Convertible Soft Top Rear Window Foaming and Tension Management

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Solution Overview

Problem

Folding tops for convertible vehicles with rear windows foamed into the top cover face aesthetic issues due to limited visibility of the soft top material and require effective tension management during adjustment movements, while also needing compact storage in open positions.

Innovation Solution

A folding top design where the upper and side edge areas of the rear window are foamed into the top cover, with the lower edge connected internally via foaming or bonding, creating a clean finish and allowing the rear window to tilt without exposing the top cover's lower edge, which is hidden from view, and utilizing a PU foam profile that ends before the lower edge to ensure compact storage and tension absorption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the rear window is foamed all around into the soft top cover, then the rear window is securely held and tension is absorbed, but the lower edge area shows visible foam and limited soft top fabric visibility causing aesthetic problems

Engineering Contradiction:
Improvesecure holding of rear windowVSAvoidaesthetic appearance
Core Design Contradiction:
ReliabilityVSShape

Solution Approach 1:

The patent divides the foaming connection into two distinct zones: an internal foaming area for structural connection and an external visible area with clean fabric finish. The soft top cover is segmented into a visible exterior portion and an internal structural portion that is foamed to the rear window, allowing each zone to serve its specific function without compromise.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent extracts the foaming connection from the visible exterior surface and relocates it to the internal structure. By taking out the foam bead from the external view and positioning it internally where it connects the soft top cover to the rear window, the aesthetic appearance is preserved while maintaining the secure structural connection.

Inventive Principle:
Principle #2Taking out (Extraction)

2Force

If the soft top cover extends below the lower edge of the rear window to form the end of the folding top, then tension can be absorbed, but very little soft top fabric is visible and the finish is not clean

Engineering Contradiction:
Improvetension absorptionVSAvoidclean finish
Core Design Contradiction:
ForceVSShape

Solution Approach 1:

The patent resolves the tension absorption requirement by moving the functional connection to the internal dimensional space rather than extending the fabric externally. The soft top cover maintains adequate fabric length internally to absorb tension forces while presenting a clean external finish where the fabric ends flush with the rear window lower edge.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Volume of moving object

If the PU foam profile ends at a distance from the lower edge of the rear window, then compact storage is achieved, but the connection between soft top cover and rear window must be ensured elsewhere

Engineering Contradiction:
Improvestorage spaceVSAvoidconnection reliability
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The patent implements nesting by placing the soft top cover inside the foamed structure at the connection point. The cover is inserted into the foam bead from the interior side, creating a nested arrangement where the foam provides external structural support and the fabric provides internal covering, achieving both compact storage and reliable connection.

Inventive Principle:
Principle #7Nested doll (Nesting)

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 design achieves a clean, aesthetically pleasing finish by hiding the top cover's lower edge and ensures reliable tension absorption and compact storage of the top components in both closed and open positions, enhancing the functionality and appearance of the folding top.

Implementation Method 1

the upper and side edge areas of the rear window are foamed into the top cover

Methodology Applied
Scientific EffectFoaming: Foam

Implementation Method 2

the lower edge area connected to the soft top cover from the inside by means of a foaming or bonding

Methodology Applied
Scientific EffectAdhesive bonding: Adhesive

Data Source

PatentEP3974218B1Folding top for a convertible vehicle with movable rear window
Publication Date: 2023.02.15 MAGNA CAR TOP SYSTEMS GMBH(DE)
  • EP3974218B1 patent drawingFigure 1~2a
  • EP3974218B1 patent drawingFigure 3~5

AI summary

Folding soft top for a convertible vehicle with a soft top cover (4) and a rear window (6) foamed into the soft top cover (4), wherein the lower edge of the rear window is connected to the soft top cover from the inside, spaced apart from the lower edge (60).