WO2015078859A1

WO2015078859A1 - Improvements in or relating to elevators

Info

Publication number: WO2015078859A1
Application number: PCT/EP2014/075533
Authority: WO
Inventors: Joe Zhou
Original assignee: Inventio Ag
Priority date: 2013-11-29
Filing date: 2014-11-25
Publication date: 2015-06-04

Abstract

An improved elevator apparatus is disclosed which has variable speed of operation depending on whether the selected calling points (114) are in a low speed zone or a high speed zone. A braking device (119) is controlled by a speed detection device (112) that may be set according to different thresholds.

Description

IMPROVEMENTS IN OR RELATING TO ELEVATORS

The present disclosure relates to improvements in or relating to elevators, and in particular to an improved variable speed elevator.

The transportation efficiency of an elevator system depends on its rated speed. However the capabilities of a traction machine used to cause the elevator to ascend and descend in a hoistway are not ful!y used, as the rated speed has to take account of various safety factors.

Transportation efficiency can be improved with use of a variable speed elevator. However, a headroom height required above the hoistway shaft and a pit depth below the hoistway shaft are defined by the higher speed, meaning that the elevator system stil! takes up a lot of space in a building.

A variable speed elevator may be provided with a speed detection device at a terminal zone of an elevator car running path to continuously inspect elevator speed and position. The terminal zone may include the bottom floor and top floor. Forjudging whether the elevator speed is within acceptable limits, this control system has a central processor to generate speed patterns, and to continuously calculate the position and speed of elevator. The control system compares the calculated position and speed, with speed patterns. If the speed of elevator exceeds the requirement of the speed patterns, the control system will implement the brake system of traction machine immediately, and stop the elevator. For an elevator to run safely, this control system must be independent from the elevator machinery. Therefore, this control system is very complex, and also adds to the cost of the elevator system.

It would be desirable to implement a variable speed elevator system that can enable a smaller headroom height and/or pit depth, but at the same time avoiding the need for complex and expensive control systems.

According to a first aspect of the disclosure there is provided an elevator apparatus comprising a car for ascending and descending in a hoistway between different calling points; a control system that assigns a car speed threshold according to the calling point position of the car, wherein one or more calling points are allocated to a low speed zone and the remaining calling points are allocated to one or more high speed zones; a braking device for stopping the elevator car and comprising a speed detection device that detects the speed of the elevator car and operates the braking device if the elevator car speed exceeds a predetermined threshold, said speed detection device being arranged to selectively adjust the predetermined threshold in response to a control signal from the control system between a first threshold and one or more other higher thresholds; and a safety switch that is activated when the car enters the low speed zone and which prompts the control system to adjust the speed detection device to its lowest speed threshold.

Optionally the predetermined threshold comprises a running speed pattern comprising an acceleration portion, a constant speed portion and a deceleration portion.

Optionally, the low speed zone comprises one or more adjacent calling points at one or more ends of the hoistway.

Optionally, the low speed zone speed threshold is equal to a strike speed limitation set by a car buffer and/or a counterweight buffer.

Optionally, the speed detection device comprises a trigger component that moves under centrifugal force to engage with a speed detection switch.

Optionally, the safety switch comprises a switch component provided at the hoistway and a trigger component provided at the elevator car.

The disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic illustration of selected aspects of an elevator system;

Figure 2 illustrates an embodiment of a speed detection device for use in the elevator system of figure 1 ;

Figure 3 is a graph illustrating various available running speed patterns according to an embodiment of the disclosure; and

Figure 4 illustrates aspects of a low speed zone of an elevator system.

Aspects of a cable elevator system are shown schematically in figure 1. An elevator car 100 ascends and descends within a hoistway 102. The car 100 is connected to a counterweight 104 by a rope 106 that extends over a drive device 108 which comprises a driving sheave 110, speed detection device 112, and a brake device 119. The elevator car 100 is arranged to stop at various calling points 1 14, which may be different floors of a building. These are represented by dotted lines in the figure, showing the position of the lower part of the car 100 for each calling point. The car 100 and counterweight 104 run on guide rails. A safety gear 116 is also provided at the car 100. A car buffer 1 15, counterweight buffer 117 and control system 118 are also provided.

The disclosure allocates the calling points (floors) of the elevator to two types of speed zones, a high speed zone and a low speed zone. The low speed zone comprises at least the top and bottom calling points, and may optionally comprise a set of top-most and/or a set of bottom-most calling points, for example the top three and the bottom three calling points. The high speed zone may optionally comprise a plurality of high speed zones.

