Patent GB-1356856-A (GB)
Title: Elevator control system
IPC: B66B1/18
Filed: 1971-06-29
Abstract: 1356856 Multi-car control system HITACHI Ltd 29 June 1971 [1 July 1970 (2) 10 July 1970 20 July 1970] 30455/71 Heading B8L In a three car elevator system, serving ten floors, the cars being regarded as operating in a loop 1U-9U-10D-2D-1U, the car motions are correlated in dependence upon the intervals, as defined below, between them, according to one of the following methods: (i) the cars are considered in pairs, and the succeeding car is caused to by-pass hall calls when the interval between them is greater than a predetermined value. (ii) All three cars are considered and an intermediate car is caused to by-pass hall calls if the interval between it and the preceding car is greater than the interval between it and the succeeding car. When the interval to the preceding car is less than that to the succeeding car, one or other of the other cars will by-pass hall calls.  The interval Tab between cars A, B for example, car B succeeding A, is defined by: Tab = K, Dab + K 2 Cba, where k 1 , k 2  are constants, Dab is the physical distance between points ahead of cars A, B respectively, by an amount dependent on their respective operating speeds, and Cba is the number of hall and car calls allotted to car B, for floors between it, and car A. Detecting car positions, Fig. 4 (not shown).- Depending on the position of, for example car C in the shaft, switches (S1UC .. S2DC) selectively close, selectively connecting resistors (R1UC ... R2DC) of scaled magnitudes into an operational amplifier circuit, whose outputs for each car, are two position signals C-a, C-b, of equal magnitude and opposite sign. Determining the spaoial distance for example Dab, and identifying the succeeding car for car A, Fig. 6 (not shown).-Operational amplifiers (OP3A, OP4A) output separation signals of car A relative to cars B or C respectively, which if positive, pass gate (BL1A) (BL2A) to diodes (D1A, D3A), and, if negative, indicating that the cars B or C are ahead of car A, are subtracted, using amplifiers (OPSA, OP6A) from a constant potential to convert the signal into a succeeding one, thus regarding any car ahead, as being behind on the loop. The least of the distance signals appears at diode (D5A), and the circuit utilizing comparators (CP1A-CP4A) and or gates (OK1A, OR2A) identifies the succeeding car. Determining the number of calls Cba between cars B and A, Fig. 8 (not shown).-All car and hall calls for the car succeeding A are received at AND gates (A1UA3-A2DA3), and, in dependence on the position signals of cars A, B, C, fed to the OR and INHIBIT gates, only those AND gates between car A and the succeeding car are enabled, producing a voltage across rA proportional to the number of hall and car calls for the succeeding car, between it and car A. The signals Cba and Dab are combined in an adding circuit, Fig. 9 (not shown) which outputs control signals (SHA-A, -B-C) to control the response of cars to call signals in accordance with method (ii) above. Allocation of hall calls.-A hall call register (HCR), Fig. 10 (not shown) stores hall calls, the calls being passed singly, via order selector (STS, Figs. 2, 10) via an analogue circuit, Fig. 13 (not shown), whose output corresponds to the specific hall call to logic circuits, Figs. 12, 14 and 15 (not shown), which respectively, determine the spacial distances, number of calls, and add them, between the specific hall call and each of the cars. The least of the quantities is selected out to identify the car which will respond to the call, a display (RD), Fig. 2 (not shown) being given at the floor. Performance of method (i), Fig. 16 (not shown).-The interval signal for any one car is passed to a comparator (CMA), where it is composed with a given predetermined interval (TS).