Antifriction Bearing Monitoring Using Capacitive Shaft and Noise Sensing
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Solution Overview
Problem
Current condition monitoring of antifriction bearings in rotating electric machines is limited, as vibration measurements are not applicable in the low frequency range and do not provide direct information on essential physical behaviors like oscillating bearing force, contact angle, and tilting angles, making it difficult to assess the bearing's condition effectively.
Innovation Solution
An arrangement that includes capacitor electrodes to measure capacitive shaft displacement, microphones to detect sound waves, voltage sensors to measure voltage differences, and optical pyrometers to assess temperature, with processors evaluating the bearing condition in real-time, providing insights into remaining lifetime and service needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If acceleration measurement is used for condition monitoring, then the measurement is applicable for all types of bearings, but the measurement is not applicable in low frequency range and identification of local behaviour is difficult
Solution Approach 1:
The patent replaces the mechanical vibration measurement system with an electrical measurement system. Specifically, it uses voltage sensors to measure voltage differences between the rotating shaft and static parts, and capacitance sensors to measure changes in capacitance between the shaft and bearing housing. These electrical measurements can capture low frequency variations (including DC components) that mechanical acceleration sensors cannot detect, while still being applicable to antifriction bearings.
Solution Approach 2:
The patent introduces electrical parameters (voltage and capacitance) as intermediary measurements between the mechanical bearing operation and the diagnostic information. The voltage differences and capacitance changes serve as mediators that reflect the mechanical state of the bearing (such as clearance variations, lubrication conditions, and load distribution) without requiring direct mechanical contact or high frequency vibration analysis.
2Reliability
If acceleration measurement is used, then bearing monitoring is possible, but information on essential physical behaviour such as oscillating bearing force, contact angle, and tilting angle is not obtained
Solution Approach 1:
The patent changes the measurement parameters from mechanical acceleration to electrical parameters (voltage and capacitance). These electrical parameters are sensitive to the physical state of the bearing and can provide information about oscillating bearing forces, contact angles, and tilting angles through their variation patterns. The voltage difference measurements reflect changes in electrical potential caused by mechanical displacement and bearing operation, while capacitance measurements reflect changes in electrical field geometry caused by bearing clearance variations and shaft position changes.
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 solution enhances condition monitoring by providing accurate, real-time data on antifriction bearing health, enabling early detection of wear and potential failures, thus improving maintenance efficiency and preventing motor failures.
Implementation Method 1
one or more capacitor electrodes (114) configured and positioned adjacent to the antifriction bearing (184) to measure a capacitive shaft displacement parameter (134) from an interaction with an electrically conducting part (182) of the rotating shaft (180)
Implementation Method 2
a microphone (118) configured and positioned adjacent to the antifriction bearing (184) to measure sound waves caused by the antifriction bearing (184) as a bearing noise parameter (138)
Implementation Method 3
a voltage sensor (116) configured to measure a voltage difference between the rotating shaft (180) and a static part of the rotating electric machine (186) as a bearing current parameter (136)
Implementation Method 4
an optical pyrometer (110) configured to measure a temperature of the rotating shaft (180) as a shaft heat parameter (130)
Data Source
Figure 1
Figure 2A~2B
Figure 3A~4B
AI summary
An arrangement (100) for monitoring an antifriction bearing (184) of a rotating shaft (180) of a rotating electric machine (186). The arrangement (100) includes: one or more capacitor electrodes (114) to measure a capacitive shaft displacement parameter (134)); one or more of the following additional measurement sensors: a microphone (118) to measure a bearing noise parameter (138), a voltage sensor (116) to measure a bearing current parameter (136), and/or an optical pyrometer (110) to measure a shaft heat parameter (130); and one or more processors (160) configured to evaluate (150) a condition (152) of the antifriction bearing (184) based on the capacitive shaft displacement parameter (134) and one or more of the following: the bearing noise parameter (138), the bearing current parameter (136), and/or the shaft heat parameter (130).