An elevator system according to the disclosure comprises a speed detection device 1 12, which is preferably installed at the running components of the system, for example in a speed governor formed as part of a speed detection device 1 12. The speed detection device 1 12 comprises one or more speed detection switches, which trigger the brake device 1 19 when a specific speed threshold is met or exceeded. These specific speed threshold(s) correspond to permitted speeds in the high speed zone.

An example of a speed detection device 112 is shown in figure 2. This example speed detection device comprises components that are selectively operable for use in three different speed zones. It will be appreciated that the number of speed zones could be varied. The device 1 12 comprises speed detection switches 200, 202, 204 and speed triggers 206, 208, 210. The innermost speed detection switch 200 operates when the lowest speed is detected, and successive outer speed detection switches operate when successively greater speeds are detected. The speed triggers 206, 208, 210 can detect speed of the elevator car and activate the detection speed switches 200, 202, 204 accordingly. These components may be installed on an overspeed governor. The speed triggers may be centrifugal blocks 206, 208, 210. The speed switches 200, 202, 204 are installed at different radial positions and are static. That means these switches 200, 202, 204 can be activated by different speeds, when the respective speed trigger comes into engagement with the speed switch. The position of these centrifugal blocks can be changed when a pulley speed of governor changes. It is also possible to use one centrifugal block to trigger a plurality of speed switches. In the high speed zone, there may be multiple speeds. The value of these speeds can depend on the load in the car, which can be measured by a car weight sensor installed at the end-connection of rope, car frame or car body. That means if destination calling points are located in the high speed zone, the elevator can have different operation speeds according to the load in the car. If the car's load is balanced with the counterweight, the car speed can be set to a maximum value.

In the high speed zone, the car speed can be monitored by speed detection switches 200, 202, 204. For example, in high speed zone there may be three operation speeds, which means there will be three speed detection switches and three limitation speeds accordingly. If the car operation speed exceeds the limitation speed, the brake device 119 will be implemented by elevator control system.

If a destination floor is located in high speed zone, the elevator operation speed may be set to one of a number of operation speed curves, as shown in figure 3. Here, the elevator car has four operation speeds, meanwhile there are four speed limitations. Operation speed curves 300 are shown for each operation speed, and each comprises an acceleration portion, a constant speed portion, and a deceleration portion. The operation speeds shown by the graphs 300 are designed to be slightly less than respective speed limitations 302, 304, 306, 308. As well as these four speed limitation, there is a maximum speed limitation 310, beyond which safety gear 116 will be triggered.

Different operation speeds may have different speed limitations associated with them. In these speed limitations, the brake device 1 19 will be triggered if elevator running speed exceeds the speed limitation. If elevator speed exceeds the maximum speed limitation 310, the safety gear 116 will be activated by the overspeed governor.

In the high speed zone, two types of overspeed protection are provided: one is protection provided by the safety gear 1 16, another is protection provided by the brake device 119. The protection of safety gear is used for the maximum speed. The protection of the brake device 119 is used for the other speeds. When the car speed reaches the limit of the other speeds, the control system 118 can enable the brake device 1 19 according to the detection speed switches.

The operation speed of elevator may be set by the control system 1 18 according to the load in the car. Figure 3 shows examples of different operation speeds that can be set, as defined by the speed curves which show the speed between initial and final calling points. Before the elevator will operate, the control system 1 18 gets information of the load in the car from a car weight sensor, and sets the operation speed according to the load in the car. Then the elevator can run with this operation speed. Once the operation speed is set by control system, a corresponding speed limitation 302, 304, 306, or 308 is also set. In figure 3, every speed limitation 302, 304, 306, or 308 has a corresponding speed detection switch 200, 202, 204, such as those shown in figure 2. For example, the speed limitation 302 has speed detection switch 200, the speed limitation 304 has speed detection switch 202. The control system 118 can judge if the elevator speed exceeds the speed limitation 302, 304, 306, 308 by the speed detection switch 200, 202, 204, which is set in advance. If a speed detection switch is activated, it means the elevator speed exceeds the speed limitation 302, 304, 306, or 308. At this moment, elevator control system will let the brake device 1 19 work immediately and stop the elevator.

In the low speed zone, overspeed protection is provided only by the brake device 1 19. If the speed of the car exceeds the speed limitation 302 of the low speed zone, the detection speed switches 200 of the speed detection device 1 12 work instantly. Meanwhile the brake device 1 19 will also operate and stop the car immediately.

