Motor Vehicle Rear Structure Continuous Plastic Joining

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Solution Overview

Problem

Current vehicle structural parts, formed by welding steel sheets, suffer from reduced stiffness due to discontinuous welding points, stress concentrations, high weight, and complex assembly processes, which contradict the goal of lightweight solutions.

Innovation Solution

A rear structural part of a motor vehicle comprising plastic components assembled with continuous joining segments, where each segment is at least 10 cm long and has minimal discontinuities, providing uninterrupted connections and increased stiffness, with the plastic material comprising a resin matrix and reinforcing fibers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If discontinuous welding points are used to join steel sheets, then the assembly process is simpler, but the stiffness and resistance of the structure are reduced and stress concentrations occur

Engineering Contradiction:
Improveassembly processVSAvoidstiffness and resistance
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent applies continuous joining segments (adhesive bonds or welded seams) instead of discontinuous welding points to join the steel sheets. This continuous connection eliminates the gaps between welding points, providing uninterrupted structural support that increases stiffness and resistance while distributing stresses evenly across the entire joint area, preventing stress concentrations.

Inventive Principle:
Principle #20Continuity of useful action

2Strength

If the density of metal and number of sheets are increased to improve strength, then the structural resistance is enhanced, but the total weight increases

Engineering Contradiction:
Improvestructural resistanceVSAvoidtotal weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent employs a composite construction consisting of multiple steel sheets with different mechanical properties (specifically mentioning sheets with different yield strengths). By combining sheets of varying strengths and optimizing their arrangement, the structure achieves high structural resistance while minimizing the total amount of metal required, thereby reducing overall weight compared to using uniform high-density metal throughout.

Inventive Principle:
Principle #40Composite materials

3Strength

If the number of sheets forming a structural part is increased to improve design flexibility, then the structural performance is enhanced, but the assembly line complexity increases

Engineering Contradiction:
Improvestructural performanceVSAvoidassembly line complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent divides the structural part into multiple steel sheet segments that can be manufactured separately and then assembled together. This segmentation allows each sheet to be optimized for specific structural requirements while enabling modular assembly processes. The use of continuous joining segments simplifies the assembly operation, making it suitable for automated assembly lines despite the increased number of components.

Inventive Principle:
Principle #1Segmentation

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 enhances the stiffness and resistance of the structural part, reduces stress concentrations, and simplifies assembly while aiming for a lightweight solution by using plastic components with continuous joining segments.

Implementation Method 1

the plastic material comprising a resin matrix and reinforcing fibers

Methodology Applied
Scientific EffectComposite materials: Composite Materials

Implementation Method 2

the continuous joining segments each have a minimum length of 10 cm and leave between them discontinuities of at most 10 mm

Methodology Applied
Scientific EffectAdhesive bonding: Adhesive

Data Source

PatentEP3562733B1Motor vehicle superstructure rear portion with continuous interconnections
Publication Date: 2021.06.16 COMPAGNIE PLASTIC OMNIUM SA
  • EP3562733B1 patent drawingFigure 1~2
  • EP3562733B1 patent drawingFigure 3~4
  • EP3562733B1 patent drawingFigure 5~6

AI summary

A rear portion of a motor vehicle superstructure comprises at least one rear side post formed by a plurality of components (19, 21) assembled together and characterised in that the components (19, 21) are mostly made of plastics and in that all the components (19, 21) are firmly joined along continuous interconnection segments.