EP2367747B1 - Method for monitoring a lift puller, a lift puller monitoring device and a lift assembly with such a monitoring device - Google Patents

Description

The invention relates to an elevator support means monitoring device, an elevator installation with such a monitoring device and a method for monitoring an elevator support means according to the preamble of the independent claims.

The elevator support means monitoring device is permanently installed in an elevator installation or can be installed for temporary use. The elevator system consists essentially of a car, which is connected via lift support means with a counterweight. By means of a drive which acts selectively on the elevator support means, directly on the car or the counterweight, the car is moved along a, substantially vertical, cabin carriageway. The car lane is usually integrated in a building in a shaft and thereby limited by shaft walls, shaft ceiling and shaft floor. The car lane can also be attached to a building or a building structure, whereby parts of the shaft walls, shaft cover and shaft floor omitted, or must not be defined by solid materials. In this case, the shaft essentially corresponds to the space which is determined by the movement and arrangement of elevator components as well as by the required safety distances and safety spaces. The shaft, or the shaft walls are provided with access, which optionally allow access to the cabin.

The elevator support means thus carry the car and the counterweight. In many cases, these elevator support means are not only exposed to load-bearing forces but they transmit, for example by means of traction, a drive force from the drive to the car or to the counterweight.

In many cases, the elevator support means are provided with load-bearing tension members, which are surrounded by a traction-optimizing sheathing. The Lifting agent is subject to wear and tear. Lifting means must therefore be monitored over their period of use in order to prevent failure of the elevator support means, or to be able to replace the elevator support means early.

Such monitoring methods can be done manually, for example by visual inspection. At best, the elevator support means may also be provided with optical wear marks as in the example EP1275608 is disclosed.

Other methods provide a magnetic inductive test, such as by Prof. Dr.-Ing. K.Feyrer in his publication for the dimensioning and monitoring of running wire ropes ISBN 3-8169-1481-0; Chapter 7 is presented. In elevator technology, many other methods are known. Another monitoring method, such as in the WO00 / 58706 presented, measures a resistance of tension members and sets it in relation to the load-carrying capacity of the load-bearing medium. Other methods, such as in the EP0731209 disclosed, use indicator wires, which are admixed to the Zugträger and mitverdrillt. Tearing of an indicator strand indicates increasing aging of the suspension.

In the EP 1 818 444 A1 The magnetic flux leakage through the wire bundle of a rope is measured to detect damage to the rope.

An object of the invention is to provide a monitoring method for monitoring elevator support means, which allows a statement about the current state of an elevator support means and possibly a weighting of this condition.

This object is achieved by a method for monitoring an elevator support means according to claim 1, by an elevator support means monitoring device according to claim 9, as well as an elevator installation according to claim 10. In this case, at least one characterizing property of an elevator support or of a tension member of an elevator support means is monitored, and sudden or discrete changes of this characterizing property are detected, preferably by means of an elevator support means monitoring device. In the following, a state of the elevator support means by means of evaluation determined by the successive, abrupt changes of this characterizing property.

A support means, or its tension member has typical characterizing properties. Such a typical property may be, for example, an electrical resistance, a light transmission characteristic or a sound transmission behavior, etc. be. A disturbance in the tension member or in the suspension element has an influence on this characterizing property. Thus, for example, in the case of a breakage of a single wire of a tension member, an electrical resistance changes, which causes a sudden change in the total resistance of the individual tension member. This sudden change is detected and counted as a discrete, or sudden, change in the characterizing property of the tension member. The detection of the number of sudden changes thus allows a statement about the state of the tension member, or the suspension element.

Advantageously, the state of the elevator-carrying means is determined on the basis of a sum [N] of the abrupt changes in the characterizing property. Alternatively or additionally, the state of the elevator-carrying means is determined on the basis of a frequency [dN / dt] of the sudden changes in the characterizing property. In a further alternative or supplementary embodiment, the condition of the elevator-carrying means is determined, preferably in the elevator support means monitoring device, on the basis of a temporal change in the frequency [dN / dt / dt] of the sudden changes in the characterizing property.

The detection of the sum [N] of the sudden changes in the characterizing property makes it possible to estimate the individual changes made in the tension member or in the elevator support means and accordingly enables the condition of the support means to be estimated, if the number of changes is related to a statistically possible number that can be tolerated is set by individual changes.

