Motor Vehicle Rear Floor Stiffening via Segmentation and Local Reinforcement

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Solution Overview

Problem

Existing motor vehicle rear floors lack sufficient stiffness, particularly at the front part, which is exacerbated by the presence of an upper floor that covers the access zone for the fuel tank gauge, leading to inadequate resistance to loads during loading.

Innovation Solution

The rear floor is designed with a front part and a rear part connected by means of a transverse crosspiece and inclined portions, with a counter-stamped portion creating additional contact surfaces to enhance stiffness, and the upper floor is fixed to these surfaces using welding means, including a stiffening bracket facing the transverse crossmember.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If the upper floor covers the front part of the rear floor to form a flat loading space, then the loading space flatness is improved, but the stiffness of the rear floor at the front part deteriorates

Engineering Contradiction:
Improveloading space flatnessVSAvoidstiffness of rear floor
Core Design Contradiction:
ShapeVSStrength

Solution Approach 1:

The rear floor is divided into two separate parts: a front part and a rear part, connected by connecting means. This segmentation allows the front part to be specifically reinforced with stiffening means while maintaining the overall structure. The upper floor covers the front part to provide flatness, while the stiffening means are integrated into the front part structure to compensate for the stiffness reduction caused by the covering.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Stiffening means are specifically applied to the front part of the rear floor where the upper floor covers it. This local reinforcement ensures that the area under the upper floor maintains sufficient stiffness despite being covered, while other areas of the rear floor maintain their original structural properties.

Inventive Principle:
Principle #3Local quality

2Strength

If the hole in the front part of the rear floor is filled to ensure stiffness, then the stiffness of the rear floor is improved, but the access to the fuel tank gauge deteriorates

Engineering Contradiction:
Improvestiffness of rear floorVSAvoidaccess to fuel tank gauge
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The access zone for the fuel tank gauge is extracted as a separate functional element within the front part of the rear floor. The stiffening means are designed to surround or reinforce this extracted access zone rather than completely filling it, allowing the access function to be maintained while providing structural reinforcement to the overall front part structure.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The stiffening means are strategically positioned to reinforce the front part of the rear floor while leaving the access zone for the fuel tank gauge open or minimally affected. This localized approach ensures stiffness enhancement without compromising the operational access to the fuel gauge.

Inventive Principle:
Principle #3Local quality

3Device complexity

If the rear floor is designed in two parts to simplify design, then the design complexity is reduced, but the stiffness at the connection area deteriorates

Engineering Contradiction:
Improverear floor design complexityVSAvoidstiffness at connection area
Core Design Contradiction:
Device complexityVSStrength

Solution Approach 1:

The rear floor is segmented into front and rear parts connected by connecting means, which simplifies the overall design and manufacturing process. The stiffening means are then integrated into the front part to specifically address the stiffness issue at the connection area, maintaining the benefits of segmentation while compensating for the potential weakness at the joint.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The stiffening means are merged with the front part of the rear floor structure, creating an integrated component that provides both structural reinforcement and maintains the simplified two-part design. This combination ensures that the connection area between the front and rear parts achieves sufficient stiffness without requiring additional complex connection mechanisms.

Inventive Principle:
Principle #5Merging (Combining)

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

This configuration significantly reduces the risk of deformation during loading and allows for the use of the rear floor in various vehicle types without major modifications, while maintaining access to the fuel tank gauge.

Implementation Method 1

The upper floor is fixed to the counter-stamping of the front part of the rear floor by welding means

Methodology Applied
Scientific EffectWelding: Welding

Data Source

PatentEP2817202B1Motor vehicle comprising a two-part rear floor and means for stiffening the front part
Publication Date: 2016.04.13 RENAULT SA
  • EP2817202B1 patent drawingFigure 1
  • EP2817202B1 patent drawingFigure 2

AI summary

Motor vehicle comprising a rear floor (2) comprising a front part (3) and a rear part (4) which are connected by connecting means, a front floor connected to the front part (3) of the rear floor (2), an upper floor (5) covering the front part (3) of the rear floor (2) and a fuel tank positioned under the rear floor (2). The rear floor (2) comprises means (7) for stiffening the front part (3) in contact with the upper floor (5).