High-rise buildings often have several elevator groups, and it is necessary to develop a system for the control of traffic between different elevator groups to ensure that they can operate even in abnor- mal situations. A frequent problem in high-rise build- ings is also that, especially for passengers changing from one elevator group to another, the waiting times may become too long in congestion situations, which impairs the performance of the elevator system.

High-rise buildings having more than 40-50 floors of- ten comprise one or more change floors (sky lobbies) which are only served by certain elevator groups. In this case, the building is divided into at least two sections, depending on the number of change floors.

The elevator groups are often divided into zones in the direction of elevation of the building, in which case a given destination can only be reached using elevators belonging to a given zone. Local elevator groups serve. each floor within their respective zones.

The building may also contain express zones where ele- vators travel past several floors without stopping.

The lower section up to the sky lobby is served by lo- cal elevator groups in their respective zones and the upper section above the sky lobby is served by a cor- responding system with local elevator groups. Passen- gers reach the sky lobby directly from the ground floor by using shuttle elevators, which do not stop at any other floors.

Congestion of traffic may become a problem at a sky lobby when the transportation capacity of an elevator group is too low for some reason. The supply traffic to the sky lobby should be in balance with the traffic leaving the floor. Congestion arises e. g. in the morn- ing when passengers arrive in the building if in this situation elevators are missing from the local eleva- tor groups. Congestion also arises in situations where shuttle elevators are out of use and the outgoing traffic in the building is heavy. In the event of-an exceptional situation involving heavier traffic than during normal incoming and outgoing peak traffic, e. g. evacuation of passengers from the building because of a fire, earthquake or bomb scare, congestion is likely to occur at the sky lobby.

According to US patent 4838385, an algorithm has been created which coordinates the arrivals and departures of elevators at a sky lobby so that the amount of time spent on changing elevators is minimized. The object of the invention is to minimize the combined waiting times in the building. According to specification US 5785153, elevators arriving at the sky lobby are syn- chronized in order that the shuttle elevators and the local elevators should be at the sky lobby at the same time. According to the invention, this is achieved by controlling the elevator speeds or by delaying an ele- vator by keeping its doors open longer than usual.

Calls'for elevators can also be cancelled or avoided.

According to the specification, empty elevators can be kept waiting in the upper part of the building or they may be directed to the ground floor.

The object of the invention is to create a new type of method for organizing the operation of elevator groups so that a balance prevails between the traffic leaving

a sky lobby and the traffic arriving at it in a situa- tion of exceptionally bad congestion.

As for the features characteristic of the invention, reference is made to the claims.

According to a preferred embodiment of the invention, the congestion of traffic occurring at the sky lobby in an exceptional situation is controlled by consider- ing the traffic between different elevator groups. One of the advantages of the invention is that, by using the arrangement of the invention, a congestion situa- tion preferably at a sky lobby can be brought under control. The idea is to maintain the traffic supplied to the sky lobby at the same level of intensity as the traffic leaving the sky lobby even when the transpor- tation capacity of a local group or shuttle group has been momentarily reduced. According to a preferred em- bodiment of the invention, the operation of elevator groups in buildings having one or more sky lobbies is so organized that congestion of traffic at the sky lobby is prevented via a group control system.

The group control system of the invention collects traffic data for the whole building both from local and shuttle elevator groups and is therefore aware of the traffic situation in the entire building. Accord- ing to a preferred embodiment of the invention, using a traffic forecaster comprised in the group control system, the system prepares a forecast regarding con- gestion occurring on the entrance floor and the sky lobby and identifies the traffic type of the building.

According to a preferred embodiment, local elevator groups and shuttle elevator groups monitor the number of passengers entering and leaving the elevator cars by means of light cells and car load weighing devices.

The traffic data are sent to a control procedure ac- cording to the invention which generates building- specific statistics. The group control system collects passenger traffic data from different elevator groups in order to prepare a forecast regarding queue build- up in sky lobbies and on the entrance floor. Using the traffic forecaster comprised in the control system, the latter computes a forecast of the queue of passen- gers being built up in the sky lobby and preferably identifies the traffic type prevailing in the build- ing, which information is used as a basis for dividing the elevator groups into different traffic service classes (TSC classes) in order to regulate the accel- eration, velocity and stopping time of the elevator groups so as to balance the traffic at the, sky lobby.

The congestion of traffic at the sky lobby can also be advantageously prevented by returning all unoccupied elevators to a floor where traffic is becoming con- gested, unoccupied elevators being empty elevators that have not been allocated to serve calls by other passengers. To retard an elevator group, some eleva- tors are excluded from appropriate elevator groups.

If the transportation capacity of a shuttle elevator group is insufficient to handle the amount of traffic to be supplied to the sky lobby within a given span of time in a down-peak traffic situation, then the fol- lowing modes of action are applied to avoid conges- tion. In local elevator groups supplying traffic to the sky lobby, some elevators can be excluded from service or their degree of admission can be reduced, which means that these elevators are operated with cars not completely filled. In addition, the stopping times of the elevators can be increased and their ac- celeration or maximum speed can be reduced as required in the prevailing situation. Correspondingly, the

shuttle elevators must be caused to leave the sky lobby sooner in a down-peak traffic situation, which according to the invention is accomplished as follows.

