Vehicle Roof Panel Flexible Zone for Thermal Expansion Management

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Solution Overview

Problem

Steel roofs in vehicles hinder the installation of communication devices like 5G antennas due to poor electromagnetic wave transmission, and replacing them with plastic panels causes differential thermal expansion issues leading to appearance defects.

Innovation Solution

A plastic panel embedded in a steel housing with a flexible zone that absorbs thermal expansion deformations, ensuring better clearance and flushness, featuring a flexible element like an accordion structure that lowers the edge of the outer skin during expansion, and a seal to manage thermal expansion differentials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a plastic panel is used to replace steel roof for electromagnetic wave transmission, then electromagnetic wave transmission is improved, but differential thermal expansion causes appearance defects

Engineering Contradiction:

Improveelectromagnetic wave transmissionVSAvoidappearance quality

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies a flexible zone within the inner lining structure that can deform to accommodate thermal expansion differences between the plastic panel and steel housing. This flexible zone acts as a buffer that absorbs dimensional changes during temperature variations, preventing the panel edges from detaching or deforming visibly, thus maintaining appearance quality while using plastic for electromagnetic transparency

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent modifies the physical parameters of the panel structure by introducing a flexible zone with different mechanical properties than the rigid inner lining. This flexible zone has higher elasticity and can undergo greater deformation without permanent damage, allowing the structure to adapt to thermal expansion while maintaining a flush appearance with the housing edges

Inventive Principle:

Principle #35Parameter changes

2Strength

If a double-layer plastic panel design is used to achieve necessary strength, then structural strength is improved, but differential expansion generates visible deformations

Engineering Contradiction:

Improvepanel strengthVSAvoidpanel deformation

Core Design Contradiction:

StrengthVSShape

Solution Approach 1:

The flexible zone is integrated into the inner lining of the double-layer panel structure. This flexible element allows the panel to expand and contract with temperature changes without transferring excessive stress to the outer skin, preventing visible deformations while maintaining the structural strength provided by the rigid inner lining and adhesive bonding

Inventive Principle:

Principle #30Flexible shells and thin films

3Stability of the object's composition

If the panel is rigidly fixed to the housing, then structural stability is improved, but thermal expansion creates stresses and deformations

Engineering Contradiction:

Improvestructural stabilityVSAvoidperipheral clearance and flushness

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The inner lining is segmented into three distinct zones: a rigid fixing zone that provides structural stability and anchors the panel to the housing, a flexible zone that absorbs thermal expansion stresses, and a peripheral zone that maintains appearance quality. This segmentation allows each zone to perform its specific function without interfering with the others

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The flexible zone acts as a transition element between the rigid fixed portions and the panel edges, allowing controlled deformation during thermal expansion while maintaining overall structural stability and preventing visible defects at the panel periphery

Inventive Principle:

Principle #30Flexible shells and thin films

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 effectively minimizes appearance defects and maintains a consistent finish by covertly absorbing thermal expansion deformations, ensuring proper sealing and reducing aerodynamic noise while allowing electromagnetic waves to pass through.

Implementation Method 1

differential expansion in sunlight, leading to intrinsic stresses that generate visible deformations

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

a flexible zone, that is to say a zone of greater flexibility than the rest of the inner load-bearing lining

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 3

an outer skin with an appearance of plastic material fixed by gluing around its entire periphery to an inner load-bearing lining of plastic material

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentEP4015353B1Panel for bodywork part with limited thermal deformation

Publication Date: 2023.10.11 COMPAGNIE PLASTIC OMNIUM SA

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AI summary

The invention relates to a panel (40) of a body part (10) of a vehicle (200), comprising an outer skin (50) with a plastic appearance fixed by gluing around its entire periphery to an inner lining (60) of plastic structure, characterized in that the inner lining (60) has on at least part of its periphery, successively from the edge (70) of the panel (40), a fixing zone (80) by gluing to the outer skin (50) and then a flexible zone (90).