Patent GB-1271817-A (GB)
Title: Improvements in or relating to lift control systems
Inventor: HARDY CLIFFORD
IPC: B66B1/16
Filed: 1969-09-17
Abstract: 1,271,817. Lift control systems. EXPRESS LIFT CO. Ltd. 16 Sept., 1970 [17 Sept., 1969], No. 45818/69. Heading B8L. A position selector for a lift comprises a unit A1 whose count indicates the position of the car when it is stationary, the count being translated into a form suitable for operating control and indicating circuits by means of a decoder B1 A memory unit C1 stores the count of the unit A1 and re-sets it to the same number after interruption of the supply. A count unit A2 is associated with a decoder B2 and memory unit C2. When the car is stationary, the count of the unit A2 is at a datum value representing a lower count limit. A call for service causes pulses generated by unit D1 to be applied to the units A1, A2, through control units E1, E2, which determine the direction of count and prevent the associated unit A1 or A2 from counting beyond certain limits. When the car is to reach its maximum speed in answering a call, a predetermined number of pulses are added to the units A1, A2, until the unit A2 reaches an upper count limit. This predetermined number represents the distance before a stopping-floor at which slowdown is initiated if the car is travelling at top speed. When the car is in motion, pulses are applied to unit A1 through the unit E1 from unit D2, these pulses being generated in response to signals from sensing elements on the car cooperating with elements located at selected positions in the shaft, for example. When the count in unit A1 reaches a number corresponding to the floor at which service is required, slowdown is initiated and the unit E1 1 prevents the further application of pulses from the unit D2 to the unit A1. The slowdown signal also causes the output of unit D2 to be applied to unit A2 through the unit E2 to reverse its count towards the lower limit which is reached by the time the car reaches the required floor. When the call is for service at a floor not sufficiently removed from the car to attain its maximum speed, the unit A1 reaches a count corresponding to the required floor before the unit A2 reaches its upper limit. Slowdown procedure is initiated before the car starts to run, and pulses from the unit D2 are all applied to the unit A2 to return this unit to the lower limit. The unit D1 supplies pulses to re-set the units A1, A2, into synchronism with the car when the car is at the top or bottom floors. If an emergency stop is made, the unit D1 provides pulses to bring the units A1, A2, into synchronism with the car without driving the car to a terminal floor. The unit D2 comprises a number of logic gates and is adapted to produce a short pulse each time a sensing element on the car produces a signal, and to produce two short pulses if the car changes its direction while the sensing element is producing an output signal, Fig. 2 (not shown). The unit D1 comprises a number of logic gates to advance and re-set the units A1 A2, Fig. 3 (not shown). The control units E1 and E2 also comprise logic gates while the units A1, A2, are basically reversible binary counters adapted to count 64 and 8 pulses respectively. The unit A2 comprises three JK bi-stable elements controlled by two AND or NOT logic elements connected between adjacent stages which determine the direction of counting. Similarly unit A1 comprises six JK bi-stable elements interconnected through logic elements, Figs. 4, 5a, 5b (not shown). If the selector serves four floors, for example, the car senser produces a pulse at each of six positions, two between each adjacent pair of floors, the unit A1 only varying through positions 1-7. The lower and upper limits of unit A2 are positions one and six respectively. The distance before a floor at which slowdown is initiated when the car has maximum speed is substantially two and a half floor-spacings. The memory unit C2 comprises three latch-up reed relays, each connected to outputs of a respective one of bi-stable elements in the unit A2 through a pair of gates. Each relay has an actuating and a releasing coil, and a magnetic bias to maintain it in an operated condition when actuated by an external signal. The unit C1 is similar to the unit C2. The decoding units B1 B2, comprise logic gates, the outputs of.the unit B2 determining the speed of the car during each journey. The outputs of the unit B1 indicate the position of the car to the lift control circuits.