EV Body Load Paths Around Battery Case for Crash Weight Balance
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Solution Overview
Problem
Existing vehicle-body structures for electric automotive vehicles face challenges in balancing collision safety and weight reduction, particularly in distributing and absorbing collision loads effectively while protecting large battery volumes and maintaining structural integrity.
Innovation Solution
A vehicle-body structure that optimizes member strength by dispersing collision loads through a network of longitudinal load-transmitting members, side sills, and a battery case, with specific configurations such as first and second longitudinal load-transmitting members, cross members, and protrusion portions to absorb and distribute collision forces efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the strength of the front side member is increased to properly deal with large collision load, then collision safety is improved, but vehicle body weight increases
Solution Approach 1:
The front side member is divided into multiple segments with different thicknesses along its longitudinal direction. The front portion has a first thickness, the intermediate portion has a second thickness greater than the first, and the rear portion has a third thickness greater than the second. This segmentation allows the structure to distribute collision loads to multiple discrete locations (front, intermediate, and rear portions) rather than concentrating them at a single point, thereby improving collision safety while avoiding the need to uniformly increase the thickness and weight of the entire front side member.
Solution Approach 2:
Different portions of the front side member are given different local qualities in terms of thickness and strength. The intermediate and rear portions have greater thickness (higher local quality) to handle concentrated collision loads, while the front portion maintains a smaller thickness. This local quality variation allows the structure to reinforce only where necessary to withstand collision forces, improving overall collision safety without proportionally increasing the total weight of the front side member.
2Weight of moving object
If the front side member is made thinner to reduce vehicle body weight, then weight reduction is achieved, but collision safety deteriorates due to insufficient strength to handle large collision loads
Solution Approach 1:
The front side member is segmented into portions with different thicknesses, allowing the overall weight to be reduced compared to a uniformly thick design, while still providing sufficient strength at critical locations. The front portion can be thinner to reduce weight, while the intermediate and rear portions have greater thickness to ensure collision safety when loads are transmitted to these locations.
Solution Approach 2:
The front side member exhibits local quality variations where only specific portions (intermediate and rear) have increased thickness for strength, while other portions (front) have reduced thickness for weight savings. This allows the structure to achieve weight reduction while maintaining collision safety through strategic reinforcement at load-bearing locations.
3Loss of energy
If the under member is configured to deform easily to absorb collision load, then collision load absorption is improved, but the strength of the front side member must be increased to handle remaining loads, causing weight increase
Solution Approach 1:
The front side member is segmented into portions with different thicknesses to optimize the balance between load absorption and weight. The intermediate and rear portions with greater thickness can handle the loads transmitted from the under member's deformation, while the front portion maintains reduced thickness. This segmentation allows the system to achieve effective collision load absorption through under member deformation without requiring a uniform increase in front side member thickness that would cause weight increase.
Solution Approach 2:
The front side member has local quality variations with increased thickness at intermediate and rear portions to handle concentrated loads from under member deformation, while the front portion has reduced thickness. This allows the structure to support the collision load absorption function of the under member without proportionally increasing overall 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 absorbs collision loads, reduces vehicle weight, and enhances safety by dispersing forces across multiple structural elements, thereby improving overall collision safety and weight reduction.
Implementation Method 1
first longitudinal load-transmitting members respectively extending from respective vehicle-rear portions of the right-and-left front side frames to the right-and-left side sills along an upper face of the floor panel
Implementation Method 2
second longitudinal load-transmitting members respectively extending from the respective vehicle-rear portions of the right-and-left front side frames toward a vehicle-front portion of the battery case along a lower face of the floor panel
Implementation Method 3
the collision load which has not been absorbed by deformation of the under member is absorbed by deformation of the front extension portion of the case body portion of the battery unit
Data Source
Figure 1
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Figure 3
AI summary
A vehicle-body structure comprises a dash panel, a pair of right-and-left front side frames, a pair of right-and-left side sills, a pair of right-and-left first longitudinal load-transmitting members respectively extending from respective vehicle-rear portions of the right-and-left front side frames to the right-and-left side sills along an upper face of the floor panel, and a pair of right-and-left second longitudinal load-transmitting members respectively extending from the respective vehicle-rear portions of the right-and-left front side frames toward a vehicle-front portion of the battery case along a lower face of the floor panel.