Patent GB-619583-A (GB)
Title: Improvements in and relating to controllers for electric motors
IPC: B60L15/22
Filed: 1946-12-13
Abstract: 619,583. Control of D.C. motors; controllers. RAY, W. T., FERGUSON, A. D., and METROPOLITAN-VICKERS ELECTRICAL O., Ltd. Dec. 13, 1946, No. 36858. [Class 8 (iii)] In series-parallel systems with means affording regenerative operation with the motors in two or more circuit combinations, there is provided a controller comprising a main operating member having successive ranges of movement establishing respectively the two or more motor combinations for motoring operation and adapted in each range progressively to remove series resistance in the armature circuit for each of said ranges, a second operating member for selecting the appropriate motor connections for motoring and braking, and providing in braking operating a plurality of motor combinations in accordance with the position of the selector member, and including means rendering the main member effective only in one range of movement thereof to control the resistance in the motor armature circuit when the selector member is set for each of said motor combinations for braking operation. A separate reversing lever may be provided. A main hand wheel 1 is mounted on a shaft 10 which is geared to a shaft 14 carrying a contact drum 15. Movement of this drum governs the removal of resistance from the motor armature circuit and controls contactors effecting transitions between series, multiple series and parallel connections of the motors. The contact drum may comprise two parts, a second part 15a being mounted on a shaft 16 geared to the shaft 14. A brake lever 3, on the shaft 10, is geared to a shaft 21 mounting a contact drum 22, movement of which governs contactors controlling the motor connections during regeneration, and also provides weak field operation of the motors. A selector lever 2, mounted on shaft 23, actuates a contact drum 24 controlling contactors providing series and parallel connections of the motors during braking. A reverse key 4, mounted coaxially with the lever 2, is coupled to a reverser drum 26 through a mechanical linkage device. In the first range of movement of the hand wheel 1 from the " off " position, the motors are connected in series and starting resistance is progressively removed by movement of the hand wheel through the range. This is followed by transition notches and a range of notches providing removal of armature resistance with the motors in a multiple series connection. Further transition notches are followed by a range providing parallel connection of the motors with progressive removal of armature resistance. The hand wheel is indexed to indicate the appropriate motor connections. The selector drum 24 is provided with an " off," a " motoring " and two other positions in which multiple series and parallel connections of the motor armatures are respectively afforded during braking. In these two latter positions, the motor field windings are separately excited from a generator. The braking lever 3 is movable to " off," " motoring " and two weak field positions in addition to a range of notches providing regenerative braking with progressive increase of the excitation of the generator referred to above. The lever 4 is provided with the usual "off," " forward " and " reverse " positions. The shaft 23 carries a cam 31 having indentations co-operating with a roller 35 on a spring-biassed lever 36 pivoted on a vertical shaft 37. A tail portion 38 of the lever is movable in a slot 39 of a disc 40 mounted on the shaft 21. The slot 39 is so shaped that, when the selector lever 2 is in the " off " position, movement of the braking lever 3 is prevented. Further, when the lever 2 is moved to the " motoring " position, movement of the lever 3 is restricted to the motoring range, and, when the lever 2 is moved to the multiple series or parallel braking positions, movement of the arm 3 is restricted to the braking range. The lever 2 is locked in its selected position when the lever 3 is in any position other than the " off " position. Interlocking between the selector lever 2 and the reverser key 4 is provided by flanges on the cam 31 which co-operate with the end of a lever 49 which is fixed on a shaft forming part of the mechanical linkage between the key 4 and the drum 26. The arrangement is such that, in the " off " position of the selector lever, the reverser lever can be moved to either operative position, and, in the " off " position of the reverser lever, movement of the lever 2 is prevented. When the reverser is in an operative position, the selector. drum may be moved from its " off " position, whereupon movement of the reverser to the " off " position is prevented. The drums 15 and 22 are also mechanically interlocked. The shaft 14 carries a cam 50 co-operating with a roller on a spring-biassed lever 51 which has a tail portion coacting with a disc 55 on the shaft 21. The arrangement is such that movement of the lever 3 from the " off " position is prevented when the main hand wheel is in any position other than the full series, multiple series, or full parallel notches. When the main hand wheel occupies one of such notches, however, the lever 3 may be moved to provide field weakening, and, in such event, the hand wheel is locked in position. A further spring-biassed lever 60 co-operates with arms 62 and 65 which are mounted on the shafts 21 and 14 respectively. The cams are arranged so that, when the lever 3 is moved to the " motoring " or " weak field " notches, the hand wheel 1 may be moved to any operative position, it being then impossible to return the lever 3 to the " off " position, the interlocks between the other contact drums preventing movement of the selector and reverser handles except when the main wheel is in the " off " position. With the braking lever set in a braking position, the hand wheel 1 may be moved freely within the series range, but it cannot be moved past such range. When the hand wheel 1 occupies a position within the series range, movement of the braking lever, and therefore of the selector and reverser levers, is prevented. Specification 619,437 is referred to.