The acceleration or maximum speed of the shuttle ele- vator groups is increased, and the service level for traffic against the direction of peak traffic is low- ered. Some or all of the unoccupied shuttle elevators are returned to the sky lobby.

According to a preferred embodiment, in mixed traffic consisting of incoming and outgoing traffic as well as inter-floor traffic, the acceleration and speed of all elevator groups are increased.

According to a second preferred embodiment of the in- vention, in an up-peak traffic situation as passengers want to get from the entrance floor to upper floors and congestion is to be expected at the sky lobby, the following procedure is adopted. The acceleration and top speed of local elevators are increased or their stopping time is reduced for the upper floors or the service level for downward traffic is lowered. The transportation capacity of shuttle elevators is re- duced by increasing e. g. the stopping time or by re- ducing the speed or acceleration of the elevators. In the case of bad congestion at the sky lobby, some of the shuttle elevators can also be excluded from the group.

In the following, the invention will be described in detail with reference to the attached drawings.

-Fig. 1 illustrates an elevator group system as used in very high buildings.

-Fig. 2 visualizes the method of the invention as a block diagram.

-Fig. 3 represents the mode of action according to the invention in a down-peak situation in a building.

Fig. 1 shows how the elevator groups are arranged in a high-rise building. In the building illustrated in the figure, local elevator groups A, B, C, D, E and F are in operation, each serving a number of floors-within its respective zone. One local elevator group may com- prise e. g. 4-8 elevators. The floors marked with X are express zones of local elevator groups where the ele- vators do not stop at all. A change floor H (sky lobby) divides the building into two sections, forming the destination for shuttle elevators G departing from the entrance floor I. At the same time, the sky lobby H constitutes an entrance floor for the local elevator groups departing from that floor. Local elevator group F only serves passengers going downward from the sky lobby H. Passengers going upward from the sky lobby H are served by elevator groups D and E, which have been arranged in a manner corresponding to groups A, B, C.

The elevators in the shuttle elevator group G operate only between the entrance floor I and the sky lobby H without stopping at the other floors.

The group control system of the invention is called META. Fig. 2 shows the connections between the META group control system of the invention and other fac- tors controlling the elevator groups. The META group control system has been developed to control conges- tion at a sky lobby in abnormal situations, such as situations where elevators are out of use or when the building is being evacuated because of a danger. The META group control unit collects measured traffic data

from each local elevator group. Each local elevator group and each shuttle elevator group also has its own traffic forecaster supplying information to the META control unit. In addition to the measured instantane- ous data, the META group control system of the inven- tion also comprises a traffic forecaster which pro- duces a forecast of future loading of the elevator groups in the entire building. The META control system is continuously informed of the traffic prevailing in the building and, based on this information, it pre- pares a forecast regarding congestion at the sky lobby. META is a computer control unit supervising the operation of the elevators on different floors on the basis of traffic data collected from all the elevator groups. The control unit ; also monitors queue build-up on the entrance floor and at the sky lobby on the ba- sis of the number of passengers arriving and leaving the floor, and registers the data. If congestion is to be expected, then the META control system estimates the traffic type in the building and, in a situation differing from normal peak traffic congestion, directs elevator groups into different TSC classes (TSC = traffic service class) in order to clear the conges- tion situation.

When queue build-up is detected at the sky lobby, which in high-rise buildings functions as an entrance floor for the local elevator groups operating above and below it, the META control unit directs the groups into different service classes depending on the traf- fic type prevailing in the building. The various ele- vator groups are divided simultaneously into different TSC classes according to whether the service provided by the elevator group in question should be retarded or accelerated to avoid congesting traffic at the sky lobby. Table 1 presents a division into different TSC

classes. On the basis of the TSC classes, the META system makes changes for certain elevators regarding acceleration, velocity and stopping times, including the door open time and speed of door opening and clos- ing (door performance class).

TABLE 1. TSC classes in the META control system TSC CLASSES ELEVATOR ACCELERATION/door performance class Smooth 0, 8-0, 9 m/s2/comfortable High 1,1-1,2 m/s/top Normal 1, 0 m/s2/high Table 2 presents different traffic types. Different traffic types in the building vary depending on the situation, and they are used by the META control sys- tem as a basis for dividing elevator groups into TSC classes to avoid congestion. Down-peak traffic refers to traffic from upper floors to the exit floor. Up- peak traffic means traffic from the entrance floor to upper floors. Inter-floor traffic takes place between upper floors, so none of these passengers arrive at or depart from the entrance floor of the building. Mixed traffic consists of incoming, outgoing and inter-floor traffic components. When no queues are detected, the situation is described as light or normal traffic, and the elevators are operated without the action of META control. According to the traffic type prevailing in the building, the system determines whether unoccupied elevators are to be returned to floors where they are needed, whether elevators are to be excluded from a group, or whether the operation and stopping times of the elevators are to be accelerated or retarded.

