Vibration-Based Rotational Speed Measurement Without Tachometers
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Solution Overview
Problem
Existing methods for measuring rotational speed of motor shafts are space-consuming, complex, and unable to provide accurate and real-time diagnostics, especially in power transmission systems with multiple shafts.
Innovation Solution
A method and device that utilize a vibration sensor to acquire a signal, filter it into a sinusoidal signal, and generate a pulse waveform to derive rotational speed parameters, eliminating the need for additional sensors and allowing for accurate, fast, and space-efficient measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a tachometer is installed to measure rotational speed, then measurement accuracy is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent extracts the speed measurement function from a separate tachometer device and integrates it into the existing vibration sensor system. By processing the vibration signal already present in the system, the invention eliminates the need for additional speed sensing hardware, thereby reducing device complexity while maintaining measurement capability
Solution Approach 2:
The vibration sensor is made multi-functional by enabling it to perform both its original vibration monitoring function and the new rotational speed measurement function. The same sensor and processing electronics are used for both purposes, eliminating the need for dedicated speed measurement hardware and reducing overall system complexity
2Measurement precision
If multiple tachometers are installed on each shaft in a power transmission system, then rotational speed measurement is improved, but the amount of space required increases
Solution Approach 1:
Each vibration sensor on the shafts performs dual functions: monitoring vibrations for condition monitoring purposes and measuring rotational speed. This eliminates the need for separate tachometer installations on each shaft, significantly reducing the space required in the power transmission system while maintaining accurate speed measurement capability across all shafts
3Ease of operation
If average rotational speed is estimated from vibration signal spectrum, then measurement simplicity is improved, but diagnostic accuracy deteriorates
Solution Approach 1:
The patent applies preliminary signal processing actions (filtering and envelope detection) to the vibration signal before analysis. By pre-processing the signal to extract the modulating envelope that contains speed information, the system maintains measurement simplicity while significantly improving diagnostic accuracy compared to direct spectral analysis of the raw vibration signal
Data Source
AI summary
A device for measuring a parameter indicative of a rotational speed of a component includes a wired or wireless input configured to receive a vibration signal from a vibration sensor, a boost filter configured to filter the vibration signal, based on a predetermined frequency range, into a sinusoidal signal and, a comparator configured to generate a pulse waveform signal from the sinusoidal signal in order to read the value of the parameter. Also a motor or pump controller including the device.