Speed Reducer Failure Diagnosis Using Resonant Motor Current
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Solution Overview
Problem
Existing methods for diagnosing reduction gear failure struggle to detect signs of failure at an early stage due to increased motor current being masked by fluctuations, making it difficult to determine wear-related issues accurately.
Innovation Solution
A device and method that identify an acceleration/deceleration period and process motor current to determine the amplitude peak value of specific frequency components, utilizing natural frequencies of the mechanical apparatus to enhance detection sensitivity by resonating with gear meshing forces, allowing for early detection of reduction gear failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If motor current is monitored during acceleration/deceleration period, then failure diagnosis can be performed during work operation, but detection sensitivity is insufficient when wear is not progressed
Solution Approach 1:
The patent utilizes vibration analysis by monitoring motor current at specific frequency bands corresponding to natural frequencies of the mechanical apparatus. When the gear rotational speed approaches a natural frequency during acceleration/deceleration, resonance occurs in the meshing direction, amplifying the vibration signal and making wear detection possible even at early stages when current increase is minimal.
Solution Approach 2:
The patent changes the parameter being monitored from general motor current magnitude to specific frequency components of motor current. By analyzing the amplitude peak values of frequency components within specific frequency bands (centered on natural frequencies), the system can detect subtle changes caused by wear that are otherwise buried in general current fluctuations.
2Measurement precision
If general motor current is monitored, then wear detection is possible when wear progresses significantly, but early stage wear cannot be detected due to current fluctuations masking the signal
Solution Approach 1:
The patent exploits resonance phenomena where the mechanical apparatus naturally vibrates at specific frequencies. By monitoring motor current at these natural frequencies during acceleration/deceleration periods, the system amplifies wear-related signals through resonance, enabling early detection before wear progresses to a stage where general current increases become apparent.
Solution Approach 2:
The patent performs failure diagnosis during the acceleration/deceleration periods when the gear rotational speed naturally passes through the natural frequency range. This preliminary monitoring during operational transitions allows detection of early wear signs before they develop into significant failures, rather than waiting for pronounced current increases.
3Productivity
If frequency spectrum analysis is performed during acceleration/deceleration, then diagnosis can be done during work period, but specific gear frequency components are difficult to isolate from other fluctuations
Solution Approach 1:
The patent applies local quality by focusing analysis on specific frequency bands corresponding to natural frequencies of the mechanical apparatus rather than analyzing the entire frequency spectrum. This localized approach isolates gear-related frequency components from other fluctuations by concentrating measurement efforts where resonance amplifies the target signals.
Solution Approach 2:
By utilizing the natural vibration frequencies of the mechanical apparatus, the patent creates resonance conditions that amplify gear meshing frequencies. This allows specific gear frequency components to be distinguished from background noise through their enhanced amplitude at resonant frequencies during acceleration/deceleration phases.
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 enables accurate and early diagnosis of reduction gear failure by isolating the gear frequency component within specific frequency bands, improving detection sensitivity and distinguishing wear-related increases in motor current from other fluctuations.
Implementation Method 1
one specific frequency band includes one of the natural frequencies at which the mechanical apparatus is oscillated by resonance in a meshing direction of a gear of the one reduction gear
Data Source
AI summary
A failure diagnosing device diagnoses failure of a plurality of reduction gears of a mechanical apparatus which includes a plurality of operation parts, a plurality of motors, and the plurality of reduction gears. The failure diagnosing device includes an acceleration/deceleration period identifying module configured to identify an acceleration/deceleration period of operation of one of the plurality of operation parts, a motor current processing module configured to acquire a peak value of an amplitude of a frequency component of motor current in a specific frequency band of one motor that drives the one operation part, in the acceleration/deceleration period, and a determining module configured to determine whether a sign of failure exists in one of the reduction gears.