WO2020098945A1

WO2020098945A1 - An elevator system equipped with a load-bearing belt system and a tension equalizing device

Info

Publication number: WO2020098945A1
Application number: PCT/EP2018/081423
Authority: WO
Inventors: Sergio ROTH; Christopher PIMENTEL
Original assignee: Thyssenkrupp Elevator Innovation And Operations Ag
Priority date: 2018-11-15
Filing date: 2018-11-15
Publication date: 2020-05-22

Abstract

The invention relates to an elevator system comprising a load-bearing belt system adapted to support an elevator cabin, and a device which is adapted to respond to changes in the tension distribution throughout the load-bearing belt system. The invention also relates to a tension equalizing process in an elevator system comprising a load-bearing belt system.

Description

An elevator system equipped with a load-bearing belt system and a tension equalizing device

The invention relates to an elevator system equipped with a load-bearing belt system and a device for equalizing the tension distribution therein. An elevator system refers to all component parts related to a working elevator, e.g., elevator cabin, counterweight, cables. The terms “elevator” and“elevator system” are used interchangeably throughout. A load-bearing belt system comprises one or more load-bearing belts. Said belts are subject to constant stress and strain as a result of the load attached to it. Situations may arise when one or more than one load-bearing belt in these systems experiences a higher weight force compared to other load- bearing belts within the belt system.

When the weight of the elevator cabin, is not shared equally among the load-bearing belts, one or more belts experience an increase or decrease in tension. This can occur due to the slight variation in stretch of one belt compared to another belt. Preferably, belts in a load-bearing belt system have similar degrees of “stretch”, i.e., they can preferably withstand similar amounts of tension before breaking. In an ideal world, belts in a load-bearing belt system would be identical, with an identical degree of stretch. However, in reality, there are variations. Therefore, whilst a load-bearing belt system may comprise four identical belts, the stretch of these belts may not be so identical. In cases where a load-bearing belt system is already in operation and the belts have been used and exposed to substantial amounts of tension, said belts are likely to have varying degrees of length and consequently, varying degrees of stretch.

An imbalance of weight and consequently tension among the belts of a load-bearing belt system, causes the belts to wear faster and as such can lead to situations where at least one belt becomes damaged causing the other belts to compensate for it. The other belts will then wear out faster thus the lifetime of the overall belt system is significantly reduced. Furthermore, an elevator system which employs ropes as the load-bearing means requires larger pulleys than an elevator system which employs belts as the load-bearing means. Due to the difference in circumference values of the respective pulleys, the pulley used for an elevator system with belts must complete a higher number of rotations in order to allow the belt to cover the same amount of distance as the elevator system with ropes. A small difference in wearing between belts, however, generates a significantly larger accumulated difference in tension, i.e., stroke tension, compared to the tension generated in an elevator system with ropes. The excessive tension experienced by belts in an elevator system causes them to wear out faster than ropes. When the need for belt replacement occurs on a regular basis, it becomes not only inconvenient, due to the elevator being rendered out of service during the maintenance work, but also costly due to the requirement of manual labour and replacement parts. Once the elevator is serviced, it is just a matter of time before the next maintenance service becomes due.

It is thus desired to have an elevator system with load-bearing belts, which is“self-servicing” i.e., it can, without intervention of a technician, optimize its working conditions to improve the longevity of the load-bearing belt system.

The present invention aims to solve this problem by providing an elevator system comprising

(a) a load-bearing belt system adapted to support an elevator cabin and;

(b) a device adapted to equalize the tension distribution throughout the belt system, wherein the device is integrated with the elevator system so that it can constantly equalize any tension imbalance among the belts. The device can optionally be adapted to also measure the weight of the load experienced by the load-bearing belt system. . This provides an elevator system, with an improved lifespan, in particular, with an improved lifespan of the load-bearing belts. The measurement of weight distribution can advantageously provide information regarding the overall weight of the load and thus facilitates detection of possible excess weight applied to the belt system. This is useful for example, when an elevator controller has to calculate the amount of energy needed to start movement without causing any sudden directional changes which would be uncomfortable for the passengers travelling in the elevator cabin.

