GB1436741A - Elevator system - Google Patents

Abstract

1436741 Elevator control systems WESTINGHOUSE ELECTRIC CORP 2 May 1973 [17 May 1972] 20908/73 Heading B8L In an elevator control system including circuitry, Fig. 12 (not shown), providing elevator car speed profile control signals, the circuitry includes a terminal slowdown control 558 exerting an overriding control if an overspeed condition is detected for a car approaching a terminal landing. If the car is decelerating at a constant, desired rate the pattern of notches 1042 on blade 1040, detected by light emitting diode; photo-diode, -resistor or -transistor pair 1046, 1048 triggers monostable 1052 controlling switch 1053 intermittently grounding point 1051 so that the output VSE of low pass filter amplifier 1054 is substantially zero see (1084, 1086), Fig. 20A (not shown). In the event of car overspeed, point 1051 is grounded for a relatively longer proportion of the time; see (1084), Fig. 20B (not shown), so that voltage VSE becomes positive (1086<SP>1</SP>). In comparator 1056, voltage VSE is compared with reference V 1 representing a tolerable degree of overspeed, and should VSE exceed V 1 signal SPSW is applied to driver (552), Figs. 12, 21 (not shown), causing elevator speed control to be effected by signal TSAN which results from the summing, in amplifier 1090, of the voltage VSE with the rectified output of a tachometer (not shown) connected to the elevator motor drive shaft, signal TSAN thus ensuring that the car comes to rest once an overspeed condition is detected. Voltage VSE is also compared with a voltage V 2 (V 2 >V 1 ) representing an emergency stop speed, and should VSE exceed V 2 , signal TOVSP initiates an emergency stop state which, in view of memory 1068 is retained until the apparatus is reset at 1082 by maintenance personnel. Switching by driver (552) from normal speed, to terminal overspeed control may be discontinuous, or a blended transition may take place. Driver operation is interlocked with the car doors, or presence of the car near landings or the end of the hatchway. A blade 1040 may be mounted adjacent each end of the hatchway (62), Fig. 1 (not shown), the optical, or alternatively magnetic proximity, detector being on the car, or detector-blade positions may be interchanged. The speed pattern generator disclosed herein and utilized in the absence of any terminal overspeed, is disclosed and claimed in Specification 1,437,742. The floor selector disclosed herein is disclosed and claimed in Specification 1,436,743.