Vehicle-Body Lower Structure with Protrusion-Based Side Sill Load Transfer
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Solution Overview
Problem
Existing vehicle-body lower structures face challenges in transmitting rearward collision loads to the side sill without increasing mass and cost, particularly due to reinforcement members that extend beyond the side sill front end.
Innovation Solution
A vehicle-body lower structure design featuring a side sill with a closed cross section and an outer-side reinforcement member attached from inside the cross section, where the reinforcement member's rear end engages with a protrusion part of the main body part to transmit collision loads efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an outer-side reinforcement member is provided that extends to the rear side of the side sill further than the side sill front end part, then the side sill front end part is reinforced against small overlap collision, but the mass and cost increase
Solution Approach 1:
The outer-side reinforcement member is divided into two functional segments: a side face part extending along the side face of the front end part, and a main body part disposed closer to the side face part with a protrusion part. This segmentation allows the reinforcement member to provide necessary strength while limiting its extension to only where structurally required, preventing unnecessary mass increase.
Solution Approach 2:
The reinforcement member is designed with non-uniform distribution of material properties - the side face part provides localized reinforcement along the side face, while the main body part with protrusion part provides concentrated reinforcement at the critical engagement position. This local quality approach ensures strength is provided exactly where needed without extending the reinforcement member unnecessarily to the rear, thus avoiding mass and cost increases.
2Strength
If an outer-side reinforcement member is provided that extends to the rear side of the side sill further than the side sill front end part, then the side sill front end part is reinforced against small overlap collision, but the manufacturing cost increases
Solution Approach 1:
The reinforcement member is segmented into a side face part and a main body part with distinct functions, allowing for optimized manufacturing processes for each segment and reducing overall material consumption, which directly lowers manufacturing cost.
Solution Approach 2:
By concentrating reinforcement only where structurally necessary (side face part along the side face and main body part at the engagement position), the design avoids unnecessary material usage and processing, thereby reducing manufacturing cost while maintaining required strength.
3Ease of manufacture
If the outer-side reinforcement member is attached from outside the closed cross section, then the attachment process is simpler, but the structural integrity and load transmission efficiency decrease
Solution Approach 1:
Instead of attaching the reinforcement member from the outside of the closed cross section, the invention inverts the attachment approach by attaching it from inside the closed cross section. This allows the side face part to engage the side face of the front end part and the main body part with protrusion part to engage the rear end of the side face part, creating a more reliable load transmission path that maintains structural integrity while still being manufacturable.
Data Source
AI summary
A side sill in a lower part and on an outer side in a vehicle width direction of a vehicle and forms, in its inner part, a closed cross section that extends in a front-rear direction of the vehicle; the side sill includes a side sill outer that has a front end and a main body located behind the front end, an outer-side reinforcement member that has a shape extending along a front face part and a side face part of the front end of the side sill outer is joined to the front end from inside or outside the closed cross section, a front end of the main body is opposed to a rear end of a side face part of the outer-side reinforcement member in the front-rear direction, and the main body has a protrusion part that protrudes to the inner side of the closed cross section.