Method for operating an elevator

Abstract

The invention relates to a method for operating an elevator installed in connection with a building, particularly a high rise elevator, in which method the expected rope sway is monitored using building acceleration data obtained by means of a sensor to calculate a building sway, and whereby based on the building sway and the position of an elevator car a rope sway is estimated, which rope sway is compared with a threshold value to determine the amount of rope sway and to deduct operation measures for the elevator based on the amount of the rope sway, characterized by the succession of following steps determining elevator car position determining change of rope sway based on the car position and the building acceleration data if it is concluded that rope sway is not increasing, then calculating the number of rope sway cycles n(zca,) within a building sway period Tbuilding and calculating a new (decreasing) rope sway amplitude x based on said number of rope sway cycles n(zca,) and a damping factor I.

Claims

1. A method for operating an elevator installed in connection with a building, the method comprising: determining an elevator car position of an elevator car in the elevator; determining a rope sway amplitude of a rope sway of a rope coupled to the elevator car based on the elevator car position and a building sway of the building, the building sway determined based on building acceleration data obtained from a building acceleration sensor of the building; determining whether the rope sway is increasing based on the determined rope sway amplitude; in response to a determination that the rope sway is not increasing, calculating a number of rope sway cycles n(Z.sub.car) of the rope sway within a constant time period, and calculating a new decreased rope sway amplitude x of the rope sway based on the number of rope sway cycles n(Z.sub.car) and a damping factor ζ; and controlling an operation of the elevator based on a comparison of the new decreased rope sway amplitude x with a threshold value.

2. The method of claim 1, wherein the constant time period is a building sway period T.sub.building.

3. The method claim 2, wherein the number of rope sway cycles n(Z.sub.car) within the building sway period T.sub.building is calculated according to Equation 1: $\begin{array}{cc}n\left(z_{\mathrm{car}}\right)=\frac{T_{\mathrm{building}}}{T_{\mathrm{rope}}\left(z_{\mathrm{car}}\right)}& \left[\mathrm{Equation}1\right]\end{array}$ wherein, in Equation 1, T.sub.rope is an elevator rope segment period, and Z.sub.car is the elevator car position.

4. The method of claim 3, wherein the new decreased rope sway amplitude x is calculated according to Equation 2:
x(t.sub.0+T.sub.building)=x(t.sub.0).Math.e.sup.−2πnζ  [Equation 2] wherein, in Equation 2, x(t.sub.0) is the determined rope sway amplitude, x(t.sub.0+T.sub.building) is the new decreased rope sway amplitude x, and n is the number of rope sway cycles n(Z.sub.car) within the building sway period T.sub.building.

5. The method of claim 1, wherein the controlling the operation of the elevator includes changing a car speed of the elevator car.

6. The method of claim 1, wherein the controlling the operation of the elevator includes changing a floor stopping time of the elevator car.

7. The method of claim 1, wherein the controlling the operation of the elevator includes temporarily excluding one or more landing floors of the elevator from service.

8. An elevator configured to be installed in a building, the elevator comprising: an elevator car and a counterweight in an elevator shaft, the elevator car and the counterweight connected via one or more ropes, at least one rope of the one or more ropes extending over a sheave; an elevator motor configured to drive the sheave to cause the elevator car and the counterweight to move in the elevator shaft; and an elevator controller configured to control an operation of the elevator based on a result of a comparison of a particular rope sway amplitude of a rope sway of a rope of the one or more ropes with a threshold value, wherein the particular rope sway amplitude is determined based on determining an elevator car position of the elevator car in the elevator, determining a rope sway amplitude of the rope sway based on the elevator car position and a building sway of the building, the building sway determined based on building acceleration data obtained from a building acceleration sensor of the building, determining whether the rope sway is increasing based on the determined rope sway amplitude, and in response to a determination that the rope sway is not increasing, calculating a number of rope sway cycles n(Z.sub.car) of the rope sway within a constant time period, and calculating the particular rope sway amplitude as a new decreased rope sway amplitude x of the rope sway based on the number of rope sway cycles n(Z.sub.car) and a damping factor.

