GB191025385A - Improvements in Electric Motors and their Application to the Rectification of Alternating Electric Currents. - Google Patents

Abstract

25,385. Montgomery, J. J. Nov. 1. Commutator switching-arrangements.-For rectifying alternating currents, a commutator is driven by a motor excited by the alternating current and imparting to it a succession of positive and negative accelerations in synchronism and conterminous as regards time with the variations of excitation, so that it moves with an undulatory step-by-step progression which is always in exact synchronism with each alternating-current wave, even though these are unequal. In the form described, the field magnet of the motor is of soft iron or steel, preferably in the form of two iron rings 1, 1, so that, when put together, they form an annular channel for the field coil 5. The inner projecting portions of these rings are cut through at intervals to form pole-tips 3, 3 of equal dimensions, those of one ring being exactly opposite those of the other. The rotatable element 6 is a light wheel having soft iron or steel bars or projections 7 of about the same width as the pole tips of the field magnets and similarly spaced. If the motor is given an angular motion, for example by turning a knob a by hand, the field magnet being excited by a shunt circuit from the alternating- current supply, and the electric, magnetic, frictional, and mechanical elements having been properly co-ordinated in the manner indicated in the Specification, the rotor continues to revolve and carry the commutator forwards in an undulating manner in exact synchronism with the individual waves of alternating current. One or more sets of pole-tips 3 may be used with the full set of bars 7, and conversely. The commutator is secured to the motor shaft, and comprises as many conducting-segments 8 as there are steps in one rotation of the motor. Each segment alternately is connected to one of two rings 10, and brushes 11 convey the alternating current to these rings. Each commutator brush 12 is independently adjustable, and both are mounted upon a rocker so that they may be simultaneously adjusted to make and break contact with the commutator segments at the zero points of the alternating-current wave. A polarized relay may be used in conjunction with the commutator to fix the direction of the direct current. Several commutators may be arranged on the motor shaft.