Patent GB-949761-A (GB)
IPC: B66B1/20
Abstract: 949,761. Lift control systems. WESTING- HOUSE ELECTRIC CORPORATION. Feb. 13, 1962 [March 10, 1961; May 16, 1961], No. 5408/62. Drawings to Specification. Heading B8L. An elevator system comprising a plurality of cars serving a plurality of floors, which are divided into zones, is provided with means operable from each floor for registering demands for service in any of the zones and control means for assigning successive ones of the cars to successive ones of the zones in response to service demands in the zones wherein the order of such assignments depends upon a predetermined relationship of the service demands for the different zones. The dispatching of a car from the terminal first floor is prevented until the expiration of a predetermined loading interval, e.g. 5 seconds, after the selection of the car as the " next " car, during which period no passenger has entered or left the car, this being determined by photo-electric cells. The car may be prevented from leaving the floor for longer predetermined intervals, such as fifteen or thirty seconds which are varied automatically in accordance with the system conditions. If the loading interval has not expired, a car which has been selected as the next car to leave the terminal floor may be started therefrom immediately upon a predetermined loading of the car, such as upon the loading of the car to its rated capacity. Also, upon a predetermined loading of a car which is conditioned for down travel, a car which has been selected as the next car to leave the lower terminal floor may be dispatched immediately therefrom, although the loading interval has not yet expired. Such operation may be maintained for at least a predetermined time after cessation of the condition which initiated such operation. Floor calls.-The floor and car calls are registered by buttons actuating relays provided with cancelling coils which cancel the call registration as a car stops at the floor to answer the call. The floors above the terminal floor are divided into a plurality of up and down zones. If there are more down zones requiring service than there are cars conditioned for down travel and which are located above these zones, or if there is at least one down zone requiring service and this zone is above the highest car conditioned for down travel, a down zone demand for service is registered, whereupon the first car which becomes available for assingment is conditioned to travel to the highest floor for which a down call is registered provided that this floor is above the highest down-travelling car. A car which subsequently becomes available may be dispatched to a point intermediate the remaining down zones requiring service if there is more than one such zone, provided that such down zones are not located above the highest car conditioned for down travel. A car which has been assigned to serve a specific down zone by-passes all floors for which floor calls are registered and which are located between the car and the zone to which it is assigned and proceeds directly to the assigned zone. After answering all the down floor calls in the zone, it then answers all down floor calls for floors below the zone and to which another car has not been assigned. The up zone calls are answered in a corresponding manner. Priority floor calls.-Preferential service may be provided for floors at which calls have been unanswered for at least a predetermined time by assigning an available car to serve a zone in which there is such a floor, i.e. to serve a timed-out up or down zone, in preference to a non-timed-out up or down zone. If there is more than one timed-out down zone, an available car may be dispatched to the highest such zone. If a plurality of calls are registered the zones are given preferential service in the sequence timed-out down zones, timed-out up zones, non-timed-out down zones, non-timedout up zones. Priority service for the lower terminal floor.- If all the cars have been absent from the first (terminal) floor for a predetermined time, the nearest unassigned car which is set for down travel may be selected to proceed to the first floor without answering any registered floor calls other than priority down floor calls. If no car is at the first floor and no car is set for down travel, a call may be registered automatically for the first floor. Up-peak operation.-When the loading of a car at the first floor reaches a predetermined value, such as capacity loading, the system may be transferred to up-peak operation until a car subsequently leaves the first floor without a capacity load, a car conditioned for down travel is loaded to a predetermined value, a predetermined number of cars, is located at the first floor or until no car call is registered for a car at the first floor during a predetermined interval after the car has been selected as the next car to leave the first floor. In the up-peak operation, the priority service for the first floor is operated, as referred to above, but the unassigned car selected to return to the first floor may answer a priority call only if a predetermined interval of time has not expired during which all the cars have been absent from the first floor. After this interval, the car will not answer any down floor call. If fewer than a predetermined number of cars are located at the first floor, none of these cars may become available for -assignment to serve another floor. Light traffic operation.-If traffic diminishes so that one car or cars are available continuously for a predetermined time interval, all the available cars are conditioned to park. Each available car is returned automatically to the first floor when it receives a parking signal and on its arrival its motor generator set is shut down. The doors may remain closed or open.