The detection of the frequency [dN / dt] of the abrupt changes in the characterizing property makes it possible to detect an accumulation of individual changes in the tensile carrier or in the elevator carrier. An accumulation may indicate that an increasing fatigue of a Zugträgermaterials takes place, but it may also mean that an operating mode of the elevator is changed. Such changes may be increased load transports or the like.

Advantageously, a frequency evaluation is created taking into account an actual operating time. Thus, the time evaluation [dN / dt] is advantageously evaluated over the actual operating time.

The detection of the temporal change in the frequency [dN / dt / dt] of the abrupt changes in the characterizing property makes it possible, in particular, to quickly detect an increase in the frequency of fracture. Such an increase indicates that a load is distributed over increasingly less load-bearing tensile member shares and possibly there is an aging of the material.

Advantageously, the state of the elevator support means determined in this way can be called up in the elevator support means monitoring device. Alternatively or additionally, the specific state of the elevator support means can be displayed directly by the elevator support means monitoring device. In a further alternative or supplementary embodiment, the specific state of the elevator support means is forwarded by the elevator support means monitoring device to a central elevator control. In another alternative or supplementary embodiment, the elevator support means monitoring device triggers an alarm upon reaching a limit state and / or it directly activates a safety device.

In this way, an exchange of suspension elements or at most a detailed examination, for example by means of a magnetically inductive measuring method or by means of ultrasound, etc., can be planned as required.

Advantageously, the abrupt change in the characterizing property is detected by detecting a relative change between a first and a second elevator support means or between a first and a second tensile carrier of the elevator support means.

Thus, several tension members can be measured directly. It is not necessary here that a change can be assigned to a single tension member. The changes are evaluated in their entirety via the tension members integrated in the measuring circuit.

In an advantageous embodiment, the elevator means used or the tension member used of the elevator support means includes electrically conductive wires. This design is common. The wires are assembled into a wire bundle. The elevator support means or the used tension member of the elevator support means are designed to transmit tensile forces and the characterizing property of the elevator support means or of the tension member is advantageously an electrical resistance.

Advantageously, measures are provided for filtering identified changes. A measuring signal is subject to external influences. Thus, the operation of an elevator system naturally causes signal interference. In the presented embodiment, filters are provided which reduce signal interference or background noise of the signal. Advantageously, the elevator support means monitoring means includes means for filtering the detected deviations. This filtering is, for example, a grounding of the two-sided ends of the elevator support means or the tension member. The earthing is effected, for example, by means of a high earthing resistance in comparison to the internal resistance of the elevator support means or of the tension member.

Advantageously, the elevator support means comprises a plurality of tension members and these tension members are divided into two or pairs of tensile member regions. Advantageously, the tension members of a tension member area are interconnected in series and the paired tension member areas are connected to a respective half-bridge.

Alternatively, the elevator support means comprises a plurality of tension members, and these plurality of tension members are divided into four or four groups or double pairs of tension members. The tensile carriers of a Zugträgerbereiches are turn each interconnected in series and the groups of four of Zugträgerbereichen are each connected to a full bridge.

Of course, a plurality of such half or full bridges can be formed for monitoring an elevator support means or the elevator support means of an entire elevator installation.

Bridge circuits are proven circuits, especially in the detection of resistors. With this design, it is easy to detect and evaluate sudden changes between individual tension members or tension member areas, since the bridge circuit is a comparative circuit.

The elevator support means is preferably a carrying strap. The strap consists of several tension members. The tension members are surrounded by a, preferably electrically insulating jacket and spaced from each other and electrically insulated from each other. As a shell material, for example, polyurethane or other plastics or rubber are. Of course, the jacket can also be constructed in multiple layers or in several parts. The tension members are advantageously made of a steel strand, which is twisted and stranded in a known manner from a plurality of wires.

Advantageously, a group of tension members are combined to form such a strap, or the tension members of a support belt are advantageously divided into two or four Zugträgerbereiche. The Zugträgerbereiche are thus advantageously composed of tension members of a single support belt.

Alternatively, the Zugträgerbereiche can also be composed of tension members of several straps and all tension members, which are composed for example of several support means are accordingly divided into two or four Zugträgerbereiche or a multiple thereof. The Zugträgerbereiche all straps are thus composed according to this embodiment of tension members of all straps of the elevator system.

