KR100861639B1 - Electrical signal application strategies for monitoring a condition of an elevator load bearing member - Google Patents

Abstract

The elevator load bearing member 30 monitoring device includes a controller 42 for applying a selected electrical signal to the tension member 32 of the load bearing member 30. In one example, the connector 40 is associated with the ends of the load bearing member 30 to form an electrical interface between the controller 42 and the tension member 32. The connector 40 facilitates forming an electrical circuit loop along the tension member 32 such that only non-adjacent tension members are energized at a selected time. Various circuit configurations are disclosed. The electrical signal applied in one example has a negative potential compared to the ground potential of the hoistway in which the elevator belt is used. In another example, the electrical signal includes a plurality of pulses and has a duty cycle of about 1 percent.

Elevator load bearing member, electrical circuit loop, duty ratio, non-conductive jacket, ground potential

Description

ELECTRICAL SIGNAL APPLICATION STRATEGIES FOR MONITORING A CONDITION OF AN ELEVATOR LOAD BEARING MEMBER}

The present invention relates generally to monitoring a load bearing member in an elevator system. More specifically, the present invention relates to circuit arrangements using electricity-based monitoring techniques.

Elevator systems typically include cars and counterweights suspended by rope or belt configurations. The drive machine moves the rope or belt to bring the desired movement of the car to different levels, for example in the building. Traditionally, steel ropes have been used. Recently, other types of load bearing assemblies have been introduced. One example is a coated steel belt having a plurality of steel cords housed within a polyurethane jacket.

With the introduction of new belts, the need for new monitoring techniques has arisen to check the quality of belts over time. The jacket on the tension member obstructs visual inspection. Coated steel belts have an extended life, but it is desirable to monitor the condition of the belt to detect any deterioration in the strength of the tension members in the belt (ie steel cord). Several surveillance techniques have been developed.

One approach is to use electricity to measure the properties of the tension member, ie the strength of the belt. One exemplary technique relies on the fact that the cross-sectional area of a steel cord tension member is directly related to the electrical resistance of the member. Thus, monitoring the resistance of the tension member provides an indication of the state of the tension member.

In order to use resistance-based inspection techniques, an efficient strategy for constructing an electrical circuit so that the resistance of the tension member can be measured is required. The present invention focuses on its need, for example, by providing unique circuit configurations and strategic electrical signal characteristics to enable efficient monitoring of tension members in coated steel belts.

In general terms, the present invention is a circuit arrangement that enables efficient electrical-based monitoring of elevator load bearing members.

One exemplary method includes applying an electrical signal to at least one tension member that includes a plurality of pulses and has a duty ratio of less than about 10 percent. In one embodiment, the duty cycle is less than about 1 percent. Low duty ratios minimize the amount of electrical energy delivered by the tension member, which tends to reduce the likelihood of any corrosion by using the tension member as an electrical conductor.

In the case where the load bearing member has a plurality of spaced apart conductive tension members, the exemplary method strategically applies an electrical signal only to tension members that are not adjacent to each other to avoid creating an electric field between the spaced apart tension members. It includes. This technique avoids any deterioration or corrosion of the tension members that may be caused by introducing electricity along the tension members.

In one embodiment, at least two non-adjacent tension members are electrically connected to the tension members connected to the electrical signal, which form a loop or circuit through which the electrical signal propagates.

According to one example, the electrical signal applied to the tension member is selected such that the tension member effectively becomes a cathode for the hoistway in which the load bearing member is used. This is done in one example by controlling the potential of the electrical signal so that the potential is negative relative to the ground potential of the hoistway.

In another example, the electrical signal is applied only to the non-adjacent tension member at a given time.

Various features and advantages of the invention will be apparent to those skilled in the art from the following detailed description of the presently preferred embodiments. The drawings that accompany the detailed description can be briefly described as follows.

1 schematically illustrates a selection of an elevator system that includes an elevator load bearing member monitoring assembly designed in accordance with an embodiment of the present invention.

2 is a perspective view of a portion of an elevator belt schematically showing useful electrical connectors in conjunction with embodiments of the present invention.

Figure 3 schematically illustrates an exemplary circuit configuration designed in accordance with an embodiment of the present invention.

4 schematically shows another circuit configuration.

5 shows another circuit configuration.

6 illustrates another exemplary circuit configuration.

7 illustrates another exemplary circuit configuration.

1 schematically shows an elevator system 20 in which a car 11 and counterweight 24 move in a hoistway 26. The driver 28 causes the movement of the load bearing member 30, which results in the desired movement of the car 22 and the corresponding movement of the counterweight 24. Movement of the elevator system is known.

As shown in FIG. 2, an exemplary load bearing member 30 is a coated steel belt having a plurality of steel cord tension members 32 housed within a polyurethane jacket 34. As can be appreciated from the figure, the tension member 32 comprises a plurality of steel strands wound with a cord in a known manner. Jacket member 34 generally surrounds each tension member and fills the space between the tension members. The tension member 32 extends in the longitudinal direction (ie as shown by L in FIG. 2) in parallel along the length of the belt 30. This invention is not limited to a specific kind of load bearing member.