The elevator system according to the invention supports an elevator cabin via the load-bearing belt system. The device is adapted to respond to changes in tension distribution throughout the load-bearing belt system, and is optionally adapted to also measure the total weight of the cabin, e.g., when the cabin has no passengers, or when it is at or above capacity.

The device installed in the inventive elevator system comprises:

- one or more mechanical actuator, wherein a mechanical actuator comprises as component parts:

— a housing including a first fluid chamber and an outlet connection point;

preferably the device comprises two or more mechanical actuators, more preferably three or more mechanical actuators, most preferably four or more mechanical actuators. A preferred example of a mechanical actuator is a hydraulic cylinder, wherein the fluid chamber preferably comprises an amount of oil;

— a piston housing comprising a piston head and a piston rod, wherein said piston housing is adapted to guide the piston rod and is comprised within the housing;

- a pressure regulator comprising one or more outlets and a pressure gauge; the pressure regulator preferably comprises a second fluid chamber wherein said fluid is preferably oil. Preferably, the second fluid chamber is a fluid equalizing chamber. Preferably, the pressure regulator is adapted to register a total pressure change when there is a change in the total load. There is no limit to the number of outlets provided on the pressure regulating chamber. A most preferred number of outlets is in the range of between 1 to 10. Ultimately, the minimum number of outlets provided on the pressure regulator will depend upon the number of belts used within the load-bearing belt system. The outlets are adapted to connect with the at least one mechanical actuator via a fluid transportation means, e.g., a pipe or tubing. Preferably, the outlet connection point comprises an attachment means, e.g., a nozzle, which facilitates said attachment. The pressure regulator may also comprise at least one sensing mechanism, e.g., a sensor, wherein said sensing mechanism is preferably comprised within the pressure gauge. Preferably the sensing mechanism is adapted to be activated when an imbalance of tension among the belts of the load-bearing belt system occurs.

- a controller;

the pressure regulator is also preferably connected with the controller via an information transmitter, e.g., via a wire connection. This connection preferably provides for the transmission of signals from the pressure regulating chamber to the controller and vice versa. The controller is preferably adapted to read the total pressure of the load-bearing belt system, more preferably it is adapted to read the total pressure of the load-bearing belt system when a change in the total load arises. The controller is also preferably adapted to measure the total weight of the load on the load-bearing belt system. More preferably, the controller is adapted to measure the total weight of the load on the load-bearing system when a change in the total load arises and/or when a pressure differential arises among the one or more mechanical actuators. In such a situation, the sensing mechanism within the pressure gauge is preferably activated which is then detected by the controller. The controller then carries out a weight measurement. This is advantageous because the measurement of the total weight distribution provides information regarding the overall weight of the load supported by the load-bearing belt system and thus facilitates detection of possible excess weight applied to the belt system.

The load-bearing belt system comprises:

- one or more load-bearing belts, preferably two or more load-bearing belts, more preferably three or more load-bearing belts, most preferably four load-bearing belts. Each load-bearing belt preferably has at least one end termination, preferably two end terminations at each lengthwise end of the belt. It is preferred that a first end termination is connected to the device, and a second end termination is connected to the load, for example, an elevator cabin. This

advantageously provides for a direct connection between the load-bearing belt system with the mechanical actuators of the device. The mechanical actuators of the device are pressurized. Preferably each mechanical actuator is subjected to the same pressure, thereby ensuring that the force applied to each belt of the load-bearing belt system is the same.

A pressure differential or a pressure change preferably occurs when an imbalance of tension among the belts of the load-bearing belt system arises. Thus, a direct relationship exists between the tension of the belts of the load-bearing belt system and the measured pressure. When a pressure differential occurs, at least one of the mechanical actuators will experience either an increase or a decrease in its internal pressure. This change in pressure translates into a movement of at least one piston rod in an upwards or downwards direction.