Advantageously, the tension members of an elevator support means are combined to a single bridge circuit, a half or full bridge. alternative For example, the tension members of an elevator-supporting means can also be divided into a plurality of bridge circuits.

The elevator support means monitoring device advantageously includes an evaluation unit which contains the processors, storage media, circuit components such as bridge resistors, voltage stabilizers, etc. required for evaluation. The elevator support means monitoring device may be divided into functional groups, which may also be integrated into an elevator control or may be designed separately. The elevator support means monitoring device advantageously further includes a connection device for connecting the Zugträgerbereiche to the evaluation.

With the described interconnections of suspension elements and tension members, needs-based designs of the elevator support means monitoring device can be provided. The straps can, for example by means of the connection device, are simply contacted at their ends, as for example in our application EP08169452.3 is shown. This makes it possible to realize overall reliable and cost-effective monitoring of suspension elements.

The elevator support means monitoring device can be installed for continuous monitoring of the suspension in an elevator system. This allows continuous monitoring. Alternatively, however, a temporary use of the monitoring device is possible. Thus, in a regular measurement, a frequency of sudden changes can be recorded. In a later measurement, the newly determined frequency can be compared with the former measured variable and the necessary measures can be determined on a case-by-case basis.

It is particularly advantageous if the evaluation of the sudden changes taking into account a travel movement of the elevator car takes place. This is due to the fact that a possible breakage of a single wire in the following rolling over of a deflection roller usually again generates a sudden change. This is often a result of the rollover Break point briefly pushed together and then separated again. This will now be done at each subsequent overrun. Based on the geometric distance and arrangement of pulleys and a driving curve with knowledge of the respective position of the car in the shaft, the location of each break can now be located and stored. Already registered breakages can therefore be ignored in the detailed analysis.

Thus, inter alia, a degree of wear of the suspension means can be determined more reliably and, if necessary, a location of damage clusters can be identified and analyzed in detail.

Advantageously, the elevator means for monitoring means includes a breakage monitoring device. This can detect or detect a break of the tension member. This detection takes place, for example, if the resistance of the relevant elevator means, the relevant tension member or the relevant Zugträgerbereiches is determined at approximately infinity or if a current flow in the relevant elevator means, in the relevant Zugträger or in the relevant Zugträgerbereich is interrupted or if a balancing voltage of the previously explained half or full bridge reaches a threshold voltage value. Advantageously, the elevator support means monitoring means activates a safety device upon detection of the breakage of the tension member or it triggers a corresponding alarm, whereby, for example, the elevator system is stopped after completion of a pending driving command. Thus, the overall safety of the elevator system can be increased. An elevator system usually uses at least two straps, which are provided, for example, each with about twelve individual tension members. In case of failure of a single of these twenty-four train carriers, the plant would be driven immediately to a stop and stopped there. This additionally improves the safety of use as a whole.

Advantageously, a resistance value of the tension member is detected in each case. The individual resistance of a tension member increases according to experience in the course of the operating time, since individual wires break and a single resistance of a Zoom in to the train carrier. On the one hand, a permissible limit resistance can now be determined and, when this limit resistance is reached, a replacement of the suspension element is undertaken. But it can also, in addition or alone, the temporal change of the resistance value [dR / dt] are evaluated and a replacement of the suspension means can be provided if a temporal increase in resistance, which at the same time corresponds to an accumulation of individual fractions, is determined.

The respective limit values are determined for the conventional suspension means, preferably by means of comparison tests.

In the following the invention will be explained in more detail by means of embodiments in connection with the schematic figures.

