Elevator Tension Member Wear Detection via Electrical Resistance
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Solution Overview
Problem
Existing monitoring systems for elevator support structures, such as belts or ropes, struggle to accurately determine the remaining strength of these structures due to non-uniform degradation caused by cyclic bending, leading to potential safety issues and premature retirement of support structures.
Innovation Solution
A method and system that utilize electrical resistance measurements of tension members in the support structure, connected in series, to monitor wear and determine the remaining strength. The system is connected to a main controller and load weight sensors to gather data on elevator traffic patterns, allowing for dynamic adjustment of resistance thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed resistance threshold is used for monitoring support structure wear, then the monitoring system is simple to operate, but the determination of remaining strength becomes inaccurate due to non-uniform degradation from cyclic bending
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed resistance threshold to a dynamic threshold that adapts based on actual traffic patterns. The system continuously monitors traffic data and adjusts the resistance threshold accordingly, allowing the monitoring parameters to change over time rather than remaining static. This resolves the contradiction by enabling accurate remaining strength determination through adaptive thresholds while maintaining operational simplicity through automated adjustments.
Solution Approach 2:
The patent implements feedback by using actual traffic pattern data to continuously refine and adjust the resistance threshold. The system monitors traffic conditions, compares them against degradation models, and updates the threshold to reflect current operational realities. This feedback loop enables precise remaining strength assessment while the automation of the process prevents excessive complexity in system operation.
2Reliability
If resistance threshold is determined without considering actual traffic patterns, then the monitoring system is easier to implement, but the support structure may be retired prematurely or used beyond safe limits
Solution Approach 1:
The patent applies preliminary action by establishing degradation models and resistance thresholds based on expected traffic patterns before actual operation begins. The system pre-calculates threshold values using anticipated traffic data, allowing for safe and reliable monitoring from the start of operation. This preliminary preparation ensures safety while simplifying implementation, as the complex threshold adjustment logic is already established before the system goes live.
Solution Approach 2:
The patent utilizes parameter changes by adjusting the resistance threshold based on actual traffic pattern parameters. Instead of using a fixed threshold, the system modifies the threshold parameter dynamically according to measured traffic conditions. This approach improves reliability by aligning the threshold with actual operational stresses while maintaining ease of implementation through automated parameter adjustment rather than manual recalibration.
3Measurement precision
If frequent resistance measurements are taken to improve monitoring accuracy, then the remaining strength determination becomes more precise, but the energy consumption and system complexity increase
Solution Approach 1:
The patent applies periodic action by scheduling resistance measurements at optimized intervals rather than continuously. The system determines measurement frequency based on traffic patterns and degradation rates, performing measurements periodically when most informative. This approach achieves precise wear detection by capturing critical degradation events while minimizing energy consumption by avoiding unnecessary continuous measurements.
Solution Approach 2:
The patent implements partial action by performing resistance measurements selectively based on traffic conditions and risk assessment. Rather than measuring at all times, the system performs measurements when traffic patterns indicate higher degradation risk or when previous measurements suggest approaching threshold values. This selective measurement strategy maintains precision for critical assessments while reducing overall energy consumption compared to continuous monitoring.
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 approach allows for more accurate and less conservative determination of resistance thresholds, extending the useful service life of the support structures, reducing maintenance costs, and ensuring safer elevator operations.
Implementation Method 1
Some electrical characteristics, such as electrical resistance or impedance, of the cables, cords or tension members in the support structure will vary as the cross-sectional areas of the tension members decrease.
Data Source
Figure 1
Figure 2A~2B
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AI summary
A method of wear detection of a supporting structure (16) of an elevator system (10) includes measuring an electrical resistance of at least one tension member (26) of a supporting structure (16) via a monitoring system (24), the supporting structure (16) operably connected to an elevator car (12) and one or more sheaves (18) of an elevator system. A threshold resistance is determined utilizing one or more indicators of an actual traffic pattern of the elevator car (12). The measured electrical resistance is compared to the threshold resistance, the result of the comparison indicative of wear of the at least one tension member (26).