Twisted Fine-Wire Cable Structure for Small-Diameter Bend Resistance

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Solution Overview

Problem

Existing electronic wires and cables for automobiles face challenges in maintaining bending resistance while reducing their diameter, which is desirable for weight reduction.

Innovation Solution

The development of an electronic wire and cable configuration that includes a conductor formed from multiple small-diameter twisted wires with a specific annealing process, combined with an insulating layer and a polyurethane resin jacket, to achieve a balance between tensile strength and breaking elongation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If the diameter of electronic wires is reduced for weight reduction, then weight decreases, but bending resistance deteriorates

Engineering Contradiction:
Improveweight of electronic wireVSAvoidbending resistance
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The conductor is divided into multiple fine wires (7 to 19 wires per strand, 2 to 7 strands) instead of a single solid wire. This segmentation allows the wire to flex more easily during bending while maintaining electrical conductivity, thus improving bending resistance despite reduced overall diameter for weight reduction.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The electronic wire uses a composite structure combining copper conductors with specific insulating resin materials. The conductor consists of multiple fine copper wires twisted into strands and bundled together, providing both mechanical flexibility and electrical performance, enabling the wire to maintain bending resistance while achieving smaller diameter.

Inventive Principle:
Principle #40Composite materials

2Weight of moving object

If the diameter of electronic wires is reduced, then weight reduction is achieved, but reliability under repeated bending deteriorates

Engineering Contradiction:
Improveweight of electronic wireVSAvoidreliability under repeated bending
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

The conductor is divided into multiple fine wires (7 to 19 wires per strand, 2 to 7 strands) instead of a single solid wire. This segmentation allows the wire to flex more easily during bending while maintaining electrical conductivity, thus improving bending resistance despite reduced overall diameter for weight reduction.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent specifies precise parameter ranges: wire diameter (0.03-0.15mm), number of wires per strand (7-19), number of strands (2-7), breaking elongation (8-15%), and tensile strength (200-400MPa). These controlled parameters ensure the conductor maintains reliability under repeated bending while achieving reduced diameter for weight reduction.

Inventive Principle:
Principle #35Parameter changes

3Weight of moving object

If smaller diameter wires are used, then weight decreases, but the balance between tensile strength and breaking elongation becomes difficult to maintain

Engineering Contradiction:
Improveweight of electronic wireVSAvoidbalance between tensile strength and breaking elongation
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The patent specifies precise parameter ranges: wire diameter (0.03-0.15mm), number of wires per strand (7-19), number of strands (2-7), breaking elongation (8-15%), and tensile strength (200-400MPa). These controlled parameters ensure the conductor maintains reliability under repeated bending while achieving reduced diameter for weight reduction.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The electronic wire uses a composite structure combining copper conductors with specific insulating resin materials. The conductor consists of multiple fine copper wires twisted into strands and bundled together, providing both mechanical flexibility and electrical performance, enabling the wire to maintain bending resistance while achieving smaller diameter.

Inventive Principle:
Principle #40Composite materials

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

This configuration provides excellent bending resistance and twisting resistance even when the diameter is small, effectively addressing the need for reduced weight while maintaining performance.

Implementation Method 1

a conductor formed from annealed copper wire

Methodology Applied
Scientific EffectAnnealing: Annealing

Data Source

PatentEP3664104B1Electric wire and cable
Publication Date: 2025.04.23 SUMITOMO ELECTRIC INDUSTRIES LTD
  • EP3664104B1 patent drawingFigure 1
  • EP3664104B1 patent drawingFigure 2
  • EP3664104B1 patent drawingFigure 3

AI summary

Provided are an electronic wire and a cable which are excellent in bending resistance even when a diameter is small. The electronic wire has a conductor and a resin insulating layer coated on the conductor. The conductor is a double twisted wire in which twisted wires formed by twisting a plurality of wires are twisted, a diameter of the wire is 0.05 mm or more and 0.2 mm or less, a cross-sectional area of the conductor is 1.0 mm2 or more and 3.0 mm2 or less, a breaking elongation of the conductor is 10% or more and 17% or less, a tensile strength of the conductor is 200 MPa or more and 400 MPa or less, and the insulating layer is disposed to be in close contact with the conductor and has a solid structure.