Method for self-testing a monitoring device monitoring an integrity status of a suspension member arrangement in an elevator

Abstract

A method for self-testing a monitoring device monitoring an integrity status of an elevator suspension member arrangement includes the monitoring device having a voltage generation arrangement for generating electric voltages and applying the electric voltages to cords in suspension members of the suspension member arrangement. The monitoring device has a voltage analyzer arrangement for detecting a deterioration in the integrity status based on modifications in the applied electric voltages upon transmission through the cords. The method includes the steps of: specifically modifying the generated electric voltages to systematically induce modifications in the applied electric voltages upon transmission through the cords which, under normal operation conditions of the monitoring device, would be interpreted by the monitoring device as indicating the deterioration in the integrity status; verifying whether the deterioration in the integrity status is correctly detected; and initiating a self-test-failure-action if the deterioration in the integrity status is not correctly detected.

Claims

1. A method for self-testing a monitoring device monitoring an integrity status of a suspension member arrangement in an elevator, wherein the monitoring device generates electric voltages and applies the electric voltages to electrically conductive cords in suspension members of the suspension member arrangement, and wherein the monitoring device detects a deterioration in the integrity status based on modifications in the applied electric voltages upon transmission through the cords, the method comprising the steps of: modifying the generated electric voltages to systematically induce modifications in the applied electric voltages which modified applied electrical voltages upon transmission through the cords would be interpreted by the monitoring device as indicating the deterioration in the integrity status; verifying whether the deterioration in the integrity status is correctly detected; and initiating a self-test-failure-action in the elevator when the deterioration in the integrity status is not correctly detected.

2. The method according to claim 1 wherein the monitoring device generates the electric voltages as first and second alternating voltages being phase-shifted with respect to each other and analyzes a neutral point voltage resulting upon applying the first and second alternating voltages to a first group of the cords and a second group of the cords respectively in the suspension members of the suspension member arrangement respectively, transmission of the first and second alternating voltages through the first and second groups of cords and superimposing the transmitted first and second alternating voltages, and wherein the monitoring device detects a first type of deterioration in the integrity status based on the analysis of the neutral point voltage, the method including the steps of: modifying the generated first and second alternating voltages to induce modifications in the neutral point voltage upon transmission through the cords that would be interpreted by the monitoring device as indicating the first type of deterioration in the integrity status; verifying whether the first type of deterioration in the integrity status is correctly detected; and initiating the self-test-failure-action in the elevator when the first type of deterioration in the integrity status is not correctly detected.

3. The method according to claim 2 including: modifying the generated first and second alternating voltages by temporarily switching-off the first alternating voltage while generating the second alternating voltage and verifying whether the first type of deterioration in the integrity status is correctly detected; subsequently modifying the generated first and second alternating voltages by temporarily switching-off the second alternating voltage while generating the first alternating voltage and verifying whether the first type of deterioration in the integrity status is correctly detected; and initiating the self-test-failure-action in the elevator when the first type of deterioration in the integrity status is not correctly detected for both modifications.

4. The method according to claim 2 wherein the monitoring device measures resulting voltages after a voltage drop along the cords in the suspension members of the suspension member arrangement upon applying the first and second alternating voltages, and wherein the monitoring device detects a second type of deterioration in the integrity status based on a detected modification in the measured resulting voltages, the method including the steps of: modifying the generated first and second voltages to induce modifications in the resulting voltages that would be interpreted by the monitoring device as indicating the second type of deterioration in the integrity status; verifying whether the second type of deterioration in the integrity status is correctly detected; and initiating the self-test-failure-action in the elevator when the second type of deterioration in the integrity status is not correctly detected.

5. The method according to claim 4 including modifying the generated first and second alternating voltages by temporarily reducing a magnitude of the generated first and second alternating voltages to a value which is lower than a resulting voltage value that would be interpreted by the monitoring device as indicating the second type of deterioration in the integrity status.

