Wire Harness Shielding Performance via Ground Position Inversion

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Solution Overview

Problem

Conventional flat shielded cables used in wire harnesses have suboptimal shielding performance due to the direction and distance of induction currents generated by noise relative to signal transmission.

Innovation Solution

A wire harness design where a conductor is connected to ground between the exposed conductor section and the second device, ensuring the induction current and signal flow in the same direction, with the exposed conductor section positioned closer to the second device and within a specific distance from the shielding member's end, reducing noise interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the conductor is connected to ground at the exposed conductor section, then the shielding performance is improved, but the induction current flows in the opposite direction to the signal causing noise interference

Engineering Contradiction:

Improveshielding performanceVSAvoidnoise interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies inversion by changing the grounding position from the exposed conductor section to a position between the exposed conductor section and the second device. This reverses the direction of induction current flow to match the signal flow direction, transforming the harmful opposite-direction current into a beneficial same-direction current that cancels noise through common-mode rejection.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If the exposed conductor section is positioned closer to the first device, then the signal transmission is maintained, but the induction current flows over a longer distance increasing noise influence

Engineering Contradiction:

Improvesignal transmissionVSAvoidnoise influence

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by strategically positioning the exposed conductor section closer to the second device rather than uniformly distributing it. This localized positioning reduces the distance over which induction currents can accumulate noise, creating a specific zone of reduced electromagnetic interference while maintaining signal transmission integrity.

Inventive Principle:

Principle #3Local quality

3Reliability

If the induction current and signal flow in opposite directions, then the grounding is effective, but the noise affects the signal due to differential mode interference

Engineering Contradiction:

Improvegrounding effectivenessVSAvoidsignal noise

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful opposite-direction induction current into a beneficial same-direction current by repositioning the ground connection. This transformation allows the induction current to flow in the same direction as the signal, enabling common-mode noise rejection where the noise affects both conductors equally and can be eliminated through differential signaling.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 significantly enhances shielding performance by minimizing the distance induction currents flow, thereby reducing noise influence on signals, as evidenced by improved measurement results across various frequency ranges.

Implementation Method 1

the induction current generated by the noise flowing through the at least one of the conductors flows in the direction toward the second device

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a signal is transmitted from the first device to the second device through a conductor other than the conductor provided with the exposed conductor section

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

the at least one of the conductors is connected to a ground at a position between the exposed conductor section and the second device

Methodology Applied

Scientific EffectGrounding: Earthing

Data Source

PatentUS10262769B2Wire harness

Publication Date: 2019.04.16 YAZAKI CORP

AI summary

A wire harness includes a flat shielded cable, a first device connected to one end of the flat shielded cable, and a second device connected to the other end of the flat shielded cable. The flat shielded cable includes a plurality of conductors arranged in parallel, an insulating jacket section that covers the plurality of conductors and has an exposed conductor section which exposes a part of at least one of the conductors, and a shielding member that covers an outer periphery of the jacket section. A signal is transmitted from the first device to the second device through a conductor other than the conductor provided with the exposed conductor section. The at least one of the conductors is connected to a ground at a position between the exposed conductor section and the second device.