of these phases and the remaining phase. A single commutator 19 common to both armature windings may replace the separate commutators. In a modification, three armatures are mounted on a common shaft with a common commutator 28 for two of the armature windings and a separate commutator 30 for the remaining winding. The field windings 31, 32, 33, are connected across different pairs of phases of a three-phase supply. In a further arrangement, two repulsion motors are coupled through toothed gear wheels with a single wheel on a common output shaft, Fig. 9 (not shown), or three motors may be so coupled, Fig. 10 (not shown). Three motors may have their shafts coupled in alignment, Fig. 11 (not shown). In the case of a motor having three separate field windings or three motors each having a separate field winding, each winding may be connected across a neutral and a different phase of the same three-phase supply.