Lower Vehicle-Body Structure Side Collision Protection
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Solution Overview
Problem
Existing vehicle body structures are inadequate in protecting sensitive components like battery units during lateral collisions, as they fail to effectively distribute collision loads and often interfere with cross members, leading to potential damage.
Innovation Solution
A lower vehicle-body structure featuring a first cross member on the front floor panel, a second cross member in the kick-up portion positioned higher than the first, and a high-strength portion on the rear end of the front floor panel coupled to side sills, which enhances the structural integrity against side collisions and avoids interference with the battery unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a floor cross member is disposed on an intermediate portion of the front floor panel to couple side sills, then the side frame interference with battery unit is reduced, but the proof stress of the rear end portion of the front floor panel against side collision is insufficient
Solution Approach 1:
The front floor panel is segmented into multiple functional zones: a first cross member on the intermediate portion for basic coupling, a second cross member on the kick-up portion for elevated bridging, and a high-strength portion on the rear end for enhanced collision resistance. This segmentation allows each zone to perform its specific function optimally without interfering with the battery unit.
Solution Approach 2:
The high-strength portion is applied locally to the rear end portion of the front floor panel where collision forces are most severe. This localized reinforcement provides the necessary proof stress improvement without requiring the entire floor panel to be strengthened, thus avoiding unnecessary weight increase while protecting the battery unit effectively.
2Stability of the object's composition
If a cross member is provided on the lower side of the kick-up portion with end portions bent downward, then structural bridging is achieved, but the battery unit protection performance is insufficient due to potential interference
Solution Approach 1:
The second cross member is positioned on the kick-up portion which elevates it to a higher vertical dimension compared to the first cross member. This dimensional change in the vertical direction allows the cross member to perform its bridging function while being positioned above the battery unit, thereby avoiding interference and protecting the battery from collision forces.
3Ease of manufacture
If the front floor panel structure is simplified without high-strength portions, then manufacturing ease is improved, but the proof stress against side collision is insufficient
Solution Approach 1:
Instead of uniformly strengthening the entire front floor panel which would complicate manufacturing, the high-strength portion is applied only to the rear end portion where collision forces are most severe. This localized approach maintains ease of manufacture for the majority of the panel while providing necessary strength enhancement where required.
Data Source
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AI summary
An object is to provide a lower vehicle-body structure of a vehicle capable of improving the proof stress of a rear end portion of a front floor panel against a side collision and avoiding the interference between a cross member of a kick-up portion and a battery unit. The lower vehicle-body structure of a vehicle includes: a first cross member 6 disposed on an intermediate portion of a front floor panel 1 in a vehicle front-rear direction so as to serve as a bridge in a vehicle width direction; a second cross member 40 disposed in a kick-up portion 10 between the front floor panel 1 and a rear floor panel 12 so as to serve as a bridge in the vehicle width direction at a position in which at least a center portion in the vehicle width direction is higher than the first cross member 6; and a battery unit disposed below at least the front floor panel 1 to a rear end position of the front floor panel 1, wherein a high-strength portion 70 for the front floor panel 1 is formed on a rear end of the front floor panel 1 on a lower end portion of the kick-up portion 10, the high-strength portion 70 being coupled to both of a pair of left and right side sills 2.