Fig. 1

eine Gesamtansicht einer Aufzugsanlage mit 1:1 gehängter Kabine,

Fig. 2

eine schematische Ansicht einer Aufzugsanlage mit 2:1 gehängter Kabine,

Fig. 3

ein erstes Beispiel eines Aufzugstragmittels,

Fig. 4

ein weiteres Beispiel eines Aufzugstragmittels,

Fig. 5

ein erstes Anordnungsbeispiel einer Aufzugstragmittel-Überwachungseinrichtung,

Fig. 6

ein weiteres erstes Anordnungsbeispiel einer Aufzugstragmittel-Überwachungseinrichtung,

Fig. 7

ein Beispiel einer Brückenschaltung

Fig. 8

ein Messbeispiel einer Brückenspannungsmessung

Fig. 9

ein Beispiel zur Ermittlung von sprungartigen Veränderungen

Fig. 10

eine Analyse eines Auswerteergebnisses

Fig. 11

eine alternative Analyse eines Messergebnisses

Fig. 12

ein Beispiel einer Aufzugstragmittel-Überwachungseinrichtung unter Verwendung einer Halbbrückenschaltung,

Fig. 13

ein erstes Verschaltungsbeispiel von Aufzugstragmitteln mit Halbbrückenschaltung,

Fig. 14

ein zweites Verschaltungsbeispiel von Aufzugstragmitteln mit Halbbrückenschaltung,

Fig. 15

ein Beispiel einer Aufzugstragmittel-Überwachungseinrichtung unter Verwendung einer Vollbrückenschaltung,

Fig. 16

ein erstes Verschaltungsbeispiel von Aufzugstragmitteln mit Vollbrückenschaltung,

Fig. 17

ein zweites Verschaltungsbeispiel von Aufzugstragmitteln mit Vollbrückenschaltung,

Show it:

Fig. 1

an overall view of an elevator installation with a 1: 1 suspended cabin,

Fig. 2

a schematic view of an elevator system with 2: 1 suspended cabin,

Fig. 3

a first example of an elevator support,

Fig. 4

another example of an elevator support,

Fig. 5

a first arrangement example of an elevator means monitoring device,

Fig. 6

another first arrangement example of an elevator means monitoring device,

Fig. 7

an example of a bridge circuit

Fig. 8

a measurement example of a bridge voltage measurement

Fig. 9

an example for the determination of sudden changes

Fig. 10

an analysis of an evaluation result

Fig. 11

an alternative analysis of a measurement result

Fig. 12

an example of an elevator means monitoring means using a half-bridge circuit,

Fig. 13

a first connection example of elevator support means with half-bridge circuit,

Fig. 14

A second connection example of elevator support means with half-bridge circuit,

Fig. 15

an example of an elevator means monitoring means using a full bridge circuit,

Fig. 16

a first connection example of elevator support means with full bridge circuit,

Fig. 17

a second connection example of elevator support means with full bridge circuit,

In all figures, the same reference numerals are used for equivalent components.

A possible first overall arrangement of an elevator installation with an elevator support means monitoring device is in Fig. 1 shown. The elevator installation shown there is installed in a shaft 2. The shaft 2 is bounded by shaft walls 5, by a shaft ceiling 3 and by a shaft bottom 4. In the shaft 2, a car 7 and a counterweight 8 are installed. The car 7 and the counterweight 8 are each guided by an associated car lane 10, or counterweight lane 11 and interconnected by means of an elevator support means 9 such that the car 7 and the counterweight 8 can move against each other in the shaft. In the example shown, the support means 9 is driven by a arranged in the region of the shaft ceiling 3 elevator drive 12 with traction sheave 13. The elevator support means 9 is connected by means of a suspension element end connection 16 to the car 7, or to the counterweight 8. The car 7 can be moved in the shaft 2 by the drive 12 along the shaft walls 5. In at least one of the shaft walls 5 accesses 6 are arranged. By a controller 15, the drive is controlled so that the car stops at each desired access 6 to allow entry, loading and / or a corresponding leaving, or unloading the car 7.

In the Fig. 1 shown elevator system is directly or 1: 1 suspended. This means that a peripheral speed of the traction sheave 13 directly corresponds to a driving speed of the car 7.

In this example, the counterweight-side suspension means end connection 16 is provided with a contacting unit 17. With this contacting unit 17, in this example, electrically conductive individual tensile carriers of the elevator support means 9 are electrically contacted. Directly on this contacting unit 17, a circuit head 18 is mounted, which interconnects individual tension members of the elevator support means 9, so that a desired circuit is formed.

The cabin-side suspension means end connection 16 is likewise provided with a contacting unit 17, which makes it possible to connect the elevator support means to an elevator support means monitoring device 20. The elevator support means monitoring device 20 includes a corresponding connection device, for example in the form of terminals or power strips. The elevator means monitoring means 20 is further connected to the controller 15. This connection can be made by means of bus system, wireless or conventional wiring technology. The elevator support means 20 is arranged near the cabin side support means end connection 16 in the example.

