Alternating Lay Direction Elevator Wire for Fretting Detection
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Solution Overview
Problem
Elevator load bearing members, such as ropes and belts, deteriorate over time due to cyclic bending, making it crucial to monitor conditions like corrosion and wire breakage for safety, but existing methods struggle to effectively detect deterioration, especially fretting, which can be masked by line contact between wires.
Innovation Solution
A load bearing member with tension elements comprising multiple layers of wires arranged in alternating lay directions, surrounded by a jacket material, and equipped with an inspection device to monitor electrical resistance, promoting point contact and increased stress detection of deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wires are arranged in parallel layers with same lay direction, then manufacturing is simplified, but deterioration detection precision deteriorates due to line contact masking fretting
Solution Approach 1:
The patent applies asymmetry by arranging wires in alternating lay directions (e.g., first layer with lay direction +α, second layer with lay direction -α) rather than parallel identical arrangements. This asymmetric configuration causes wires to contact at discrete points rather than along lines, creating visible fretting marks that enable precise deterioration detection while maintaining manufacturing feasibility through systematic angular alternation.
Solution Approach 2:
The patent inverts the conventional approach by using opposite lay directions instead of identical lay directions. This inversion transforms the contact pattern from continuous line contact (which masks deterioration) to discrete point contact (which reveals deterioration through fretting marks), thereby solving the detection precision problem while preserving structural integrity.
2Measurement precision
If alternating lay directions are used, then deterioration detection precision improves through point contact, but device complexity increases due to multi-layer wire arrangement
Solution Approach 1:
The patent applies local quality by assigning different lay directions to different layers (first layer: +α, second layer: -α, third layer: +α, etc.). This localized differentiation creates point contact zones specifically at layer interfaces where deterioration occurs, enabling targeted detection without requiring complex overall restructuring. Each layer maintains its specific angular characteristic optimized for its detection function.
Solution Approach 2:
The patent segments the wire arrangement into multiple distinct layers with alternating lay directions. This segmentation isolates contact points to specific layer boundaries, creating discrete detection zones that simplify the analysis of deterioration patterns. The segmented structure allows systematic monitoring of each interface independently, reducing the complexity of overall system assessment.
3Reliability
If multiple layers with alternating lay directions are implemented, then fretting detection reliability improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses parameter changes by defining specific angular relationships between layers (e.g., +α and -α relative to the axis). These parameter specifications provide clear manufacturing targets that balance detection reliability with manufacturability. The angular parameters are chosen to optimize point contact formation while remaining achievable with standard manufacturing tolerances, thereby resolving the conflict between reliability and manufacturing precision.
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
The alternating lay direction configuration enhances the detection of fretting and deterioration by increasing contact stresses, allowing for more reliable monitoring and maintenance of load bearing members, ensuring safer elevator operation.
Implementation Method 1
The alternating lay direction configuration enhances the detection of fretting and deterioration by increasing contact stresses
Implementation Method 2
equipped with an inspection device to monitor electrical resistance
Data Source
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AI summary
A tension element for use in a load bearing member of an elevator system includes a first layer having a plurality of first wires and a second layer having a plurality of second wires. The second layer is positioned radially outward of and surrounds the first layer. The first layer has a first lay direction and the second layer has a second lay direction. The second lay direction is opposite the first lay direction.