Vehicle Body Lower Structure With Overlapping Flanges for Battery Protection
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Solution Overview
Problem
Existing vehicle body lower part structures fail to efficiently absorb collision energy while preventing damage to the battery during a collision, leading to potential battery damage due to the displacement of pressure-broken portions.
Innovation Solution
A vehicle body lower part structure with a side frame and battery frame configuration, featuring joint flanges that overlap and deform to absorb collision energy, preventing direct contact with the battery, and utilizing a battery frame with protrusions and recesses to enhance rigidity and deformation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an easily pressure-broken portion (bead) is provided on a cross member to absorb collision energy, then collision energy absorption is improved, but the broken portion forms a mass that displaces toward the battery and transmits load to the battery, worsening battery protection
Solution Approach 1:
The cross member is segmented into multiple regions with different thicknesses: a first region with standard thickness, a second region (collision absorption portion) with reduced thickness for energy absorption, and a third region with increased thickness for strength. This segmentation allows the structure to absorb collision energy while preventing broken portions from contacting the battery.
Solution Approach 2:
Different portions of the cross member are given different local qualities: the collision absorption portion has reduced thickness to facilitate deformation and energy absorption, while the third region has increased thickness to maintain structural strength and prevent battery contact. This local quality differentiation resolves the contradiction between energy absorption and battery protection.
2Reliability
If the cross member is designed to break easily under pressure to absorb collision energy, then collision safety is improved, but the structural integrity and load-bearing capacity are reduced
Solution Approach 1:
The cross member is divided into functional segments: a collision absorption portion with reduced thickness for controlled breaking, and a third region with increased thickness for maintaining structural integrity. This segmentation allows the structure to break where needed while remaining strong where required.
Solution Approach 2:
The thickness parameter of the cross member is varied across different regions: reduced in the collision absorption portion to enable energy absorption through deformation, and increased in the third region to maintain structural strength. This parameter change resolves the contradiction between reliability under collision and overall structural strength.
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
Efficient absorption of collision energy is achieved while protecting the battery, improving collision safety performance and contributing to sustainable transportation systems.
Implementation Method 1
the first joint flange and the second joint flange are formed to accept deformation with respect to a collision load
Implementation Method 2
the collision absorption portion is deformed downward, and thereby, it is possible to prevent the collision absorption portion from coming into contact with the battery arranged within the battery pack
Data Source
AI summary
A vehicle body lower part structure includes: a side frame that connects a side sill to a battery pack that is arranged below a floor portion; and a battery frame that supports a battery within the battery pack. A first joint flange that is joined to a case bottom portion of the side frame is arranged such that a second joint flange that is joined to the case bottom portion of the battery frame overlaps an upper side in an upward-downward direction of the first joint flange.