Eddy Current Carrying Strap Wear Detection for Elevator Belts
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Solution Overview
Problem
Existing methods for determining the wear of steel cables in carrying straps, especially in elevator systems, are unreliable as they cannot distinguish between diameter changes due to mechanical stress and actual wear, leading to premature discard of the entire belt.
Innovation Solution
A drive system equipped with an eddy current sensor and evaluation unit that generates an alternating electromagnetic field to detect changes in the cord ropes' arrangement and diameter, allowing for a more precise determination of the discard value by analyzing the attenuation of the field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If electrical resistance measurement is used to determine cord wear, then the measurement can be performed electrically, but the method cannot distinguish between diameter changes due to mechanical stress and actual wear
Solution Approach 1:
The patent replaces electrical resistance measurement with eddy current measurement. The eddy current sensor generates an alternating electromagnetic field that induces eddy currents in the conductive cords. The attenuation of this field provides a measurement signal that is not affected by cord diameter changes due to mechanical stress, thereby solving the problem of distinguishing actual wear from stress-induced diameter changes.
Solution Approach 2:
The patent changes the measurement parameter from electrical resistance to eddy current field attenuation. By using a non-contact eddy current sensor that measures the attenuation of an alternating electromagnetic field, the system obtains a measurement that reflects only actual cord wear and not diameter changes caused by mechanical loading.
2Ease of operation
If visual inspection is used to check cord wear, then the method is simple to perform, but wear of embedded steel cords is difficult to determine
Solution Approach 1:
The patent replaces visual inspection with eddy current measurement. The eddy current sensor detects changes in the electromagnetic field caused by cord wear, providing an automated, precise measurement method that works effectively for embedded cords that are not visible during visual inspection.
3Quantity of substance
If the full length of steel cable is used for electrical resistance measurement, then the measurement is comprehensive, but severe wear in a short section may be undetected
Solution Approach 1:
The patent applies segmentation by using multiple eddy current sensors positioned at different locations along the carrying belt. Each sensor measures the attenuation of the electromagnetic field at its specific position, enabling detection of localized wear in short sections of the cords while maintaining comprehensive coverage through the distributed sensor array.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method provides a reliable and accurate assessment of the carrying strap's condition, enabling timely replacement and reducing unnecessary replacements by differentiating between mechanical stress-induced changes and actual wear.
Implementation Method 1
an eddy current sensor (8) which is designed to generate an alternating electromagnetic field (10) and to detect an attenuation of the alternating field (10) by eddy currents induced by the alternating field (10) in the cords (6)
Implementation Method 2
detect an attenuation of the alternating field (10) by eddy currents induced by the alternating field (10) in the cords (6)
Data Source
Figure 1
Figure 2~3
Figure 4~6
AI summary
The invention relates to a device (2) for determining a discard value for a support belt (4) with embedded, electrically conductive cord ropes (6), comprising: an eddy current sensor (8) designed to generate an alternating electromagnetic field (10) and to detect attenuation of the alternating field (10) by eddy currents induced by the alternating field (10) in the cord ropes (6), and an evaluation unit (12) connected to the eddy current sensor (8) via a signal connection (14), wherein the evaluation unit (12) is configured to determine a discard value for the support belt (4) based on the sensor signal.wherein the discard value represents a change in the arrangement (18) of the cord ropes (6) in the support belt (4) to a predetermined reference rope arrangement (20) of the cord ropes (30) in the support belt (28) and/or a change in the rope diameters (22) of the cord ropes (6) to predetermined reference diameters (24) for the cord ropes (30). Furthermore, the invention relates to a corresponding method and a drive system with such a device (2).