EP3269674A1 - Method and device for monitoring a load carrier for a lift facility - Google Patents

Abstract

A method and a correspondingly designed device (7) for detecting damage in a suspension element (2) of an elevator installation (1) are proposed. The device (7) has a pulse generator (8) for generating at least one first electrical pulse signal (4a), the first pulse signal (4a) being fed into the tension member (3) via a first connection (5a) of the suspension element (2) can. A detector (9) detects at least one second electrical pulse signal (4b) at the first connection (5a), the second pulse signal (4b) being caused by the first pulse signal (4a) when the first electrical pulse signal (4a) is at a point of damage (6) is reflected in the tension member (3) or on a second connection (5b) of the suspension element (2). The device (7) has a processor (10) for evaluating the detected second pulse signal (4b) with regard to its pulse amplitude and / or pulse polarity, a timer (11) for measuring a time period ("t) between the feeding in of the first electrical pulse signal (4a) ) and the detection of the second electrical pulse signal (4b) and an error message (12) for generating an error message if an evaluation result deviates from at least one predefined tolerance value and / or the measured time period (”t) exceeds a target value.

Description

The present invention relates to a method and apparatus for monitoring a suspension means, such as e.g. a suspension rope or a support belt of an elevator system.

Elevator systems typically include at least one cabin which is generally moved along a hoistway by means of a rope-type suspension means. In general, a counterweight is provided, which is also suspended from the suspension means and moves in the opposite direction to the cabin. To move the cab, the support means is typically driven by means of a motor driven pulley or drive shaft. In order to reduce, inter alia, a load on the traction sheave or shaft, the suspension element is usually attached to or with its ends to fixing within the elevator shaft.

The support means may for example be a belt, a rope or the like. In the course of operation of the elevator system, the suspension element is repeatedly bent and / or counterbalanced, for example, by repeated deflection on deflection rollers or the traction sheave, and thus subjected to high mechanical loads. To be able to reliably prevent, for example, tearing or breaking of the suspension element due to such mechanical loads and thus possibly associated crashes of the car, a condition of the suspension element must be monitored continuously and at suitable intervals to ensure safety of a lift system and damage in this suspension means in time and reliably detected.

Monitoring of an electrical resistance of an electrically conductive support means has been recognized in principle as a way to detect damage in the suspension means. However, with regard to such a method based on measurement of electrical resistances, it can be assumed that at least slight mechanical damage within the suspension element will not be reliably and promptly detected in all circumstances.

A method for detecting damage in a suspension means is in WO 2014130029 A1 in which at least a part of the suspension element is exposed to an alternating electrical voltage and an electrical resistance in the part of the suspension element is measured, by means of which it is possible to deduce damage states in the suspension element.

EP 0849208 B1 discloses methods of inspecting a pull rope. In this case, the traction cable comprises a plurality of targets, which are provided over the length of the traction cable at a distance from each other. The targets have a property such as a magnetic permeability property. The property is monitored so that changes in the spacing between targets can indicate an impairment of the pull rope.

Among other things, there may be a need for an alternative method or apparatus for detecting damage in a suspension system of an elevator installation. In particular, there may be a need for such a method or device by means of which even slight damage can be detected early and reliably.

The invention has for its object to be able to reliably monitor a suspension means of an elevator installation, which comprises at least one tension member, in a simple manner.

This object can be met by the subject matters of any one of the independent claims. Advantageous embodiments are defined in the dependent claims.

The invention is based on the knowledge to be able to monitor a line or a cable in terms of characteristics of a pulse processing in itself. The knowledge according to a pulse signal is applied to a line. The pulse traverses the line and is applied to an unevenness of the line, e.g. Resistance or reactance changes, (partially) reflected. That is, a rupture or rupture within the conduit may cause a pulse signal propagating in the conduit to become discontinuous at a crack interrupted location but to be reflected or attenuated. The reflected pulse travels along the line back to the feed point. In other words, as the characteristics of an electrical pulse signal after it has passed back and forth through part or all of a line, its state is observed and conclusions are made about the presence of damage within that line.