9. The elevator of claim 8, wherein the elevator controller is configured to selectively control the operation of the elevator based on changing a car speed of the elevator car.

10. The elevator of claim 8, wherein the elevator controller is configured to selectively control the operation of the elevator based on changing a floor stopping time of the elevator car.

11. The elevator of claim 8, wherein the elevator controller is configured to selectively control the operation of the elevator based on temporarily excluding one or more landing floors of the elevator from service.

12. The elevator of claim 8, wherein the elevator controller is connected with a rope sway control system that is external to the elevator controller, the rope sway control system configured to determine the particular rope sway amplitude, perform the comparison of the particular rope sway amplitude with the threshold value, and transmit a signal to the elevator controller to cause the elevator controller to control the operation of the elevator based on the result of the comparison of the particular rope sway amplitude with the threshold value.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Hereinafter, the invention is described by the aid of the enclosed drawings in which:

(2) FIG. 1 shows a flow-chart of the inventive elevator,

(3) FIG. 2 shows a method flow diagram of the inventive method and

(4) FIG. 3 shows examples of building acceleration and rope sway amplitudes.

DETAILED DESCRIPTION

(5) FIG. 1 shows an elevator 10 comprised in a building having an elevator shaft 12. The building is particularly a high rise building as for example a skyscraper and correspondingly, the elevator shaft 12 is a very long shaft of a high rise elevator. In the elevator shaft 12, an elevator car 14 and a counterweight 20 with their top are connected via upper suspension ropes 22 running over an upper traction sheave 16. Further the elevator car 14 and the counterweight 20 are with their bottom connected via lower compensation ropes 24 running over a lower compensation sheave 18. The car 14 and counterweight 20 are moved via the suspension ropes which are in friction co-action with the traction sheave which is connected to the output shaft of an elevator motor.

(6) The elevator 10 has an elevator controller 26 controlling elevator motor 16 and thus the movement of the elevator car 14. Further the elevator 10 comprises call input means, e.g. destination call panels in the lobby and on the floors for the input of a destination floor or driving direction. The elevator controller also comprises a car allocation model, which allocates a given call to an elevator under consideration of pre-determined optimisation criteria as e.g. passenger waiting time, passenger driving time, total ride time, energy consumption etc.

(7) Connected with the building is a building acceleration sensor 28 which measures any acceleration acting on the building, e.g. caused by seismic activity or wind pressure. The elevator controller 26 is connected with a rope sway control system 30 which may be part of the elevator controller 26 or may be located apart from it whereby even a location in a cloud server is possible.

(8) The sway control system 30 comprises an elevator position prediction module 32. The elevator position prediction module 32 comprises motion profiles for the elevator car for all possible allocation situations. Thus the module 32 can predict from the current allocation situation and from the current elevator car position and/or movement data the motion profile of the car position over the time on its travel between departure floor and the final destination floor. The allocation based travel data and the current position/movement of the elevator car are obtained from the elevator controller 26 via the input line 34.

(9) In the a first embodiment where rope sway situations are already calculated beforehand by means of a virtual model in the engineering phase, precalculated amplification data tables are used for real-time rope sway amplitude calculation. These data tables are calculated beforehand by means of simulator.

(10) In a second alternative embodiment, the rope sway control system 30 further comprises a simulator of the elevator system. The simulator comprises all physical parameters of the elevator of its roping and all the damping parameters correlated to it. The heart of the rope sway control system 30 of both the first and the second embodiment is a real-time rope sway calculation unit 36 which gets the predicted car position data from the elevator position prediction unit 32. In the first embodiment, said data tables are used; in the second alternative embodiment the simulator is used for calculating the complete physical data.

