Magnetostrictive Torque Sensor Coil Layout for Lower Capacitance
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Solution Overview
Problem
The electrostatic capacitance between the coil windings of the detection coils in a magnetostrictive torque sensor affects the accuracy of torque detection.
Innovation Solution
The detection coils are arranged with their centerlines misaligned perpendicularly in parallel extending portions to reduce electrostatic capacitance, and are formed on opposite sides of a flexible substrate to minimize the impact of dielectric polarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the detection coils are placed close to each other on the flexible substrate to reduce space, then the device size is reduced, but the electrostatic capacitance between the coil windings increases which deteriorates measurement accuracy
Solution Approach 1:
The patent applies asymmetry by misaligning the centerlines of the first and second coil windings in the parallel extending portions. Specifically, the centerline of the first coil winding and the centerline of the second coil winding are intentionally offset in the direction perpendicular to their respective centerlines, creating an asymmetric arrangement that reduces electrostatic capacitance between the coils while maintaining compact device dimensions.
Solution Approach 2:
The patent utilizes the thickness dimension of the flexible substrate by forming the first coil winding on the front side and the second coil winding on the back side of the substrate. This three-dimensional arrangement, combined with the lateral misalignment in parallel extending portions, effectively reduces the electrostatic capacitance between coils while maintaining a compact overall device size.
2Ease of manufacture
If the coil windings are arranged parallel to each other to simplify the structure, then the manufacturing is easier, but the electrostatic capacitance between the windings increases which reduces measurement accuracy
Solution Approach 1:
The patent maintains the simplicity of parallel coil arrangements while introducing asymmetric misalignment of centerlines in the parallel extending portions. This approach preserves ease of manufacture through simple parallel routing, yet improves measurement accuracy by reducing electrostatic capacitance through the intentional centerline offset.
3Reliability
If the detection coils are formed on both sides of the base material to achieve the desired magnetic detection, then the detection capability is improved, but the electrostatic capacitance between the coils increases which affects measurement accuracy
Solution Approach 1:
The patent forms the first and second detection coils on opposite sides of the flexible substrate base material, utilizing the thickness dimension to achieve the desired detection capability. The electrostatic capacitance issue is resolved by combining this vertical arrangement with lateral misalignment of centerlines in parallel extending portions, creating a three-dimensional configuration that maintains detection capability while reducing parasitic capacitance.
Solution Approach 2:
By misaligning the centerlines of coils on opposite sides of the substrate in the parallel extending portions, the patent reduces the electrostatic capacitance between these coils while maintaining their detection functionality. This asymmetric arrangement allows the system to achieve both reliable torque detection and improved measurement accuracy.
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 configuration improves the accuracy of torque measurement by reducing errors caused by electrostatic capacitance, enhancing the precision of the magnetostrictive torque sensor.
Implementation Method 1
a magnetostrictive torque sensor for measuring torque that is applied to a rotating shaft having magnetostrictive characteristics
Implementation Method 2
measures the torque by a change in inductance of the plurality of detection coils due to a change in magnetic permeability of the rotating shaft
Implementation Method 3
the electrostatic capacitance between the coil winding of the first detection coil and the coil winding of the second detection coil, which are placed to sandwich the base material of the flexible substrate, affects the accuracy of torque detection
Data Source
AI summary
A magnetostrictive torque sensor for measuring torque that is applied to a rotating shaft having magnetostrictive characteristics, includes a flexible substrate having a plate-shaped base material made of a flexible dielectric material and a plurality of detection coils formed by conductor patterns on front and back sides of the base material, and a measurement unit that measures the torque by the change in inductance of the plurality of detection coils due to the change in magnetic permeability of the rotating shaft, wherein the plurality of detection coils includes a first detection coil comprising a first coil winding including a first inclined portion inclined to one side with respect to an axial direction of the rotating shaft, and a second detection coil comprising a second coil winding including a second inclined portion inclined to the other side with respect to the axial direction of the rotating shaft, wherein the flexible substrate includes parallel extending portions where the first coil winding and the second coil winding extend parallel to sandwich the substrate, and wherein a centerline of the first coil winding and a centerline of the second coil winding are misaligned in a direction perpendicular to their respective centerlines in the parallel extending portions.