According to the invention, a method is provided for detecting damage in a suspension element with at least one tension member for an elevator installation. In this method, at least a first electrical pulse signal is fed to a first terminal of the support means in the tension member, the first terminal being at or near one end of the suspension means. The first electrical pulse signal is applied at a point of damage (eg wear / breakage or breakdown) in the tension member or at a second attachment of the suspension means which is on or near another end of the suspension means is at least partially reflected and transmitted back to the first terminal. The reflected electrical pulse signal or a reflected portion of this pulse signal is detected at the first terminal as a second electrical pulse signal. The detected second pulse signal is evaluated with regard to its pulse amplitude and / or pulse polarity. The farther the pulse signal is propagated in the tensile carrier, the more the pulse signal is attenuated and consequently has a smaller amplitude. A time duration Δt, which lasts between the input of the first pulse signal and the detection of the second pulse signal, is measured. If an evaluation result of at least one predefined tolerance value deviates and / or the measured time duration Δt exceeds a setpoint value, an error message is sent, for example, to a monitoring / maintenance center for this elevator installation. In this case, the tolerance value may represent a difference of the pulse amplitude and / or the pulse polarity between the first and the second pulse signal.

The set value may be defined by a transmission time of an electrical pulse signal corresponding to a period of time from propagation of this pulse signal from the first terminal after reflection at the second terminal and back again to the first terminal. If the time duration Δt exceeds the setpoint and no second pulse signal has been detected, this means that the method has not been performed properly either because of hardware or because of software errors. In this case, the transmission time can be calculated from a preparation speed v of an electrical pulse signal in the tension member. After the transmission time, it is also possible to determine a position in the tensile carrier at which the pulse signal was reflected and can thus be deduced from damage within the suspension element if a linear causality between the pulse amplitude and the length of the tensile carrier or the transit time Δt can be determined is.

gilt für eine niedrige Signalfrequenz (z.B. 50 Hz bis 100 kHz). In einem höheren Frequenzbereich von z.B. bis 10 MHz erhält man daraus $v=\frac{1}{\sqrt{{\epsilon }_r}},$

wobei c die Lichtgeschwindigkeit in Vakuum, nämlich 30cm/ns darstellt und der ε _r grösser als 1 und für Metallmaterialien üblicherweise kleiner als 10 ist. Eine Ausbereitungsgeschwindigkeit ν von einem Impuls in einem Zugträger beträgt somit typischerweise ca. 40% bis 65 % der Lichtgeschwindigkeit beträgt. Als Alternative kann man eine Laufzeit Δt zwischen dem Einspeisen des ersten Impulssignals und dem Detektieren eines zurückgekommenen zweiten Signalimpuls ablesen, wenn der Zugträger in einem guten Zustand und dessen Länge l auch bekannt ist. Somit kann die Ausbereitungsgeschwindigkeit ν durch eine Gleichung $v=\frac{2l}{\mathrm{\Delta }t}$

ebenfalls berechnet werden. Dabei kann ein Zeit-Offset zwischen dem Generieren des ersten Impulssignals und dem Detektieren des zweiten Impulssignals eine Anwendung zur Zeitverzögerung finden.Depending on which frequency the generated pulse signal has, the preparation speed ν can be calculated on the basis of material constants of the suspension element or tension carrier, such as an inductance L ₀ and a capacitance C ₀ or the dielectrics ε _r . A mathematical equation of the preparation speed $v=\frac{1}{\sqrt{L_0{\mathrm{<figure-callout\; id="0"\; label="C"\; filenames="imgf0003.png"\; state="\{\{state\}\}">C</figure-callout>}}_0}}$

applies to a low signal frequency (eg 50 Hz to 100 kHz). In a higher frequency range of eg up to 10 MHz one obtains from it $v=\frac{1}{\sqrt{{\epsilon }_r}}.$

where c is the speed of light in vacuum, namely 30cm / ns and the ε _{r is} greater than 1 and for metal materials usually less than 10. A preparation speed v of an impulse in a tensile carrier is thus typically about 40% to 65% of the speed of light. As an alternative, one can use a running time Δt between the feeding of the first Pulse signal and detecting a returned second signal pulse read when the tension member in a good condition and its length l is also known. Thus, the speed of preparation ν can be determined by an equation $v=\frac{2l}{\mathrm{\Delta }t}$

also be calculated. Here, a time offset between the generation of the first pulse signal and the detection of the second pulse signal may find an application for time delay.

