Front Vehicle-Body Structure Side Sill Design for Small Overlap Collision Safety

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Solution Overview

Problem

Existing front vehicle-body structures face challenges in preventing the front wheel from breaking into the vehicle cabin during small overlap collisions without increasing the number of parts or vehicle weight.

Innovation Solution

The front vehicle-body structure features a side sill with a unique cross-sectional design, where the side sill inner portion has higher buckling strength than the outer portion, and a flange portion is positioned closer to the vehicle-width-direction inner side than the wheel's center line, guiding the retreating front wheel to the outer side during collisions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a bulkhead is provided on the inner side of the torque box to catch the retreating front wheel, then the front wheel breaking into the vehicle cabin is suppressed, but the vehicle weight increases

Engineering Contradiction:
Improvecollision safetyVSAvoidvehicle weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The side sill is designed with non-uniform buckling strength along its length, with the first portion having lower buckling strength than the second portion. This local quality differentiation allows the side sill to deform preferentially at the first portion during collision, guiding the front wheel outward without requiring additional reinforcement members throughout the entire structure.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention changes the buckling strength parameter of the side sill by varying its cross-sectional shape or thickness along the length. The first portion has reduced buckling strength compared to the second portion, creating a controlled weak point that directs deformation during collision and eliminates the need for heavy bulkhead reinforcement.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If reinforcement members are added to the vehicle body structure to prevent front wheel intrusion, then collision safety is improved, but the number of parts and complexity increase

Engineering Contradiction:
Improvecollision safetyVSAvoidnumber of parts
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts the reinforcement function from separate bulkhead members and integrates it into the side sill structure itself. By designing the side sill with differentiated buckling strength, the structure inherently provides the needed collision protection without requiring additional extraction of reinforcement members.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The side sill serves multiple functions: it provides structural support during normal operation and simultaneously acts as a collision management element during small overlap collisions. The differentiated buckling strength design allows it to perform both functions without requiring separate specialized components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Ease of operation

If the side sill outer portion has lower buckling strength than the inner portion, then the retreating front wheel is guided to the outer side, but the structural integrity may be compromised

Engineering Contradiction:
Improvewheel guidance functionVSAvoidside sill structural integrity
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The side sill features local quality variation with the first portion having lower buckling strength than the second portion. This creates a controlled deformation zone that guides the wheel outward while maintaining overall structural integrity through the stronger second portion.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The side sill is segmented into two portions with different buckling strength characteristics. The first portion (with lower strength) handles the collision guidance function, while the second portion (with higher strength) maintains structural integrity, creating a functional segmentation within the single component.

Inventive Principle:
Principle #1Segmentation

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 design effectively guides the retreating front wheel to the outer side, suppressing its entry into the vehicle cabin and reducing the need for additional reinforcement members, thus minimizing weight and part count while enhancing collision safety.

Implementation Method 1

the side sill outer portion has a buckling load in a front-rear direction that is relatively lower than that of the side sill inner portion, and hence deformation is preferentially generated in the side sill outer portion in an easy manner when the retreating front wheel comes into contact with the side sill

Methodology Applied
Scientific EffectBuckling: Deformation

Data Source

PatentEP3789275B1Front vehicle-body structure of vehicle and vehicle comprising the front vehicle-body structure
Publication Date: 2023.11.29 MAZDA MOTOR CORP
  • EP3789275B1 patent drawingFigure 1
  • EP3789275B1 patent drawingFigure 2
  • EP3789275B1 patent drawingFigure 3

AI summary

[Problem] A front vehicle-body structure of a vehicle capable of suppressing a case where a front wheel breaks into the vehicle cabin space side at the time of a small overlap collision is provided. [Means for Solution] The front vehicle-body structure of the vehicle includes: a front wheel 6 including a wheel 6a; and a side sill 30 extending in a front-rear direction on a rear side of the front wheel 6. In the front vehicle-body structure, the side sill 30 has a side sill inner portion 31 positioned on a vehicle-width-direction inner side, and a side sill outer portion 40 positioned on a vehicle-width-direction outer side, vehicle-width-direction end portions of the side sill inner portion 31 and the side sill outer portion 40 are joined to each other at a joined portion 96 formed by causing the vehicle-width-direction end portions to abut against each other, the side sill inner portion 31 has a higher buckling strength in the front-rear. direction than the side sill outer portion 40, the joined portion 96 has a second joined portion 96c extending in a direction inclined to the vehicle-width-direction outer side toward a rear side, and a first joined portion 96a bent from the second joined portion 96c, extending to a front side, and positioned on a front-end portion of the side sill 30, and the first joined portion 96a is positioned to be closer to the vehicle-width-direction inner side than a center line L0 of the wheel 6a in the vehicle width direction.