Side Sill Inner Structure for Small-Overlap Collision Resistance

Solution Overview

Problem

Conventional vehicle-body structures face issues with increased weight and manufacturing costs due to the need for reinforcing members to prevent deformation of the side sill in small overlap collisions, particularly when collision loads are high.

Innovation Solution

A lower vehicle-body structure featuring a side sill with a closed-cross section formed by a side sill outer and inner, and a cross member joined to the side sill inner, which includes bending and slant face portions that increase the side sill's vertical width and generate a large reaction force to suppress deformation without additional reinforcing members.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If reinforcing members are provided inside the side sill to prevent bending deformation in small overlap collision, then the side sill can resist collision load, but the weight and manufacturing costs increase

Engineering Contradiction:

Improveside sill resistance to bending deformationVSAvoidweight of reinforcing members

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The side sill inner cross-sectional shape is changed by forming bending portions that bend toward the inside of the side sill. This geometric parameter change increases the moment of inertia and section modulus of the side sill inner, enabling it to resist bending deformation without adding reinforcing members. The slant face portions further optimize the stress distribution by extending obliquely from the bending portions toward the side sill outer.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The side sill inner is transformed from a simple linear structure to a three-dimensional form with bending portions that create vertical and horizontal dimensions. The bending portions extend in the vehicle longitudinal direction and bend toward the inside, creating a complex spatial configuration that enhances structural strength without increasing weight through additional components.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Strength

If reinforcing members are provided inside the side sill to prevent bending deformation in small overlap collision, then the side sill can resist collision load, but the manufacturing costs increase

Engineering Contradiction:

Improveside sill resistance to bending deformationVSAvoidmanufacturing cost of reinforcing members

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The side sill inner cross-sectional shape is changed by forming bending portions that bend toward the inside of the side sill. This geometric parameter change increases the moment of inertia and section modulus of the side sill inner, enabling it to resist bending deformation without adding reinforcing members. The slant face portions further optimize the stress distribution by extending obliquely from the bending portions toward the side sill outer.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The reinforcing function is merged into the side sill inner itself rather than being a separate component. The bending portions and slant face portions are integrated into the side sill inner structure, eliminating the need for separate reinforcing members and their associated manufacturing and assembly costs.

Inventive Principle:

Principle #5Merging (Combining)

3Strength

If the side sill inner width is increased to generate larger reaction force, then the deformation suppression capability improves, but the vehicle width increases

Engineering Contradiction:

Improvereaction force generation capabilityVSAvoidvehicle width

Core Design Contradiction:

StrengthVSLength of moving object

Solution Approach 1:

The side sill inner is transformed from a simple linear structure to a three-dimensional form with bending portions that create vertical and horizontal dimensions. The bending portions extend in the vehicle longitudinal direction and bend toward the inside, creating a complex spatial configuration that enhances structural strength without increasing weight through additional components.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The bending portions create curved geometries that bend toward the inside of the side sill, optimizing the distribution of collision loads. The curved shape of the bending portions and the oblique extension of the slant face portions allow for more efficient stress distribution, generating larger reaction forces without requiring a linear increase in the side sill inner width.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Data Source

PatentUS12448050B2Lower vehicle-body structure of vehicle

Publication Date: 2025.10.21 MAZDA MOTOR CORP

AI summary

A side sill constituting a vehicle body comprises a side sill outer and a side sill inner. Each of an upper-side side face portion (upper face portion) and a lower-side side face portion (lower face portion) of the side sill inner comprises a second bending portion (bending portion) being formed by each of the upper face portion and the lower face portion bent toward an inside of the side sill, an upper-side slant face portion and a lower-side slant portion which respectively extend toward the side sill outer in an oblique direction such that a width, in a vertical direction, of the side sill inner gradually increases, and a second upper face portion and a second lower face portion (vehicle-width-direction face portions) which respectively extend in a vehicle width direction toward an inward side, in the vehicle width direction, from the second bending portion.