Typically, the suspension element is fixed to a fixture at or near one of its ends. The fixing device may, for example, be a component permanently mounted in the elevator installation, such as, for example, a strut permanently mounted in an elevator shaft or a carrier-medium bearing mounted thereon. A course and attachment positions and types of attachment of the support means 2 may be configured in various ways. The first pulse signal is then fed through the first terminal, which is assigned to the fixing device, into the suspension element or the tension member. Often the support means is also fixed to or near both its opposite ends in each case to a fixing device. In this embodiment, the first and the second terminal can be attached to the fixing device.

According to an advantageous embodiment of the invention, the first electrical pulse signal is generated as an electrical current pulse or voltage pulse by a pulse generator, wherein the pulse width / duration and / or the pulse amplitude of the first electrical pulse signal are adjustable. Perhaps the pulse generator can be designed as a high-speed analog-to-digital converter, a FPGA (Field Programming Gate Array) or a pulse width modulator (PWM). If the pulse signal contains more than one pulse, a time interval between successive pulses should advantageously be selected such that back-reflected pulses can be unambiguously assigned. In other words, a time interval between successive pulses should be chosen such that even at maximum transit time of the pulses within the suspension means a reflected back pulse reaches the detector before a next pulse is fed into the suspension means. This can considerably simplify detection and / or assignment of the pulses or back-reflected pulses.

According to an advantageous embodiment of the invention, the second connection is adapted to the support means such that the first electrical pulse signal which prepares in the suspension element is at least partially reflected at the second connection. This means that the suspension element or the tension member is not adapted electrically. The reflection factor for a pulse preparation in an electrically adjusted line is equal to zero. Therefore, the second terminal and the tension member should have different characteristic impedances.

According to an advantageous embodiment of the invention, the generated first electrical pulse signal for feeding into the tensile carrier, e.g. amplified coupled by an electronic amplifier, so that the pulse signal can propagate with sufficient power or strength in the train carrier.

According to a further advantageous embodiment of the invention, the feeding of the first electrical pulse signal and the detection of the second electrical pulse signal are synchronized with each other. The synchronization can be done for example by a high-speed timer.

According to another advantageous embodiment, the method for the at least one tensile carrier of the suspension element to the individual, some or all of them can be performed simultaneously. The method can also be carried out manually and / or automatically when the elevator installation is out of operation, in a maintenance or installation state or in a waiting time. Ideally, to avoid a measurement disturbance due to bending or deformation of the suspension element, the method is performed when an elevator car or a counterweight is at a lowest or highest position in a hover, because at that moment the suspension element has a longest free-running part between a reversing roller / a traction sheave and a fixing device has.

• einem Impulsgenerator zum Generieren mindestens eines ersten elektrischen Impulssignals, wobei das erste Impulssignal über einen ersten Anschluss des Tragmittels in den mindestens einen Zugträger eingespeist werden kann,
• einem Detektor zum Detektieren mindestens eines zweiten elektrischen Impulssignals an dem ersten Anschluss, wobei das zweite Impulssignal durch das erste Impulssignal verursacht wird, wenn das erste elektrische Impulssignal an einer Schadenstelle in dem Zugträger oder an einem zweiten Anschluss des Tragmittels reflektiert wird,
• einem Prozessor zum Auswerten des detektierten zweiten Impulssignals hinsichtlich dessen Pulsamplitude und/oder Pulspolarität,
• einen Zeitmesser zum Messen einer Zeitdauer Δt zwischen dem Einspeisen des ersten elektrischen Impulssignals und dem Detektieren des zweiten elektrischen Impulssignals,
• einem Fehlermelder zum Generieren einer Fehlermeldung, wenn ein Auswertungsergebnis von mindestens einem vordefinierten Toleranzwert abweicht und/oder die gemessene Zeitdauer Δt einen Sollwert überschreitet.