2 also shows a connector 40 for forming an electrical connection with the tension member 32. Although not specifically shown, in one example, the connector 40 includes a connector member that penetrates through the jacket member 34 to form an electrical connection with at least selected ones of the tension members 32. The connector 40 in the example of FIG. 1 is attached to each end of the belt 30 and is adapted to connect the tension member 32 with the controller 42 suitably programmed to implement the selected electrical based monitoring technique. Provide an interface. Exemplary connector 40 includes a first portion 46 and a second portion 48 received at both ends of belt 30. The securing member 50 allows the connector 40 to be secured in a desired position near the end of the exemplary belt 30.

The controller 42 preferably monitors the state of the tension member 32, ie the state of the belt 30, by monitoring the selected electrical properties of the tension member. In one example, the resistance of each tension member is monitored to make a measurement regarding the cross-sectional area of the tension member, which provides an indication of deterioration or local deformation of the tension member over time. This description includes various circuit configurations that enable the controller 42 to make the necessary measurements. Exemplary controller 42 includes an ohm meter section 44 that each makes a measurement regarding the electrical resistance of tension member 32.

3 schematically illustrates one exemplary circuit structure designed in accordance with an embodiment of the invention. In this example, each tension member 32A-32L is individually connected to the controller 42. Each tension member thus forms its own circuit as shown schematically in FIG. 3 (although only the connection between the controller 42 and the tension member 32A is shown as the only connection). Similar connections are made with each individual tension member. One advantage of this configuration is the ability to individually monitor any one of the tension members. Alternatively, this configuration makes it possible to monitor all tension members simultaneously. If all tension members are properly powered, there will be no potential difference between the tension members and there is no risk of inter-cord corrosion.

One possible cause of the risk of corrosion may arise if a sufficient electric field is formed between the cords so that ions may move between the tension members. Minimizing this migration of ions minimizes the risk of corrosion.

Another example configuration is shown in FIG. 4 in which the tension members 32A and 32G form a single circuit loop to be monitored as the controller 42 applies an electrical signal to the circuit. In this example, one of the connectors 40 interfaces with the controller 42. The other connector 40 includes an electrical coupling 60 that connects the tension members 32A, 32G together to form a circuit loop. In this example, the tension members are made of two six sets of groups such that the first and seventh tension members (ie, 32A, 32G) form one circuit, while the second and eighth tension members form another circuit. do. Similarly, the sixth and twelfth tension members form one circuit. Using this strategy maintains a maximum distance between two tension members that are simultaneously energized to deliver electrical signals applied by the controller 42. Maintaining the maximum distance between the conductive tension members minimizes the risk of corrosion associated with moving ions that may move across the belt 30 because of the electric field formed between the tension members. By using non-adjacent tension members to form circuit loops, the method of the present invention minimizes the risk of corrosion associated with the application of electricity to the tension members.

Six electrical couplings 60 have been used to form six separate circuit loops along the belt 30, but FIG. 4 shows only one electrical coupling 60. One advantage of a configuration such as that shown in FIG. 4 is that only one of the connectors 40 is required to make a substantial connection with the controller 42, which is an electrical connection between the connector 40 and the controller 42. Minimize the cost or complexity of the coupling (ie wiring). At one end of the belt 30 the electrical coupling 60 in the connector 40 can be effectively internal to the connector so that no external wiring is required near the end of the belt.

5 shows another exemplary circuit configuration. In this example, three groups of three tension members are electrically connected using electrical couplings 60 and 62 to form a circuit loop. In some cases, for individual tension members (or even two tension members), the length of the belt 30 may be too short to form a circuit long enough to obtain a signal-to-noise ratio that allows sufficiently accurate monitoring. . The configuration as shown in FIG. 5 facilitates forming a better signal to noise ratio for a relatively short belt by increasing the number of tension members in a single circuit loop. In this example, the tension members 32A, 32E, and 32I form a first circuit loop. Tension members 32B, 32F, and 32J form another loop. Likewise, two additional loops are more suitably formed to maintain the maximum feasible distance between tension members to be energized at any given time. By only applying voltage to the non-adjacent tension member, the method of the present invention minimizes the risk of corrosion of the tension member.

FIG. 6 shows another example with the same advantages as FIG. 4, wherein the connection with the controller 42 is formed by one of the connectors 40. In this example, four tension members 32A, 32D, 32G, and 32J form a single circuit loop. Three electrical couplings 60, 62, 64 are required to form the loop. One of the connectors 40 includes couplings 60 and 64 and does not require any external wiring, which may be advantageous in many circumstances. Although not specifically shown, the configuration shown in FIG. 6 for use with a belt having twelve tension members preferably includes three sets of four tension members, each connected by a single circuit loop.