(11) Via the movement profile established by the elevator position prediction unit 32 and physical data of the elevator from the simulator/the data tables, the real-time rope sway calculation unit can—together with the data from the acceleration sensor 28—calculate the rope sway which is going to happen along the whole journey of the elevator car along its path in the elevator shaft 12. The rope sway amplitudes are then calculated considering the predicted car position on its way, and the current building sway measured by the sensor 28. If the rope sway amplitudes which will occur along the predicted positions of the elevator car exceed at least one threshold value, this means that an excessive rope sway amplitude will be expected along the travel of the elevator car, normally at a certain position of the elevator car, at which the natural sway frequency of the free length of the suspension ropes 22 and compensation ropes 24 build up with the building sway frequency. In this case a signal is outputted via the output line 38 back to the elevator controller 26 which is either able to modify or cancel the elevator travel itself.

(12) Optionally, the signal may operate a rope sway limitation device 40, for example a roller touching the elevator rope to suppress the rope sway which is retractable after the critical position has been passed by the elevator car.

(13) Optionally, the elevator further comprises at least one rope displacement sensor 41 which may be an optical sensor. This rope displacement sensor 41 allows the verification of the estimated rope sway data with the actual rope sway to verify and adapt the estimated data which leads to a better accuracy of the prediction.

(14) Of course the rope sway control system 30 and/or all components 32, 34, 36 thereof may be part of the elevator controller or being located in separate modules connected with the elevator controller 26 via a data connection.

(15) In summary, the inventive method and the inventive elevator as shown in FIG. 1 is able to predict non-desired rope sway conditions in good time before they really happen, in good time before the elevator really assumes the non-desired position. Thus, the elevator controller 26 is able to take countermeasures in good time beforehand to avoid these non-desired situations or to act against them.

(16) FIG. 2 shows a method flow-chart of the rope sway monitoring of an elevator during a car travel. With the input of an elevator call and the subsequent allocation of an elevator, the elevator journey is via the elevator position prediction module known to the rope sway calculation unit 36 which performs the method of FIG. 2. The calculation routine starts at 42 and progresses to step 44 in which a calculation period is updated. In the embodiment of FIG. 2, the calculation period is selected to meet the building sway period, but the calculation period could also be selected differently. Building sway period may a constant given by the builder. In step 46 the motion profile from the elevator controller is obtained and the position of the elevator car in the middle of the building sway period is predicted. Further in step 48 the effective building acceleration for the current building sway period is calculated, using the current signal of the building acceleration detector 28. In step 50 it is based on the data tables 34 (first embodiment) or the simulator data 34 (second embodiment) determined whether the current rope amplitude still increases or has already reached a maximum.

(17) If the rope amplitude increases the process branches to step 52, in which the current rope sway amplitude increase is determined. The rope sway is calculated in step 52 with a first calculation method using an amplification model (e.g. the data tables).

(18) Otherwise a decrease of the rope sway is calculated in step 54 with a second calculation method using a damping model. Use of the damping model is explained as follows.

(19) Decrement of rope sway takes place in logarithmic manner. In real-time rope amplitude calculation, the calculation time step is equal to building sway period T.sub.building (a constant, usually given by the builder). The elevator rope segment period T.sub.rope however is a function of car position z.sub.car in the shaft. The following relation is defined, that gives the number of rope sway cycles n within one building sway cycle.

(20) $\begin{array}{cc}n\left(z_{\mathrm{car}}\right)=\frac{T_{\mathrm{building}}}{T_{\mathrm{rope}}\left(z_{\mathrm{car}}\right)}& \left(1\right)\end{array}$

(21) In other words, n(z.sub.car) is a function of elevator car position. The rope segment period T.sub.rope values are calculated a-priori for different car locations and different rope segments, using the simulator. The values are stored in an array that is used during real-time amplitude calculation. The rope segment period T.sub.rope used in the calculation corresponds to the first natural mode of the rope segment.

(22) So the value of the elevator rope segment sway amplitude x (i.e., the value of the exponential decay envelope) after one building cycle is calculated as
x(t.sub.0+T.sub.building)=x(t.sub.0).Math.e.sup.−2πnζ  (2)

(23) In (2), ζ is a damping factor, which may be a predefined constant, which may be selected when data tables 34 are calculated. Alternatively, damping factor ζ may be defined as a function of elevator car position and concurrent rope sway amplitude.

