Wire Harness Branching Point Protection with Variable Thickness

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Solution Overview

Problem

Conventional protective sheets for wire harness branching points, when thickened to improve protection, often lead to loosening and unintended separation from the harness due to increased rigidity.

Innovation Solution

A protective member with a band-shaped fixing strip portion of smaller thickness than the protective sheet, wound around the trunk harness to securely attach and protect the branching point, utilizing a two-layer structure of resin materials with different properties for enhanced flexibility and abrasion resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the thickness of the protective sheet is increased to improve protection performance, then the protective performance is improved, but the rigidity is enhanced causing the lap winding portions to loosen and the protective sheet to separate from the wire harness

Engineering Contradiction:
Improveprotective performanceVSAvoidattachment stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The protective member is divided into three distinct parts: a protective sheet portion for protection, and two separate band-shaped fixing strip portions for attachment. This segmentation allows each part to be optimized independently - the protective sheet can be thick for protection while the fixing strips are thin for flexibility and secure attachment.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different parts of the protective member have different thicknesses tailored to their specific functions. The protective sheet portion has greater thickness for protection, while the fixing strip portions have smaller thickness for flexibility and secure winding around the wire harness, preventing loosening.

Inventive Principle:
Principle #3Local quality

2Reliability

If the thickness of the protective sheet is increased to improve protection performance, then the protective performance is improved, but the rigidity is enhanced making the protective sheet too rigid for secure attachment

Engineering Contradiction:
Improveprotective performanceVSAvoidease of attachment
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The protective member is divided into a protective sheet portion and separate fixing strip portions. This allows the fixing strips to be optimized for ease of attachment through winding and adhesion, while the protective sheet maintains thickness for protection.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The fixing strip portions have reduced thickness compared to the protective sheet, providing the flexibility needed for easy winding around the wire harness and secure attachment, while the protective sheet maintains adequate thickness for protection.

Inventive Principle:
Principle #3Local quality

3Reliability

If a two-layer structure with different resin materials is used, then flexibility and abrasion resistance are enhanced, but the manufacturing complexity increases

Engineering Contradiction:
Improveflexibility and abrasion resistanceVSAvoidstructural complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The protective member uses a two-layer composite structure with different resin materials optimized for specific functions - one layer for flexibility and another for abrasion resistance. This composite approach enhances overall reliability while the integration into a single molded piece keeps manufacturing feasible.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP3822126B1Protective member for wire harness, and branching structure of wire harness
Publication Date: 2023.01.04 YAZAKI CORP
  • EP3822126B1 patent drawingFigure 1
  • EP3822126B1 patent drawingFigure 2
  • EP3822126B1 patent drawingFigure 3

AI summary

A protective member (10) for a wire harness (1), having a branching point (99) between a trunk harness (2A) and a branch harness (2B), includes a protective sheet portion (11) to be wound around an outer circumference of at least the trunk harness (2A) near the branching point; a pair of band-shaped fixing strip portions (12) extending from the protective sheet portion (11) and to be wound around on the trunk harness (2A) at a pair of spots. The branching point is between the pair of the spots. The protective member (10) is formed from a resin. The fixing strip portions (12) are smaller in thickness than the protective sheet portion (11).