Patent GB-190930262-A (GB)
Title: Means for Controlling Electric Motors.
Inventor: WITTEK WILHELM
IPC: H02P7/18
Filed: 1909-12-28
Granted: 1911-01-30
Abstract: 30,262. Wittek, W. Dec. 28. Master control systems; push-button control systems; electric braking; controllers, actuating - mechanism for. - The current in the solenoid of a starter for electric cars is regulated by the pointer of an instrument such as an ammeter, speedometer, or the like, capable of indicating the momentary value of the current, speed, &c. In one form, the pointer H, Fig. 2, of the dial G bridges, consecutively, pairs of contacts C as it moves over its dial, and intermittently makes the circuit of a solenoid S, which operates the controller by a pawl L and ratchet R. The pointer may carry a brush T, Fig. 4, biassed towards the end by a spring. Stepped ribs B1 ... B7, Fig. 3, are arranged in circular arcs about the pointer pivot O, and each pair of contacts are arranged behind the end of each rib. The sudden rush of current after each step of the controller, in the case of ammeter control, causes the pointer to travel far enough to allow the spring to pull the brush T on to the next consecutive rib. The fall in current consequent upon acceleration of the motor allows the pointer to travel backwards and short-circuit the pair of contacts arranged against that rib. The circuit of the solenoid is under the control of a push-switch D<2>, and a switch D<1> is in parallel to the contacts C. In another method, the contacts C, Fig. 6, are arranged as shown on a vertically movable plate PL, and an additional pawl L' and wheel R', actuated from the solenoid by a lever HE, are driven step by step as the actuating-rod ST is returned by a spring F. The current-indicating lever H is deflected in a counter-clockwise sense after bridging any pair of contacts C, and the plate PL is immediately afterwards dropped by rack-and-pinion gearing Z', Z<2>, placing the next succeeding pair of contacts in the path of the lever H. This hunting action of the contacts C may be obtained by mounting a single pair on a plate driven similarly to the wheel R', the single pair in this case following up the lever H and accelerating the motor with a gradually increasing current. In another form of the invention, a motor M, Fig. 10, driving the controller through gearing M' against a resetting-spring F, has its supply circuit controlled by a resistance switch G, the arm of which H is the indicating-lever of the governing-instrument. The movement of the controller over its braking notches may be governed similarly to that over the starting-notches; or a separate braking-switch may be used, controlled by a separate solenoid under the control of the governing-instrument. All the solenoids operating the motor controllers on all the cars of a train may be connected in series and controlled from one instrument. The controllers may be actuated and re-set by pneumatic pressure or by suction. The resetting-device consists of a spring vane mounted eccentrically in a casing and forced by air into a central position over an outlet port in the casing. The controller may be moved in both forward and reverse directions by providing two oppositelystepped ratchet wheels on the spindle, the pawl of each being actuated by a tappet on one of a pair of rods both driven by the operating solenoid. A separate solenoid under the control of the operator causes one or other of the tappets to engage its pawl. The application of the system to the control of two cars in series and under the regulation of one instrument is illustrated in Fig. 14, S', S<2> being the forward and reversing solenoids respectively. In this case, the switches D<2>, D<3>, D<4>, operating the forward, reverse, and re - setting solenoids S', S<2>, S<3>, respectively of one car, must be opened, and its switch D<1> closed to shunt the governing-contacts C on that car, leaving the circuit to the instrument of the other car open at its switch D<2>. Electric motors under the control of a reversing-switch and an ammeter &c. are arranged on each motor-car, so that each motor BE, Fig. 16, in reciprocating a pivoted rod W<1> about its pivot W, causes one pawl L or L' to engage its ratchet-wheel R to move the controller in one direction. The other pawl is temporarily drawn back and knocked out of action by a fixed projection A or A<1>.