(24) The use of equations (1) and (2) enables fast and reliable real-time calculation of rope sway in damping situation.

(25) Both steps 52 as well as 54 branch back to step 56 wherein the rope sway value corresponding to the middle of the current period is updated based on steps 52 or 54. Afterwards the method proceeds to decision step 58, wherein it is checked whether the updated rope sway values necessitates protective measures. If no, the process branches to step 64 in which it is waited until the end of the building sway period and then branches back to step 44. If yes, in step 60 any current active sway protection method is verified, e.g. by reading the operating status of the rope sway limitation device 40 from the elevator controller 26. Afterwards a differentiation is made depending on the priority of the situation, i.e. depending on the value of any sudden increase of building sway, e.g. after an earth quake. In case of a high priority protective measures are immediately taken in step 62. These measures include any changes on the car path to avoid the non-desired situation and/or the activation of rope sway limitation devices and/or a stop of the elevator operation after releasing the passengers e.g. at the nearest landing. The process then waits till the end of the building sway period and branches back to step 44.

(26) If the priority is lower it is branched from step 60 to step 64 where it is waited until the end of the building sway periods and then it branches back to step 44.

(27) This process ensures a reasonable adapted response to any non-desired sway conditions in advance, which allows safety measures, as e.g. the release of passengers already at an early stage before the non-desired situation is going to take place.

(28) FIG. 3 shows schematically the function of the rope sway control system 30 of FIG. 1 by means of an example.

(29) In FIG. 3 FIG. 3a shows a very schematic illustration of a predicted car position in an elevator shaft with a length of 200 m. 22a is the suspension rope between car 14 and traction sheave 16, while 22b designates the suspension rope part between the traction sheave 16 and the counter weight 20. Accordingly, 24a designates the compensation rope part between the car 14 and the compensation sheave 18, while 24b designates the compensation rope part between the compensation sheave 18 and the counter weight 20. The predicted situation is sensible for excessive rope sway as the car suspension rope 22a as well as the counterweight compensation rope 24b extend feely nearly along the whole shaft length.

(30) FIG. 3b shows a current signal of a building acceleration sensor 28 for the building in which the elevator 10 is installed.

(31) FIG. 3c shows the amplitudes of rope sway for the different suspension and compensation rope parts 22a,b and 24a,b calculated by the rope sway control system 30 for the predicted car and counterweight positions according to FIG. 3a. The system comprises several limits for the rope sway amplitudes which lead to certain measures, if exceeded.

(32) The lowest amplitude limit is the VAS limit. VAS means “Variable speed selection” which means that the exceeding of this limit leads to running the elevator slower than normal when elevator approaches a terminal landing.

(33) The next higher limit is the PES limit, where by PES stands for “Performance selection”. The passing of this limit by the estimated rope sway amplitudes leads to the running of the elevator with reduced speed, i.e. half speed not only when approaching a terminal landing.

(34) The highest limit which is only shown in FIG. 3b is the PARK limit. Exceeding this limit leads to an immediate parking of the elevator car at a safe (non-resonant) floor during extreme sway conditions.

(35) Thus, the elevator is well adapted to handle in advance any situations with respect to the building which may lead to non-desired rope sway conditions, as e.g. earth quakes, strong wind, objects hitting the building etc.

(36) The invention is not delimited to the enclosed embodiments but it can be varied within the scope of the following patent claims.

LIST OF REFERENCE NUMBERS

(37) 10 elevator 12 elevator shaft 14 elevator car 16 traction sheave 18 compensation sheave 20 counter weight 22 suspension ropes 24 compensation ropes 26 elevator controller 28 building acceleration (sway) sensor 30 rope sway control system 32 elevator position prediction module 34 input line from the elevator controller to the rope sway control system 36 rope sway calculation unit 38 output line from the rope sway control system to the elevator controller 40 rope sway limitation device 41 (real-time) rope displacement sensor 42-64 process steps of the rope sway calculation routine