Battery Pack End Plate With Buckling Struts for Side Impact Loads
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Solution Overview
Problem
Existing battery packs for electrified vehicles face challenges in efficiently packaging and protecting battery cells, particularly in distributing compressive forces and absorbing energy to prevent damage from external impacts.
Innovation Solution
A multi-row battery pack design featuring structured end plates with cantilevered struts and a preload system, where the end plates exert more force on interior rows than outside rows, and are curved to distribute load evenly and absorb energy through buckling struts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional rigid end plates are used to protect battery cells from external impacts, then protection strength is improved, but energy absorption capability deteriorates because rigid structures transmit impact forces directly to the battery cells
Solution Approach 1:
The end plate is segmented into multiple cantilevered struts that can independently deform during impact. Each strut acts as an individual energy absorption element, allowing the structure to dissipate impact energy through controlled deformation rather than transmitting it directly to the battery cells.
Solution Approach 2:
The cantilevered struts are designed with specific width-to-thickness ratios (at least 3:1) and curved geometries that change their mechanical properties during deformation. These parameter changes enable the struts to transition from a rigid protective state to a compliant energy-absorbing state during impact events.
2Device complexity
If uniform force is applied to all battery cell rows, then structural simplicity is improved, but interior rows experience excessive compressive forces that can cause cell damage
Solution Approach 1:
The end plate applies different forces to different regions of the battery cell rows. The cantilevered struts are positioned and dimensioned to create localized force distribution patterns that reduce compressive forces on interior rows while maintaining adequate support for outside rows, addressing the non-uniform stress problem through spatially varying structural properties.
3Reliability
If battery cells are allowed to expand freely during operation, then cell performance is improved, but uneven expansion causes internal stress and potential structural failure
Solution Approach 1:
The cantilevered struts incorporate curved geometries that provide compliant support during battery cell expansion. The curved shapes allow the struts to flex and adapt to the expanding cells, maintaining support while accommodating volume changes and reducing internal stress concentrations that would otherwise lead to structural failure.
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 design effectively distributes compressive forces across battery cells, reduces the risk of damage from external impacts by absorbing energy, and maintains even pressure distribution during cell expansion, enhancing the safety and efficiency of battery pack packaging.
Implementation Method 1
absorbing energy through buckling struts
Implementation Method 2
distributes compressive forces across battery cells
Implementation Method 3
The side plates may be under tension such that they exert force on the end plate to hold the end plate against the end cells
Data Source
AI summary
An end plate for a vehicle battery pack is specially designed to span multiple rows of battery cells and to protect the cells if an object strikes the side of the vehicle. The end plate includes a curved front wall, a flat rear wall, and several cantilevered struts perpendicular to the rear walls. The cantilevered struts are dimensioned such that they buckle to absorb energy rather than transmitting force to the battery cells.