Preferably this movement causes a transfer of oil between the fluid chamber of the mechanical actuator and the fluid equalizing chamber of the pressure regulator. This change in oil level at a first outlet in the fluid equalizing chamber causes the oil levels at the neighbouring outlets (which are connected to the other mechanical actuators) to compensate for the change and adjust accordingly. Consequently, an adjustment in the internal pressure of the neighbouring mechanical actuators also arises. Any adjustment of oil flow into or out of a fluid chamber of the mechanical actuator causes the respective piston rod to move in an upwards or downwards direction. It is possible that a number of piston rods will move in one direction whilst a number of piston rods will move in the opposite direction. It is also possible that a piston rod will not move whilst other piston rods move in opposite or the same direction.

The process of adjusting the internal pressure of the mechanical actuators continues until a new equilibrium internal pressure is reached.

The consequent movement of the piston rods causes the belts which are connected to the piston rods via their respective end terminations to also move in an upwards or downwards direction. This advantageously results in an equalization of the weight distribution among the belts of the load-bearing belt system and thus an equalization of the tension within the belts themselves.

This can be referred to as the equalization process. It is preferred that at the end of this process, each mechanical actuator is under the same pressure. In some cases, there may be a variation of pressure among the mechanical actuators, this can be dependent on the type and quality of belt in the load-bearing belt system.

It is also envisaged that when a change in the weight of the load occurs, or a tension imbalance occurs, either or both of which results in e.g., two belts of the load-bearing belt system experiencing an increase in tension and e.g., two belts of the load-bearing belt system experiencing a decrease in tension, it is possible that the subsequent increase and decrease in pressure at the respective mechanical actuators balance out. In this situation, the total pressure remains the same and no adjustment of piston rods and consequently load-bearing belts is required.

In a preferred embodiment of the invention, the mechanical actuator is adapted to better respond to changes in the tension distribution throughout the load-bearing belt system, i.e., better adapted to perform the equalization process. The adaptation involves removal or re shaping of one or more component part of the actuator. For example, the mechanical actuator can comprise no internal spring, this simplifies the equalization process and provides that the piston rod of the actuator is the main adjustable part within the actuator.

Another example is the removal of at least one seal from the piston housing, this helps reduce friction within the actuator. Removal of a seal from the housing in which the piston housing is comprised can also help reduce friction

Another example is the reduction in the length of the stroke, i.e., when the piston travels from top to bottom or vice versa.The stroke length can be reduced by about 10% to 60%, so for example, a stroke length of 120mm can be reduced to 50 mm. The term“about” includes values within ± 2% of the given values. This makes it easier to install the device, in particular the mechanical actuator, in the elevator system.

Another example is a reduction in the length of the piston housing. Normal operation requires that this part of the mechanical actuator is polished to a high degree. This increases its cost. A reduction in length can help reduce such costs, as well as facilitate installation of the devicein the elevator system.

In a preferred embodiment, the mechanical actuator can comprise one of the above adaptations or a combination of one or more in order to reduce belt tension deviation within the belt system. Each of these adaptions, taken either alone or in combination, advantageously improves the tension deviation, i.e., reduces the degree of deviation of tension between belts in a load-bearing belt system, whilst maintaining a quality ride of the elevator.

In a preferred embodiment of the invention, the piston rod comprised within the device of the elevator system has a stroke length in the range from 40 mm to 70 mm, more preferably in the range from 45 mm to 60 mm, most preferably in the range from 48 mm to 55 mm. This advantageously provides a device which can conform to a restricted space of an elevator system. In a preferred embodiment of the invention, the piston housing comprised within the device of the elevator system has a length in the range from 250 mm to 480 mm, more preferably in the range from 260 mm to 460 mm, most preferably in the range from 275 mm to 440 mm. This advantageously provides a device which can conform to the restricted space of an elevator system.

In a preferred embodiment of the invention each mechanical actuator is adapted to adjust its internal pressure according to the tension distribution in the load-bearing belt system. This advantageously allows for equalization of weight and tension among the belt system, thereby facilitating an elongation of the lifespan of the load-bearing belt system

In a preferred embodiment of the invention, the mechanical actuators of the device are adapted to operate under a pressure, preferably they are adapted to operate under a pressure of 0.0001 GPa to 0.1 GPa, more preferably, under a pressure of 0.001 GPa to 0.001 GPa, most preferably under a pressure 0.001 GPa to 0.01 GPa.

