Composite Magnetic Dust Core Insulation via Mechanical Collapse
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Solution Overview
Problem
Existing magnetic materials for dust cores, particularly in vehicle engine control units and choke coils, face challenges in high frequency ranges due to poor pigment homogeneity in silicone resin coatings, leading to degraded insulation properties and increased magnetic losses, making them unsuitable for small, high-frequency applications.
Innovation Solution
A composite magnetic material is developed using magnetic metal powder with a Vickers hardness of 230≦Hv≦1000 and an insulating material with a compressive strength of 10000 kg/cm2 or lower, which is mechanically collapsed and interposed within the powder to prevent contact and enhance insulation and heat resistance, allowing for high-temperature annealing and improved permeability and magnetic loss performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If silicone resin with pigment coating is used on metal powder surfaces, then magnetic material can be formed, but insulation properties are abruptly degraded when silicone resin decomposes during high-temperature annealing
Solution Approach 1:
The patent extracts and removes the problematic organic pigment components from the coating system, retaining only the essential insulating binder. This extraction eliminates the decomposition issue during high-temperature annealing while preserving the necessary insulation properties, allowing annealing temperatures to reach 1000°C or higher without insulation degradation.
Solution Approach 2:
The patent changes the compositional parameters of the coating by adjusting the binder content to 5-20 mass% and eliminating pigment components. This parameter change transforms the coating from an organic-based insulation layer to a thermally stable inorganic-based insulation layer, enabling high-temperature annealing while maintaining insulation properties.
2Loss of energy
If high-temperature annealing is performed to relieve strain in magnetic metal powder, then hysteresis loss is reduced, but thermal decomposition of silicone resin occurs and metal particles sinter together
Solution Approach 1:
The patent extracts the organic components (silicone resin and pigment) that cause thermal decomposition and sintering, replacing them with an inorganic binder system. This extraction allows the metal powder to withstand high-temperature annealing (1000°C or higher) without decomposition-induced sintering, while still enabling strain relief to reduce hysteresis loss.
Solution Approach 2:
The patent creates a composite coating structure combining inorganic binder with insulating properties, replacing the organic silicone resin-pigment composite. This new composite material maintains particle separation during high-temperature annealing while enabling the thermal processing needed to reduce hysteresis loss through strain relief.
3Reliability
If pigment is added to silicone resin for insulation, then insulation properties are provided, but homogeneity of pigment in silicone resin is poor
Solution Approach 1:
The patent extracts and removes the pigment component from the coating formulation, eliminating the homogeneity problem entirely. The insulation function is maintained through the inorganic binder system without requiring dispersed pigment particles, thus achieving uniform composition and reliable insulation properties.
Solution Approach 2:
The patent achieves homogeneous composition by eliminating the multi-component pigment-binder system and using a simplified inorganic binder formulation. This homogeneous coating structure ensures consistent insulation properties without the aggregation and distribution issues inherent in pigment-containing systems.
4Volume of moving object
If dust core is made smaller for decreasing size of electronic devices, then device size is reduced, but magnetic loss increases due to inability to perform high-temperature annealing
Solution Approach 1:
The patent extracts the thermal instability limitation from small dust cores by removing organic components that decompose at high temperatures. This enables even miniaturized dust cores to undergo high-temperature annealing for strain relief, thereby reducing hysteresis loss and magnetic loss despite the reduced size.
Solution Approach 2:
The patent changes the thermal stability parameter of the coating by using inorganic binders with high decomposition temperatures. This parameter change allows small dust cores to withstand the high-temperature annealing process needed to reduce magnetic loss, overcoming the size-related constraints of previous organic-based coatings.
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 improves insulation properties and heat resistance, enabling dust cores with favorable permeability and low magnetic losses even in high frequency ranges, suitable for small, high-frequency applications like vehicle ECUs and choke coils.
Implementation Method 1
the insulating material has a compressive strength of 10000 kg/cm2 or lower and is in a mechanical collapsed state, and the insulating material in a mechanical collapsed state is interposed in the magnetic metal powder
Implementation Method 2
a thermal treatment is performed on the compact
Implementation Method 3
when the silicone resin is decomposed during high-temperature annealing, not only eddy-current loss becomes large, but also a decrease in permeability is caused in a high frequency range
Data Source
AI summary
A composite magnetic material is manufactured having magnetic properties that can excellently cope with the decreasing size and increasing electric current of magnetic elements, such as choke coils, and can be used in a high frequency range, a dust core using the composite magnetic material, and a method of manufacturing the same. The dust core includes magnetic metal powder and an insulating material, in which the magnetic metal powder has a Vickers hardness (Hv) of 230 ≦ Hv≦ 1000, the insulating material has a compressive strength of 10000 kg/cm2 or lower and is in a mechanical collapsed state, and the insulating material in a mechanical collapsed state is interposed in the magnetic metal powder.