Magnetostrictive Torque Sensor Eccentricity Compensation
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Solution Overview
Problem
Conventional magnetostrictive torque sensors experience decreased detection accuracy due to relative eccentricity between the shaft and the sensor, particularly in high vibration environments, caused by misalignment, temperature changes, or external stress.
Innovation Solution
A torque sensor design featuring a pair of cylindrical detection units with detection coils inclined at specific angles, forming a series-parallel circuit, and connected via specific lines to mitigate the effects of eccentricity, enhancing detection accuracy by canceling out offset voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional magnetostrictive torque sensor with detection coils arranged on a cylindrical flexible substrate is used, then the sensor can detect torque transmitted by a shaft, but detection accuracy decreases due to relative eccentricity between the shaft and sensor caused by misalignment, temperature change, or external stress
Solution Approach 1:
The detection coils are segmented into multiple groups (first detection coils and second detection coils) with different inclination angles. Each group detects torque components in different directions, and the results are combined to calculate the total torque, thereby compensating for eccentricity effects
Solution Approach 2:
Detection coils are arranged with different local orientations (inclination angles) around the shaft. The first detection coils are inclined at a predetermined angle while the second detection coils are inclined at a different angle, allowing each local region to detect specific torque components that together provide accurate total torque measurement despite eccentricity
2Measurement precision
If detection coils are arranged with different inclination angles to compensate for eccentricity, then torque detection accuracy is maintained under eccentric conditions, but the device complexity increases due to multiple coil arrangements and series-parallel circuit configurations
Solution Approach 1:
Multiple detection coils with different inclinations are merged into a unified series-parallel circuit configuration. The first and second detection coils are electrically connected in series-parallel arrangements, allowing their output signals to be combined and processed together to calculate torque while maintaining a relatively simple overall circuit structure
Solution Approach 2:
The detection coil system serves multiple functions: each coil group detects torque components in different directions, the series-parallel configuration provides both signal combination and eccentricity compensation, and the entire system can measure torque accurately under various shaft positions and orientations
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 effectively suppresses the decrease in torque detection accuracy due to eccentricity, allowing for precise torque measurement even in challenging environments, thereby improving vehicle control systems.
Implementation Method 1
a shaft (2) having magnetostrictive properties
Implementation Method 2
a sensor which senses a change in magnetic permeability of the shaft based on changes in inductances of coils arranged near the shaft
Data Source
AI summary
A torque sensor to detect torque transmitted by a shaft having magnetostrictive properties is provided with a pair of cylindrical detection units arranged around the shaft and aligned side-by-side in an axial direction of the shaft, and first and second connection lines connecting the pair of detection units. Each detection unit includes first to fourth detection coils stacked in a radial direction. A series circuit formed by series connecting the first and fourth detection coils is parallel connected to a series circuit formed by series connecting the second and third detection coils. The first and second connection lines are configured to connect between corresponding connecting portions of the first and fourth detection coils and between corresponding connecting portions of the second and third detections coils, respectively. The torque transmitted by the shaft is detected based on a potential difference between the first connection line and the second connection line.