Patent GB-1485660-A (GB)
Title: Elevator system
IPC: B66B1/30
Filed: 1974-11-18
Abstract: 1485660 Automatic elevator speed control WESTINGHOUSE ELECTRIC CORP 18 Nov 1974 [28 Nov 1973] 49740/74 Heading G3N In the generation of speed patterns, Fig. 2, for  an elevator car, wherein the desired speed pattern is represented by the voltage across capacitor 100, and, for a journey of one floor, capacitor 100 is charged at a rate set by variable resistor AP towards a clamp voltage, set by slider IS on resistance chain 112, 114, 116, 118, and representing an intermediate maximum speed, and discharged at a rate set by slider DT when means (4UL), Fig. 1 (not shown) or (4DL, not shown) for the destination floor is encountered by the car, whereas for a journey of more than two floors, the capacitor is charged at the same rate towards a clamp level set by high speed setting slider HS, and is discharged a) at a rate determined by the setting of slides D & DT towards the clamp level IS until means (5UL) or (5DL) for the destination floor is encountered by the car, and thence, b) discharged in the same manner as for the one floor journey, there is provided means, including relay (Z), Fig. 4 (not shown), with contacts Z-1, Z-2, active during a journey of two floors to maintain charging of the capacitor 100 towards the high speed clamp level HS for a predetermined time after the notching type selector of the system has reached a position two floors from the car's last stop, and disenabling response of the car to the means (5UL) or (5DL) for the destination floor, the time being so selected that the capacitor 100, discharging towards the level IS after expiry of the predetermined time, attains the latter voltage level at, or shortly before the means (4UL) or (4DL) for the destination floor is encountered. Thus, a more favourable pattern 70, 84 is attained than that 70, 80, 82 which would prevail if the two floor journey were controlled as are the journeys exceeding two floors. A timing relay is provided to ensure that, the car having encountered the high speed slowdown means (5UL) or (5DL) for destination floor, response of the car to an interleaving intermediate slowdown means (4UL) or (4DL) of a closer floor is inhibited. The car will stop at any intermediate floor when there are no calls ahead of it. Levelling and stopping. When levelling switch (1UL) or (1DL) encounters cam (62), capacitor 100 is discharged to level LS corresponding to a creep speed, and to a lower voltage, determined by setting LSS and corresponding to zero speed, when both switches are on the cam. Facility for re-levelling in the event of overshoot is provided. The notching selector is stepped by signals from staggered detectors (AL, BL Fig. 1), moving in one floor steps until it encounters a floor requiring service. Protective apparatus, Figs. 7, 8 (not shown). Relays (OVU), (OVD) are sensitive to the armature voltage of D.C. motor 20 of a gearless elevator Ward-Leonard drive including tachogenerator feedback, and one or other of them is energized should the elevator move in a direction opposite to that set, to disenable the control system, which must then be manually reset, as it must be if relay (ADT) is energized, such occurring if the rate of change of armature voltage, hence elevator acceleration is excessive.