Insulated Wire Adhesive Layer for Stator Slot Insertion
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Solution Overview
Problem
Existing insulated wires face issues with slippage of insulating papers during insertion into stator core slots and bending, leading to interference and reduced insulation performance, especially at high temperatures, and require complex additional insulating layers for high partial discharge initiation voltage at bent portions.
Innovation Solution
An insulated wire design featuring an insulating layer on a conductor with an adhesive layer of specific thickness and composition, and an insulating paper on the adhesive layer, providing strong fixing strength and high partial discharge initiation voltage without additional layers, even at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating paper is disposed at coil housing grooves and a varnish is used to immobilize the coil, then the coil is immobilized and insulation between the coil and stator core is provided, but slippage of insulating papers occurs during insertion, leading to interference with the rotor
Solution Approach 1:
An adhesive layer is applied to the outer periphery of the insulating layer before the insulating paper is wound around it. This preliminary application of adhesive ensures that the insulating paper is securely fixed from the beginning, preventing slippage during insertion operations while maintaining insulation properties.
2Reliability
If a prepreg sheet with thermosetting adhesive layer is used to prevent contact between stator core and conductor coil, then contact is prevented, but at high temperatures (200°C or higher), the thermosetting adhesive layer is softened and loses adhesiveness
Solution Approach 1:
The adhesive layer is formulated with specific physical properties: a tensile modulus at 250°C within the range of 0.9×10^7 to 1.2×10^8 Pa and a thickness of 2 to 50 μm. These parameter specifications ensure the adhesive maintains its bonding strength and does not soften at high temperatures, preventing loss of adhesiveness while effectively preventing contact between the stator core and conductor coil.
3Reliability
If an additional insulating layer is provided at bent portions to obtain high partial discharge initiation voltage, then high PDIV is achieved, but the production process becomes complicated due to the need to determine position after bending
Solution Approach 1:
The adhesive layer is applied to the outer periphery of the insulating layer before the insulated wire undergoes bending. This preliminary application eliminates the need to determine the position after bending and apply additional insulating layers subsequently. The adhesive layer remains in place throughout the bending process, maintaining high partial discharge initiation voltage while simplifying the production process.
4Strength
If the adhesive layer thickness is increased to improve fixing strength, then fixing strength is improved, but the overall wire diameter increases and bending workability deteriorates
Solution Approach 1:
The adhesive layer thickness is precisely controlled within the range of 2 to 50 μm. This optimized thickness provides sufficient fixing strength to prevent slippage of the insulating paper while maintaining the flexibility and bending workability of the insulated wire. The specific thickness parameter balances the competing requirements of strength and manufacturability.
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 insulated wire configuration prevents slippage, maintains high partial discharge initiation voltage at bent portions, and offers excellent heat resistance and bending workability, simplifying the production process and enhancing insulation properties.
Implementation Method 1
an adhesive layer on the outer periphery of the insulating layer... the adhesive layer having a particular thickness and having a tensile modulus at 250° C. in a particular range
Implementation Method 2
the resin constituting the adhesive layer does not have a melting point... even under a high temperature (for example, 200° C.), the insulating paper can be fixed to the insulating layer with strong fixing strength
Implementation Method 3
an insulating layer on the outer periphery of a conductor having a rectangular cross-section... an insulating paper on the outer periphery of the adhesive layer
Data Source
AI summary
An insulated wire, having: an insulating layer on the outer periphery of a conductor having a rectangular cross-section; an adhesive layer on the outer periphery of the insulating layer; and an insulating paper on the outer periphery of the adhesive layer, wherein the adhesive layer has a thickness of 2 to 50 μm, and wherein a resin constituting the adhesive layer does not have a melting point and has a tensile modulus at 250° C. of 0.9×107 to 1.2×108 Pa; a coil, comprised of this insulated wire; and an electrical or electronic equipment.