EP0563836B1 - Method to measure the driving capability of a transporting device - Google Patents

Abstract

The invention relates to a method of measuring the driving capability of a drive, provided with a carrying rope run over a driving pulley, of a hoisting system, in particular a lift system, with a car hanging on one end of the carrying rope and a counterweight hanging on the other end of the carrying rope, the carrying rope being relieved of load on one side until the driving pulley slips under the carrying rope in sliding friction such that a measured value is determined in the process from which the driving capability is deduced, and to a lift system for carrying out the method. <IMAGE>

Description

The invention relates to a method for measuring the driveability of a conveyor system drive provided with a supporting cable guided over a traction sheave, in particular an elevator system with a car hanging on one end of the supporting cable and a counterweight hanging on the other end of the supporting cable.

Elevator systems that are driven by a traction sheave suspended from a suspension cable must be checked for their driving ability at intervals of two years. The driveability indicates the slip resistance of the friction connection between the suspension cable and the traction sheave.

According to the technical rules for lifts, edition July 1989, TRA102, published by the Association of Technical Inspection Associations e.V., Essen, the car loaded with 1.5 times the nominal load must be stopped when driving downwards with the greatest possible braking. It is desirable if the ropes slide over the traction sheave, since the lowest friction value then acts between the rope and the traction sheave. Under these conditions, the car loaded with 1.5 times the nominal load must come to a standstill again.

According to the test specification, a higher load on the elevator system is caused than in normal operation. However, the test does not provide any information as to whether the system is for a slightly larger Load than 1.5 times the nominal load would slip. Furthermore, a rope slide is often not achieved during the test, so that the static friction between the rope and the support disk still acts here. Furthermore, it is disadvantageous that the entire elevator system is subjected to high stresses due to the increased load of 1.5 times the nominal load and thus wears out more. Furthermore, loading the car with additional weights up to 1.5 times the nominal load is time-consuming and labor-intensive.

DE 39 11 391 A1 discloses a method for detecting physical parameters, in particular movement parameters of a goods and / or elevator, in which, among other things, the slip resistance (driving ability) of the cable driven by the traction sheave is determined. The driving ability of the cable is determined with a force transducer, which is arranged between the cable and a fixed point by means of a cable clamp. By turning the traction sheave, the tensile force acting on the cable is increased until either a determined limit value is reached or the cable begins to slide on the traction sheave.

A disadvantage of this method is that the tensile force additionally acting on the cable pull by the force measuring signal transmitter considerably increases the loads on the elevator installation. Furthermore, a slipping of the cable on the traction sheave is not achieved if a further increase in tractive force is ruled out for safety reasons.

Furthermore, GB-A-2 217 285 describes a method for checking the friction between the traction sheave and the Cable pull of an elevator known that is carried out during normal driving. The car load and movement as well as the slip between the traction sheave and the cable are measured. The test is carried out by driving a short distance, which only has an acceleration and deceleration driving state, and a long driving path, which has an additional driving state at constant speed. With this method, the elevator system is not excessively stressed, but normally the rope does not slip heavily on the traction sheave. Therefore, the limit range of the friction between the traction sheave and the cable pull, ie the driving ability, cannot be determined.

Furthermore, from SU-A-779 845 a method for determining the driving ability between traction sheave and cable pull of an elevator is known, in which the car counterweight is placed on the buffer located in the shaft pit and the traction sheave is rotated further until it slips under the cable pull or the the rope section assigned to the counterweight slackens. First, the counterweight on the buffer is relieved until the counterweight and car are balanced. Then the further relief is measured with a dynamometer. The disadvantage of this is that the driving ability is measured on a cable section which does not come to rest on the traction sheave during normal driving, ie which does not wear out. As a result, the wear and tear of the cable pull is not taken into account in the driving ability measurement described in this way. Attaching the dynamometer to the buffer is easy, but the measurement and control is in the elevator shaft pit difficult and dangerous due to the limited space.

Starting from the latter method, it is therefore the object of the invention to specify a measuring method in which the wear of the suspension cable is taken into account.

This object is achieved with a method according to claim 1.