The execution after Fig. 1 where a circuit head 18 is used on the counterweight side is advantageously used in 1: 1 hung elevator systems, since in this case the interconnection of the tension members takes place directly at the counterweight and accordingly no leads leading away from the counterweight are required.

A possible other overall arrangement of an elevator installation with an elevator support means monitoring device is in Fig. 2 shown. In this embodiment, the elevator system 2: 1 is suspended. This means that a peripheral speed of the traction sheave 13 corresponds to a double value of the driving speed of the car 7. In contrast to the execution according to Fig. 1 For example, in this example, the elevator support means 9 is fixed with its two ends in the shaft using suspension means end connections 16, and the elevator support means 9 is connected to car 7 and counterweight 8 via support rollers or deflection rollers 14. According to this example, both ends of the support means are in turn provided with contacting units 17, but both contacting units 17, or both ends of the elevator support means 9 connected by connecting lines 19 to the elevator support means monitoring device 20. In the elevator support means monitoring device 20, the necessary interconnections are made. The elevator carrier monitoring device 20 is in turn connected to the controller 15 of the elevator installation 1.

The elevator support means monitoring device 20 is usually permanently installed in the elevator installation 1 and constantly monitors the elevator support means 9. Of course, it can also be used temporarily in the system only in time-defined time windows. In this case, any contacting units 17 are advantageously left in the elevator installation 1 and only the elevator support means monitoring device 20 is temporarily used or removed again. Thus, with an elevator support means monitoring device 20 several systems can be monitored.

FIG. 3 and FIG. 4 show typical elevator support means 9, as in the elevator systems according to Fig. 1 or 2 are usable. Fig. 3 shows a belt-like support means 9 which is provided with six parallel tension members 21. The tension members 21 consist of a stranded arrangement of steel wires 23. The tension members are embedded in a jacket material 22, which jacket 22 holds the individual tension members 21 at a distance from each other and isolates them from each other and from the environment. The belt shown has on one side traction grooves, which allow a good transfer of traction forces and which lead the belt at the same time and it has on the opposite side a flat end surface with a thin cladding layer. The illustrated belt includes six individual tension members 21. Other types of belt include, for example, twelve tension members.

Fig. 4 shows another embodiment of an elevator support means 9. This support means 9 includes four parallel tension members 21. The tension members 21 are also surrounded by a jacket 22, wherein the jacket 22 has an upper shell half 22.1 and a lower shell half 22.2. The two shell halves are made, for example, of different materials, for example, the upper shell half 22.1 consists of a material with high traction, while the lower shell half 22.2 consists of a sliding material. Again, the coat keeps the individual tension members 21 apart from each other and he isolated them to the environment.

In the examples, the tension members 21 are arranged parallel to each other. Of course, other arrangements of tension members are possible. Thus, the tension members can also be arranged in layers.

As a rule, an elevator installation includes a plurality of elevator support means 9, which carry the elevator car 7 together. The elevator support means 9 are arranged parallel to each other and thus act as a common support means.

Fig. 5 shows an interconnection of an elevator support means 9 with the elevator support means monitoring device 20 as in the elevator installation Fig. 2 used. The two-sided ends of the elevator support means 9 are equipped with contacting units 17 and by means of these contacting units 17, the tension members 21 of the suspension element 9 are connected via connection lines 19 to the elevator support means monitoring device 20. The elevator support means monitoring device 20 has a connection to the controller 15. Thus, for example, the elevator system is shut down in case of need, or via this connection, for example, an operating state of the elevator system is transmitted. Thus, the elevator support means monitoring device 20 can use, for example, the actual operating time for evaluation.

Fig. 6 In contrast, shows an interconnection of an elevator support means 9 with the elevator support means monitoring device 20 as in the elevator system Fig. 1 used. The two-sided ends of the elevator support means 9 are in turn equipped with contacting units 17. A contacting unit 17 is in this case equipped with a circuit head 18. The circuit head 18 switches two tensile carriers 21 together to form a train carrier region connected in series. The connection 19 to the elevator support means monitoring device 20 can thereby be reduced to one end of the support means 9.

