Insulated Wire Composite Coating for Crack Resistance
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Solution Overview
Problem
Motors with high-speed switching and increased voltage require insulation designs that resist partial discharge, but the coil forming process applies stress leading to cracks, wrinkles, and film separation in enameled wires, reducing insulation properties.
Innovation Solution
An insulated wire with a first polyamide-imide resin coating layer containing dispersed inorganic fine particles and a second polyamide-imide or polyimide resin coating layer, providing improved flexibility and partial discharge resistance, with a lubricating layer on the outer circumference, and specific winding diameter ranges to prevent cracking during elongation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the insulating film is made thinner to reduce coil end height, then the height of coil end portion is reduced, but the insulating film is more susceptible to cracks, wrinkles, and film separation under stress
Solution Approach 1:
The patent applies composite materials by combining polyamide-imide resin with inorganic fine particles (such as silica, alumina, or titania) to create an insulating film that maintains thin dimensions while achieving enhanced mechanical strength and flexibility. This composite structure prevents cracks and film separation under stress, resolving the contradiction between reduced coil end height and maintained insulation reliability.
2Power
If the conductor diameter is increased to handle higher power output, then the power output is increased, but the amount of strain on windings during coil forming increases, causing cracks and wrinkles
Solution Approach 1:
The composite insulating film made from polyamide-imide resin and inorganic fine particles provides enhanced flexibility and tensile strength, allowing it to withstand the increased strain from larger conductor diameters during coil forming without developing cracks or wrinkles.
Solution Approach 2:
The patent changes the physical and chemical parameters of the insulating film by incorporating inorganic fine particles with specific size ranges (0.1-10 μm) and surface treatments, which modify the film's mechanical properties to accommodate higher power conductors while maintaining integrity during manufacturing.
3Reliability
If the insulating film is made more rigid to resist partial discharge, then the partial discharge resistance is improved, but the insulating film becomes more prone to cracking under stress
Solution Approach 1:
The patent creates a composite material system where inorganic fine particles (providing rigidity and partial discharge resistance) are dispersed within a polyamide-imide resin matrix (providing flexibility). This combination achieves both high partial discharge resistance and sufficient flexibility to prevent cracking under stress during coil forming operations.
Data Source
AI summary
An insulated wire includes a conductor, a first insulation coating layer which is provided directly on the conductor and includes a polyamide-imide resin including dispersed inorganic fine particles, and a second insulation coating layer which is provided on the outer circumference of the first insulation coating layer and includes a polyamide-imide resin or a polyimide resin. A minimum winding multiplied diameter that does not cause a crack in the first insulation coating layer when the insulated wire is elongated by 30% by a method in compliance with JISC 3216 “5.1.1” and is wound around a winding bar is greater than 2d but smaller than 4d (where d is a conductor diameter of the insulated wire).