By relieving the cable pull on one side, the cable tension ratio is brought into greater imbalance without the entire lift system being subjected to greater stress. The rope tension ratio is changed until the traction sheave slips under the pull rope. This ensures that the tensile force transmitted from the traction sheave to the rope by friction is transmitted by means of sliding friction.

The car or the counterweight is placed on the measuring device arranged in a fixed position in the elevator shaft, with the traction sheave being rotated further in the same direction of rotation until the traction sheave slips under the supporting cable. By placing the car or the counterweight on the measuring device, the weight of the car or the counterweight hanging on the suspension cable is reduced. The weight relief is registered by the measuring device. As the load is relieved, the traction sheave begins to slip under the suspension cable. This means that the critical rope tension ratio has been reached and the driving ability of the suspension rope / traction sheave connection can be calculated.

The measuring device in the elevator shaft is advantageous so arranged that the landing point of the car or the counterweight is within the normal travel range of the elevator system. The driving ability is thus determined on a rope section which is exposed to wear and tear from normal operation of the elevator system.

In another embodiment of the method it is provided that the car is connected to a fixed point arranged above it via an auxiliary rope and the measuring device, the traction sheave being rotated further in the same direction of rotation after hanging up until the traction sheave slips under the suspension rope. The auxiliary rope absorbs part of the weight of the car. The relief is recorded with the measuring device.

Alternatively, the counterweight can be hung on the auxiliary rope with the measuring device instead of the car.

In a preferred embodiment it is provided that the auxiliary rope is led from the elevator shaft into a machine room arranged above to a fixed point. The measuring device can be conveniently arranged between the auxiliary rope and the fixed point.

The length of the auxiliary rope is advantageously chosen so that the suspension point of the car or counterweight is within the normal driving range, preferably in the most frequently used driving range of the elevator system. This measures the ability to drive on a section of rope that is subject to great wear.

In another embodiment it is provided that a rope clamping device is attached to the supporting rope, which is placed on the stationary measuring device, after the attachment the traction sheave is rotated in the same direction until the traction sheave slips under the supporting rope. With this method, a relief according to the invention can be achieved either on the car side or on the counterweight side of the suspension cable, so that when the traction sheave slips under the suspension cable, the critical cable tension ratio, i.e. the driving ability can be calculated.

Pressure transducers, strain gauges or spring scales are advantageously used as measuring devices. Spring scales allow direct reading of the relieving amount of weight. The measured values of Pressure transducers or strain gauges can advantageously be temporarily stored on data loggers or directly digitally processed on a microcomputer. As an alternative to this, the measured values can also be displayed analogously on an x / y recorder. The measured relief over time is advantageously plotted as a load curve.

In addition to measuring the driving ability between the traction sheave and the suspension cable, the same measuring arrangement can also be used to determine the actual weight of the car, counterweight and the half-load from the difference. All that is required is that when the car or counterweight is attached or suspended, the support cable is fixed to the traction sheave with a cable clamp, so that after the traction sheave is turned further, the support cable leading to the attached or suspended car or counterweight sags and the weight of the car or Counterweight can be measured with the measuring device.

In the following, three preferred variants of the method are explained with reference to the attached figures, with further advantageous configurations being shown in the figures.

Fig. 1

zwei beispielhafte Meßkurven,

Fig. 2

eine Aufzuganlage als Schema,

Fig. 3

eine Aufzuganlage mit Meßvorrichtung und aufgesetztem Aufzug,

Fig. 4

eine Aufzuganlage mit Meßvorrichtung und aufgesetztem Gegengewicht,

Fig. 5

eine Aufzuganlage mit Hilfsseil befestigt am Fahrkorb,

Fig. 6

eine Aufzuganlage mit Hilfsseil befestigt am Gegengewicht,

Fig. 7

eine Aufzuganlage mit am fahrkorb- bzw. gegengewichtsseitigen Tragseilteil befestigter Klemmvorrichtung.

The figures show in detail:

Fig. 1

two exemplary measurement curves,

Fig. 2

an elevator system as a scheme,

Fig. 3

an elevator installation with a measuring device and an attached elevator,

Fig. 4

an elevator system with measuring device and counterweight,

Fig. 5

an elevator system with auxiliary rope attached to the car,

Fig. 6

an elevator system with auxiliary rope attached to the counterweight,

Fig. 7

an elevator system with a clamping device attached to the car or counterweight-side support cable part.