In a preferred embodiment, the device is positioned at any point around the load-bearing belt system in the elevator. It is most preferred that the device is positioned at the terminus of the belt system, i.e., at the end-point of the load-bearing belt system which is opposite to the elevator cabin attached. For example, a possible installation can be at a bedplate positioned on the top of the elevator shaft. The elevator bedplate is preferably adjustable. Another possible installation is on a level area or surface within the elevator such that the force of the weight of the elevator cabin acting on the load-bearing belt system is at its greatest.

The invention also relates to a tension equalizing process in an elevator system comprising a load-bearing belt system, wherein the process steps comprise:

a) installing a tension equalizing device into the elevator system and connecting the device with the load-bearing belt system. The device preferably comprising: one or more mechanical actuator said mechanical actuator comprising as component parts: a housing including a first fluid chamber; a piston housing comprising a piston head and a piston rod, wherein said piston housing is adapted to guide the piston rod; a pressure regulator comprising a second fluid chamber; and a controller. The device is preferably the same device as that detailed in the earlier section of this description. The load-bearing belt system preferably comprises one or more load-bearing belts having at least one end termination; b) transferring fluid, preferably oil, within the device, in particular, from a fluid chamber of a first mechanical actuator to a fluid chamber of at least one further mechanical actuator. More preferably this involves the transferring of oil from the fluid chamber of at least one mechanical actuator to the fluid equalizer chamber of the pressure regulator at the corresponding outlet, and the consequent transferring of oil from the fluid equalizer chamber of the pressure regulator to the fluid chamber or chambers of the remaining mechanical actuators of the device;

c) causing the piston rod of at least one mechanical actuator to move in an upwards or downwards direction in response to the transfer of fluid between the respective fluid chambers of the mechanical actuators and the pressure regulator;

d) returning the internal pressure of the mechanical actuators of the device to equilibrium.

This process is preferably reversible until an equilibrium pressure among all mechanical actuators is reached, and consequently, an equalization in tension among the belts of the load- bearing belt system in the elevator is achieved. The process can optionally further comprise the steps of:

e) activating the controller when a pressure differential occurs; and

f) measuring the total weight of the load.

This provides further information which may be of use for example, to an elevator controller.

The above described embodiments are intended as examples of the invention and are in no way intended as limitations. The invention is described in more detail with the help of the figures, wherein it is shown schematically

Fig. 1 shows a representation of a belt wearing on a pulley and a rope wearing on a pulley.

Fig. 2 shows a frontal view of an elevator system according to an embodiment of the invention comprising a load-bearing belt system and a tension equalizing device.

Fig. 3a shows a frontal view of an elevator system according to an embodiment of the invention comprising a load-bearing belt system and a tension equalizing device when an imbalance of tension exists between belts.

Fig. 3b shows a frontal view of the elevator system according to an embodiment of the invention comprising a load-bearing belt system and a tension equalizing device after an equalization process has occurred. herein it is shown schematically

Fig. 1 shows the set-up of an elevator comprising a rope wearing on a pulley 01 and an elevator comprising a belt wearing on a pulley 02. For ease of reference, the configuration of only one belt/pulley 02 and one rope/pulley 01 is shown, however, the experimental data recorded in tables 1 and 2 below was obtained using an elevator having four belts and an elevator having four ropes. The ratio of belts to pulleys was 1: 1 and the ratio of ropes to pulleys was 1: 1. Wear on a belt can be calculated using the following stroke tension calculation. Stroke tension refers to how much a cylinder should be moved in order to compensate for the tension generated from different belts.

