Motor Vehicle Floor Cross Member with Split Half-Shells

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Solution Overview

Problem

In vehicles with a long wheelbase, the rear floor structure lacks structural reinforcement, compromising accessibility and comfort for row 3 seats and the positioning of a common tank, which affects ergonomics and passenger comfort.

Innovation Solution

A motor vehicle floor structure featuring two side members, a floor, and a cross member with a concave upper and lower half-shell configuration that reduces vertical bulk, incorporating Omega-shaped sections and adjustable thickness for enhanced resistance and comfort, with fixing elements for seats and tanks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a conventional cross member is used to reinforce the floor structure, then structural strength is improved, but vertical footprint increases compromising accessibility and comfort for row 3 seats

Engineering Contradiction:
Improvestructural strengthVSAvoidaccessibility and comfort
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The cross member is divided into two separate half-shells (upper and lower) that are positioned on opposite sides of the floor. This segmentation allows each half-shell to be optimized independently for structural strength while minimizing the overall vertical footprint, thereby improving accessibility and comfort for row 3 seats.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of increasing vertical height to improve structural strength, the invention transitions to a different dimensional arrangement by placing half-shells on opposite sides of the floor plane. This lateral distribution of structural elements provides reinforcement without compromising the vertical clearance needed for passenger comfort.

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

2Ease of operation

If the cross member height is reduced to improve accessibility, then vertical footprint is minimized, but structural reinforcement is compromised

Engineering Contradiction:
ImproveaccessibilityVSAvoidstructural reinforcement
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

By segmenting the cross member into two half-shells positioned on opposite sides of the floor, the invention maintains structural reinforcement through distributed lateral support while minimizing vertical height, thus improving accessibility without compromising strength.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cross member utilizes composite construction with half-shells made from materials having different properties (e.g., upper half-shell from a first material and lower half-shell from a second material). This allows optimization of each component for its specific function while maintaining overall structural integrity with reduced vertical footprint.

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If uniform thickness is used throughout the cross member, then manufacturing is simplified, but structural optimization for different zones is lost

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidstructural optimization
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The cross member features non-uniform thickness distribution where the first half-shell has a first thickness and the second half-shell has a second thickness. This local quality variation allows each zone to be optimized for its specific structural requirements while maintaining manufacturability through standardized forming processes.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4164938B1Motor vehicle floor structure reinforced by a two-part cross member
Publication Date: 2024.08.14 RENAULT SA
  • EP4164938B1 patent drawingFigure 1~2
  • EP4164938B1 patent drawingFigure 3~4

AI summary

The invention relates to a motor vehicle floor structure comprising two side members extending in a longitudinal direction of the structure, a floor (7) extending between the two side members, and a cross member (10) which extends in a transverse direction of the structure and connects the side members and is attached to the floor structure, characterised in that the cross member (10) comprises a concave upper portion (12) forming a first half-shell, a concave lower portion (14) forming a second half-shell, the lower (14) and upper (12) portions being arranged on either side of the floor (7) so as to face each other, the floor (7) closing off their cavity.