According to a second aspect of the invention, a device for detecting damage in a suspension element is provided with at least one tension member for an elevator installation. The device has the following component:

• a pulse generator for generating at least one first electrical pulse signal, wherein the first pulse signal can be fed via a first connection of the suspension element into the at least one tensile carrier,
• a detector for detecting at least a second electrical pulse signal at the first terminal, wherein the second pulse signal is caused by the first pulse signal when the first electrical pulse signal is reflected at a point of damage in the tension member or at a second terminal of the suspension element,
• a processor for evaluating the detected second pulse signal with regard to its pulse amplitude and / or pulse polarity,
• a timer for measuring a time duration Δt between the input of the first electric pulse signal and the detection of the second electric pulse signal,
• an error message for generating an error message if an evaluation result deviates from at least one predefined tolerance value and / or the measured time duration Δt exceeds a setpoint value.

Alternatively or additionally, comparisons with earlier measurements, with reference measurements or with calibration measurements can be used to evaluate the detected second pulse signal. This could cause various random factors in measuring such as e.g. An aging of the suspension element and / or the device or its components are eliminated as a factor in the detection.

It should be noted that possible features and advantages of embodiments of the invention are described herein in part with reference to a method according to the invention and in part with reference to a device according to the invention. A person skilled in the art will recognize that the individual features can be suitably combined, modified or replaced, and that features described in particular for the method can be transferred analogously to the device, and vice versa, in order to arrive at further embodiments of the invention.

Hereinafter, advantageous embodiments of the invention will be described with reference to the accompanying drawings, wherein neither the drawings nor the description are to be construed as limiting the invention. The drawings are only schematic and not to scale. Like reference numerals designate like or equivalent features.

FIG 1

Eine schematische Darstellung einer erfindungsgemäßen Vorrichtung zum Detektieren von Schäden in einem Tragmittel für eine Aufzuganlage,

FIG 2

Ein Ausführungsbeispiel für Ermittlung eines Schadens (Kurzschluss, Unterbruch und Riss) in einem einzelnen Zugträger und für Ermittlung eines schadenfreien Zugträgers eines Tragmittels.

Show it:

FIG. 1

A schematic representation of a device according to the invention for detecting damage in a suspension element for an elevator installation,

FIG. 2

An exemplary embodiment for determining a damage (short circuit, interruption and crack) in a single tension member and for determining a damage-free tension member of a suspension element.

Fig. 1 shows a device 7 according to the invention for detecting damage in a support means 2 for an elevator system 1. The support means 2 may for example be a belt, a rope or the like and at least one on train highly resilient tension member 3 and one or the tension members 3 include.

In order to monitor an integrity of the suspension element 2 and to be able to detect damage in the suspension element 2 early and reliably, a device 7 for detecting such damage is provided on the elevator installation 1. The device 7 comprises a pulse generator 8, a detector 9 and a processor 10. As the pulse generator 8, a high-speed analog-to-digital converter having a sampling frequency of, for example, 20 kHz to 10 MHz can be designed to generate electric current or voltage pulses. This sampling frequency is selected in an appropriate frequency range for the suspension element 2. In general, pulse signals with a frequency in the kHz frequency range in a suspension element 2 are well transferable. The detector 9 can be arranged close to the pulse generator 8 and operated at the same frequency and period as the pulse generator 8 or be in tact. It is also possible to design a single component that can work both as a pulse generator 8 and as a detector 9.

