Magnetic Material Evaluation via Eddy Current Detection
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Solution Overview
Problem
Conventional magnetic material evaluation devices require large, costly setups to accurately measure eddy current loss in permanent magnets due to the need for thermal insulation and strong magnetic fields, leading to equipment enlargement and increased costs.
Innovation Solution
A magnetic material evaluation method using a device with an excitation coil generating a magnetic field that includes an insulating material between magnetic pieces and a detection coil with a diameter smaller than the magnetic pieces, allowing direct detection of eddy currents and eliminating the need for thermal insulation, enabling miniaturization and cost reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a thermally insulated sample chamber is used to capture eddy current loss as heat, then measurement accuracy is improved, but device size and equipment cost increase
Solution Approach 1:
The patent replaces the thermal measurement system (thermocouple in insulated chamber) with an electromagnetic detection system. The detection coil directly measures eddy current through electromagnetic induction, eliminating the need for thermal insulation and large sample chambers while maintaining measurement accuracy.
Solution Approach 2:
The detection coil acts as an intermediary between the magnetic field and the measurement system. It converts the eddy current generated in the magnet into a detectable electrical signal, enabling direct measurement without thermal conversion and eliminating the need for thermal insulation infrastructure.
2Force
If a large magnetic field generator is used to allow magnetic field to reach the magnet through the sample chamber, then magnetic field penetration is improved, but device size and equipment cost increase
Solution Approach 1:
The patent extracts the magnetic field generation function from a large external generator and integrates it into a compact excitation coil system. The excitation coil generates the necessary magnetic field locally around the magnet, eliminating the need for large magnetic field generators and reducing overall device size.
Solution Approach 2:
The patent changes the spatial arrangement by placing the excitation coil in close proximity to the magnet, creating a localized magnetic field environment. This dimensional reconfiguration allows effective magnetic field application without requiring the large-scale infrastructure of conventional magnetic field generators.
3Area of stationary object
If the coil diameter of the detection coil is larger than the magnetic piece length, then detection coverage is improved, but eddy current detection accuracy decreases
Solution Approach 1:
The patent applies local quality by matching the detection coil diameter to the specific dimensions of the magnetic piece being tested. The coil diameter is optimized to correspond to the length of individual magnetic pieces, ensuring that the magnetic field and detection are concentrated on the local region of interest, thereby improving measurement accuracy for each specific component.
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 approach allows for reliable detection of eddy currents in individual magnetic pieces, reducing equipment size and cost, while effectively identifying defects such as insulation breakdowns and internal damage without the need for strong magnetic fields or thermal insulation.
Implementation Method 1
an excitation coil that generates a magnetic field... The excitation coil generates a magnetic field that has a magnitude in a range that corresponds to the region including the insulating material between at least one magnetic piece
Implementation Method 2
a detection coil that detects the eddy current that is generated in the magnetic pieces of the magnet to be evaluated by the magnetic field
Implementation Method 3
a detection coil that detects the eddy current that is generated in the magnetic pieces of the magnet to be evaluated by the magnetic field
Data Source
Figure 1(a)~1(c)
Figure 2(a)~2(c)
Figure 3~4
AI summary
[Object] To provide a magnetic material evaluation device with a simpler configuration that can evaluate a magnet by detecting the eddy current that is generated in a magnet. [Means to solve the problem] A magnetic material evaluation device 1characterized by comprising an excitation coil 12 that generates an alternating magnetic field that has a magnitude in a range that corresponds to the region including at least two adjacent magnetic pieces 101 of the magnet 102, which is made by bonding plural magnetic pieces 101 to sandwich an insulating material 103, and a detection coil 13 for detecting the eddy current that is generated in the magnetic piece 101 by the alternating magnetic field, in which the coil diameter of the detection coil 13 is smaller than the length of one magnetic piece 101 in the direction in which the plural magnetic pieces 101 are aligned.