FIG. 1 shows two measurement curves 17 by way of example. The steep rise in the measurement curve according to FIG. 1 represents the placement of the car or the counterweights on the measuring device. The maximum is reached when the static friction acting between the suspension cable and traction sheave is exceeded. When the traction sheave is turned further, a short transient action takes place to the relief value M1 or M2 relevant for the method according to the invention with sliding friction acting between the suspension cable and the traction sheave.

In FIG. 2, G denotes the weight of the counterweight 6, F the weight of the empty car 3, which counteracts the deflection of the suspension cable 2 via a traction sheave 1. The weight of the load L acts in the same direction as the weight of the car 3, so that there is a cable tension S ₁ in the counterweight-side support cable part 5 and one in the car-side support cable part 4 Rope tension S ₂ results. The nominal load is designated with Q. A rope tension ratio can be defined from this, which results as follows: $${\text{S}}_{\text{2nd}}{\text{/ <figure-callout id="1" label="S" filenames="imgf0001.png,imgf0002.png" state="{{state}}">S</figure-callout>}}_{\text{1}}\text{=}\frac{\text{F + L}}{\text{G}}$$

The calculations and formulas described neglect the weight of the suspension ropes, the weight of the suspension cables that form the electrical connection between the car and the machine control, and the weight of any lower ropes that may be present.

In general, the counterweight 6 in elevator systems is dimensioned such that it corresponds to the weight of the empty car 3 plus half the nominal load. The unfavorable operating case occurs when the empty car 3 is stopped in the upward movement. All other operating cases up to loading the car with nominal load have a lower rope tension ratio.

In the test method according to the invention, on the one hand, it is to be ensured that the test is carried out with sliding ropes, and, on the other hand, the maximum possible load is determined which the traction sheave 1 can just hold due to the sliding friction.

To determine the maximum possible load, the rope tension ratio is increased by relieving one side until the traction sheave 1 slips under the supporting ropes 2. The relief force required for this type of operation is measured and from this the driving ability of the Traction sheave 2 calculated.

Since the driving ability for conventional elevator systems is almost independent of the load, the load can be determined from the measured value if the car weight and counterweight are known, which the system can still hold in the state of sliding friction.

In this way it is possible to make a statement about the reserve that the system has in the case of sliding friction compared to 1.5 times the overload.

• Aufsetzen des Fahrkorbes oder Gegengewichts auf die Meßvorrichtung in der Schachtgrube.
• Befestigung eines Hilfsseils am Fahrkorb oder Gegengewicht, Entlastung gegen einen Festpunkt im Maschinenraum auf die Meßeinrichtung.
• Anbringen einer Klemmvorrichtung auf den Tragseilen im Maschinenraum auf der Fahrkorb- bzw. Gegengewichtsseite, Entlastung durch Aufsetzen der Klemmvorrichtung auf die Meßeinrichtung im Maschinenraum.

Basically, three variations of the measurement are possible, whereby for each variant it is possible to increase the rope tension ratio by relieving the load on the counterweight or car side. This results in a total of six different measuring arrangements:

• Place the car or counterweight on the measuring device in the pit.
• Attachment of an auxiliary rope to the car or counterweight, relief against a fixed point in the machine room on the measuring device.
• Attaching a clamping device on the supporting cables in the machine room on the car or counterweight side, relief by placing the clamping device on the measuring device in the machine room.

Figure 3 shows a structure in which the measuring device 7 is mounted on the buffer 9 in the pit 10. The car 3 will drove to the lower floor and then placed on the measuring device 7 with the return control or by hand. After touching down, the traction sheave 1 is rotated further until the ropes 2 slip under the traction sheave 1.

