Elevator Tension Member Health Monitoring via Eddy Currents
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Solution Overview
Problem
Existing methods for inspecting tension members in elevator systems, particularly those made of carbon fiber composite, face challenges as electrical resistance-based systems do not effectively detect fatigue cycling or localized damage, especially in long belts where changes in resistance are not detectable.
Innovation Solution
An eddy current health monitoring system using a transmitter coil and receiver to generate and detect magnetic field fluctuations, indicating wear or damage, which can also identify the weakest location and compare evaluations over time, and can be used with multiple sets of transmitters and receivers to monitor different portions of the belt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If electrical resistance-based systems are used to inspect tension members, then steel wire tension members can be detected for wear and breakage, but carbon fiber composite tension members cannot be effectively inspected for fatigue cycling or localized damage
Solution Approach 1:
The patent changes the inspection parameter from electrical resistance to eddy current detection. The eddy current system uses a transmitter coil to generate an electromagnetic field that induces currents within the tension member, and a receiver coil to detect changes in these induced currents. This parameter change enables effective inspection of non-metallic materials like carbon fiber composites while maintaining the ability to detect fatigue cycling and localized damage through changes in the electromagnetic field characteristics.
2Measurement precision
If electrical resistance-based systems are used for long belts, then overall resistance can be measured, but localized damage is not detectable as a percentage of total resistance
Solution Approach 1:
The patent segments the inspection approach by using multiple transmitter-receiver coil pairs positioned at different locations along the belt. Each coil pair independently measures the electromagnetic field characteristics at its specific location, allowing localized damage to be detected without being diluted by the total belt length. This segmentation enables precise measurement of damage percentage at each inspection point, making localized damage detectable even in long belts.
3Reliability
If eddy current health monitoring system is implemented, then sensitive detection of wear or damage can be achieved, but system complexity increases
Solution Approach 1:
The patent implements a multi-functional eddy current inspection system where the same transmitter-receiver coil configuration can detect multiple types of damage including fiber breakage, wrinkled fibers, variations in fiber density, and matrix material changes. The system provides both localized damage detection and can track damage progression over time through repeated measurements, reducing the need for multiple separate inspection systems while maintaining high detection sensitivity.
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 system provides sensitive detection of breakage, fiber variations, and matrix material changes in tension members, enabling continuous monitoring and locating damage accurately, even in non-metallic materials, improving the reliability of tension member inspection.
Implementation Method 1
The controller is configured to direct an alternating current through the transmitter coil resulting in the generation of a magnetic field and eddy currents at the transmitter coil
Implementation Method 2
evaluate fluctuations in the magnetic field detected at the receiver. The fluctuations are indicative of wear or damage to the tension member
Data Source
AI summary
A health monitoring system for an electrically-conductive tension member of an elevator system belt includes a transmitter including a transmitter coil configured for placement at the tension member, a receiver configured to be positioned at the tension member, and a controller operably connected to the transmitter and the receiver. The controller is configured to direct an alternating current through the transmitter coil resulting in the generation of a magnetic field and eddy currents at the transmitter coil, evaluate fluctuations in the magnetic field detected at the receiver. The fluctuations are indicative of wear or damage to the tension member.