(iV - 1) * fl2fl * we * S

Stroke T ension = - - - p * D where:

N=number of elevator stops fl2fl=measure from floor to floor (mm) we= wearing measure difference from 2 different belts (mm)

S= suspension system (1 for 1: 1 system, 2 for 2: 1 system)

D=traction pulley diameter (mm)

Tables 1 and 2 show the variation in tension for an elevator system comprising the belt wearing on a pulley 02 and an elevator system comprising the rope wearing on a pulley 01. It is shown in table 1, that a small wearing difference in belts, generates a significantly larger accumulated tension when compared to that of the elevator system with ropes (see table 2).

With such a significant difference in tension, i.e., stroke tension between belts and ropes, there is a clear need to provide an elevator system which can overcome this drawback and make elevator systems with belts more efficient. The elevator system 500 according to the invention provides a solution to this problem by integrating a tension equalizing device 100 with a load- bearing belt system 400.

Figure 2 shows in more detail the device 100 used in the inventive elevator system 500 according to an embodiment of the invention. The device 100 is attached to the load-bearing belt system 400 comprising four belts 8, 9, 10, 11. The load-bearing belt system 400 in this embodiment is attached to and supports the elevator cabin L (not shown). The direction of weight of the cabin L is represented by arrow D. The device 100 is adapted to measure and respond to changes of weight experienced by the load-bearing belts 400. The device 100 is adapted to operate by regulating the weight force distribution and thus tension among the belts

8, 9, 10, 11 of the belt system 400.

The load-bearing belt system 400 shown in figure 2 comprises four belts; a first elevator belt 8 comprising an end termination 81 opposite the elevator cabin L, a second elevator belt 9 comprising an end termination 91 opposite the elevator cabin L, a third elevator belt 10 comprising an end termination 101 opposite the elevator cabin L and a fourth elevator belt 11 comprising an end termination 111 opposite the elevator cabin L. The first belt 8, the second belt

9, the third belt 10 and the fourth belt 11 are attached to the same elevator cabin L. Taking the first belt 8 and its end termination 81 as an example; the end termination 81 is an intermediary between the device 100 and the elevator belt 8, and allows for a connection of the elevator belt with the device 100.

In the event, for example, the first belt 8 experiences a larger weight in the direction D compared to the remaining belts 9, 10 and 11, the device 100 detects an imbalance and manoeuvers to counteract it via an upwards or downwards movement of a piston rod 14, 24, 34, 44. Such a movement results in an upwards or downwards movement of the load-bearing belt system 400. The upward and/or downward movement may be in relation to the first belt 8 which experiences the additional weight, or the remaining second belt 9, third belt 10 or fourth belt 11. The aim of the counteraction movement is to achieve an equalization of weight distribution and thus tension between all belts (first belt 8, second belt 9, third belt 10, fourth belt 11) within the load-bearing belt system 400. Said movement affects the load-bearing belt system 400 only, and the position of the elevator cabin itself preferably remains unchanged. (Figures 3a and 3b show more clearly the possible variation in movement of the belt system 200.)

The inventive elevator system 500 is adapted to achieve the above via the integration of the device 100 and its component parts:

- a first mechanical actuator la comprising a housing 1 having an outlet connection point 12; a first fluid chamber (not shown); a piston housing 11 comprising a piston head 13 and a piston rod 14, wherein the piston housing is comprised within the housing 1. The piston rod 14 extends from the housing 1 via the piston head 13 such that the piston rod 14 is connectable to the load- bearing belt 8, preferably it is connected via the end termination 81 of the load-bearing belt 8;

- a second mechanical actuator 2acomprising a housing 2 having an outlet connection point 22; a first fluid chamber (not shown); a piston housing 21 comprising a piston head 23 and a piston rod 24, wherein the piston housing is comprised within the housing 2. The piston rod 24 extends from the housing 2 via the piston head 23 such that the piston rod 24 is connectable to the load- bearing belt 9, preferably it is connected via the end termination 91 of the load-bearing belt 9;

- a third mechanical actuator 3acomprising a housing 3 having an outlet connection point 32; a first fluid chamber (not shown); a piston housing 31 comprising a piston head 33 and a piston rod 34, wherein the piston housing is comprised within the housing 3. The piston rod 34 extends from the housing 3 via the piston head 13 such that the piston rod 34 is connectable to the load- bearing belt 10, preferably it is connected via the end termination 101 of the load-bearing belt 10;