A first pulse signal 4a in this embodiment is e.g. an electrical voltage pulse. The first pulse signal 4a is fed via a first connection 5a of the suspension element 2 into a tension member 3. The detector 9 can detect the second pulse signal 4b at the first terminal 5a, the second pulse signal 4b being formed by the first pulse signal 4a such that the first pulse signal 4a is at a damage location 6 in the tension member 3 or at a second terminal 5b of the suspension means 2 is reflected and then transmitted back to the first port 5a back. The second connection 5b is adapted to the suspension element 2 or tension member 3 in such a way that an electrical pulse signal 4a that prepares in the suspension element 2 is reflected at the second connection 5b. An adapted tension member 3 is used when a pulse propagating in the tension member 3 is not reflected at one end of the tension member 3. This is the case when the second connection 5b has the same characteristic impedance as the tension member 3.

The suspension means 2 is e.g. attached at one end to a fixing device (not shown). However, the connections 5a, 5b do not have to be assigned to the two opposite ends of the suspension element 2, they can be placed anywhere on the suspension element 2, e.g. be placed on the fixer either manually or automatically. In order to be able to propagate the first pulse signal 4a generated by the pulse generator 8 with a sufficient power or pulse height in the tensile carrier 3, the first pulse signal 4a is amplified for feeding into the tensile carrier 3 by an electronic amplifier 13.

The device 7 further has a processor 10, which is connected in this illustrated embodiment both with the pulse generator 8 and with the detector 9. In particular, the processor 10 may receive signals from the detector 9 which provide the processor 10 with information about characteristics of the second pulse signal 4b detected by the detector 9. By receiving signals from the detector 9 continuously or at regular intervals and analyzing them in particular with regard to their pulse amplitudes and / or pulse polarities, the processor 10 can draw conclusions about damage within the tension carrier 3 are pulled. Such damage, which may occur, for example, in the form of cracks or fractures in a tension member 3 accommodated in the suspension element 2, is usually accompanied by a change in impedance within the tension member 3 caused by the damage. Such a local change in the impedance causes the first pulse signal 4a running in the tension member 3 to propagate differently in the tension member 3 than would be the case if no damage had occurred in the tension member 3. For example, to detect the change in impedance, the processor 10 may currently compare the second pulse signal 4b received by the detector 9 with one or the previously received second pulse signals 4b or with previously stored reference values.

The device 7 further comprises a timer 11, e.g. can be an oscilloscope. By means of the timer 11, the second pulse signal 4b can be displayed so that it is possible to read the running time .DELTA.t which has elapsed between the feeding of the first pulse signal 4a and the detection of the second pulse signal 4b. From this run time .DELTA.t can then be set to the point of damage 6 in the suspension element 2. By the timer 11, it is also possible to synchronize the feeding of the first pulse signal 4a and the detection of the second pulse signal 4b with each other.

An error message 12 of the device 7 causes an error message to be sent to a monitoring / maintenance center 15 if an evaluation result deviates from a predefined tolerance value and / or the measured time duration Δt exceeds a setpoint value. This transmission may also be through a network 16 such as the Internet or local area network (LAN), or through wires or wireless transmissions, if the monitoring / maintenance center 15 is a central office. The tolerance value may represent a difference for the pulse amplitude and the pulse polarity between the first 4a and the second pulse signal 4b. The tolerance value may also be defined in terms of a number of the damaged tension members 3. That is, an error message is generated only when a plurality of tension members 3 or a certain number of the tension members 3 are damaged. The setpoint and the tolerance value may be e.g. stored in the processor 10 or in a separate memory unit (not shown).

