Elevator with a monitoring arrangement for monitoring an integrity of suspension members with separated circuitries

Abstract

An elevator suspension member arrangement includes a monitoring arrangement monitoring an integrity status of suspension members having electrically conductive cords. The monitoring arrangement includes: a generator generating phase shifted first and second alternating voltages; input and output connectors each establishing electrical contacts to cords in one of the suspension members; a voltage analyzer measuring and analyzing a neutral point voltage resulting from applying the first and second alternating voltages to first and second cords of the one suspension member; a supply circuitry having supply lines electrically interconnecting the generator with the input connectors; and a measurement circuitry including measurement lines electrically interconnecting the analyzer with at least one of the input connectors and the output connectors. The supply and measurement lines are separated from each other whereby disturbing influences of impedances through the supply circuitry is minimized due to voltage measurements being performed through the separate measurement circuitry.

Claims

1. An elevator with a suspension member arrangement including a plurality of suspension members, each of the suspension members including electrically conductive cords, and a monitoring arrangement for monitoring an integrity status of the suspension member arrangement, the monitoring arrangement comprising: an alternating voltage generator arrangement, including at least one alternating voltage generator, for generating first and second alternating voltages being phase shifted with respect to each other; a plurality of input connectors and output connectors, each of the connectors establishing electrical contact to cords in one of the suspension members; a voltage analyzer arrangement, including at least one voltmeter, for measuring and analyzing a neutral point voltage resulting upon applying each one of the first and second alternating voltages to first and second cords of the one suspension member, respectively, and after transmission of the first and second alternating voltages through the first and second cords and superposition of the transmitted first and second alternating voltages at a neutral point at which the first and second cords are electrically interconnected; a supply circuitry including supply lines electrically interconnecting the alternating voltage generator arrangement with the input connectors and with the output connectors, and a measurement circuitry including measurement lines electrically interconnecting the voltage analyzer arrangement with at least one of the input connectors and the output connectors; and wherein the supply lines and the measurement lines are separate lines.

2. The elevator according to claim 1 wherein the input connectors and the output connectors interconnect a group of the cords in parallel to each other.

3. The elevator according to claim 1 wherein an electrical resistance through one of the supply lines is non-negligible compared to an electrical resistance through the cords contacted by the one supply line and electrically series-connected to the one supply line.

4. The elevator according to claim 1 wherein the supply lines each have a length of at least 0.2 m.

5. The elevator according to claim 1 wherein the alternating voltage generator arrangement and the voltage analyzer arrangement are configured such that electric currents transmitted through the supply lines by the application of the first and second alternating voltages are stronger than electric currents transmitted through the measurement lines by the application of the first and second alternating voltages.

6. The elevator according to claim 1 wherein the supply lines have a larger cross-section than a cross-section of the measurement lines.

7. The elevator according to claim 1 wherein first ends of the supply lines are connected to the alternating voltage generator arrangement and first ends of the measurement lines are connected to the voltage analyzer arrangement, and wherein second ends of the supply lines and second ends of the measurement lines are each directly connected to one of the input connectors or one of the output connectors.

8. The elevator according to claim 1 wherein first ends of the supply lines are connected to the alternating voltage generator arrangement and first ends of the measurement lines are connected to the voltage analyzer arrangement, and wherein second ends of both the supply lines and the measurement lines are connected to each other before being commonly connected via a connector line to one of the input connectors or one of the output connectors.

9. A monitoring arrangement for monitoring an integrity status of a suspension member arrangement of an elevator, the suspension member arrangement including a plurality of suspension members, each of the suspension member having electrically conductive cords, the monitoring arrangement comprising: an alternating voltage generator arrangement including at least one alternating voltage generator for generating first and second alternating voltages being phase shifted with respect to each other; a plurality of input connectors and output connectors, each of the connectors being configured for establishing electrical contact to the cords in one of the suspension members; a voltage analyzer arrangement including at least one voltmeter, the voltage analyzer arrangement measuring and analyzing a neutral point voltage resulting upon applying each one of the first and second alternating voltages to first and second cords of at least one of the suspension members, respectively, the first and second cords being electrically interconnected at a neutral point, and after transmission of the first and second alternating voltages through the first and second cords and superposition of the transmitted first and second alternating voltages at the neutral point the neutral point voltage is generated; a supply circuitry including supply lines electrically interconnecting the at least one alternating voltage generator with the input connectors and with the output connectors, and a measurement circuitry including measurement lines electrically interconnecting the at least one voltmeter with at least one of the input connectors and with the output connectors; and wherein the supply lines and the measurement lines are separate lines.