6. The method according to claim 1 wherein the monitoring device measures resulting voltages after a voltage drop along the cords in the suspension members of the suspension member arrangement upon application of the generated electric voltages, and wherein the monitoring device detects a specific type of deterioration in the integrity status based on a detected modification in the measured resulting voltages, the method including the steps of: modifying the generated electric voltages to induce modifications in the resulting voltages that would be interpreted by the monitoring device as indicating the specific type of deterioration in the integrity status; verifying whether the specific type of deterioration in the integrity status is correctly detected; and initiating a self-test-failure-action in the elevator when the specific type of deterioration in the integrity status is not correctly detected.

7. The method according to claim 6 including modifying the generated electric voltages by temporarily reducing a magnitude of the generated electric voltages to a value which is lower than a resulting voltage value that would be interpreted by the monitoring device as indicating the specific type of deterioration in the integrity status.

8. The method according to claim 1 including periodically performing the method steps during operation of the monitoring device.

9. The method according to claim 1 including performing the method steps upon an occurrence of predetermined events during operation of the monitoring device.

10. A monitoring device for performing the method according to claim 1 to monitor the integrity status of the suspension member arrangement in the elevator, the monitoring device comprising: a voltage generator arrangement for generating the generated electric voltages and being connected to the cords in the suspension members of the suspension arrangement by input circuitry, output circuitry, input connectors and output connectors for applying the generated electric voltages to cords; a voltage analyzer arrangement for detecting the deterioration in the integrity status based on the modifications in the generated electric voltages transmitted through the cords; and a controller component connected to the voltage generator arrangement and to the voltage analyzer arrangement for controlling operation of the monitoring device.

11. The monitoring device according to claim 10 wherein the voltage generator arrangement generates the electric voltages as first and second alternating voltages being phase-shifted with respect to each other and the voltage analyzer arrangement analyzes a neutral point voltage resulting upon applying the first and second alternating voltages to a first group of the cords and a second group of the cords respectively in the suspension members of the suspension member arrangement respectively, transmission of the first and second alternating voltages through the first and second groups of cords and superimposing the transmitted first and second alternating voltages, and wherein the monitoring device detects a specific type of deterioration in the integrity status based on the analysis of the neutral point voltage by: modifying the generated first and second alternating voltages to induce modifications in the neutral point voltage upon transmission through the cords that would be interpreted by the monitoring device as indicating the specific type of deterioration in the integrity status; verifying whether the specific type of deterioration in the integrity status is correctly detected; and initiating the self-test-failure-action in the elevator when the specific type of deterioration in the integrity status is not correctly detected.

12. The monitoring device according to claim 10 wherein the voltage analyzer arrangement measures resulting voltages after a voltage drop along the cords in the suspension members of the suspension member arrangement upon application of the generated electric voltages, and wherein the monitoring device detects a specific type of deterioration in the integrity status based on a detected modification in the measured resulting voltages by: modifying the generated electric voltages to induce modifications in the resulting voltages that would be interpreted by the monitoring device as indicating the specific type of deterioration in the integrity status; verifying whether the specific type of deterioration in the integrity status is correctly detected; and initiating a self-test-failure-action in the elevator when the specific type of deterioration in the integrity status is not correctly detected.

13. An elevator comprising: a suspension member arrangement including electrically conductive cords in suspension members of a suspension member arrangement; and a monitoring device according to claim 10 connected to the cords in the suspension member arrangement.

Description

DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows an elevator in which a monitoring device according to an embodiment of the invention may be applied.

(2) FIG. 2 shows main features of the monitoring device according to an embodiment of the invention as applied to a suspension member arrangement.

(3) The figures are only schematic representations and are not to scale. Same reference signs refer to same or similar features throughout the figures.

DETAILED DESCRIPTION

(4) FIG. 1 shows an elevator 1 in which a monitoring device 17 may be implemented in accordance with embodiments of the present invention.

(5) The elevator 1 comprises a car 3 and a counterweight 5 which may be displaced vertically within an elevator shaft 7. The car 3 and the counterweight 5 are suspended by a suspension member arrangement 9. This suspension member arrangement 9 comprises multiple suspension members 11, sometimes also referred to as suspension traction media (STM). Such suspension members 11 may be for example ropes, belts, etc. Furthermore, the elevator 1 comprises additional components such as, inter-alia, the monitoring device 17 for monitoring an integrity or deterioration status of the suspension members 11 in the suspension member arrangement 9.