berechnet werden. Bei einem Zugträger 3 mit einem Dielektrika ε _r von 4 ist die Ausbreitungsgeschwindigkeit ν also ziemlich genau 15cm/ns. Man kann die Ausbereitungsgeschwindigkeit ν durch eine mathematische Gleichung $v=\frac{2l}{\mathrm{\Delta }t}$

gleichfalls ermitteln, wenn die Länge l von einem Zugträger 3 bekannt ist, der nicht beschädigt ist. Dafür hat man nur die Laufzeit Δt von dem ersten Impulssignal 4a noch vorher zu vermessen. Falls die Ausbreitungsgeschwindigkeit ν zu schnell oder die Zeitdauer Δt zu kurz für Impulsdetektieren ist, kann ein Zeitoffset 14 zwischen dem Generieren des ersten Impulssignals und dem Detektieren des zweiten Impulssignals eingesetzt werden, wobei der Zeitoffset 14 eine Zeitverzögerung ermöglicht.The desired value may be, for example, a time duration Δt which corresponds to a propagation of the first pulse signal 4a from the first terminal 5a after reflection at the second terminal 5b and back again to the first terminal 5a. If the pulse duration of a first pulse signal 4a is selected to be 50 ns, for example, the maximum sampling frequency of the pulse generator 8 and the detector 9 may be 40 kHz, for example. A speed of preparation ν of a pulse signal in the tension member 3 can in a simple manner by a mathematical equation $v=\frac{c}{\sqrt{{\epsilon }_r}}$

be calculated. In the case of a tensile carrier 3 with a dielectric ε _r of 4, the propagation velocity ν is therefore almost exactly 15 cm / ns. One can estimate the speed of preparation ν by a mathematical equation $v=\frac{2l}{\mathrm{\Delta }t}$

also determine if the length l is known from a tension member 3, which is not damaged. For this one only has to measure the transit time Δt of the first pulse signal 4a before. If the propagation velocity ν is too fast or the time duration Δt is too short for pulse detection, a time offset 14 may be used between generating the first pulse signal and detecting the second pulse signal, the time offset 14 enabling a time delay.

In Fig. 2 an embodiment for determining a damage in an above-mentioned tension member 3 is shown. In this case, a first pulse signal 4a fed into the tensile carrier 3 first moves in a direction along the tensile carrier 3 with a positive pulse polarity, before it is then reflected at a point caused by damage and then runs back through the tensile carrier 3 in the opposite direction. In this case, the device 7 according to the invention detects at the first connection 5a of the suspension element 2 a first electrical pulse signal 4a fed into the tension member 3. A trend line K shows an envelope of the pulse amplitude of the pulse signal 4a, wherein the pulse amplitude is continuously attenuated due to loss in the course of propagation in the tension member 3. Here, the return path of the first pulse signal 4a and the first terminal 5a are shown in dashed line.

For a linear behavior of the damage location 6, a dimensionless reflection factor r describes how a reflected pulse signal is generated from the first pulse signal 4a. If the tension member 3 is electrically short-circuited, then r = -1, ie a pulse is reflected at full amplitude but with a phase shifted by 180 °, namely in a reverse polarity. If the tension member 3 is left open or interrupted, then r = 1, then the pulse is completely and in the same phase, ie in a same polarity, reflected.

A preparation or reflection of the first pulse signal 4a in a tension member 3 is in each case in the Fig. 2a, 2b . 2c and 2d shown. It is assumed that the point of damage 6 is always located at the same point of the tension member 3. 2a and 2b each show a case of a short circuit and an interruption in the tension member 3. Depending on whether a damage occurs in the tension member 3, a second pulse signal 4b is detected at the second terminal 5b as follows: FIG. Tension member reflection factor pulse polarity pulse amplitude Running time Δt 2a short circuit r = -1 - greater value shorter 2 B interruption r = 1 + greater value shorter 2c Crack 0 < r <1 + small value shorter 2d without damage 0 < r <1 + minute value setpoint

The first pulse signal 4a is reflected with an opposite negative pulse polarity ( r = -1) when there is a short at the point of damage 6. In contrast, the first pulse signal 4a is reflected at the point of damage 6 with an unchanged positive pulse polarity ( r = 1) when the tension member 3 is interrupted at this point. Ideally, the first pulse signal 4a is completely reflected in the two cases at the point of damage 6, ie the reflection factor r = ± 1. Since the entire running distance of the first pulse signal 4a in the tension member 3 is shorter than that in the case of a damage-free tension member 3, the first pulse signal 4a is transmitted with less loss. Accordingly, the detected second pulse signal 4b has a larger pulse amplitude and a shorter transit time .DELTA.t.