FIGS. 12 to 14 show a possible circuit arrangement for detecting sudden changes in an electrical resistance in tension members of the elevator support means. In the example according to Fig. 13 are three in essence identical elevator support means 9, each with four tension members 21 assembled to form a suspension element composite. Such a suspension element composite is, for example, in the elevator system according to Fig. 1 ideal for use. The support means 9 used correspond, for example, the suspension means as in Fig. 4 shown.

One end of the suspension element 9 is in each case provided with a contacting unit 17 and with this contacting unit 17 a switching head 18 is connected, which in each case combines two tension members into one tension carrier area. These two Zugträgerbereiche each define a resistor R1, or R2. Each of the support means 9 thus includes in the example Fig. 13 in each case two Zugträgerbereiche to two series-connected tension members 21. The other ends of Tragmittel- 9 are also each provided with a contacting unit 17, which allow a connection of the support means, or its tension member to the elevator support means monitoring device 20. In the illustrated example, the two tensile-carrier regions of a suspension element are now in each case to be compared as resistors R1, R2 in the elevator-support-means monitoring device 20 in a half-bridge, as in FIG Fig. 12 shown in schematic view, interconnected. Half-bridge means that only two tensile carrier areas are measured in comparison to one another, and stationary reference resistors R3 and R4 are inserted into the elevator-load-medium monitoring device 20 to complete a measuring bridge.

In the embodiment according to Fig. 13 each of the support means 9 is equipped with its own measuring bridge. This gives the advantage that each support means can be considered alone.

In the example according to Fig. 14 In contrast, a support means 9 is used with twelve tension members. These twelve tension members 21 are interconnected in pairs at one end of the suspension element and the other end of the suspension element is connected in such a way that two symmetrical tensile member regions are created, which then define an associated resistor R1 or R2. A measuring bridge arrangement is then as in the description of Fig. 12 explained. Of course, a plurality of such support means can be connected to a suspension element composite.

FIGS. 15 to 17 show another possible circuit arrangement for detecting sudden changes in an electrical resistance in tension members of the elevator support means. In the example according to Fig. 16 In turn, three substantially identical lift support means 9 are assembled with four tension members 21 to form a suspension element composite.

Both ends of the support means 9 are each provided with a contacting unit 17. The four tension members each form their own Zugträgerbereich and each of these Zugträgerbereiche each defines a resistor R1 to R4. Each of the support means 9 thus includes in the example Fig. 15 each four Zugträgerbereiche each having a tension member 21. The ends of the support means 9 are connected by means of the contacting units 17 and connecting lines 19 to the elevator support means monitoring device 20. In the illustrated example, the four traction bearer regions of a suspension element are in each case designed as resistors R1 to R4 to be compared in the elevator support means monitoring device 20 to form a full bridge, as well as in FIG Fig. 15 shown in schematic view, interconnected. Full bridge means that four Zugträgerbereiche, or their resistors R1 to R4, are measured in comparison to each other. A deviation in one of the tension members causes an imbalance in the measuring bridge, which can be evaluated accordingly.

In the embodiment according to Fig. 16 each of the support means 9 is equipped with its own measuring bridge. This also gives the advantage that each suspension can be considered alone.

In the example according to Fig. 17 In contrast, a support means 9 is used with twelve tension members. The suspension is essentially as in Fig. 3 shown constructed, wherein instead of the six tension members shown there are used twelve of them. These twelve tension members 21 are divided into four Zugträgerbereiche, in which case each Zugträgerbereich includes three series-connected tension members. These four Zugträgerbereiche now each determine a corresponding resistor R1 to R4. A measuring bridge arrangement is then as in the description of Fig. 16 explained. Of course, here too several such support means to a suspension element composite get connected. This circuit arrangement with both sides connected Tragmittelenden is preferably in accordance with elevator system Fig. 2 used. A person skilled in the art can select the suitable circuit arrangement depending on the type of suspension of the car and the counterweight as well as the number of used suspension elements and tension members.

Fig. 7 shows a principle of a measuring bridge as used to detect jump-like change in the characterizing property of one of the tension members. The characterizing property in the example shown is an electrical resistance of a tension member. The measuring bridge consists of four resistors R1 to R4 which, as explained in the preceding examples, may be tensile carrier regions or, when using a half bridge, tensile carrier regions and reference resistors. A voltage U is applied to the measuring bridge. A resulting measurement voltage .DELTA.U is determined by the equilibrium state of the four resistors R1 to R4. If one of the four resistors R1 to R4 changes, the resulting measurement voltage ΔU changes accordingly.

