Resin Floor Grounding Structure for Vehicle EMI Suppression

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Solution Overview

Problem

The challenge is to effectively suppress the influence of electromagnetic waves radiated from electric power supply and signal lines on in-vehicle equipment in vehicles with resin bodies, as the grounding performance declines with resinification, leading to potential malfunctions and increased weight due to extended grounding wires.

Innovation Solution

A vehicular grounding structure featuring a sheet-shaped wiring sheet with a conductive material for electrical connection between the power supply and electronic components, along with a sheet-shaped conductive portion electrically connected to the grounding potential, which overlaps the wiring sheet to absorb electromagnetic waves, reducing their impact on in-vehicle equipment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If the body is resinified to reduce vehicle weight, then weight reduction is achieved, but grounding performance declines and electromagnetic waves are not sufficiently absorbed

Engineering Contradiction:

Improvevehicle weightVSAvoidelectromagnetic wave influence on in-vehicle equipment

Core Design Contradiction:

Weight of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent uses a composite structure combining resin material for the floor portion with a conductive material (such as metal foil or conductive polymer) for the grounding member. This composite approach allows the vehicle to benefit from the weight reduction of resin while maintaining electromagnetic shielding and grounding performance through the conductive layer.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The grounding member serves multiple functions: it provides electrical grounding for electronic components and simultaneously acts as an electromagnetic shielding layer to absorb electromagnetic waves. This multi-functionality resolves the contradiction by addressing both weight reduction and electromagnetic protection needs within a single integrated solution.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If conductive material is directly embedded in the resin body for grounding, then grounding function is provided, but the conductive material may be damaged by stress from the resin material weight and impact

Engineering Contradiction:

Improvegrounding function reliabilityVSAvoidconductive material durability under stress and impact

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The grounding member is designed as a flexible sheet or thin film that can conform to the resin floor portion without creating concentrated stress points. This flexible structure distributes mechanical stress evenly and prevents damage to the conductive material during vehicle impact or normal operation.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent introduces an adhesive layer or bonding interface as an intermediary between the resin floor portion and the conductive grounding member. This intermediary layer cushions mechanical stress and prevents direct transmission of impact forces to the conductive material, thereby protecting the grounding function from damage.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If the conductive portion overlaps the wiring sheet on the inner portion side, then electromagnetic waves are absorbed and grounding performance is improved, but the structure becomes more complex

Engineering Contradiction:

Improveelectromagnetic wave absorptionVSAvoidgrounding structure complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The grounding member is integrated with the floor portion and wiring sheet assembly, combining multiple functions (structural support, electromagnetic shielding, and grounding) into a single unified component. This merging approach reduces overall system complexity despite the overlapping configuration, as the grounding function is embedded within the existing structural layers rather than adding separate components.

Inventive Principle:

Principle #5Merging (Combining)

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 effectively suppresses the influence of electromagnetic waves on in-vehicle equipment, improves durability by reducing the need for drilling, and aids in weight reduction by using lightweight conductive materials, while also simplifying routing and noise management.

Implementation Method 1

a sheet-shaped conductive portion electrically connected to a grounding potential, wherein the conductive portion includes a part disposed to overlap a surface of the wiring sheet on an inner portion side of the vehicle

Methodology Applied

Scientific EffectElectromagnetic wave absorption: Absorption (EM radiation)

Data Source

PatentUS10278316B2Grounding structure formed of resin material

Publication Date: 2019.04.30 TOYOTA JIDOSHA KK

AI summary

A grounding structure for a vehicle provided with a floor portion formed of a resin material includes a sheet-shaped wiring sheet including a conductive material for electrical connection between an electric power supply and an electronic component and a sheet-shaped conductive portion electrically connected to a grounding potential. The conductive portion includes a part disposed to overlap a surface of the wiring sheet on an inner portion side of the vehicle.