Vehicle Frame Member Rigidity Layout for Uniform Collision Compression

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Solution Overview

Problem

Existing vehicle frame structures with obliquely extending pipe frames face issues with non-uniform compression and reduced collision-load absorption due to local buckling when subjected to collision loads from the forward side, particularly affecting the outward-side part of the frame.

Innovation Solution

A frame member with a closed-cross section design, featuring varying bending rigidities among its walls, where the first vertical wall has the highest rigidity, followed by the second vertical wall and inner walls, ensuring uniform compression and improved collision-load absorption by preventing local buckling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the pipe frame extends obliquely forward-and-outward to absorb oblique collision loads, then the collision-load absorption capability for oblique collisions is improved, but the uniformity of compression deteriorates when collision load is applied from the forward side

Engineering Contradiction:
Improvecollision-load absorption capabilityVSAvoiduniformity of compression
Core Design Contradiction:
StrengthVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by making the first vertical wall (outward-side) thicker than the second vertical wall (inward-side), giving different structural properties to different parts of the frame. This asymmetric thickness distribution compensates for the uneven load distribution, allowing the outward-side wall to resist buckling while maintaining overall frame functionality for both oblique and frontal collisions

Inventive Principle:
Principle #3Local quality

2Ease of manufacture

If the pipe frame has a simple closed-cross section, then the manufacturing complexity is reduced, but the buckling resistance of the outward-side part deteriorates under frontal collision loads

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidbuckling resistance
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

Rather than making the entire frame structure complex, the patent applies local quality by selectively increasing the thickness of only the first vertical wall that is prone to buckling. This targeted approach enhances buckling resistance where needed while keeping the overall manufacturing process simple and the other frame components unchanged

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4647322A1Frame member for vehicle and vehicle-body front structure
Publication Date: 2025.11.12 MAZDA MOTOR CORP
  • EP4647322A1 patent drawingFigure 1
  • EP4647322A1 patent drawingFigure 2
  • EP4647322A1 patent drawingFigure 3

AI summary

A frame member comprises a first vertical wall, a second vertical wall arranged on an inward side, in the vehicle width direction, of the first vertical wall, a first lateral wall interconnecting respective upper ends of the first vertical wall and the second vertical wall, a second lateral wall interconnecting respective lower ends of the first vertical wall and the second vertical wall and forming a closed-cross section together with the first vertical wall, the second vertical wall, and the first lateral wall, and an inner wall arranged between the first vertical wall and the second vertical wall and extending in the vertical direction, interconnecting the first lateral wall and the second lateral wall. Bending rigidity of the first vertical wall is larger than that of each of the second vertical wall and the inner wall.