In the low speed zone, a safety switch 404 is installed at the elevator car, and safety triggers 406, 408 are instal led at the hoistway shaft, for example on the elevator car guide rails, in the low speed zone only. An example implementation is shown in figure 4. Here, an elevator car 100 is shown at two different calling points 400, 402. The elevator car 100 is provided with a safety switch 404 which can be actuated by safety triggers 406, 408 which are provided at first and second calling points 400, 402. The safety triggers 406, 408 are used to monitor the car position and may comprise a bar of sufficient length, as shown in figure 4. When the car runs in the low speed zone, the safety triggers 406, 408 are in contact with the safety switch 404, which means these triggers 406, 408 keep monitoring the car position. By this function of safety triggers 406, 408, the control system of elevator can know that the car 100 is running in the low speed zone. If the safety switch 404 is not activated, the control system can infer that the car position is in the high speed zone, otherwise the car position is inferred to be in the low speed zone.

When the elevator car is detected as being in the low speed zone by a safety switch and trigger, the speed detection device is switched so that the speed detection switch associated with the lowest running speed, or the innermost speed detection switch 200, is activated. This means that the low speed zone speed limitation curve (302 in figure 3) is applied and the brake device 1 19 will operate if this speed limitation is exceeded. In the high speed zone, there is no safety trigger, so the safety switch 404 cannot be activated. In the low speed zone, if car speed exceeds a low speed limitation 302, the elevator implements the emergency stop by the brake device 1 19 of drive device 108. This emergency stop is triggered by the lowest speed, or innermost, detection speed switch 200.

In low speed zone, only the brake device 1 19 is employed, because the elevator car speed is low. In high speed zone, both the safety gear 1 16 and the brake device 1 19 are employed.

If a destination floor is located in low speed zone, the elevator operation speed is set to a low operation speed curve, as shown in figure 3 which illustrates an operation speed curve for a low speed 300 of car operation, and a low speed limitation 302. If an elevator car speed exceeds the speed limitation 302, the detection speed switch 200 will be activated and the control system 1 18 will implement the brake device 1 19 immediately according to the detection speed switch 200.

In the low speed zone, the elevator car speed is limited by speed limitation 302. This value of speed limitation 302 may be set equal to a strike speed limitation of a car buffer 1 15 and/or a

counterweight buffer 1 1 7. These will generally have the same strike speed limitation although in the event that they are different either one may e chosen as the basis for the speed limitation 302. That means the pit depth and headroom height are defined by the speed limitation 302.

To simplify the control system, the elevator system uses safety switches 404 to detect the position of the car in the low speed zone, and uses detection speed switches 200 to monitor car speed. When the car is in low speed zone, the safety switch 404 works. At that moment, if the speed of elevator is over the speed requirement of low speed zone, the detection speed switch 200 works, and the brake device 1 19 works immediately and stops the elevator.

This disclosure can reduce headroom height and/or pit depth by limiting the elevator speed in the low speed zone. Also, the cost of the elevator system is reduced and the control system is simplified. Transport efficiency is improved and the technology can be retrofitted to existing elevator systems.

Various improvements and modifications can be made to the above without departing from the scope of the disclosure.

Claims

1. An elevator apparatus comprising:

a car (100) for ascending and descending in a hoistway (102) between different calling points (114);

a braking device (119) for stopping the elevator car (100);

a control system (1 18) that assigns a car speed threshold according to the calling point (1 14) position of the car (100); wherein one or more calling points (1 14) are allocated to a low speed zone in which the car runs with a lowest speed, and the remaining calling points are allocated to one or more high speed zones, in which the car can run with different operation speeds set according to the load in the car;

a speed detection device (112) that detects the speed of the elevator car (100) and operates the braking device (119) if the speed of the elevator car (100) exceeds a predetermined speed threshold, said speed detection device (112) being arranged to selectively adjust, in response to a control signal from the control system (118), the predetermined speed threshold between a lowest speed threshold and one or more higher speed thresholds according to the different operation speeds in the high speed zones;

a safety switch (404, 406, 408) that is activated when the car (100) enters the low speed zone and which prompts the control system to adjust the speed detection device (1 12) to its lowest speed threshold.

2. The elevator apparatus of claim 1 , wherein the predetermined threshold comprises a

running speed pattern comprising an acceleration portion, a constant speed portion and a deceleration portion.

3. The elevator apparatus of claim 1 or claim 2, wherein the low speed zone comprises one or more adjacent calling points (114) at one or more ends of the hoistway (102),

4. The elevator apparatus of any preceding claim, wherein the low speed zone speed threshold is equal to a strike speed limitation set by a car buffer (1 15) and/or a counterweight buffer ( 1 17).

5. The elevator apparatus of any preceding claim, wherein the speed detection device (1 12) comprises a trigger component (206, 208, 210) that moves under centrifugal force to engage with a speed detection switch (200, 202, 204).

6. The elevator apparatus of any preceding claim, wherein the safety switch comprises a switch component (404) provided at the elevator car (100) and a trigger component (406, 408) provided at the hoistway (102).