Vehicle Bottom Structure With Reinforcing Member Against Panel Deflection
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Solution Overview
Problem
The existing vehicle bottom structures in electrified vehicles face challenges in reducing the upward deflection of the share panel when an object collides with it from the lower side, potentially causing damage to the battery pack.
Innovation Solution
A vehicle bottom structure with a reinforcing member disposed between the outer cross members and the share panel, featuring a hat-shaped cross section, bolted connections, and a thinned central portion with flanges, which reduces the distance between fulcrums of bending moment and restricts panel movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the share panel is directly fastened to the lower wall of the outer cross member, then the structure is simple, but the upward deflection of the share panel increases when an object collides from the lower side
Solution Approach 1:
A reinforcing member is introduced as an intermediary component between the share panel and the outer cross member. This reinforcing member has a hat-shaped cross section with a lower wall that is fastened to the outer cross member, and a upper wall that is fastened to the share panel. This intermediary structure provides additional support points that reduce the upward deflection of the share panel during collision while maintaining overall structural simplicity.
2Device complexity
If the share panel is directly fastened to the outer cross member, then the number of components is reduced, but the distance between fulcrums of bending moment increases causing greater deflection
Solution Approach 1:
The fastening structure is segmented into multiple levels: the outer cross member remains in place, but a reinforcing member is added with its own fastening points. The reinforcing member creates additional fulcrums (fastening points) between the outer cross member and the share panel, effectively dividing the span and reducing the distance between fulcrums of bending moment, thereby reducing deflection without significantly increasing overall component count.
3Strength
If the share panel is made more rigid to prevent deflection, then collision resistance improves, but the weight of the vehicle increases
Solution Approach 1:
The solution uses a composite structural approach combining the outer cross member, the reinforcing member with hat-shaped cross section, and the share panel. This composite structure achieves enhanced collision resistance and reduced deflection through the geometric configuration and stacking arrangement of multiple lighter components rather than using a single heavy rigid panel, thereby improving strength without proportionally increasing vehicle weight.
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 configuration effectively minimizes the upward deflection of the share panel, protecting the battery pack and enhancing maintainability by reducing weight and preventing rattling, while allowing easy removal of the share panel during maintenance.
Implementation Method 1
The share panel, the reinforcing members, and the lower walls of the outer cross members are stacked and fastened by bolts at intervals in the vehicle width direction
Implementation Method 2
The welded regions of the reinforcing member include a non-bolt region in the recess of the body in the vehicle front-rear direction, a front flange and a rear flange that project forward and backward, respectively, from the non-bolt region
Data Source
AI summary
The vehicle bottom structure includes a battery pack, an outer cross member disposed below the battery pack and spaced apart in the vehicle front-rear direction, a plurality of reinforcing members, and a share panel. The lower walls of the share panel, the reinforcing member, and the outer cross member are fastened by bolts. The reinforcing member includes a body having a recess. Bolt through holes are provided in the recesses at intervals in the vehicle width direction. The reinforcing member includes a front flange and a rear flange positioned forward and rearward of the non-bolt region between adjacent bolt through holes. The non-bolt region, the front flange, and the rear flange are welded to the share panel. Both ends in the front-rear direction of the lower surface of the body are located outward from both ends in the front-rear direction of the lower wall of the outer cross member.