Patent GB-515150-A (GB)
Title: Improvements in or relating to controllers for electric motors
IPC: B60L15/20
Filed: 1938-05-25
Abstract: 515,150. Master control of D.C. motors; actuating controllers. WEST & CO., Ltd., A., and JOHNSON, C. May 25, 1938, No. 15593. [Class 38 (iii)] In a motor controller, a plurality of contactors for accelerating the motor are operated in succession by fluid-pressure means operated by a power control shaft, and a further series of contactors for establishing braking connections are operated by fluid-pressure means operated by a brake control shaft. Upon operation of a cam-shaft PSH from its off position O to its final position 10, cams M1-M10 operate fn sequence valves V1-V10 whereby contactors C1-C10 are actuated by pistons P1-P10 subjected to air pressure. The motor is thus connected to the supply and speeded up by armature resistance and shunt field control. Rheostatic braking is obtained by operation of a brake cam-shaft BSH whereby a valve V11<1> is operated and, provided the cam-shaft PSH is in its off position to operate a valve V11, a piston P11 actuates a contactor C11. A valve V6<1> is also operated and operates through a check valve CV6 to operate the piston P6 which closes contactor C6 to strengthen the motor shunt field. At a further position of the cam-shaft BSH a valve V7' is operated and in association with a further check valve CV7 operates the piston P7 which closes contactor C7 to strengthen further the shunt field. The check valves CV6 and CV7 prevent the cylinders of pistons P6, P7 from exhausting to atmosphere when only one of the valves V6, V6', or V7, V7<1>, is at the off position. The valves V1, V2, V3, V4, V9, and V10 controlling contactors in the main series circuit of the motor are fed from a common supply pipe P1, in which an overload trip valve OV1 is provided operated by coils OW1 in the armature circuit of the motor. Similarly an overload trip valve OV2 operated by coils OW2 in the shunt field of the motor controls the pressure in a pipe P2 supplying the valves controlling the shunt field circuit. When tripped the valves OV1, OV2 can be reset by operating the cam-shaft PSH to its off position. The valves V11, V11<1> controlling the brake contactor are supplied from an independent pipe P3. A driver's foot lever operates a lever 25 pivoted at 26 to a lever 22 carrying a toothed sector 21 gearing with a wheel 20 on the cam-shaft PSH, the lever 22 being biased by a spring 24. The lever 25 carries a stud which normally rests against an arm 28 and serves as a fulcrum for the lever 25. Operation of the brake cam-shaft BSH operates the arm 28 downwardly and the lever 22 is returned by the spring 24 to the off position of the cam-shaft PSH. Recoupling of the cam-shaft PSH with the driver's lever is effected by returning this lever and the brake lever to their off positions. The interlock may also operate between the cam-shaft PSH and a switch which selectively connects battery sections B1, B2, in parallel or series for supplying lighting or the motor circuit. The power cam-shaft has means for providing step-by-step movement. The contactors may be as described in Specification 509,932, and the cylindercontactor units for the series circuit arranged in a row at a level different from those of the shunt circuit. The cylinders associated with the shunt field contactors may be of insulating material as described in Specification 515,151.