Foam Wire Harness Outer Cover for Isotropic Compact Protection

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Solution Overview

Problem

Conventional outer cover bodies for electrical wires face challenges such as anisotropic mechanical properties, difficulty in reducing weight, high production costs, and poor transportation efficiency due to their solid resin composition and complex mold requirements, limiting design freedom and suitability for compact forms.

Innovation Solution

A bent thermoplastic resin foam sheet with a density between 200 and 700 kg/m³, featuring a non-foam layer on both surfaces, higher density at bending portions, and specific absorbance and bubble number density, which enhances mechanical properties and design flexibility while reducing weight and production costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If injection molding is used to manufacture outer cover body, then the outer cover body has good mechanical strength and protection performance, but the weight cannot be reduced and production costs increase due to mold requirements

Engineering Contradiction:
Improvemechanical strengthVSAvoidweight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent applies foam material with controlled porosity to manufacture the outer cover body. The foam structure provides adequate mechanical strength while significantly reducing weight compared to solid resin materials used in conventional injection molding. The porous structure allows weight reduction without compromising the protective function of the outer cover body.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The patent changes the density parameter of the outer cover body by using foam material with specific density ranges (200-700 kg/m³). This parameter change enables weight reduction while maintaining structural integrity. The density is optimized to balance weight reduction goals with mechanical strength requirements for wire harness protection.

Inventive Principle:
Principle #35Parameter changes

2Shape

If injection molding mold apparatus is used, then outer cover body with three-dimensional shape is produced, but transportation efficiency and storage characteristics deteriorate

Engineering Contradiction:
Improvethree-dimensional shapeVSAvoidtransportation efficiency
Core Design Contradiction:
ShapeVSProductivity

Solution Approach 1:

The patent segments the manufacturing process into two stages: first producing flat foam sheets, then forming them into three-dimensional outer cover bodies only when needed. This segmentation allows the material to be stored in a compact, transportation-efficient flat state while still providing the required three-dimensional protective shape during assembly.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary preparation of foam sheets with appropriate density and dimensions before forming them into final three-dimensional shapes. This preliminary action enables efficient storage and transportation of flat sheets while ensuring the material is ready for quick forming into protective covers when needed.

Inventive Principle:
Principle #10Preliminary action

3Strength

If hollow plate material with wave-form intervening member is used, then protection from external forces is provided, but mechanical properties become anisotropic and design freedom is restricted

Engineering Contradiction:
Improveprotection performanceVSAvoiddesign freedom
Core Design Contradiction:
StrengthVSAdaptability or versatility

Solution Approach 1:

The patent uses homogeneous foam material without directional wave-form structures, ensuring isotropic mechanical properties in all directions. This homogeneity provides uniform protection from external forces regardless of the direction of impact, while simultaneously enabling complete design freedom for various outer cover body shapes and wire harness configurations.

Inventive Principle:
Principle #33Homogeneity

4Volume of stationary object

If hollow plate material with large dimension uneven portions is used, then hollow structure is formed, but cutting into small shapes becomes difficult and compact outer cover body formation is prevented

Engineering Contradiction:
Improvehollow structureVSAvoidcutting ease
Core Design Contradiction:
Volume of stationary objectVSEase of manufacture

Solution Approach 1:

The patent employs foam material with fine, uniform cellular structure rather than large-scale hollow structures. This fine porous structure allows the material to be easily cut and formed into compact shapes while still providing the required hollow/foamed characteristics for weight reduction and protection.

Inventive Principle:
Principle #31Porous 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

The solution prevents anisotropy in mechanical properties, allows for compact designs, improves durability and abrasion resistance, and facilitates efficient transportation and storage by forming a lightweight, flexible outer cover body with enhanced connection strength and flame resistance.

Implementation Method 1

a bent thermoplastic resin foam sheet having a density of not less than 200 Kg/m³

Methodology Applied
Scientific EffectFoam structure: Foam

Data Source

PatentEP3648271B1Exterior body for electrical wire and wire harness with exterior body
Publication Date: 2024.01.17 FURUKAWA ELECTRIC CO LTD
  • EP3648271B1 patent drawingFigure 1
  • EP3648271B1 patent drawingFigure 2
  • EP3648271B1 patent drawingFigure 3

AI summary

Providing an outer cover body for electrical wires that can improve the degree of freedom of design while preventing anisotropy in mechanical properties and also make it possible to form even a compact outer cover body for electrical wires. An outer cover body for electrical wires that is to be attached to the outer periphery of an electrical wire, the outer cover body for electrical wires being formed of a bent thermoplastic resin foam sheet having a density of not less than 200 Kg/m3 and not more than 700 Kg/m3.