(6) In the example shown in FIG. 1, end portions of the suspension members 11 are fixed to a supporting structure of the elevator 1 at a top of the elevator shaft 7. The suspension members 11 may be displaced using an elevator traction machine 13 driving a traction sheave 15. An operation of the elevator traction machine 13 may be controlled by a control device 19.

(7) It may be noted that the elevator 1 and particularly its suspension member(s) 11 and its monitoring device 17 for detecting the deterioration status may be configured and/or arranged in various other ways than those shown in FIG. 1. For example, instead of being fixed to the support structure of the elevator 1, the end portions of the suspension members 11 may be fixed to the car 3 and/or to the counterweight 5.

(8) The suspension members 11 to be driven for example by the traction machine 13 may utilize metal cords or ropes to support a suspended load such as the car 3 and/or the counterweight 5 that is moved by the traction machine 13.

(9) FIG. 2 schematically shows main features of a monitoring device 17 for monitoring an integrity status of the suspension member arrangement 9, in which a method for self-testing may be implemented in accordance with an embodiment of the present invention.

(10) Details on possible operation principles of the monitoring device 17 are disclosed in the “applicant's prior art” (for example an overview is given in PCT/EP2016/067966) and shall only be briefly summarized herein.

(11) The monitoring device 17 comprises a voltage generator arrangement 21, a voltage analyzer arrangement 23 and some input circuitry 25 and output circuitry 27 and some input connectors 29 and output connectors 31 for applying the voltages generated by the voltage generator arrangement 21 to cords 33 of one or more suspension members 11 and for forwarding resulting voltages after transmission through the cords 33 towards the voltage analyzer arrangement 23.

(12) The voltage generator arrangement 21 comprises two alternating voltage generators 35 (G.sub.1, G.sub.2) for generating a first and a second alternating voltage. Preferably, the two alternating voltages have same waveforms but are shifted by 180° with respect to each other. The generated alternating voltages may have no DC component, i.e. the voltage is symmetrically alternating around 0V. Alternatively, the generated alternating voltages may have an additional DC component, i.e. the voltage is periodically alternating around a non-zero DC voltage. The first and second alternating voltages are applied to two different cords 33 or groups of cords 33 being interconnected in series and or in parallel within one or more suspension members 11. For this purpose, the alternating voltage generators 35 are each connected via the input circuitry 25 including internal resistances (being represented as resistances R.sub.3 and R.sub.4) to input connectors 29 contacting one or more of the cords 33 comprised in first and second groups of cords 33. Additionally, the alternating voltage generator 21 comprises a pull-up voltage source 43 for applying a pull-up voltage U.sub.max via internal resistors R.sub.1, R.sub.2 to associated branches of the input circuitry 25.

(13) It shall be noted that, in the example shown in the figure, all odd numbered cords 1, 3, 5, . . . 11 are connected in series to form a first group of cords 33 and all even numbered cords 2, 4, 6, . . . , 12 are connected in series to form a second group of cords 33. However, such configuration is only exemplary. Various other configurations of grouping cords 33 into first and second groups are imaginable. For example, a first group of cords 33 may comprise all cords of a single suspension member 11 and a second group of cords 33 may comprise all cords of another single suspension member 11, the cords 33 of a group being interconnected in parallel or some of the cords 33 of a group being interconnected in parallel and being serially connected to another portion of the group of cords 33.

(14) The applied voltages are transmitted through the cords 33 or groups of cords. At opposing ends, the cords 33 or groups of cords are connected via output connectors 31 and output circuitry 27 to the voltage analyzer arrangement 23. In the voltage analyzer arrangement 23, the ends of the two or more the cords 33 or groups of cords are interconnected via an electrical resistance R.sub.5 thereby forming a neutral point in the entire circuitry. The voltage analyzer arrangement 23 is adapted for measuring a neutral point voltage resulting upon superimposing the resulting alternating voltages occurring at the ends of the cords 33 or groups of cords after transmission through the entire suspension member(s) 11. The resulting superimposed voltage is referred to as neutral point voltage as at the neutral point, both shifted alternating voltages should neutralize each other as long as electrical characteristics through the cords or groups of cords are same. Accordingly, under normal circumstances, the neutral point voltage should have a zero alternating voltage component.