- a fourth mechanical actuator 4a, comprising a housing 4 having an outlet connection point 42; a first fluid chamber (not shown); a piston housing 41 comprising a piston head 43 and a piston rod 44, wherein the piston housing is comprised within the housing 4. The piston rod 44 extends from the housing 4 via the piston head 43 such that the piston rod 44 is connectable to the load- bearing belt 11, preferably it is connected via the end termination 111 of the load-bearing belt 11;

- a pressure regulator 5 comprising a number of outlets 51, 52, 53, 54, 55, a second fluid chamber (not shown), in particular, a fluid equalizing chamber and a pressure gauge 57;

- at least one fluid transportation means 6a and at least one information transmitter 6b, wherein the fluid transportation means 6a connects the mechanical actuators la, 2a, 3a, 4a at their respective outlet connection points 12, 22, 32, 42 with the outlets 51, 52, 53, 54 of the pressure regulator 5;

- a controller 7, wherein the controller 7 is connected to the pressure regulator 5 via an information transmitter 6b, e.g., a wire connection.

The mechanical actuators la, 2a, 3a, 4a shown herein are hydraulic cylinders. The cylinders shown in this example are subjected to the same pressure, thus, the same pressure is applied to each of the belts 8, 9, 10, 11. This in turn ensures that the weight of the load, e.g., the elevator cabin L, is shared equally among all four belts, thus also ensuring that the tension within the first belt 8 is equal to the tension within the second belt 9, the third belt 10 and the fourth belt 11. The device 100 is positioned above an elevator bed plate 300. The elevator bed plate 300 is adjustable according to requirements.

The outlets 51, 52, 53, 54, 55 of the pressure regulator 5 serve as entry ports to the fluid equalizing chamber (not shown). In this example, only four outlets 51, 52, 53, 54 of the pressure regulator 5 are required. When each of the outlets 51, 52, 53, 54 are connected with a fluid transportation means 6a, a fluid travel path is created between the hydraulic cylinders la, 2a,

3a, 4a, in particular, between the first fluid chamber of each hydraulic cylinder and the fluid equalizing chamber of the pressure regulator 5. The pressure regulator 5 also comprises a pressure gauge 57, wherein the pressure gauge 57 comprises an outlet 56 to allow the regulator 5 to be connected to the controller 7 via an electric cable 6b; and a monitoring window (not shown) to allow the pressure to be monitored. The pressure gauge 57 monitors the pressure applied to each cylinder la, 2a, 3a, 4a.

During normal operation of the elevator, the belts 8, 9, 10, 11 are subjected to tension and stretching can occur. If for example the first belt 8 of the load-bearing belt system 400 stretches more than the second belt 9, and/or the third belt 10 and/or the fourth belt 11 of the load- bearing belt system 400, then a tension imbalance within the load-bearing belt system 400 occurs. Any imbalance in tension results in a pressure change within the respective hydraulic cylinders la, 2a, 3a, 4a. Said pressure change is caused by a first transfer of oil between the first fluid chamber of the first cylinder la and the fluid equalizing chamber of the pressure regulator 5, and a subsequent compensating transfer of oil between the fluid equalizing chamber of the pressure regulator 5 at the corresponding outlets of the respective first fluid chambers of the remaining hydraulic cylinders 2a, 3a, 4a. This transfer of oil causes a change in pressure of the hydraulic cylinders la, 2a, 3a, 4a, which translates to a movement in an upwards or downwards direction of the respective piston rods 14, 24, 34, 44. Since the cylinders la, 2a, 3a, 4a are attached to the end terminations 81, 91, 101, 111 of the belts 8, 9, 10, 11 via the piston rods 14, 24, 34, 44, any repositioning of the piston rods 14, 24, 34, 44 causes the respective end terminations 81, 91, 101, 111 and thus the belts 8, 9, 10, 11 to also move in an upwards or downwards direction. The degree of said movement is dependent on the detected pressure difference between the respective cylinders la, 2a, 3a, 4a.

