Vehicle Side Rail with Low-Strength Portion for Stabilizer Mounting
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Solution Overview
Problem
The existing vehicle lower section structures face challenges in mounting stabilizers with high roll stiffness due to interference with other components and reduced impact absorbing performance when thicker suspension members are used to accommodate increased load, which compromises deformability during crashes.
Innovation Solution
A vehicle lower section structure with a suspension member featuring a side rail that includes a low-strength portion between the front and rear joint portions, allowing for easier mounting of stabilizers while maintaining impact absorbing performance, achieved through a design with varying thicknesses and reinforcing elements to manage load distribution and deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a stabilizer with high roll stiffness is mounted on the suspension member, then the vehicle's roll stiffness is improved, but the load input from the stabilizer to the suspension member increases, requiring increased plate thickness of the suspension member
Solution Approach 1:
The side rail is segmented into different thickness portions: a first thickness portion at the joint portions with higher thickness to withstand stabilizer load, and a second thickness portion at the intermediate portion with lower thickness to maintain deformability during crash. This segmentation allows the suspension member to handle both high roll stiffness requirements and impact absorption requirements simultaneously.
Solution Approach 2:
Different portions of the side rail are given different local qualities in terms of thickness. The joint portions have higher thickness (first thickness portion) to provide strength for stabilizer mounting, while the intermediate portion has lower thickness (second thickness portion) to ensure deformability during crash. This local differentiation resolves the contradiction between strength and deformability.
2Strength
If the plate thickness of the suspension member is increased to accommodate higher load from the stabilizer, then the strength is improved, but the deformability during crash is reduced, decreasing impact absorbing performance
Solution Approach 1:
The side rail is divided into functional segments: thick joint portions for strength and thin intermediate portions for energy absorption during impact. This segmentation enables the structure to bear high stabilizer loads while maintaining crash deformability and impact absorption performance.
Solution Approach 2:
The side rail exhibits local quality variation with different thicknesses at different locations. The joint portions have high thickness for strength, while the intermediate portion has low thickness for deformability during crash, thereby resolving the contradiction between load bearing capacity and impact absorbing performance.
3Stability of the object's composition
If a large stabilizer such as an active stabilizer including an electrically-controlled actuator is mounted, then the roll stiffness is improved, but the stabilizer might interfere with a multiplicity of members above the rear cross member, making mounting difficult
Solution Approach 1:
The stabilizer is mounted on the upper surface of the end portion of the rear cross member, utilizing the vertical dimension and available space above the rear cross member. This dimensional approach allows large active stabilizers with actuators to be mounted without interfering with other members, thereby improving both roll stiffness and mountability.
Data Source
AI summary
A vehicle lower section structure includes: a suspension member including a side rail extending in a vehicle front-rear direction, the side rail including a front joint portion and a rear joint portion, the front joint portion being disposed on a front side of the rear joint portion in the vehicle front-rear direction; a securing member joined to the side rail at the front joint portion and the rear joint portion; and a stabilizer secured to the side rail by the securing member. The side rail includes a low-strength portion provided between the front joint portion and the rear joint portion and the low-strength portion has a strength lower than a strength of the front joint portion and the rear joint portion.