Fig. 8 shows a corresponding measurement cycle. In this case, the resulting measurement voltage ΔU is plotted over the time t. The time t is preferably the actual operating time of the elevator system or possibly a time window assumed. A change in the resulting measuring voltage .DELTA.U occurs, for example, when a single wire 23 of a tension member 21 breaks as a result of material fatigue or force. This results in an essentially abrupt change in one of the resistors R1 to R4, corresponding to the tensile carrier region concerned. As a result, the resulting measurement voltage ΔU changes. This change is in Fig. 8 shown, with a positive or a negative change depending on the affected tensile carrier. This time course of the resulting measurement voltage ΔU is derived after the time t d (ΔU) / dt, whereby the temporal jump-like changes as in Fig. 9 clearly visible. The events that exceed or fall below a critical jump size are counted as a fraction of a wire. The number of fractions N are again in their temporal Sequence saved and summed, as in Fig. 10 shown. If the sum N of the registered fractions exceeds a critical fraction total, for example, a corresponding warning signal is set in the controller 15. Furthermore, a frequency dN / dt is determined in an evaluation unit of the elevator support means monitoring device 20. An increase in frequency indicates that a continuous load limit has been reached. Furthermore, the change in the frequency dN / dt / dt can also be evaluated. An increase in this value above a critical limit is another indication that the suspension must be replaced.

In one embodiment, the bridge circuit is provided with a limit value control, which can determine a complete failure, or a break, a Zugträgerbereiches or a tension member. Such a failure causes a correspondingly large resulting measurement voltage .DELTA.U, since a resistance of the affected Zugträgerbereiches increases to infinity.

The limit value control recognizes this condition and can shut down the elevator system immediately, if necessary after completion of a pending drive command.

Fig. 11 shows an alternative or supplementary evaluation system. Here, a resistance of a Zugträgerbereiches is detected and its derivative dR / dt is stored. This value is compared with a resistance change considered permissible. As soon as this permissible value is exceeded, the elevator installation is shut down, for example, or a maintenance message is created.

Tensile beams have the property that with increasing aging of the material a frequency of breakage of wires increases. The present evaluation system uses this property by recognizing an increase by the measurand dR / dt.

With knowledge of the present invention, the elevator expert can arbitrarily change the set shapes and arrangements. For example, it sets different warning levels, which are usually determined as results of test series.

Claims (17)

1. Method of monitoring a lift support means (9), comprising the following steps:

   - monitoring at least one characterising property of the lift support means (9) or a tension carrier (21) of the lift support means (9) by way of a lift support means monitoring device (20) connected with the lift support means (9),

   - detecting an abrupt change in this characterising property by way of the lift support means monitoring device (20) and

   - determining a state of the lift support means (9) by the lift support means monitoring device (20) by way of evaluation of a plurality of successive abrupt changes in this characterising property.
2. Method according to claim 1, wherein the state of the lift support means (9) is determined:

   - by means of a sum of the abrupt changes in the characterising property and/or

   - by means of a frequency of the abrupt changes in the characterising property and/or

   - by means of a change in the frequency of the abrupt changes in the characterising property.
3. Method according to claim 1 or 2, wherein

   - this state of the lift support means (9) can be called up in the lift support means monitoring device (20) and/or

   - the state of the lift support means (9) is indicated by the lift support means monitoring device (20) and/or

   - the state of the lift support means (9) is communicated by the lift support means monitoring device (20) to a central lift control (15) and/or

   - on attainment of a limit value state an alarm is triggered and/or a safety device is activated.
4. Method according to one of the preceding claims, wherein the abrupt change in the characterising property is ascertained

   - by means of detection of a relative change between a first and a second lift support means (9) or

   - by means of detection of a relative change between a first and a second tension carrier (21) of the lift support means (9).
5. Method according to any one of the preceding claims, wherein an electrical resistance of the lift support means (9) or of the tension carrier (21) is used as characterising property.
6. Method according to claim 5, wherein

