Powder Magnetic Core Coating for Coil Insulation Without Bobbins
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Solution Overview
Problem
Existing electromagnetic parts using powder magnetic cores face challenges in ensuring effective electric insulation between the core and coil, often requiring increased current and complex assembly due to the use of insulating paper or resin bobbins, which can lead to pinholes and reduced voltage withstand in resin coatings.
Innovation Solution
A powder magnetic core with an insulating-resin coating covering a portion of its surface, where the ratio of the coating area to the total surface area is ≤85% and the maximum unevenness depth is ≤20 μm, preventing pinholes and ensuring uniform film thickness, thereby enhancing electric insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulating paper or resin bobbin is used to ensure electric insulation between the powder magnetic core and coil, then electric insulation is improved, but the distance between the core and coil increases and assembly becomes complicated
Solution Approach 1:
The patent combines the magnetic core and insulating layer into a single integrated component. The insulating-resin coating is directly applied to the surface of the powder magnetic core, eliminating the need for separate insulating paper or resin bobbins. This merging of functions reduces the number of parts and simplifies assembly while maintaining electric insulation between the core and coil.
2Reliability
If insulating paper or resin bobbin is used to ensure electric insulation, then electric insulation is improved, but current requirements increase
Solution Approach 1:
By integrating the insulating layer directly onto the magnetic core surface, the patent eliminates additional spacing components that would increase the overall distance between the core and coil. This reduces the magnetic circuit length and allows for lower current requirements while maintaining adequate electric insulation through the directly applied insulating-resin coating.
3Reliability
If the insulating-resin coating is applied thickly to ensure insulation, then electric insulation is improved, but film uniformity decreases and pinholes form
Solution Approach 1:
The patent employs selective coating application where the insulating-resin coating is applied only to specific portions of the compact surface rather than as a uniform thick layer across the entire surface. This approach achieves adequate electric insulation at critical locations while maintaining film thickness uniformity and avoiding pinhole formation in non-critical areas.
Data Source
AI summary
A powder magnetic core includes a compact including soft magnetic powder, and an insulating-resin coating that covers a portion of a surface of the compact. A ratio of an area of the insulating-resin coating to a surface area of the compact is lower than or equal to 85%, and a maximum depth of unevenness on a surface of the insulating-resin coating is smaller than or equal to 20 μm.