The controller 7 is adapted to detect the total pressure change e.g., when the load of the cabin changes, and measures the total weight force of the overall load which is supported by the belts 8, 9, 10, 11. This allows for example, an elevator controller to calculate the amount of energy needed to achieve a smooth movement of the elevator. Figure 3a shows the elevator system 500 as described in figure 2 when there is an imbalance of tension among the belts 8, 9, 10, 11 of the load-bearing belt system 400. Figure 3b shows the movement of the belts 8, 9, 10, 11 of the load-bearing belt system 400 after the equalization process is carried out.

The equalization process is shown in figures 3a and 3b. In figure 3a, the tension on the first belt 8 and the third belt 10 has decreased causing the pressure within the respective cylinders la and 3a to also decrease. This change in pressure translates into a movement of the piston rod 14 and the piston rod 34 in a downwards direction causing the end termination 81 of the first belt 8 and the end termination 101 of the third belt 10 to shift towards to the elevator cabin (as shown by the downwards arrow A and B respectively). This movement causes a transfer of oil between the first fluid chamber of the first cylinder la and the fluid equalizing chamber of the pressure regulator 5 at the outlet 51, as well as a transfer of oil between the first fluid chamber of the third cylinder 3a and the fluid equalizing chamber of the pressure regulator 5 at the outlet 53. A pressure change results. The oil level at the neighbouring two outlets 52 and 54 (which are connected to the second cylinder 2a and the fourth cylinder 4a respectively) of the pressure regulator 5 then adjusts to compensate for the pressure change. This causes the internal pressure of the second and fourth cylinders 2a, 4a respectively to also change.

Consequently, as can be seen in figure 3b, the piston rod 14 of cylinder la then moves in an upwards direction (see arrow C), as does the piston rod 34 of cylinder 3a (see arrow E). The piston rod 24 of the second cylinder 2a and the piston rod 44 of the fourth cylinder 4a move in the opposite direction i.e., downwards (arrows D and F respectively). Thus the first belts 8 and third belt 10 are stretched while the second belt 9 and the fourth belt 11 are relaxed. This re establishes an equal tension between all belts (the first belt, 8, the second belt 9, the third belt 10, the fourth belt 11) of the load-bearing belt system 400, thus concluding the equalization process. Preferably, an equilibrium pressure is also restored.

The following tables show experimental data relating to the tension experienced within the elevator system 500 comprising a load-bearing belt system 400 with four belts 8, 9, 10 11.

Table 3 shows when no tension equalization occurred (scenario 1). Table 4 shows the difference when tension equalization occurred (scenario 2), The tension within the belt system was measured over two tests in each scenario, and readings were taken on the 10^th, 8^th, 6^th, 4^th and 2^nd floors respectively. Measuring the tension of each elevator belt at the same position allows for a comparison of values of each belt with an average value and inspection of any deviation.

KEY loosest belt tension

tightest belt tension (reference)

over the limit of 10% reference to tightest belt tension under the limit of 10% reference to tightest belt tension

KEY loosest belt tension

tightest belt tension (reference)

KEY loosest belt tension

tightest belt tension (reference)

KEY

* loosest belt tension

** tightest belt tension (reference)

⁺ over the limit of 10% reference to tightest belt tension

+⁺ under the limit of 10% reference to tightest belt tension

These results demonstrate that by incorporating a tension equalization process into the normal operation of an elevator system, significant improvements in tension distribution throughout the belt system 400 can be achieved, and consequently, an improvement in the lifespan of the belts involved. This ultimately benefits the elevator system as a whole. Reference list

