Shielded Wire Harness Sealing to Prevent Galvanic Corrosion

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Solution Overview

Problem

Conventional shield connectors experience galvanic corrosion due to contact between dissimilar metals when exposed to liquids, leading to potential deterioration of shielding performance and reduced holding force over time.

Innovation Solution

A wire harness design featuring a shield terminal press-fitted and locked to a housing at a position inside a seal member, preventing liquid ingress and maintaining electrical connection through a locking structure, thereby avoiding contact between dissimilar metals exposed to liquids.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the shield terminal is press-fitted into the housing to prevent contact between dissimilar metals, then galvanic corrosion is prevented, but the holding force between the housing and shield terminal is lowered with aging

Engineering Contradiction:

Improveprevention of galvanic corrosionVSAvoidholding force between housing and shield terminal

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The connection structure is divided into two independent functional parts: a press-fitting part that provides initial positioning and electrical connection, and a locking part that provides long-term mechanical retention. This segmentation allows each part to optimize its function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The press-fitting part is designed to first engage and establish electrical connection before the locking part engages. This preliminary action ensures proper alignment and electrical contact before the locking mechanism secures the connection for long-term retention.

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If the shield terminal is press-fitted into the housing only, then assembly is simple, but the holding force is insufficient and may decrease with aging

Engineering Contradiction:

Improveassembly simplicityVSAvoidholding force

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

Two different fastening mechanisms (press-fitting and locking) are merged into a single integrated shield terminal structure. The press-fitting part and locking part work together to provide both ease of assembly and strong, durable holding force.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If the shield terminal contacts the shield case to provide electrical connection, then electrical conductivity is improved, but galvanic corrosion occurs when exposed to liquids

Engineering Contradiction:

Improveelectrical connectionVSAvoidgalvanic corrosion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The housing acts as an intermediary component that provides electrical connection between the shield terminal and shield case while preventing direct contact between dissimilar metals. The housing's interior surface serves as a protective barrier that eliminates galvanic corrosion while maintaining electrical conductivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Prevents galvanic corrosion and maintains electrical connection durability by isolating dissimilar metals from liquid exposure, ensuring long-term shielding performance and improved durability.

Implementation Method 1

a seal member having an annular shape, the seal member being disposed in the wire insertion path to fill a gap having an annular shape and provided between an inner peripheral surface of the tubular body and an outer peripheral surface of the shielded wire, and preventing liquid that has entered the wire insertion path from an outside of the shield case from entering into an interior of the shield case through the gap

Methodology Applied

Scientific EffectSealing:

Implementation Method 2

the shield terminal includes a press-fitting part that is press-fitted and fixed to the tubular body at a press-fitting completion position farther on an interior side of the shield case than the seal member in the wire insertion path

Methodology Applied

Scientific EffectPress-fitting:

Implementation Method 3

a locking part that causes the shield terminal to be locked to a locked part of the tubular body farther on an interior side of the shield case than the seal member in the wire insertion path while being at the press-fitting completion position

Methodology Applied

Scientific EffectMechanical locking: Mechanical Fastener

Data Source

PatentUS12512652B2Wire harness

Publication Date: 2025.12.30 YAZAKI CORP

AI summary

A wire harness including: a shielded wire; a metal housing having a tubular body serving as a wire insertion path and being inserted into an outer wall body in a metal shield case, and a fixed part causing the tubular body to be fixed to the outer wall body; a tubular shield terminal being connected to a shield material; and an annular seal member disposed in the wire insertion path to fill an annular gap between the tubular body and the shielded wire, in which the shield terminal includes: a press-fitting part being press-fitted and fixed to the tubular body at a position farther on an interior side of the shield case than the seal member in the wire insertion path; and a locking part being locked to a locked part of the tubular body farther on the interior side of the shield case than the seal member.