Rectangular Insulated Wire Profile for Coil Cooling and Bending
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Solution Overview
Problem
Existing insulated wires with reduced insulating film cross-sectional area face challenges in maintaining electrical performance, conductor space factor, and bending workability, while also generating excessive heat due to high electric current flow, which affects motor efficiency.
Innovation Solution
The insulated wire features a thermoplastic resin layer with continuous protruding parts along its longitudinal direction, forming a curved portion with a specific radius of curvature and a slope less than 90°, enhancing conductor space factor, gap area for cooling, and improving bending workability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the cross-sectional area of the insulating film is reduced to improve conductor space factor, then the conductor space factor is improved, but the electrical performances (dielectric breakdown property) may deteriorate
Solution Approach 1:
The insulating film is designed with non-uniform thickness, featuring a thin portion and a thick portion. The thin portion (5-20 μm) provides sufficient insulation where needed, while the thick portion (20-50 μm) at the protruding part provides enhanced insulation and mechanical protection. This local variation in thickness allows the insulating film to simultaneously achieve high conductor space factor and maintained electrical performance.
2Productivity
If the insulating film is made thinner to improve space factor, then the space factor is improved, but the insulating film becomes more susceptible to damage and electrical breakdown
Solution Approach 1:
The protruding part is designed in advance to provide mechanical cushioning and protection to the insulating film. This protruding structure absorbs mechanical stresses and prevents direct damage to the thinner portions of the insulating film during coil winding and operation, thereby maintaining both high space factor and film durability.
3Productivity
If rectangular wire is used to reduce dead space and improve conductor space factor, then conductor space factor is improved, but bending workability for forming coils deteriorates
Solution Approach 1:
Protruding parts are added to the rectangular wire surface, creating curved features with specific radii of curvature. These curved features reduce stress concentration during bending operations, improving coil forming workability while the overall rectangular cross-section maintains high conductor space factor in the stator slot.
Data Source
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AI summary
An insulated wire containing a thermoplastic resin layer (A) as a covering layer directly or indirectly on a rectangular conductor, in which the insulated wire has at least one protruding part which is continuous in a longitudinal direction of said insulated wire, on a surface of a portion of the thermoplastic resin layer (A), which portion corresponds to at least one side of a cross-section of the insulated wire, said protruding part and a flat part of the surface having the protruding part forms a curved portion with a radius of curvature of 0.01 to 0.75 mm in the cross-section of the insulated wire, and a lateral face of the protruding part has a slope of less than 90° to the flat part of the surface having the protruding part in the cross-section of the insulated wire, a coil produced by processing the insulated wire by winding, and an electric/electronic equipment comprising the coil.