10. An elevator with a suspension member arrangement including a plurality of suspension members, each of the suspension members including electrically conductive cords, and a monitoring arrangement for monitoring an integrity status of the suspension member arrangement, the monitoring arrangement comprising: an alternating voltage generator arrangement, including at least one alternating voltage generator, for generating first and second alternating voltages being phase shifted with respect to each other; a plurality of input connectors and output connectors, each of the connectors establishing electrical contact to cords in one of the suspension members; a voltage analyzer arrangement, including at least one voltmeter, for measuring and analyzing a neutral point voltage resulting upon applying each one of the first and second alternating voltages to first and second cords of the one suspension member, respectively, and after transmission of the first and second alternating voltages through the first and second cords and superposition of the transmitted first and second alternating voltages at a neutral point at which the first and second cords are electrically interconnected; a supply circuitry including supply lines electrically interconnecting the alternating voltage generator arrangement with the input connectors, and a measurement circuitry including measurement lines electrically interconnecting the voltage analyzer arrangement with at least one of the input connectors and the output connectors; wherein the supply lines and the measurement lines are separate lines; and wherein first ends of the supply lines are connected to the alternating voltage generator arrangement and first ends of the measurement lines are connected to the voltage analyzer arrangement, and wherein second ends of both the supply lines and the measurement lines are connected to each other before being commonly connected via a connector line to one of the input connectors or one of the output connectors.

Description

DESCRIPTION OF THE DRAWINGS

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

(2) FIGS. 2 to 5 show monitoring arrangements according to various embodiments 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 arrangement 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 arrangement 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 arrangement 17 for detecting the deterioration status may be configured and 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 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. The cords or ropes may be enclosed in a sheath or cover comprising e.g. a polymer matrix material for protecting the cords or ropes against wear and/or corrosion.

(9) FIG. 2 schematically shows main features of a first embodiment of a monitoring arrangement 17 for monitoring an integrity status of one or more suspension members 11. Details on possible operation principles of the monitoring arrangement 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.

(10) The monitoring arrangement 17 comprises an alternating voltage generator arrangement 21 and a voltage analyzer arrangement 23. Furthermore, the monitoring arrangement 17 comprises some supply circuitry 25 including electrically conductive supply lines 26 and some measurement circuitry 27 including measurement lines 28 as well as some input connectors 29 and output connectors 31 for applying the voltages generated by the alternating 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.

(11) In more detail, 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 phase 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 supply circuitry 25 including internal resistances (being represented as resistances R.sub.3 and R.sub.4) to two separate input connectors 29 each contacting first ends of one or more of the cords 33 comprised in first and second groups of cords 33. The internal resistances R.sub.3 and R.sub.4 may be established due to intrinsic series resistances throughout wirings forming the supply lines.

(12) Furthermore, the opposing second ends of the two or more the cords 33 or groups of cords are interconnected via another portion of the supply circuitry 25 and an electrical resistance R.sub.5 thereby forming a neutral point in the entire circuitry.

(13) Additionally, the alternating voltage generator arrangement 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.

(14) 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.

(15) The applied voltages are transmitted through the cords 33 or groups of cords. At the opposing ends, the cords 33 or groups of cords are connected via two separate output connectors 31 and via the measurement circuitry 27 to components of the voltage analyzer arrangement 23. A portion of the measurement circuitry 27 is also connected to the input connectors 29.

(16) Particularly, the voltage analyzer arrangement 23 comprises various voltmeters 37, 39, 45, 47 and is adapted for measuring, inter-alia, the 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 circuit comprising the cords 33 in the suspension member(s) 11 and well as the supply circuitry 25 including the supply lines 26. 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.

(17) However, upon any deteriorations in the cords 33 modifying their electrical characteristics, such modifications generally lead to a lacking complete 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.

(18) 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 measurement circuitry 27 including one measurement line 28 and one of the output connectors 31 to the first one of the groups of cords 33 whereas the other voltmeter 39 is connected via the measurement circuitry 27 including another measurement line 28 and another one of the output connectors 31 to the second one of the groups of cords 33. Separate to this measurement circuitry 27, both output connectors 31 are interconnected via a portion of the supply circuitry 25 including supply lines 26 and further including the electrical resistance R.sub.5 thereby closing the loop between both groups of cords 33 and establishing the neutral point of the entire loop circuitry extending between both alternating voltage generators 35.

(19) 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 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.

(20) 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.

(21) Additionally to the neutral point voltage, the monitoring arrangement 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.

(22) 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.

(23) Accordingly, the monitoring arrangement 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.

(24) An important feature distinguishing the monitoring arrangement proposed herein from prior art approaches may be seen in the fact that the functionality of power supply from the voltage generators 35 to the cords 33 comprised in the suspension member 11 is established through another circuitry, namely through the supply circuitry 25, than the functionality of voltage measurements using the voltmeters 37, 39, 45, 47, which is established via the measurement circuitry 27.

