Soft Magnetic Component for Torque Sensor with Resin Molding Stress
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Solution Overview
Problem
Resin molding of soft magnetic materials for torque sensors leads to degradation of magnetic properties due to compression stress, resulting in reduced torque detection accuracy, sensitivity, and responsiveness.
Innovation Solution
A soft magnetic component with a specific composition of Ni, Fe, and additional elements like Mo, Nb, Cr, Cu, Ti, and W, having a saturation magnetostriction of at least -4.0 ppm and less than 0 ppm, which reduces internal compression stress and maintains magnetic properties post-molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If resin molding is applied to soft magnetic material, then manufacturing efficiency and weight reduction are improved, but magnetic properties are degraded due to compression stress
Solution Approach 1:
The invention changes the material parameters by specifying precise compositional ranges (Fe: 74-80 wt%, Ni: 18-22 wt%, Mo: 0.5-3 wt%, Nb: 0.5-3 wt%) and controlling saturation magnetostriction within -6 to -2 ppm to achieve optimal magnetic properties that are resistant to resin molding-induced compression stress
Solution Approach 2:
The invention creates a composite material system combining Fe-Ni base metal with specific amounts of Mo and Nb alloying elements, forming a multi-element soft magnetic material that exhibits enhanced magnetic properties and stress resistance when resin-molded
2Device complexity
If resin molding is applied to soft magnetic material, then component integration is improved, but detection accuracy is reduced due to hysteresis increase
Solution Approach 1:
The invention optimizes material parameters including saturation magnetostriction control (-6 to -2 ppm) and specific alloy composition to minimize hysteresis loss, thereby maintaining high detection accuracy even after resin molding process
3Loss of time
If resin molding is applied to soft magnetic material, then production time is reduced, but responsiveness is degraded due to magnetic property changes
Solution Approach 1:
The invention modifies material parameters by controlling saturation magnetostriction within -6 to -2 ppm and optimizing Fe-Ni-Mo-Nb composition to maintain fast magnetic response characteristics that are preserved through the resin molding process
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 changes in magnetic properties during resin molding, enhancing the detection accuracy and sensitivity of torque sensors while maintaining desired magnetic properties.
Implementation Method 1
having a saturation magnetostriction of at least -4.0 ppm and less than 0 ppm
Data Source
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Figure 3~4
AI summary
A soft magnetic component (7, 8, 9, 10) for a torque sensor, formed by resin-molding a soft magnetic material that contains Ni, Fe in such an amount that Fe/(Fe + Ni) is within a range from 10.0% to 16.0% in terms of mass ratio, and 3.5% by mass to 7.5% by mass of M (the M represents one or more elements selected from among Mo, Nb, Cr, Cu, Ti, and W) and has a saturation magnetostriction of at least -4.0 ppm and less than 0 ppm, is provided.