The cases of a crack ( Figure 2c ) in the tension member 3 and of a damage-free tension member 3 are respectively in Fig.2c and Fig.2d shown. It is to be assumed that the reflection at the second connection 5b and at a point of damage 6 of wear has the same reflection factor r .

In case of crack damage, the first pulse signal 4a is reflected with a reflection factor 0 < r <1. Thus, the detected second pulse signal 4b then has a smaller pulse amplitude compared to that in the above-mentioned cases of interruption and short circuit. It can also be seen that the envelope K steeper than that in 2b is. If this detected pulse amplitude is smaller than the tolerance value such as half of the pulse amplitude of the generated first pulse signal 4a, this means that the crack in the tension member 3 is to be regarded as a damage. In this case, it could also happen that two pulses would be detected in succession if the first pulse signal 4a has a sufficient power and continues to be prepared to the second port 5b despite a reflection at the point of damage and is reflected there for the second time. The detected second pulse is shown by a reference numeral 17 in dashed line.

In a good tensile medium 3, the first pulse signal 4a is first reflected at the second terminal 5b and runs back at the first terminal 5a, so that the transit time .DELTA.t corresponds to a maximum value which corresponds to the desired value, and the pulse amplitude, in contrast thereto has minimum value, because the reflection factor 0 < r <1 and the first pulse signal has covered the longest running distance.

In addition to being able to deduce a damage location 6 within the tension member 3, it can also position the damage location 6. For this purpose, the processor 10 can analyze, for example, how long the first pulse signal 4a needs in order to pass through the tension member 3 to a point of damage 6 and after its reflection to run back again to the first connector 5a. After a running time .DELTA.t has been determined, one can calculate a position of the damage site 6 at a known propagation velocity .nu.

As the further the first pulse signal 4a is propagated in the tension member, the longer the runtime Δt and more the first pulse signal 4a is attenuated, it can also be detected, even if the tension member 3 is interrupted at the connection to the second connector 5b or shorted. The first pulse signal 4a is fully reflected at this point in its current amplitude and the pulse amplitude of the second pulse signal 4b is thus comparatively greater in this case than that of a good tensile carrier 3. Even if a crack damage in the tension member 3 at or near the second Terminal 5b happens, the damage can also be determined by the inventive method, because the reflection factor r at the second terminal 5b is defined as a constant. There is hardly a possibility that the second terminal 5b and a crack damage have the same reflection factor r . The pulse amplitudes of the detected second pulse signals 5b of the two cases can thus be recognized differently.

In summary, embodiments of the method presented here or of the device 7 presented herein allow reliable detection of even minor damage within the suspension element 2 or tension carrier 3 using an electrical pulse signal by the method or device 7 according to the invention.

LIST OF REFERENCE NUMBERS

1

elevator system

2

support means

3

tension members

4a

the first pulse signal

4b

the second pulse signal

5a

the first connection

5b

the second connection

6

damaged area

7

contraption

8th

pulse generator

9

detector

10

processor

11

chronometer

12

error detector

13

amplifier

14

time offset

15

Surveillance- / maintenance center

16

network

17

a detected second pulse

K

Envelope of the pulse amplitude

l

Length of a tension member

r

reflection factor

.delta.t

running time

Claims (15)

