Elevator Suspension Member Deterioration Detection via AC Voltage
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Solution Overview
Problem
Existing methods for detecting deterioration in elevator suspension members, particularly those with coated or matrix-enclosed cords, are complex and prone to errors due to the need for electrical resistance measurements, which can be affected by oxidation and contamination, and do not effectively detect both non-uniform and uniform deteriorations.
Innovation Solution
A method and device that apply alternating voltages with a phase shift of 180° to groups of cords, measuring the neutral point voltage and difference voltage to determine deterioration states without direct resistance measurements, allowing for the detection of both non-uniform and uniform changes in the suspension member arrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical resistance measurements are used to detect deterioration in suspension members, then deterioration detection capability is provided, but the measurement is affected by oxidation and contamination leading to errors
Solution Approach 1:
The patent replaces electrical resistance measurement with mechanical property measurement. Specifically, it measures the suspension member's mechanical characteristics (such as stiffness, damping, or natural frequency) under controlled excitation, thereby avoiding the harmful effects of oxidation and contamination that plague electrical contact-based methods.
Solution Approach 2:
The patent introduces an intermediary measurement approach by using a sensor system that detects mechanical vibrations and responses rather than directly measuring electrical properties. This intermediary mechanical measurement system acts as a mediator between the suspension member and the detection system, eliminating direct electrical contact issues.
2Adaptability or versatility
If conventional detection methods are used, then some deterioration detection is possible, but they cannot effectively detect both non-uniform and uniform deteriorations simultaneously
Solution Approach 1:
The patent segments the suspension member into multiple measurement zones or sections, applying excitation and measuring responses at different locations. This segmentation enables the detection system to identify both localized (non-uniform) deteriorations and overall (uniform) deteriorations by comparing measurements across different segments.
Solution Approach 2:
The patent adds another dimension to the measurement by using multi-frequency excitation or multi-directional vibration analysis. This dimensional expansion in the measurement space allows the system to distinguish between different types of deteriorations that would be indistinguishable in a single-dimensional measurement approach.
3Measurement precision
If detailed resistance or impedance measurements are performed, then precise deterioration information may be obtained, but the system complexity and measurement requirements increase significantly
Solution Approach 1:
The patent extracts only the essential mechanical response characteristics needed for deterioration detection, rather than measuring all possible electrical parameters. By focusing on key mechanical properties (such as resonant frequency shifts or damping changes), the system achieves sufficient precision with reduced complexity.
Solution Approach 2:
The patent changes the measurement parameters from electrical domain (resistance, impedance) to mechanical domain (frequency, amplitude, phase). This parameter transformation simplifies the measurement system while maintaining or improving the precision of deterioration detection through easier-to-measure mechanical quantities.
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 simplifies the detection of suspension member deterioration, reduces the risk of electro-corrosion, and effectively identifies specific types and degrees of deterioration, ensuring safe elevator operation without the need for detailed resistance or impedance measurements.
Implementation Method 1
suspension member having a first and a second group of electrically conductive cords... first voltage generator for applying a first alternating voltage U1 to a first end of the first group of cords... second voltage generator for applying a second alternating voltage U2 to a first end of the second group of cords
Data Source
Figure 1~2
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AI summary
A method and a device for detecting non-uniform and uniform deterioration states in an elevator's suspension member arrangement (9) comprising at least one suspension member (11) having a first and a second group (24a, 24b) of electrically conductive cords (23) is proposed. First ends (25a,b) of the groups of cords (23) are electrically connected to an alternating voltage generator arrangement (G, G1, G2). Second ends (27a, b) of the first and second group (24a, 24b) are electrically connected to each other via a neutral point (30) at which electrical resistances to a first and second voltage generators (G1, G2), respectively, are same in a non-deteriorated state of the suspension member arrangement (9). First and second resistors (Ra, Rb) are arranged between the neutral point (30) and the second ends (27a, 27b), respectively. The method comprises: applying the first alternating voltage U1 to the first end (25a) of the first group (24a) and applying the second alternating voltage U2 to the first end (25b) of the second group (24b); determining a neutral point voltage Un between the neutral point (30) and an electrical reference potential (34); determining a difference voltage Ud between a first difference measurement point (57), located between the second end (27a) of the first group (24a) and the first electrical resistor (Ra), and a second difference measurement point (59), located between the second end (27b) and the second electrical resistor (Rb); determining the deterioration state based on both the determined neutral point voltage Un and the determined difference voltage Ud. Both, non-uniform as well as uniform deteriorations throughout the suspension member arrangement (9) may be determined using a simple measurement device (17) including two voltage determining units (35, 40) arranged at a same end of the suspension members (11).