(15) However, upon any deteriorations in the cords modifying their electrical characteristics, such modifications generally lead to a lacking neutralization of the phase-shifted alternating voltages, such that the resulting non-zero neutral point voltage may serve as a good indicator for any change in an integrity status of the suspension member arrangement 9.

(16) In the example shown in FIG. 2, the neutral point voltage is indirectly measured based on the measurements of two voltages U.sub.3 and U.sub.4 against ground potential using voltmeters 37, 39. Therein, one voltmeter 37 is connected via the output circuitry 27 and one of the output connectors 31 to the first one of the groups of cords 33 whereas the other voltmeter 39 being connected via the output circuitry 27 and another one of the output connectors 31 to the second one of the groups of cords 33. Both portions of the output circuitry 27 are interconnected via the electrical resistance R.sub.5. Measuring results of both voltmeters 37, 39 may be evaluated and analyzed by an analyzing unit 41. Accordingly, the analyzing unit 41 may detect a first type of deterioration in the integrity status of the suspension member arrangement 9 based on the analysis of the neutral point voltage, particularly based on any deviation from a non-zero AC component of the neutral point voltage.

(17) It shall be noted that other circuitry including one or more voltmeters and analyzing units may be applied for measuring the neutral point voltage, as described for example in more detail in the applicant's prior art.

(18) Additionally to the neutral point voltage, the monitoring device 17 may determine voltages which result after a voltage drop along cords 33 of one of the groups of cords and which are referred to herein as resulting voltages. The voltmeters 37, 39 measuring the voltages U.sub.3, U.sub.4 may enable measuring such resulting voltages, optionally additionally taking into account measurements of additional voltmeters 45, 47 measuring voltages U.sub.1, U.sub.2 as applied by the alternating voltage generator arrangement 21 to the input connectors 29. Also, the resulting voltages may be evaluated and analyzed by the analyzing unit 41. Accordingly, the analyzing unit 41 may further detect a second type of deterioration in the integrity status of the suspension member arrangement 9 based on a detected modification in the measured resulting voltages, particularly based on any substantial deviations of currently measured values for such resulting voltages in comparison to initially measured (i.e. before any significant deterioration took place) values or reference values for such resulting voltages.

(19) Accordingly, during normal operation conditions of the monitoring device 17, the monitoring device 17 may detect two types of deteriorations in an integrity status of the suspension member 11. The first type relates e.g. to failures such as interruptions or electrical shorts in one of the groups of cords. This first type of deterioration may be detected based on an analysis of the neutral point voltage. The second type of deterioration particularly relates e.g. to wear effects in the cords 33 resulting in gradually increasing the electric resistance over time. The second type of deterioration may be detected based on an analysis of the resulting voltage drop along the cords 33.

(20) In order to guarantee safe operation of an elevator 1, the elevator does not only comprise a monitoring device 17 for monitoring an integrity status of its suspension member arrangement 9, but, furthermore, the monitoring device 17 itself is specifically configured and operated for executing specific self-testing procedures. Such self-testing procedures shall reliably detect any failures or malfunctions within the monitoring device 17 which otherwise could avoid reliably detecting any deteriorations in the suspension member arrangement 9.

(21) For such purpose, the monitoring device 17 comprises a controller component 49. The controller component 49 may control the operation of the alternating voltage generators 35. Particularly, the controller component 49 may control each of the voltage generators G.sub.1, G.sub.2. Furthermore, the controller component 49 may communicate with the analyzing unit 41 of the voltage analyzer arrangement 23.

