GB804191A - Elevator control system - Google Patents

Abstract

804,191. Automatic speed control systems; control of D.C. motors. ALLMANNA SVENSKA ELEKTRISKA A.B. Oct. 4, 1956 [Oct. 5, 1955], No. 30245/56. Class 38 (4). [Also in Group XXXVII] In an elevator control system the speed of the car is influenced according to its position by a magnetic memory and a pick-up device, the former of which may comprise a magnetic tape, drum, or disc, arranged to move in correspondence, in respect to the pick-up, with movement of the car. A magnetic drum arrangement, driven by a chain attached to the car, in which the pick-ups traverse the length of the drum on a lead-screw when the drum is rotated, is described with reference to Fig. 2 (not shown). Driving-motor 40, Fig. 4, of a Ward-Leonard arrangement is controlled in accordance with the difference between the output of tachometer generator 45 and a portion of the reference voltage applied to terminals 53 selected by relay 71 from potentiometer 52 in a regulator 39 controlling the field 43 of generator 42. The magnetic drum 20 carrying signals such as shown in a development, Fig. 5, is brought into operation by a relay 74 when the selected contact on the position indicator 82 is closed by the car approaching the required floor, and energization of relay 71 is transferred from source 80 to the output of pick-up 32. The relay 71 is held whilst the pick-up is traversing signal 324 but releases at point t2, Fig. 6, to connect the slowing speed reference tapping from potentiometer 52 to the regulator. At point t4 when the car speed has acquired the desired slow running speed, signal 314 energizes relay 51 through pick-up 31 and amplifier 35 to apply brake 47 and bring the car to rest. Oppositely poled rectifiers 57, 58 in the input to regulator 39 provide for current limitation, and control of direction is effected by relays 67, 61, reversing the polarity of the reference voltage. In a modification described with reference to Fig. 7 (not shown) the speed-dependent voltage is provided by a further continuous signal 330 on the track, Fig. 8, and slowing is effected by transferring the control to a signal 320 wherein the frequency of the recorded signal is increased in predetermined regions to introduce a signal larger than the reference voltage. Reversal in this embodiment is achieved by changing over the output leads from the Ward-Leonard generator.