Figure 7 shows another example of forming two circuit loops by electrically connecting six of the tension members together in a single circuit loop. In Fig. 7, the tension members 32A, 32C, 32E, 32G, 32I, and 32K are connected together in a single circuit loop. Electrical couplings 60, 62, 64, 66, and 68 form a circuit loop. The other tension members are grouped into a second circuit. This configuration minimizes the number of circuits that need to be monitored using the controller 42. At the same time the distance between the tensioning members to which the voltage is applied is reduced compared to the example of FIG. 4, for example according to the needs of a given situation, which may be desirable. Those skilled in the art having the benefit of this description will be able to select an appropriate configuration to best meet the needs of their unique situation.

In each illustrated example, the belt 30 has twelve tension members extending along the length of the belt. Of course, other circuit configurations for other numbers of tension members may be more advantageous. Those skilled in the art having the benefit of the present invention will realize which circuit configuration will work best for their unique situation.

Another feature of some examples is the strategic control of electrical signals applied to tension member 32 to further reduce the risk of corrosion. Increasing the lateral distance between tension members having a potential difference therebetween is one technique for reducing the possibility of forming a conductive electrolytic path between energized cords. Another feature of some examples is to limit the maximum operating potential applied to the tension member 32. In one example, the maximum voltage is 2 volts. An effective monitoring signal may have a potential between 0 and 2 volts, for example.

In another example, the electrical signal includes a plurality of pulses and has a very low duty cycle such that the "on" time of the signal is low. In one embodiment, the duty cycle is about 1 percent or less, which minimizes the time for which the dislocation is applied to the tension member 32. Minimizing the on time of the electrical signal further minimizes the risk of possible corrosion.

In another example, the electrical signal is selected to have a polarity that sets the tension member 32 to the cathode relative to the environment in which the belt 32 is used. For example, the electrical polarity of the signal is negative compared to the efficient ground of the hoistway 26. Applying an electrical signal of this nature reduces the risk of corrosion when a stray current pathway is formed between the tension member and the hoistway or building ground.

Although electrical application of the tension member of the elevator load bearing member has been described, various techniques may exist to minimize the risk of corrosion. The combination of two or more of the above methods further reduces the risk of corrosion and enables efficient electrical based monitoring of elevator belts.

The foregoing description is illustrative rather than limiting in nature. Modifications and variations of the disclosed examples will be apparent to those skilled in the art without necessarily departing from the spirit of the invention. The scope of legal protection given to this invention can only be determined by studying the following claims.

Claims (23)

A state monitoring method of an elevator load supporting member having a plurality of spaced apart conductive tension members, And applying a selected electrical signal to at least one of the tension members including a plurality of pulses and having a duty ratio of less than 10%. The method of claim 1, comprising applying a signal to one of the tension members at a time. The method of claim 1, comprising connecting at least two tension members in a conductive manner and applying an electrical signal to the connected tension members. 2. The method of claim 1, comprising setting a tension member that transmits a signal to the cathode relative to the hoistway in which the belt assembly is used. 5. The method of claim 4, comprising controlling the potential of the electrical signal so that the potential becomes negative compared to the ground potential of the hoistway. The method of claim 1, wherein the electrical signal is applied to only non-adjacent tension members at a time. 2. The method of claim 1, comprising measuring the resistance of the tension member based on the applied signal. And a controller for selectively applying an electrical signal to at least one tension member comprising a plurality of pulses and having a duty ratio of less than 10%. The apparatus of claim 8, comprising a connector to form a conductive connection between the controller and the tension member. 10. The apparatus of claim 9, wherein the connector comprises at least one coupling connecting at least two tension members together. 10. The apparatus of claim 8, wherein the controller applies an electrical signal such that the tensioning member that transmits the signal is cathode to the hoistway in which the belt assembly is used. 12. The apparatus of claim 11, wherein the electrical signal has a polarity that is negative compared to the ground potential of the hoistway. The apparatus of claim 8, wherein the electrical signal is applied to only non-adjacent tension members at a time. 10. The apparatus of claim 8, wherein the controller measures the resistance of the tension member and measures the state of the load bearing member based on the measured resistance. 9. The apparatus of claim 8, wherein the controller simultaneously applies a signal to all of the plurality of tension members. A plurality of conductive tension members, Non-conductive jacket which generally wraps tension member, An elevator load bearing member assembly comprising a controller for selectively applying an electrical signal to at least one of the tension members, the plurality of pulses having a duty ratio of less than 10%. 17. The elevator load bearing member assembly of claim 16, comprising a connector to form a conductive connection between the controller and the tension member. 18. The elevator load bearing member assembly of claim 17, wherein the connector comprises at least one coupling connecting at least two tension members together. 17. The elevator load bearing member assembly of claim 16, wherein the electrical signal has a negative polarity compared to the ground potential of the hoistway in which the assembly is used. 17. The elevator load bearing member assembly of claim 16, wherein the duty cycle is less than 1%. The method for monitoring the condition of an elevator load bearing member according to claim 3, wherein the tension member is a non-adjacent tension member. The apparatus of claim 10, wherein the tension member is a non-adjacent tension member. 19. The elevator load bearing member assembly of claim 18, wherein the tension member is a non-adjacent tension member.

Images