Lower Vehicle-Body Structure Multi-Level Fixation Rigidity

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Solution Overview

Problem

The existing vehicle-body structure, where the mount member is fixed to the lower face of the floor tunnel, does not adequately suppress the decrease in vehicle-body rigidity, particularly due to the discontinuous division of floor cross members by the floor tunnel.

Innovation Solution

A lower vehicle-body structure with a connecting member that overlaps the floor cross members in the longitudinal direction, fixed at multiple positions at different levels, enhancing the interconnection between the vehicle floor and floor cross members, and optionally incorporating an upper step portion and reinforcing members to form a closed cross section, thereby improving rigidity and load transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the mount member is fixed to the lower face of the floor tunnel, then the power transmission mechanism is supported, but the vehicle-body rigidity decreases due to discontinuous floor cross members

Engineering Contradiction:

Improvesupport functionVSAvoidvehicle-body rigidity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The connecting member extends in the vehicle width direction at a position overlapping the floor cross members in the longitudinal direction, creating a multi-level fixation structure that adds dimensional complexity to overcome the rigidity loss from the floor tunnel discontinuity

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The connecting member integrates multiple fixation positions at different levels (first, second, and third fixation positions) to combine the floor cross members and vehicle floor into a unified rigid structure, effectively treating them as a single load-bearing element

Inventive Principle:

Principle #5Merging (Combining)

2Strength

If additional reinforcing members are added to improve rigidity, then vehicle-body rigidity increases, but the number of parts increases

Engineering Contradiction:

Improvevehicle-body rigidityVSAvoidnumber of parts

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The connecting member serves multiple functions simultaneously: it connects the floor cross members to the vehicle floor, provides multi-level fixation for enhanced rigidity, and eliminates the need for separate reinforcing members, thereby reducing overall part count while maintaining structural strength

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The invention extracts the reinforcing function from separate reinforcing members and integrates it into the connecting member itself, which already exists to connect the floor cross members, thereby eliminating redundant components

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS11008049B2Lower vehicle-body structure

Publication Date: 2021.05.18 MAZDA MOTOR CORP

AI summary

A lower vehicle-body structure comprises a vehicle floor comprising a bottom face portion and a floor tunnel which protrudes upwardly and extends in a vehicle longitudinal direction, a pair of right-and-left floor cross members extending in a vehicle width direction on both sides of the floor tunnel, and a connecting member provided to extend in the vehicle width direction at a position which overlaps the floor cross members in the vehicle longitudinal direction and be fixed to at least one of the vehicle floor and the floor cross members at plural fixation positions. These plural fixation positions are located at plural different levels in a range of a height of the floor cross members.