100 tension equalizing device

200 load-bearing belt system 400 attached to device 100

300 elevator bed plate

400 load-bearing belt system

500 elevator system

01 rope wearing on a pulley

02 belt wearing on a pulley

D 1 diameter when belt is on pulley

D2 diameter of pulley la first mechanical actuator

1 housing

11 piston housing

12 outlet connection point

13 piston head

14 piston rod

2a second mechanical actuator

2 housing

21 piston housing

22 outlet connection point

23 piston head

24 piston rod

3a third mechanical actuator

3 housing

31 piston housing

32 outlet connection point

33 piston head

34 piston rod

4a fourth mechanical actuator 4 housing

41 piston housing

42 outlet connection point

43 piston head

44 piston rod

5 pressure regulator

51 first outlet

52 second outlet

53 third outlet

54 fourth outlet

55 fifth outlet

56 outlet

57 pressure gauge

6a fluid transportation means 6b information transmitter

7 controller

8 first elevator belt

81 first end termination

9 second elevator belt

91 second end termination

10 third elevator belt

101 third end termination

11 fourth elevator belt

111 fourth end termination

D direction of weight

L elevator cabin

Claims

1. An elevator system (500) comprising

(a) a load-bearing belt system (400) adapted to support an elevator cabin (L) and

(b) a device (100),

wherein the device (100) is adapted to respond to changes in the tension distribution throughout the load-bearing belt system (400),

wherein the device (100) comprises:

- one or more mechanical actuator (la, 2a, 3a, 4a) said mechanical actuator comprising as component parts:

- a housing (1, 2, 3, 4) including a first fluid chamber;

-a piston housing (11, 21, 31, 41) comprising a piston head (13, 23, 33, 43) and a piston rod (14, 24, 34, 44) wherein said piston housing (11, 21, 31, 41) is adapted to guide the piston rod (14, 24, 34, 44);

- a pressure regulator (5) comprising a second fluid chamber;

wherein the load-bearing belt system (400) comprises:

- one or more load-bearing belts (8, 9, 10, 11) having at least one end termination (81, 91,

101, 111)

wherein the load-bearing belt system (400) is connected with the load (L) and the device (100).

2. The elevator system (500) according to claim 1 characterized in that the mechanical actuator (1, 2, 3, 4) is adapted respond to changes in tension distribution throughout the load- bearing belt system (400), wherein said adaption involves the removal or re-shaping of one or more component part.

3. The elevator system (500) according to claims 1 or 2, characterized in that at least one

piston rod (14, 24, 34, 44) has a stroke length in the range from 40 mm to 70 mm.

4. The elevator system (500) according to any of the preceding claims, characterized in that at least one piston housing has a length in the range from 250 mm to 480 mm.

5. The elevator system (500) according to any of the preceding claims characterized in that the piston rod (14, 24, 34, 44) of the mechanical actuator (1, 2, 3, 4) comprised in the device (100) is adapted to move in an upwards or downwards direction upon a change in tension among the one or more belts (8, 9, 10, 11) of the load-bearing belt system (400) during operation of the elevator system (500).

6. The elevator system (500) according to any of the preceding claims characterized in that the one or more mechanical actuator (1, 2, 3, 4) of the device (100) is adapted to adjust its internal pressure according to the tension distribution in the load-bearing belt system (400).

7. The elevator system (500) according to any of the preceding claims characterized in that the one or more mechanical actuator (1, 2, 3, 4) of the device (100) is adapted to operate under a pressure range of 0.0001 GPa to 0.1 GPa.

8. A tension equalizing process in an elevator system (500) comprising a load-bearing belt system (400), wherein the process steps comprise:

a. installing a device (100) into the elevator system (500) and connecting the device (100) with the load-bearing belt system (400), wherein the device (100) comprises:

- one or more mechanical actuator (la, 2a, 3a, 4a) said mechanical actuator comprising as component parts: a housing (1, 2, 3, 4) including a first fluid chamber; a piston housing (11, 21, 31, 41) comprising a piston head (13, 23, 33, 43) and a piston rod (14, 24, 34, 44);

- a pressure regulator (5) comprising a second fluid chamber;

wherein the load-bearing belt system (400) comprises:

101, 111);

b. transferring fluid, from a fluid chamber of a first mechanical actuator (la, 2a, 3a, 4a) to a fluid chamber of at least one further mechanical actuator (la, 2a, 3a, 4a), wherein this process is reversible until an equilibrium pressure among the load-bearing belts is reached.