(22) For performing a self-testing procedure, the controller component 49 may temporarily interrupt the normal monitoring operation of the monitoring device 17. Particularly, the controller component 49 may temporarily modify an operation of the alternating voltage generator arrangement 21 such as to modify the generated electric voltages in a way in that modifications in the applied electric voltages upon transmission through the cords 33 are systematically induced which, under normal operation conditions of the monitoring device 17, would be interpreted by the voltage analyzer arrangement 23 of the monitoring device 17 as indicating a critical deterioration in the integrity status of the suspension member arrangement 9. The controller component 49 may then communicate with the voltage analyzer arrangement 23, particularly with its analyzing unit 41, and verifying whether the induced “virtual” deterioration is correctly detected. As long as this is the case, normal operation of the monitoring device 17 may be resumed, i.e. the controller component 49 may control the voltage generators 35 to generate their standard monitoring voltages. However, in case the controller component 49 determines that the provoked “virtual” deterioration was not correctly detected in the voltage analyzer arrangement 23, this will be taken as indicating any failure or malfunction in the monitoring device 17 and suitable self-test-failure-actions may be initiated.

(23) Particularly, as the monitoring device 17 is adapted for detecting the above-mentioned two types of deteriorations, the self-testing procedure may also comprise two types of sub-procedures.

(24) In a first sub-procedure, the controller component 49 may control the alternating voltage generators 35 to, first, temporarily switch-off the first voltage generator G.sub.1. Accordingly, no first alternating voltage is applied anymore to the first group of cords 33 and an asymmetry in the resulting voltages after transmission through both groups of cords 33 at the neutral point is induced. As a consequence, the neutral point voltage should have a non-zero AC component. Subsequently, the controller component 49 may control the alternating voltage generators 35 to switch-on the first voltage generator G.sub.1 again and switch-off the second voltage generator G.sub.2 instead. Also, in this configuration, an asymmetry in the resulting voltages is induced resulting in a non-zero AC component at the neutral point.

(25) In both situations, the voltage analyzer arrangement 23 should detect the non-zero AC component and should indicate that a significant deterioration in the integrity status of the suspension member arrangements 9 was detected. If this is not the case for both sub-procedures, this will be recognized by the controller component 49 as indicating a malfunction in the monitoring device 17. Such malfunction could be for example a failure in the alternating voltage generators 35, in the input and output circuitries 25, 27 or in the input and output connectors 29, 31 or their contacts to the cords 33.

(26) In a second sub-procedure, the controller component 49 may control the alternating voltage generators 35 for temporarily reducing an amplitude of the generated alternating voltages. This amplitude may refer to the AC component only or may refer to a combination of an AC component and a DC component. Specifically, the amplitudes may be reduced to a value which is lower than a value which, under normal operation conditions of the monitoring device 17, would be interpreted by the voltage analyzer arrangement 23 of the monitoring device 17 as indicating the second type of deterioration in the integrity status of the suspension member arrangement 9.

(27) Again, if the temporarily induced “virtual” deterioration is correctly detected by the voltage analyzer arrangement 23, the controller component 49 may control the voltage generator arrangement 21 to resume normal operation for continuing standard monitoring. However, if the “virtual” deterioration is not correctly detected, this may be interpreted by the controller component 49 as indicating a malfunction in the monitoring device 17 and a suitable self-test-failure-action may be initiated.

(28) For initiating the self-test-failure-action, the monitoring device 17 or, particularly, its controller component 49 may for example communicate with the elevator controller 19. Particularly, as a type of self-test-failure-action, the elevator controller 19 may be instructed to stop normal operation of the elevator 1. For example, any motion of the drive traction machine 13 driving the elevator car 3 may be stopped, immediately or after an evacuation of passengers. Additionally or alternatively, the monitoring device 17 may issue an alarm or initiate issuing an alarm e.g. in a remote control center.

(29) Finally, it should be noted that the term “comprising” does not exclude other elements or steps and the “a” or “an” does not exclude a plurality. Also, elements described in association with different embodiments may be combined.

(30) In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.

LIST OF REFERENCE SIGNS

(31) 1 elevator 3 car 5 counterweight 7 elevator shaft 9 suspension member arrangement 11 suspension member 13 traction machine 15 traction sheave 17 monitoring device 19 control device 21 voltage generator arrangement 23 voltage analyzer arrangement 25 input circuitry 27 output circuitry 29 input connectors 31 output connectors 33 cords 35 voltage generator 37 voltmeter 39 voltmeter 41 analyzing unit 43 pull-up voltage source 45 voltmeter 47 voltmeter 49 controller component