GB441699A - Improvements in control systems for electrically propelled vehicles - Google Patents

Abstract

441,699. Master control of D.C. motors. GRIMSDALE, A. E. K-O., 43, King Edward Avenue, Worthing, Sussex, and ASSOCIATED ELECTRICAL INDUSTRIES, Ltd., Crown House, Aldwych, London. July 30, 1934, Nos. 22223 and 34203. [Class 38 (iii)] Non - regenerative braking.-In a control system for a vehicle, in which remotely operated contactors energized from the source of supply for the vehicle control the driving motor or motors, a run-back braking contactor is provided having normally-closed contacts 24 short-circuiting the armature 5 and series field 6, the operating coil 28 of said contactor being connected across the supply in a circuit including contacts 32, 35, on the controller 33 which governs the operation of the motor or motors, said contacts being closed when the controller is in an operative position, and opened when the controller occupies its "off" position. The contacts 24 of the run-back braking contactor may be normally closed by a spring as indicated at 25. With a reversing switch 9 in the forward position, failure of the voltage supply results in closure of contacts 24 so that a circuit is completed across the motor armature and series field, which circuit may include a portion of a resistance 26. Thus, if the vehicle is on an ascending gradient, protection against running back is effected. Similar protection is obtained when the controller 33 is returned to its " off " position. When the contacts 24 close, interlock contacts 41 open to de-energize the motor control circuits. Emergency braking with the vehicle travelling in the forward direction may be obtained upon voltage failure, or, when the controller is in the " off " position, upon failure of the control circuits on the vehicle, by throwing the reversing switch 9 to the reverse position. The whole of the resistance 26 is included in the braking circuit thus completed, and the limited speed is higher than for running-back conditions. In a modification, Fig. 2 (not shown), a braking switch, separate from the normal reversing switch, is provided for obtaining the emergency braking during forward motion of the vehicle. This braking switch includes, in addition to contacts which, in the braking position, interrupt the control circuits, further contacts which include either the whole or part of the normal series starting resistance, or a resistance employed for normal braking. The braking circuit made by this switch may be completed directly or may include the contact 24 of the run-back braking contactor. The braking switch is provided with a transitional position in which contacts directly short-circuit the motor armature and its series field, so that sparking is prevented, and movement of the switch from the braking to the running position may be effected without first bringing the vehicle to rest. The operating handle of the braking switch works in a gate, Fig. 3 (not shown), which ensures a pause between operation of the switch from the running position to the transitional position, and from the transitional position to the braking position. By arranging for the normal reversing switch to be included in the motor circuit in both positions of the reversing switch, emergency braking may be obtained for both directions of operation. Specification 429,194 is referred to.