Shaft Motion Measuring Device with Removable Sleeve
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Solution Overview
Problem
Conventional strain gauge-based systems for measuring shaft relative movement, such as torsion, face challenges in achieving high accuracy due to complex calibration requirements, exposure to contamination and mechanical/thermal stress, and reduced calibration frequency, leading to lower measurement accuracy in power plant operations.
Innovation Solution
A movement measuring device comprising a sleeve and sensor system, where the sleeve is fixedly connected to the shaft, allowing for separate calibration away from the shaft, reducing exposure to contaminants and stresses, and enabling more frequent calibration for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the strain gauge is mounted directly onto the shaft surface, then the measurement of relative motion can be performed, but the strain gauge is exposed to contamination, mechanical stress, and thermal stress which distorts the measurement and reduces accuracy
Solution Approach 1:
A sleeve is introduced as an intermediary component between the shaft and the sensor. The sleeve is rigidly connected to the shaft at two different axial positions, creating a protected measurement environment. The sensor measures the relative displacement between these two connection points, which corresponds to the shaft's relative motion, while the sleeve shields the sensor from harmful factors like contamination, mechanical stress, and thermal stress.
2Measurement precision
If the strain gauge is calibrated directly on the shaft, then calibration can be performed, but the calibration process is complex and rarely performed, resulting in low accuracy
Solution Approach 1:
The calibration process is extracted from the shaft and performed on the sleeve independently. Since the sleeve can be removed from the shaft, calibration can be conducted in a controlled environment away from the complex shaft system. This simplifies the calibration process significantly, allowing it to be performed more frequently and accurately without the complexities associated with direct shaft calibration.
3Measurement precision
If the strain gauge is mounted directly on the shaft, then relative motion measurement is achieved, but frequent calibration is difficult due to power plant downtime requirements
Solution Approach 1:
The sleeve serves as a removable intermediary that facilitates easy calibration. The sensor can be calibrated on the sleeve without requiring the shaft to be in place or the power plant to shut down. This separation allows calibration to be performed quickly and efficiently during routine maintenance activities, eliminating the need for extended power plant downtime and enabling more frequent calibration cycles.
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 solution enhances the accuracy of relative movement measurement by allowing off-shaft calibration, protecting the sensor from contamination and stress, and increasing measurement signal strength, thereby improving the precision of torsional movement determination.
Implementation Method 1
the sensor is arranged to measure at least one relative motion of the sleeve from the first sleeve plane to the second sleeve plane
Data Source
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AI summary
The invention relates to a motion measuring device (3) for measuring the relative motion of a shaft (1), comprising a sleeve (18) which is arranged to be rigidly connected to the shaft (1) in a first sleeve plane (15), which is perpendicular to a sleeve rotation axis (27) of the sleeve (18), and in a second sleeve plane (17), which is spaced apart from the first sleeve plane (15) in an axial direction with respect to the sleeve rotation axis (27), during operation of the motion measuring device (3), and a sensor (8) which is arranged to measure at least one relative motion of the sleeve (18) from the first sleeve plane (15) to the second sleeve plane (17), wherein, when the sleeve (18) is rigidly connected to the shaft (1) during operation, the relative motion of the shaft (1) from the first sleeve plane (15) to the second sleeve plane (17) essentially corresponds to the relative motion of the sleeve.which allows the wave relative motion to be determined by measuring the sleeve relative motion of the sensor (8).