Rotating Machine Retaining Ring Inspection via Optical Imaging
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Solution Overview
Problem
In rotating electric machines, retaining rings are prone to deformation and potential cracking or breakage due to centrifugal forces, requiring periodic visual inspection that can only be done when the machine is stopped, limiting the frequency and timing of defect detection during operation.
Innovation Solution
An inspection method using image pickup elements to acquire images of patterns on the retaining rings' outer surfaces before and during operation, allowing for the calculation of distortion distribution and non-destructive, real-time defect detection without stopping the machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visual inspection is performed by pulling out the rotor from the stator, then the presence or absence of defects in the retaining rings can be inspected, but the inspection cannot be executed during the operation period and the execution frequency is limited to once every several years
Solution Approach 1:
The patent replaces the mechanical disassembly-based visual inspection system with an optical imaging system. Image pickup elements (cameras) mounted on the stator capture images of the retaining rings during rotor rotation, eliminating the need to mechanically pull out the rotor for inspection. This substitution enables continuous monitoring during operation while maintaining defect detection capability.
Solution Approach 2:
The inspection system transitions from a static inspection approach (machine stopped, rotor pulled out) to a dynamic inspection approach (machine operating, rotor rotating). The image pickup elements are positioned to capture images of the rotating retaining rings, allowing inspection to occur during the dynamic operation period rather than requiring the system to be stationary.
2Reliability
If the rotor is pulled out from the stator for visual inspection, then defects can be detected, but the machine must be stopped and the inspection process becomes complex and time-consuming
Solution Approach 1:
The complex mechanical process of pulling out the rotor and performing visual inspection is replaced by a simple optical imaging system. Cameras mounted on the stator automatically capture images of the retaining rings during normal operation, eliminating the need for complex disassembly procedures while maintaining reliable defect detection through image analysis.
3Reliability
If periodic visual inspection is performed, then defects may be detected, but defects occurring between inspections cannot be identified and the machine must be stopped for inspection
Solution Approach 1:
The inspection system enables continuous monitoring of the retaining rings during the entire operation period of the machine. Image pickup elements continuously capture images as the rotor rotates, allowing defects to be detected at any stage of operation without interrupting the useful action of the machine. This eliminates the periodic stoppage required by traditional inspection methods.
Solution Approach 2:
The discontinuous periodic visual inspection is replaced by continuous optical imaging during operation. The image pickup system continuously monitors the retaining rings throughout the operation period, enabling real-time defect identification without requiring the machine to be stopped for inspection intervals.
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
Enables continuous inspection of retaining rings during operation, improving defect detection accuracy and allowing for timely maintenance by quantifying the degree of breakage and identifying defects not visible through visual inspection.
Implementation Method 1
imaging a pattern formed on an outer peripheral surface of a retaining ring
Data Source
AI summary
Provided an inspection method for a rotating electric machine, including: a first step of acquiring a first image by imaging a pattern formed on an outer peripheral surface of a retaining ring over an entire circumference of the retaining ring with use of an image pickup element mounted to a non-rotating portion of the rotating electric machine under a state in which the retaining ring is rotated; a second step of acquiring a second image by imaging the pattern over the entire circumference of the retaining ring with use of the image pickup element under the state in which the retaining ring is rotated, the second step being executed after the first step with an operation of the rotating electric machine interposed; and a third step of acquiring a distortion distribution of the retaining ring based on the first image and the second image.