The following rope tension ratio results at this operating point: $$\frac{{\text{S}}_{\text{<figure-callout id="1" label="2nd S" filenames="imgf0001.png,imgf0002.png" state="{{state}}">2nd </figure-callout>}}}{{\text{S}}_{}}\text{=}\frac{\text{G}}{{\text{F - <figure-callout id="1" label="M" filenames="imgf0001.png,imgf0002.png" state="{{state}}">M</figure-callout>}}_{\text{1}}}$$

M ₁ ends the measured value with the car in place.

FIG. 4 shows the structure known from SU-A-779 845, the measuring device being mounted on the buffer 9 in the shaft pit 10. The counterweight 6 is moved to the lower floor and then placed on the measuring device with the return control or by hand. After touching down, the traction sheave 1 is rotated further until the ropes 2 slip under the traction sheave 1. The following rope tension ratio results at this operating point: $$\frac{{\text{S}}_{\text{<figure-callout id="1" label="2nd S" filenames="imgf0001.png,imgf0002.png" state="{{state}}">2nd </figure-callout>}}}{{\text{S}}_{}}\text{=}\frac{\text{F}}{{\text{G - M}}_{\text{2nd}}}$$

M _{2 means} the measured value with the counterweight attached.

FIG. 5 shows the method according to the invention, an auxiliary rope 12 being fastened to the car 3, which is led through the opening 18 for the ropes in the machine room floor 19 to a fixed point 11 above the floor 19.

Claims (8)

1. Method of measuring the driving capacity of a drive unit, which is provided with a carrying cable (2) guided over a driving pulley (1), in a conveyer system, in particular an elevator system, with a cage (3) suspended on one end (4) of the carrying cable (2) and a counterweight (6) suspended on the other end (5) of the carrying cable, wherein the carrying cable (2) is relieved of load at one end, through the setting-down of the cage (3) or counterweight (6) onto a measuring device (7), to the extent where the driving pulley (1) is slipping through, in sliding friction, under the carrying cable (2), and in the process the gravitational force of the load-relief (M), from which the driving capacity is deduced, is directly detected with the measuring device (7), characterised in that the measuring device (7) is disposed in the elevator shaft (8) in such a way that the setting-down point of the cage (3) or of the counterweight (6) is situated within the normal range of travel of the elevator system, and that the driving capacity (T) can be determined, as a critical cable tension ratio, from the gravitational force of the load-relief (M) by $$\mathit{\text{T}}\text{=}\frac{\mathit{\text{G}}}{\mathit{\text{F - M}}}$$

   

   where F is the loading on the carrying cable, on that side of the driving pulley which is to be subjected to load-relief, before the relieving of the load, and G is the loading on the carrying cable on the other side of the driving pulley.
2. Method according to claim 1, characterised in that the cage (3) is connected, via an auxiliary cable (12) and the measuring device (7), to a fixed point (11) existing above it, the driving pulley (1) being rotated further in the same direction of rotation, after the connection of the cage (3), until the said driving pulley (1) is slipping through under the carrying cable (2).
3. Method according to claim 1, characterised in that the counterweight (6) is connected, via an auxiliary cable (12) and the measuring device (7), to a fixed point (11) existing above it, the driving pulley (1) being rotated further in the same direction of rotation, after the connection of the counterweight (6), until the said driving pulley (1) is slipping through under the carrying cable (2).
4. Method according to claim 2 or 3, characterised in that the auxiliary cable is guided from the elevator shaft (8) into a machine room (13) disposed above it and to the fixed point (11).
5. Method according to claim 2, 3 or 4, characterised in that the length of the auxiliary cable (12) is selected in such a way that the point of suspension of the cage or of the counterweight is situated within the most travelled range of travel of the elevator system.
6. Method according to claim 1, characterised in that there is attached to the carrying cable a cable-clamping device (14) to which the measuring device (7), which is preferably disposed in a stationary manner, is connected, the driving pulley being rotated further in the same direction, after the setting-down operation, until the said driving pulley (1) is slipping through under the carrying cable (2).
7. Method according to one of the preceding claims, characterised in that pressure-measuring cells, expansion-measuring strips or spring balances are used as the measuring device (7).
8. Method according to one of the preceding claims, characterised in that the measuring device is connected to a data-logger, an x/y-recorder or a microcomputer (16) and the measurement data are recorded in the form of load curves (17).

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