TABLE 2. Different traffic types in a building TRAFFIC TYPES

Down-peak traffic Up-peak traffic Mixed traffic Light and normal traffic In the case of heavy down-peak traffic, the META sys- tem assigns the local elevator groups the TSC class smooth', and in this case their acceleration is low- ered to a value between 0.8-0.9 m/s2, the speed is reduced-and the stopping times are increased-a little (door performance class = comfortable, Table 1) in or- der to reduce the number of people arriving at the sky lobby. It is possible to exclude local elevators from operation or reduce their degree of admission, in which case the elevators : will be running with cars not completely filled. Correspondingly, the TSC class pa- rameter for the shuttle elevators is assigned the value high', which means that their acceleration is increased to the value of 1.1-1.2 m/s2, their speed is increased and unoccupied shuttle elevators are re- turned under META control to the congested floor. In addition, the stopping times for the shuttle elevators are shortened (door performance class top, Table 1).

When up-peak traffic prevails in the building, there is a relatively large number of passengers wanting to go up from the entrance floor, so that congestion is to be expected. If some elevators in the local groups are out of use, then the operation of the shuttle ele- vators is retarded and the service provided by the lo- cal group is accelerated. The acceleration of local elevator groups is increased to 1.1-1.2 m/s ;' (TSC high), their speed is increased and the stopping time for the elevators at the upper floors is shortened, thus also accelerating the operation of the doors. The

level of service provided by local elevators is re- duced for traffic in the direction opposite to the peak traffic direction, i. e. for downward traffic. The service provided by the shuttle group is retarded by reducing the elevators to service class smooth', and in a heavily congested situation shuttle elevators can be excluded from the group. In normal up-peak condi- tions, the elevators operate without the action of META group control, unoccupied elevators being re- turned to. the entrance floor. If heavy mixed traffic prevails in the building, then the service class (TSC class) of all elevator groups is raised to the value high', which means that their acceleration will be 1.1- 1.2 m/s2 and the maximum speed is increased.

When no congestion is detected in the sky lobby, all elevator groups are again classified into TSC class normal' (door performance class = high, Table 1).

During normal traffic, the shuttle elevators are re- turned to floors where the forecast produced by the META control system foresees congestion of traffic. In this case, an elevator leaving the sky lobby is accel- erated and an elevator arriving there is retarded.

The META control system displays traffic congestion information via a building monitoring system, thus in- forming the building manager about congestion situa- tions. Information relating to congestion and empty elevators can also'be displayed via floor-specific monitors and via display devices placed inside eleva- tor cars (showing e. g. texts like room left', full' or congestion on intermediate floor'. The control systems of all different elevator groups communicate with the META control system, informing it about the state of the elevators and the numbers of people leav- ing and arriving at different floors. The number of

passengers entering and leaving the cars is measured using data obtained from load weighing devices and light cells mounted in the cars. Congestion in the lobby is ascertained using lobby detectors.

The door operation speeds are also controlled in ac- cordance with the TSC classes. Generally, it can be stated that, in a congestion situation, the stopping time of elevators is shorter and therefore the open time of the doors and their opening and. closing-times-.. are shortened on other floors except the congested floors. When adjusting these, it is necessary to take traveling comfort into account. Although traffic is often congested on the entrance floor, relatively long stopping times and normal door speeds should be ap- plied because the number of passengers is also large.

Fig. 3 visualizes a building with a sky lobby H and elevator groups 20,21 and 22 departing from it. Ele- vator group 20 serves floors below the sky lobby. The arrows in the figure indicate the traveling direction in a situation where exceptionally heavy down-peak traffic prevails in the building and the only way to get out of the building to the street level I is to use the shuttle group 22. In a down-peak traffic situation, a considerable number of passengers are trying to get to the exit floor and the traffic may become congested because of the elevator groups trying to reach the sky lobby. Using the procedure of the in- vention, elevator groups 20 and 21 serve passengers going to the sky lobby H, and to reduce the number of passengers arriving there it is possible to exclude some elevators from groups 21 or 20 or operate the elevators with a lower degree of admission, i. e. with cars not completely filled. The arrivals of elevator groups 21 and 20 at the sky lobby H can also be re-

tarded by influencing their stopping times, i. e. also the speed of opening and closing of elevator doors and the length of time the doors remain open, or by reduc- ing the acceleration of the elevators or by lowering their top speed. The speed of service of the shuttle elevators 22 from the sky lobby can be increased by automatically returning unoccupied elevators there without an external call. Other expedients for accel- erating the arrival of elevators 22 at floor I include <BR> <BR> increasing the accelerantion of the elevators, increas- ing the top speed, lowering the level of service for incoming traffic of people traveling from the ground floor I to upper floors in the building.

It is obvious to the person skilled in the art that different embodiments of the invention are not limited to the example described above, but that they may be varied within the scope of the claims presented below.