Patent GB-607860-A (GB)
Title: Improvements in the control of electric motors driving elevators and other travelling devices
IPC: B66B1/52
Filed: 1944-08-14
Abstract: 607,860. Push-button lifts. IGRANIC ELECTRIC CO., Ltd. Aug. 14, 1944, No. 15498. Convention date, Aug. 13, 1943. [Class 40 (i)] A control system for an electric motor driving an elevator or other travelling device comprises electro - responsive means adapted upon energization to effect stopping of said motor, manual switch means operable at will to effect starting of said motor, condenser means adapted to be charged in response to starting operation of said manual switch means, and means whereby said electro-responsive means are energized by the energy stored in said condenser means upon entry of said travelling device into a given zone of travel. In an arrangement in which the travelling device moves between the limits of a range of travel, and stops on the way where calls are registered, condenser means are provided through the medium of which reversal of the travelling device at the ends of its travel may be prearranged, said condenser means being controlled automatically to pre-arrange a reversal of the travelling device, but only when such reversal is required for response to a call registered. Upon actuation of a lift car push-button 21 for upward travel to a second floor, a condenser 41 is charged and a circuit is completed through a floor selector 8, driven with the lift, to energize a self-maintaining relay 25 and close an " up " reversing switch 4. Energization of a coil 34a of a retiring cam closes a floor limit switch 16 which completes a circuit through the coil of a main switch 24 to connect the lift-motor armature 2a to the line. The brake 32 is lifted and the motor operates to move the car upwardly until the condenser 41 is discharged, over contacts of a travelling-nut selector switch 11, through the coil 29b of a relay 29. A relay 33 is energized to de-energize the coil of the retiring cam which actuates the limit switch 17, whereupon the switch 24 is opened and the brake applied. The relay 33 is maintained energized for a period after de-energization of the switch 24 so that the limit switch 17 is kept open to allow discharge of passengers. De-energization of the relay 33 allows further upward movement of the lift. If a floor pushbutton 14b, for example, has been actuated to charge a condenser 39, this condenser discharges over contacts 9e, 9a and 9b to energize the relay 29 and stop the car when the lift reaches the third floor. Upward movement of the car then continues until the car reaches the top landing, where a limit switch 28 opens to de-energize the relays 4 and 25. Just prior to the actuation of the limit switch 28, a limit switch 31 is closed to energize the relay 29 which causes the relay 33 to actuate the retiring cam and open the limit switch 19, and the elevator will remain at the top landing. If the elevator is at the top floor and an " up push-button such as switch 13b is actuated, the relay 26 is energized and a condenser 37 is charged. Closure of relay 26 closes a " down " reversing switch 5 which effects energization of the retiring cam relay to close the limit switch 19 and the main switch 24. The lift moves downwardly and, when it reaches the second floor, the condenser 37 imparts a part of its charge to a condenser 56, and the grid of a valve 50 is thereby rendered of sufficiently positive potential with regard to the cathode as to make the valve conductive. The relay coil 25a is energized through the valve and the relay 25 closes a self-maintaining contact, so that, when the lift reaches the lowest floor, the relay 26 is de-energized, but the relay 25 remains closed, the switch 5 being opened and the switch 4 closed to reverse the lift at its lowest limit of travel. The car travels upwardly to the second floor, whereupon the condensers 37 and 56 discharge through the coil 29a of the relay 29 and the main switch 24 is opened. If, while the car is travelling upwardly, a "down" button' such as the switch 14a is actuated, the relay 25 is energized and the condenser 38 is charged. After stopping at the second floor, the car will proceed to the third floor where the condenser ,38 is connected to a condenser 61 to make a valve 51 conductive. The relay 26 is closed and maintained through contacts 26b. Upon arriving at the upper limit the relays 25 and 4 are opened and the switch 5 is closed to move the car downwardly to the third floor whereat the condensers 38 and 61 discharge through the coil 29a to stop the lift. When the car is travelling downwardly, following its reversal to answer a first landing call, if intermediate landing buttons are operated, the car will stop at landings where " down " buttons have been operated and will pass those where " up " buttons have been operated. When the car reaches its lower limit it will reverse to answer the calls registered by the " up " buttons, stopping in the natural order regardless of the order in which the buttons have been operated. If the car has passed a floor travelling upwardly when an " up " button on that floor is operated, the car will go to the upper limit, reverse, and go to its lower limit, where it reverses again to answer the call on that floor. Any suitable type of lift-motor may be used. The control circuits may be supplied from A.C. mains through a rectifier. The condensers only may be supplied with D.C., all the other circuits being supplied with A.C. and the push-button switches suitably modified.