Rotating Shaft Vibration Analysis for Early Fault Detection
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Solution Overview
Problem
Existing methods for condition monitoring of machines with rotating shafts are inadequate in detecting early signs of deterioration due to high noise levels in mechanical vibrations, particularly in machines with slowly rotating parts.
Innovation Solution
A condition analyzing system that includes a sensor unit for measuring vibrations, a data processing system for digital signal processing, and a computer program for enhancing repetitive signal patterns, allowing for the detection of weak mechanical signals in noisy environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional vibration measurement methods are used, then the measurement system is simple and easy to operate, but the detection precision is insufficient due to high noise levels masking weak mechanical signals
Solution Approach 1:
The patent applies preliminary action by performing signal processing operations (bandpass filtering, rectification, low-pass filtering) on the vibration signal before final analysis. This preprocessing enhances the weak repetitive signals associated with bearing defects while suppressing noise, thereby improving detection precision without requiring fundamentally new measurement equipment
Solution Approach 2:
The patent replaces direct mechanical detection with electronic signal processing. Instead of relying solely on mechanical amplification or more complex mechanical sensors, the invention uses digital signal processing techniques to extract weak signals from noisy measurements, substituting mechanical complexity with electronic/computational methods
2Productivity
If manual measurement methods are used, then the equipment cost is low, but the productivity is reduced due to time-consuming manual operations
Solution Approach 1:
The patent implements self-service by enabling the measurement system to automatically process and analyze vibration signals without requiring continuous manual intervention. The automated signal processing pipeline (filtering, rectification, envelope detection) allows the system to independently identify bearing defects, significantly improving productivity while maintaining reasonable complexity through standardized processing algorithms
3Reliability
If early detection of machine deterioration is pursued, then machine reliability is improved, but the difficulty of detecting and measuring increases due to weak signals being masked by noise
Solution Approach 1:
The patent applies periodic action by focusing on detecting repetitive signal patterns that occur at characteristic frequencies related to bearing defect rates. By synchronizing the detection process with the expected periodicity of defect signals and using envelope detection to extract these repetitive patterns, the system can identify early signs of deterioration even when individual defect signals are weak and buried in noise
Solution Approach 2:
The patent uses an intermediary approach by introducing envelope detection as a intermediate processing step. The envelope of the vibration signal contains information about the modulation caused by bearing defects, and extracting this envelope provides a clearer representation of defect patterns. This intermediary transformation makes the weak defect signals more detectable without requiring direct observation of the原始 weak signals
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 effectively detects early indications of machine deterioration by enhancing repetitive signal patterns, even in noisy environments, thereby enabling timely maintenance and preventing sudden failures.
Implementation Method 1
a sensor unit for measuring vibrations, wherein the measured value depends on a vibration movement
Data Source
Figure 1
Figure 2A
Figure 2B~2C
AI summary
A method for causing a computer (14, 50, 33, 920) to analyse the condition of a machine (6) having a rotating part (7,8), the method comprising the steps: receive an analogue electric measurement signal (SEA) dependent on mechanical vibrations emanating from rotation of said shaft; sample said analogue measurement signal at a sampling frequency (fs) so as to generate a digital measurement data signal (SMD) in response to said received analogue measurement data; perform a decimation (S2100, S2110) of the digital measurement data signal (SMD) so as to achieve a digital signal (SRED) having a reduced sampling frequency (fSR1, fSR2); control (S2100, S2110) the reduced sampling frequency (fSR1, fSR2) such that the number of sample values per revolution of the shaft (8) is kept at a substantially constant value; and perform a condition analysis function (F1, F2, Fn) for analysing the condition of the machine dependent on said digital signal (SRED) having a reduced sampling frequency (fSR1, fSR2).