Magnetostrictive Torque Sensing With Sensor Rotation Prevention
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Solution Overview
Problem
Conventional magnetostrictive torque measurement devices face errors due to the magnetostrictive sensor rotating with respect to its supporting case, leading to inaccurate torque measurements.
Innovation Solution
A torque measurement device design that includes a case which does not rotate, a rotating shaft with a magnetostrictive effect part, and a magnetostrictive sensor supported by the case through an outer ring or one-way clutch, preventing the sensor from rotating with respect to the case, thereby maintaining accurate measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the magnetostrictive sensor is arranged in the vicinity of the magnetostrictive material on the rotating shaft, then torque measurement is enabled, but the sensor may rotate with respect to the case supporting it, causing measurement errors
Solution Approach 1:
The patent introduces an outer ring as an intermediary component between the case and the magnetostrictive sensor. The outer ring is rotatably supported by the case and the magnetostrictive sensor is supported by the outer ring, creating a stable measurement reference frame that prevents sensor rotation relative to the case while enabling torque measurement through the magnetostrictive effect.
Solution Approach 2:
The patent replaces direct mechanical support of the sensor by the case with a magnetic field-based support system. The magnetostrictive sensor detects changes in magnetic permeability of the magnetostrictive material on the rotating shaft, substituting direct mechanical coupling with magnetic field interaction to prevent sensor rotation while maintaining measurement capability.
2Device complexity
If the magnetostrictive sensor is directly supported by the case, then the structure is simple, but the sensor rotates with respect to the case during operation
Solution Approach 1:
The outer ring serves as a mediating structure between the case and the magnetostrictive sensor. This intermediary component adds minimal complexity to the support structure while effectively preventing sensor rotation, thereby maintaining measurement precision without significantly increasing device complexity.
Solution Approach 2:
The patent extracts the rotational freedom requirement from the sensor support system. By separating the rotational function (handled by the outer ring rotating on the shaft) from the sensor support function (handled by the case supporting the outer ring), the sensor itself remains stationary relative to the case while the outer ring accommodates shaft rotation.
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 design effectively prevents the magnetostrictive sensor from rotating with respect to the case, enhancing measurement accuracy and reducing torque measurement errors.
Implementation Method 1
When a torque is applied to the rotating shaft, the magnetostrictive material undergoes elastic torsional deformation, and thus change occurs in the magnetic permeability of the magnetostrictive material due to a reverse magnetostrictive effect.
Implementation Method 2
a magnetostrictive sensor arranged in the vicinity of the magnetostrictive material for detecting change of the magnetic permeability of the magnetostrictive material
Data Source
AI summary
A torque measurement device includes a case that does not rotate even during use; a rotating shaft rotatably supported to the case and having a magnetostrictive effect part whose magnetic permeability changes according to a transmitted torque; and a magnetostrictive sensor having a detection part arranged closely adjacent to the magnetostrictive effect part so that a voltage changes according to change of the magnetic permeability of the magnetostrictive effect part, and being supported to the case; and the torque measurement device has a rotation-preventing construction configured to prevent the magnetostrictive sensor from rotating with respect to the case.