GB1287921A - - Google Patents

Abstract

1287921 Lift control systems WESTING- HOUSE ELECTRIC CORP 24 Nov 1969 [17 Dec 1968 (2)] 57375/69 Heading B8L In a multicar lift control system scanning means operates continuously to detect the position of cars and registered calls, and cars travelling in a first direction are allocated a predetermined number of calls for said first direction on successive scans, but if a call is not allocated in this way (e.g. because each moving car has its quota of calls) a "demand" signal is generated which causes an available (i.e. uncommitted) car to be assigned to serve the demand, the allocations being continually reviewed and modified if necessary as the situation changes. The scanner is pulse driven and scans rapidly up and down in the order of the landings for car position, car calls and landing call signals which are processed by solid-state logic circuits so that the total calls allocated to a given car do not exceed the predetermined number. A landing call will be allocated to a car having a car call for that floor providing the car is close to that floor, otherwise it will be allocated in the normal way, that is, to the car closest behind the call. If that car has its quota it is allocated to the next car and so on. A demand created by failure to allocate a call as above is met by assigning the nearest available car, whether it is above or below the calling floor. Only one demand is dealt with on each scan, up calls being dealt with on up scans and vice-versa. Allocation is up-dated on each scan, and an alternative car distribution pattern can be simulated and acted upon if improved service would result. In addition to allocating calls the system operates to prevent cars answering calls under certain circumstances, e.g. if the car has its quota of calls or is fully loaded, or has already made a predetermined number of stops, and unless so prevented any car will stop for a landing call which it encounters in its travel, even if it has not been allocated to it. Distances are assessed by counters, normally one count per landing although more than one count may be used if landings are widely spaced. When no car is at a preferred floor (e.g. lower terminal) an artificial demand is created unless a car with few calls is near. Priority is given to down calls which have been unanswered for more than a predetermined time, by falsifying the position of a car in such circumstances so that that car appears to be more favourably placed to answer the call than it really is. Priority can also be given to a predetermined zone. The description incorporates Specification 1,196,981.