Inverter Surge-Resistant Insulated Wire with PPS Resin Layer
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Solution Overview
Problem
Insulated wires used in inverter-related equipment face challenges with high partial discharge-occurring voltage, adhesive strength, abrasion resistance, thermal-aging resistance, solvent resistance, and packing factor, particularly in narrow spaces within rotary electric machines, where insulation performance and coating shape maintainability are compromised during bending and thermal aging.
Innovation Solution
An inverter surge-resistant insulated wire with an enamel baked layer, an extrusion-coated resin layer formed from a polyphenylene sulfide resin composition, and an adhesive layer to enhance adhesive force, combined with a method of crystallizing the PPS resin composition after assembly to improve mechanical and thermal performances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the enamel layer is increased to achieve high partial discharge-occurring voltage (500 V or more), then the insulation performance is improved, but the number of passages through the baking furnace increases and the adhesive force between the conductor and the enamel layer is reduced
Solution Approach 1:
The insulation structure is divided into multiple layers: an enamel layer (50 μm or less) and an extrusion-coated resin layer. This segmentation allows the enamel layer to maintain adequate thickness for basic insulation while the additional resin layer provides the remaining insulation thickness needed to achieve 500 V or more partial discharge-occurring voltage, thereby avoiding excessive enamel layer thickness that would reduce adhesive force.
Solution Approach 2:
The patent uses a composite insulation structure combining an enamel layer and an extrusion-coated resin layer made from polyphenylene sulfide resin composition. This composite approach allows each layer to contribute differently to the overall insulation performance, enabling achievement of high partial discharge-occurring voltage (500 V or more) without requiring excessive enamel layer thickness that would compromise adhesive force.
2Reliability
If the thickness of the enamel layer is increased to achieve high partial discharge-occurring voltage, then the insulation performance is improved, but the abrasion resistance and solvent resistance of the coating are reduced
Solution Approach 1:
The insulation function is segmented between the enamel layer and the extrusion-coated resin layer. The enamel layer maintains optimal thickness for adhesive strength and surface resistance, while the additional resin layer provides the necessary insulation thickness for high partial discharge-occurring voltage without compromising the surface properties of the enamel layer.
Solution Approach 2:
The composite structure combines an enamel layer with an extrusion-coated resin layer made from polyphenylene sulfide resin composition. This allows the enamel layer to maintain its excellent abrasion and solvent resistance properties while the combined structure achieves the required insulation thickness for 500 V or more partial discharge-occurring voltage.
3Productivity
If the cross-sectional area of the insulation coating is reduced to increase the packing factor in narrow spaces, then the space utilization is improved, but the insulation performance and coating shape maintainability are compromised
Solution Approach 1:
The patent uses a composite insulation structure combining an enamel layer and an extrusion-coated resin layer made from polyphenylene sulfide resin composition. This composite structure provides high insulation performance and excellent coating shape maintainability even when the total insulation thickness is optimized for high packing factor in narrow spaces within rotary electric machines.
Solution Approach 2:
The patent specifies that the extrusion-coated resin layer has a tensile modulus of elasticity at 25°C of 2,500 MPa or more and at 250°C of 10 MPa or more. These parameter specifications ensure that the resin layer maintains its shape and insulation performance even when the overall insulation thickness is reduced to increase packing factor.
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 achieves high partial discharge-occurring voltage, excellent solvent and abrasion resistance, maintains insulation performance at worked portions, and ensures coating shape integrity after thermal aging, while reducing stress on the insulation coating during assembly.
Implementation Method 1
heating the assembled insulated wire, to a temperature of 120°C or higher, to cause crystallization of the polyphenylene sulfide resin of the insulated wire
Data Source
AI summary
An inverter surge-resistant insulated wire, having an enamel baked layer, an adhesive layer, and an extrusion-coated resin layer, around the outer periphery of a conductor, wherein the sum of the thickness of the enamel baked layer, the extrusion-coated resin layer, and the adhesive layer is 60 µm or more, wherein the thickness of the enamel baked layer is 50 µm or less, and wherein the extrusion-coated resin layer is formed from a polyphenylene sulfide resin composition, which contains a polyphenylene sulfide polymer having a melt viscosity at 300°C of 100 Pa·s or more, 2 to 8 mass% of a thermoplastic elastomer, and an antioxidant, and which has a tensile modulus of elasticity at 25°C of 2,500 MPa or more, and a tensile modulus of elasticity at 250°C of 10 MPa or more.