Heat-Shrink Covered Rectangular Wire for Gap-Free Bent Insulation

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Solution Overview

Problem

Existing flat wires with bent portions in an edgewise direction often experience gaps between the conductor and the covering layer, leading to higher partial discharge inception voltages.

Innovation Solution

A flat wire design featuring a flat conductor with bent portions in an edgewise direction, covered with a heat-shrinkable tube that shrinks to form a tight, gap-free covering layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional covering layer is applied to a flat conductor with bent portions, then the conductor is protected, but gaps form between the conductor and covering layer leading to higher partial discharge inception voltage

Engineering Contradiction:
Improvepartial discharge inception voltageVSAvoidcontact between conductor and covering layer
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by utilizing the thermal properties of the heat-shrinkable tube. The tube is heated to a specific temperature range (80°C to 150°C) to activate its shrinkage function, transforming it from a loose state to a tightly contracted state that conforms to the conductor's bent portions, thereby eliminating gaps and improving contact precision

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The heat-shrinkable tube undergoes a phase transition when heated. The thermal energy causes the polymer material to change from a relaxed state to a contracted state through phase transition, enabling the tube to automatically adapt to the conductor's shape including bent portions, ensuring gap-free coverage and low partial discharge inception voltage

Inventive Principle:
Principle #36Phase transitions

2Reliability

If the covering layer is made tight to eliminate gaps, then partial discharge inception voltage is reduced, but the manufacturing process becomes more complex

Engineering Contradiction:
Improvepartial discharge inception voltageVSAvoidcovering layer formation process
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The heat-shrinkable tube performs self-service by automatically shrinking and conforming to the conductor's shape when exposed to heat. This self-adjusting mechanism eliminates the need for complex manual operations or additional equipment to ensure tight contact, reducing manufacturing complexity while achieving gap-free coverage

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The heat-shrinkable tube is pre-designed with shrinkage capabilities built into its material structure. This preliminary preparation allows the tube to automatically perform the tightening function when heated, eliminating the need for post-application adjustments or complex forming equipment, thus simplifying the overall manufacturing process

Inventive Principle:
Principle #10Preliminary action

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 ensures a low partial discharge inception voltage by maintaining close contact between the conductor and the covering layer, even with bent portions.

Implementation Method 1

the covering layer is formed by covering the flat conductor having the bent portions with a heat-shrinkable tube and shrinking the heat-shrinkable tube

Methodology Applied
Scientific EffectThermal shrinkage: Thermal Contraction

Data Source

PatentEP4553864A1Rectangular wire, coil, and thermal shrinkage tube
Publication Date: 2025.05.14 DAIKIN INDUSTRIES LTD
  • EP4553864A1 patent drawingFigure 1
  • EP4553864A1 patent drawingFigure 2~3
  • EP4553864A1 patent drawingFigure 4

AI summary

A flat wire including a flat conductor having at least one bent portion bent in an edgewise direction and a covering layer formed on the outer periphery of the flat conductor is provided, wherein the covering layer is formed by covering the flat conductor having bent portion with a heat-shrinkable tube and shrinking the heat-shrinkable tube.