Method for detecting damage in a suspension element (2) with at least one tension member (3) for an elevator installation (1), comprising the following steps: Feeding at least one first electrical pulse signal (4a) to a first connection (5a) of the suspension element (2) into the at least one tension member (3), Detecting at least one second electrical pulse signal (4b) at the first terminal (5a), the second electrical pulse signal (4b) being caused by the first electrical pulse signal (4a) when the first electrical pulse signal (4a) is applied at a point of damage (6th ) in which at least one tensile carrier (3) or at a second connection (5b) of the suspension element (2) is at least partially reflected, Evaluating the detected second electrical pulse signal (4b) with regard to its pulse amplitude and / or pulse polarity, Measuring a time duration (Δt) between the input of the first electrical pulse signal (4a) and the detection of the second electrical pulse signal (4b), - Reporting an error condition when an evaluation result of at least one predefined tolerance value deviates and / or the measured time duration (At) exceeds a setpoint. The method of claim 1, wherein
the first electrical pulse signal (4a) is generated as an electrical current pulse or voltage pulse by a pulse generator (8), wherein the pulse duration and / or the pulse amplitude of the first electrical pulse signal (4a) can be adjusted. Method according to claim 1 or 2, in which
the feeding of the first electric pulse signal (4a) and the detection of the second electric pulse signal (4b) are synchronized with each other. The method of claim 1, wherein
the setpoint value corresponds to a transmission time of an electrical pulse signal (4a, 4b) from the first terminal (5a) after a reflection at the second terminal (5b) back to the first terminal (5a). Method according to claim 1 or 2, in which
the at least one tolerance value represents a difference of the pulse amplitude and / or the pulse polarity between the first (4a) and the second electrical pulse signal (4b). Method according to one of the preceding claims, in which
the method for the at least one tension member (3) of the suspension element (2) for the individual, some or all of them can be carried out simultaneously. Method according to one of the preceding claims, in which
the method is performed manually and / or automatically when the elevator installation is out of operation, in a maintenance or installation state or in a waiting time. Device (7) for detecting damage in a suspension element (2) with at least one tension member (3) for an elevator installation (1), comprising: - A pulse generator (8) for generating at least a first electrical pulse signal (4a), wherein the first pulse signal (4a) via a first terminal (5a) of the support means (2) in the at least one tension member (3) can be fed a detector (9) for detecting at least one second electrical pulse signal (4b) at the first terminal (5a), the second pulse signal (4b) being caused by the first pulse signal (4a) when the first electrical pulse signal (4a) is reflected at a point of damage (6) in the tension member (3) or at a second connection (5b) of the suspension element (2), a processor (10) for evaluating the detected second pulse signal (4b) with regard to its pulse amplitude and / or pulse polarity, a timer (11) for measuring a time duration (Δt) between the input of the first electrical pulse signal (4a) and the detection of the second electrical pulse signal (4b), - An error message (12) for generating an error message when an evaluation result of at least one predefined tolerance value deviates and / or the measured time duration (At) exceeds a target value. Apparatus (7) according to claim 8, wherein
the first electrical pulse signal (4a) can be generated as an electrical current pulse or voltage pulse by a pulse generator (8), wherein the pulse duration and / or the pulse amplitude of the first electrical pulse signal (4a) can be adjusted. Device (7) according to claim 9, wherein
the device (7) comprises a coupled amplifier (13) for amplifying the generated first electrical pulse signal (4a) to feed the amplified first pulse signal (4a) in the at least one tensile carrier (3) Device (7) according to one of claims 8 to 10, wherein
the timer (11) is provided for synchronizing the feeding of the first electric pulse signal (4a) and the detection of the second electric pulse signal (4b). Apparatus (7) according to claim 8, wherein
the second connection (5b) is adapted to the suspension element (2) in such a way that the first electrical pulse signal (4a) which prepares in the tension support (3) is reflected at the second connection (5b). Apparatus (7) according to claim 8, wherein
the setpoint value corresponds to a transmission time of a first electrical pulse signal (4a, 4b) from the first connection (5a) after a reflection at the second connection (5b) back again to the first connection (5a). Apparatus (7) according to claim 8, wherein
the at least one tolerance value represents a difference of the pulse amplitude and / or the pulse polarity between the first (4a) and the second electrical pulse signal (4b). Device (7) according to one of claims 8 to 14, wherein
the device (7) can be activated manually and / or automatically when the elevator installation is out of operation, in a maintenance or installation state or in a waiting time.

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