   - the abrupt changes are filtered and

   - as device for filtering the abrupt changes use is made of earthing of the two ends of the lift support means (9) or of the tension carrier (21) and

   - the earthing is carried out by way of an earthing resistance which is high by comparison with an internal resistance of the lift support means (9) or the tension carrier (21).
7. Method according to any one of the preceding claims, wherein

   - several tension carriers (21) of the lift support means are divided up into two tension carrier zones and

   - the tension carriers (21) of a tension carrier zone are respectively connected together in series and these two tension carrier zones are compared with one another and

   - the abrupt changes in the characterising property are counted in correspondence with an abrupt change in a difference between the compared tension carrier zones.
8. Lift support means monitoring device for monitoring a support means, wherein the lift support means monitoring device includes

   - a connecting device for connecting the lift support means monitoring device (20) with a lift support means (9) and

   - a device for detecting and evaluating a characterising property of the lift support means (9) or a tension carrier (21) of the lift support means (9) with use of one of the methods according to any one of claims 1 to 7.
9. Lift installation with a lift support means monitoring device according to claim 8, wherein

   - the lift installation (1) comprises at least one lift cage (7), counterweight (8) and lift drive (12) and wherein the lift support means (9) connects the lift cage (7) with the lift drive (12) and the counterweight (8) and the lift drive (9) raises and lowers the counterweight (8) and the lift cage (7) by way of the lift support means (9),

   - the lift support means (9) includes at least one tension carrier (21) which can transmit tension forces from the lift drive (12) and/or the counterweight (8) to the lift cage (7) and

   - at least one end of the lift support means (9) is connected by way of the connecting device with the lift support means monitoring device (20).
10. Lift installation according to claim 9, wherein

    - the lift support means (9) or the tension carrier (21) of the lift support means (9) comprises electrically conductive wires (23) which are combined to form a wire bundle and which can transmit tension forces and

    - the characterising property of the lift support means (9) or the tension carrier (21) is an electrical resistance.
11. Lift installation according to claim 9 or 10, wherein

    - the lift support means (9) comprises several tension carriers (21) and these several tension carriers (21) are divided into paired tension carrier zones and

    - the tension carriers (21) of each tension carrier zone are connected together in series and the tension carrier zones of each pair are connected to form a half bridge.
12. Lift installation according to claim 9 or 10, wherein

    - the tension support means (9) comprises several tension carriers (21) and these several tension carriers (21) are divided into double pairs of tension carrier zones and

    - the tension carriers (21) of each tension carrier zone are connected together in series and the double pairs of tension carrier zones are connected to form a respective full bridge.
13. Lift installation according to any one of claims 10 to 12, wherein the lift support means monitoring device (20) comprises a breakage monitoring device which can detect a breakage of the tension carrier (21) and the lift support means monitoring device (20) on detection of breakage of the tension carrier activates a safety device, wherein a breakage of the tension carrier (21) is detected when

    - an electrical resistance of the relevant lift support means (9), the relevant tension carrier (21) or the relevant tension carrier region is detected approximately endlessly or

    - a current flow in the relevant lift support means, in the relevant tension carrier or in the relevant tension carrier zone is interrupted or

    - a balancing voltage of the half bridge or full bridge reaches a limit voltage value.
14. Lift installation according to any one of claims 9 to 13, wherein the lift support means monitoring device (20) is constructed as a stationary component of the lift installation (1) and constantly monitors at least one characterising property of the tension carrier (21) of the lift support means (9) and in that case continuously evaluates and detects abrupt changes in this characterising property.
15. Lift installation according to any one of claims 9 to 13, wherein the lift support means monitoring device (20) is constructed for temporary use in the lift installation (1) and monitors at least one characterising property of the tension carrier (21) of the lift support means (9) in continuing time windows and evaluates and detects abrupt changes in this characterising property in these time windows or over time windows.
16. Lift installation according to claim 15, wherein the lift support means monitoring device (20) selects a critical time window and determines a state of the tension carrier (21) by a sum of the abrupt changes in the characterising property within the critical time window and the critical time window is the time window with the most abrupt changes in the characterising property.
17. Lift installation according to claim 13, wherein the breakage monitoring device is constructed as a separate component of the lift support means monitoring device and is integrated or incorporated as a stationary component in the lift installation (1).

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