Composite Hatchback Door with Integrated Transparent Lighting

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Solution Overview

Problem

Producing a hatchback door made of plastic material that balances strength, stiffness, and cost-effectiveness, particularly for complex shapes, while avoiding the use of sheet metal and glass, has proven difficult in existing technologies.

Innovation Solution

A hatchback door composed of three separate plastic components - a load-bearing inner panel, a top outer panel, and a bottom outer panel - glued together, with the top outer panel featuring a hole for the rear windscreen-wiper pin and an annular edge to prevent paint dripping, and the bottom outer panel optionally incorporating a light source for logo display, using composite and transparent materials for structural integrity and aesthetic features.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If a hatchback door is made of plastic material to reduce weight, then weight is reduced, but strength and stiffness may be insufficient

Engineering Contradiction:
Improveweight of hatchback doorVSAvoidstrength and stiffness of hatchback door
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The patent employs composite plastic materials with reinforced structures to achieve both weight reduction and adequate mechanical strength. The inner panel uses a composite material comprising a polypropylene matrix with glass fiber reinforcement, providing high strength-to-weight ratio while maintaining stiffness requirements for the hatchback door.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The hatchback door is divided into multiple separate plastic components (inner panel, top outer panel, bottom outer panel) that are glued together. This segmentation allows each component to be optimized for its specific function while collectively achieving the required overall strength and stiffness, and enables complex shapes to be obtained with economically advantageous assembly processes.

Inventive Principle:
Principle #1Segmentation

2Shape

If complex shapes are used for hatchback door to characterize vehicle style, then aesthetic quality is improved, but assembly process becomes laborious and costly

Engineering Contradiction:
Improvecomplex shape of hatchback doorVSAvoidassembly process complexity and cost
Core Design Contradiction:
ShapeVSEase of manufacture

Solution Approach 1:

The hatchback door is divided into multiple separate plastic components (inner panel, top outer panel, bottom outer panel) that are glued together. This segmentation allows each component to be optimized for its specific function while collectively achieving the required overall strength and stiffness, and enables complex shapes to be obtained with economically advantageous assembly processes.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Multiple functional features are integrated into single components during molding. For example, the inner panel incorporates recesses for sealing elements, mounting structures for external components, and reinforcement ribs all in one piece, reducing the number of separate parts and assembly operations required.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3257694B1Hatchback door for motor-vehicles
Publication Date: 2020.05.06 CENTRO RICERCHE FIAT SCPA
  • EP3257694B1 patent drawingFigure 1
  • EP3257694B1 patent drawingFigure 2
  • EP3257694B1 patent drawingFigure 3

AI summary

A hatchback door (P) for motor vehicles comprises a load-bearing inner panel (1) made of composite plastic material, a top outer panel (2) made of plastic material glued on the top portion of the load-bearing inner panel (1), and a bottom outer panel (3) made of plastic material glued on the bottom portion of the load-bearing inner panel (1). The top outer panel (2) comprises a first layer made of transparent plastic material (20) and a second layer made of opaque plastic material or of opaque paint (21). The opaque layer (21) covers only some parts of the transparent layer (20) in such a way that the top outer panel (2) is transparent in a central part (22) thereof overlying a rear-window opening (10) of the load-bearing inner panel (1) and in its peripheral portions (23) that are to function as transparent elements for two lateral sets of lights (24) and for a third top set of lights (25). The sets of lights (24, 25) are without a front transparent element and are connected to a rear side of the top outer panel (2). The transparent peripheral portions (23) of the top outer panel (2) constitute the front transparent elements of the sets of lights (24, 25).