Patent GB-401389-A (GB)
Title: Improvements in and relating to electric control systems for elevators and the like
IPC: B66B1/36
Filed: 1932-06-01
Abstract: 401,389. Control of D.C. motors. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Taylor, R. B. ; 206, 2nd Street, Scotia, New York, U.S.A.) June 1, 1932, No. 15554. Convention date, June 1, 1931. [Class 38 (iii).] A lift 10 is driven by a motor 11 supplied from a Ward-Leonard generator 13 and is levelled at a floor at which stoppage is desired by means of oscillating discharge devices 24, 25 carried by the lift and cooperating with shielding vanes 34, 35 located in alignment in the hatchway, the action being similar to that disclosed in Specification 394,045, the devices 24, 25 effecting progressive steps of deceleration, the action being also similar to that disclosed in Specification 316,193, [Class 38 (iii), Electric motor control systems &c.]. Movement of the car switch 40 to downward position 41 energises "down" contactor 21 and relay 51, the contactor 21 completes a circuit to the generator field 17 over resistors 60, 61 in parallel (relay 71 being closed by reason of being deenergised through opening of contacts 70 on the car switch), and relay 51 causes removal of brake 57 on the motor. Movement of car switch to position 43 causes closure of relay 100 to include resistor 105 in parallel with resistors 60, 61 and to maintain itself and contactor 21 over contacts 102, 103 respectively and over interlocks on contactor 21. Movement of car switch to position 44 causes closure of relay 112 to short-circuit resistors 60, 61 and 105. Return of car switch to " off " position causes immediate opening of relay 112 and preparation at controls 70 of the anode circuit of valves 24, 25. As the motor speed falls, relay 73 closes to complete this anode circuit and the valves oscillate. As the lift approaches the floor, grid and anode coils 32, 33 of valve 25 are shielded by interposition of the vane 34, and this valve ceases to oscillate, whereupon the anode relay 27 lifts and causes an associated relay 84 to drop, but no control function is effected by these relay movements. Further descent of the lift causes similar action of valve 24 and relays 26, 83. Lifting of relay 26 completes another maintaining circuit for contactor 21 irrespective of original maintaining circuit therefor, and dropping of relay 83 opens the maintaining circuit of relay 100, thus excluding parallel resistor 105, opening original maintaining circuit of contactor 21 and preparing at contacts 75 an energising circuit for relay 71. When valve 25 leaves the influence of the vanes 34, relay 27 drops and relay 84 lifts to complete the energising circuit of relay 71 which opens to exclude parallel resistor 61. When valve 24 leaves the influence of the vane 34, relay 26 drops and relay 83 lifts, relay 83 is without effect, but dropping of relay 26 opens the second maintaining circuit of contactor 23 and relay 51 in series therewith, the generator field circuit is thus opened and the brake 57 applied. Should the lift overshoot the floor, the valve 25 cooperates with the vane 35 and relay 27 lifts and completes an energising circuit for "up" contactor 20. Excessive overshoot will cause valve 24 also to cooperate with vane 35 with consequent lift of relay 26 and drop of relay 83, the latter causing deenergisation ofrelay 71 and inclusion of resistor 61 in parallel with resistor 60. The lift is thus relevelled. Acceleration during starting can be controlled by a flywheel machine associated with the generator field 17 as disclosed in Specification 370,532.