(25) Specifically, power supply is established through the supply lines 26 connecting the voltage generators 35 with the input connectors 29, whereas voltage measurements are executed through measurement lines 28 each connecting one of the voltmeters 37, 39, 45, 47 with one of the input connectors 29 and output connectors 31. Accordingly, any voltage drops or impedances occurring throughout the supply circuitries 25, as indicated by the electrical resistors R.sub.3, R.sub.4, upon substantial electric currents being supplied by the voltage generators 35 may not substantially influence the voltage measurement functionality.

(26) While FIG. 2 shows some details of a monitoring arrangement 17 monitoring an integrity of cords 33 in a single suspension member 11, the approach shown in FIG. 3 relates to an embodiment, in which a monitoring arrangement 17 is adapted for monitoring an integrity of cords 33 in multiple suspension members 11. Therein, the principle of alternating voltage generation and supply to the cords 33 via supply circuitries 25, on the one hand, and voltage measurements using voltmeters 37, 39, 45, 47 via measurement circuitries 27, on the other hand, is similar to the embodiment of FIG. 2. Again, substantial electric power is generated by the alternating voltage generators 35 and supplied through supply lines 26 being separate to measurement lines 28 via which voltage measurements may be performed with the voltmeters 37, 39, 45, 47.

(27) Therein, the supply lines 26 and the measurement lines 28 do not only extend within a monitoring device 49 forming part of the monitoring arrangement 17 but also between the monitoring device 49 and the input and output connectors 29, 31 attached to each of the suspension members 11.

(28) In order to be able to not only monitoring a single suspension member 11 but a plurality of suspension members 11, the monitoring arrangement 17 furthermore comprises a multiplexer arrangement 51. While a first suspension member 11 may be fixedly connected to the first alternating voltage generator G.sub.1, the other suspension members 11 may be sequentially electrically connected to the other voltage generator G.sub.2 using the multiplexer arrangement 51. Therein, the multiplexer arrangement 51 is not only adapted for selectively connecting portions of the supply circuitry 25 connected to the second voltage generator G.sub.2 but also for selectively connecting portions of the measurement circuitry 27. Accordingly, the multiplexer arrangement 51 is configured for both, multiplexing a power supply provided by the alternating voltage generator arrangement 21 as well as multiplexing the measurement circuitry 27 for selectively connecting one of the voltmeters 37, 39 to the output connector 31 of one of the suspension members 11.

(29) In the given example, each suspension member 11 may form a single circuitry for electrically connecting the alternating voltage generator arrangement 21 with the voltage analyzer arrangement 23. Therein, an input connector 29 contacts several but not all cords 33 comprised in this suspension member 11 and interconnects them in parallel. An output connector 31 contacts the remaining cords 33 of this suspension member 11 at the same end of the suspension member 11, i.e. the input connectors 29 and the output connector 31 are placed adjacent to each other at a first end of the suspension member 11 but are electrically separate from each other. At an opposite second end of the suspension member 11, an interconnecting connector 32 electrically interconnects all of the cords 33 of this suspension member 11. Further details on the interconnection scheme of such embodiment are described in the applicant's prior art.

(30) Another approach for monitoring the integrity of each of multiple suspension members 11 is depicted in the embodiments shown in FIGS. 4 and 5.

(31) Therein, each of the suspension members 11 has its own alternating voltage generators 35 and its own voltmeters 37, 39 associated therewith. It is to be noted that FIGS. 4 and 5 are very schematic and mainly visualize some essential features of embodiments of the present invention relating to the separate supply and measurement circuitries 25, 27.

(32) In both cases, supply lines 26 of the supply circuitries 25 and measurement lines 28 of the measurement circuitries 27 are at least partially separated from each other. Furthermore. in both cases, first ends of the supply lines 26 are connected to one of the voltage generators 35 and first ends of the measurement lines 28 are connected to one of the voltmeters 37, 39.

(33) However, in the embodiment of FIG. 4, both the supply lines 26 and the measurement lines 28 are directly connected to the input and output connectors 29, 31. In other words, opposing second ends of the supply lines 26 and the measurement lines 28 are each directly connected to one of the input connectors 29 or one of the output connectors 31. Accordingly, the supply lines 26 and the measurement lines 28 are separate from each other not only within the monitoring device 49 but also in a region between the monitoring device 49 and the input and output connectors 29, 31.

(34) In contrast hereto, in the embodiment of FIG. 5, the second ends of both the supply lines 26 and the measurement lines 28 are connected to each other at a location within the monitoring device 49 before being commonly connected via a connector line 50 one of the input and output connectors 29, 31. In other words, not both types of lines 26, 28 are directly connected to one of the input and output connectors 29, 31, but before reaching such connector, the two lines 26, 28 are already interconnected and the remaining distance is then bridged by the connector line 50. For example, internal to the monitoring device, the supply lines 26 and the measurement lines 28 are provided as separate wires or conductors, whereas external of the monitoring device, the functions of both types of lines 26, 28 are combined in the connector line 50.

(35) 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.

(36) 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.