Vehicle Lower Structure With Dual Battery Frame Fixing for Collision Loads
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Solution Overview
Problem
The existing vehicle lower part structure with a battery frame functioning as a vehicle body frame fails to maintain a satisfactory fixed state of side frames during vehicle collisions, leading to inadequate collision safety performance.
Innovation Solution
A vehicle lower part structure that includes a battery frame with side and cross portions, and rear side frames connected to the battery frame, featuring cross-portion and side-portion fixing portions to maintain the fixed state during collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the side frames are connected to the battery frame with a single fixing structure, then the device complexity is reduced, but the reliability of the fixed state during collision deteriorates
Solution Approach 1:
The fixing structure is divided into two independent fixing portions: a cross-portion fixing portion that fixes the rear side frame to the cross portion, and a side-portion fixing portion that fixes the rear side frame to the side portion. This segmentation allows each fixing portion to independently resist different方向的 forces during collision, thereby improving reliability without significantly increasing overall complexity.
Solution Approach 2:
Different portions of the battery frame are assigned different fixing functions: the cross portion handles loads from the rear side frame through the cross-portion fixing portion, while the side portion handles loads through the side-portion fixing portion. This local differentiation of fixing qualities ensures optimal load distribution and maintains fixed state reliability under various collision conditions.
2Device complexity
If the battery frame structure is simplified to function as both battery enclosure and vehicle body frame, then the device complexity is reduced, but the strength during collision deteriorates
Solution Approach 1:
The battery frame is designed to serve multiple functions: it encloses the battery pack and simultaneously functions as the vehicle body frame structure. The side portions and cross portion of the battery frame collectively provide both battery protection and structural strength during collisions, eliminating the need for a separate vehicle body frame and maintaining strength through multi-functional design.
Solution Approach 2:
The battery frame is segmented into side portions and a cross portion, each with specific structural characteristics optimized for different loading conditions. The side portions extend in the vehicle width direction to resist lateral forces, while the cross portion connects them to resist longitudinal forces, collectively providing adequate collision strength.
3Strength
If the cross portion is extended further forward to improve load transmission, then the strength during collision is improved, but the volume of the battery frame increases
Solution Approach 1:
The cross portion is designed with optimized dimensions and positioning to provide adequate load transmission capability. Rather than extending the cross portion maximally forward, the design uses a compact cross portion with sufficient structural strength to transmit collision loads effectively, thereby avoiding unnecessary volume increase while maintaining required strength.
Data Source
AI summary
The vehicle lower structure includes a battery frame that surrounds the battery and includes a pair of side portions that extend in the vehicle front-rear direction and a cross portion that extends in the vehicle width direction and connects the rear ends of the side portions to each other, a pair of left and right side frames that extend in the vehicle front-rear direction and have a front end portion connected to the battery frame, and the rear side frame includes a cross-portion fixing portion that is fixed to the cross portion and a side-portion fixing portion that is fixed to an upper surface of the side portion on a vehicle front side rather than the cross-portion fixing portion.