Automobile Exterior Part Assembly for Sink Mark-Free Stiff Corners

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Solution Overview

Problem

Existing automobile exterior part assemblies face issues with visible sink marks and inadequate static stiffness due to the design of hollow cavities and narrow adhesion angles, which hinder effective adhesive application and bonding.

Innovation Solution

A connection structure comprising a first and second box-like structure integrated with the outer skin, featuring inclined top plates and engagement grooves, allows for increased adhesion angles and reinforces the hollow corners, thereby preventing sink marks and enhancing static stiffness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a hollow cavity is designed on the lateral side extremities of the outer skin to increase the adhesion angle, then the adhesion angle is improved, but the outer skin will have visible sink marks on the external face

Engineering Contradiction:
Improveadhesion angleVSAvoidsurface quality
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent applies nesting by placing the second box-like structure inside the hollow cavity of the outer skin. The second box-like structure is inserted into the embedding groove formed by the inclined top plate of the first box-like structure, effectively filling the hollow cavity from within. This nested configuration allows the adhesion angle to be increased by the inclined top plate while the second box-like structure prevents adhesive shoveling and eliminates sink marks by providing internal support during the bonding process.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Adaptability or versatility

If a hollow cavity is formed inside an outward protruding structure such as a convex tail wing, then aerodynamic function or technical element integration is improved, but the static stiffness of the outer skin becomes insufficient

Engineering Contradiction:
Improvefunctional integrationVSAvoidstatic stiffness
Core Design Contradiction:
Adaptability or versatilityVSStrength

Solution Approach 1:

The second box-like structure is nested within the hollow cavity of the outward protruding structure, filling the internal space and providing structural reinforcement. This nested configuration maintains the aerodynamic function and technical element integration enabled by the hollow cavity, while simultaneously improving the static stiffness of the outer skin by adding internal structural support.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent employs composite construction by integrating the first box-like structure (integrally formed with the outer skin) and the second box-like structure (inserted into the embedding groove) within the hollow cavity. This composite structure combines the outer skin with reinforced box-like elements, creating a multi-material construction that enhances static stiffness while preserving the functional hollow cavity for aerodynamic or technical purposes.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP4446144B1An exterior part assembly of automobile
Publication Date: 2026.01.21 YANFENG PLASTIC OMNIUM AUTOMOTIVE EXTERIOR SYST CO LTD
  • EP4446144B1 patent drawingFigure 1~2
  • EP4446144B1 patent drawingFigure 3~4
  • EP4446144B1 patent drawingFigure 5~6

AI summary

Exterior part assembly of automobile, comprising an outer skin (1) and an inner panel (2) assembled together by means of an first box-like structure (3) arranged at an inner side face of the outer skin, a second box-like structure (4), and an bonding layer (5), wherein the outer skin comprises an upper member (101), a rounded corner (102), and a lower member (103), and a hollow cavity (C) is formed inside the rounded corner; wherein the first box-like structure (3) includes an inclined top plate (31) extending obliquely through the hollow cavity in the longitudinal direction from an end of the lower member (103) to a centre portion of the rounded corner (102) such that an embedding groove is formed between the inclined top plate (31) and the upper member (101), wherein the second box-like structure (4) is shaped to engage with, and be inserted in the embedding groove to close the hollow cavity (C) with its outer wall.