Aluminum Battery Box Bottom Sheet for Intrusion and Corrosion Resistance
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Solution Overview
Problem
Existing battery boxes for electric and hybrid vehicles face challenges in achieving a balance between light weight, high stiffness, resistance to intrusion, leak-tightness, corrosion resistance, temperature accommodation, and sufficient strength, while also providing protection during crashes and maintaining battery integrity.
Innovation Solution
A battery box bottom part made from an aluminum alloy sheet with specific compositions (2.5-4.0% Mg, 0.1-0.8% Mn, 0.4% or less Si, 0.5% or less Fe, 0.5% or less Cu, 0.1% or less Cr, 0.1% or less Zn, 0.1% or less Ti, and unavoidable impurities up to 0.05% each) is produced through casting, homogenization, and hot/cold rolling to achieve a thickness of 2-6 mm, with a preferred H2X temper for enhanced mechanical and corrosion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the battery box is made lighter to improve vehicle running performance, then weight is reduced, but structural strength and crash resistance deteriorate
Solution Approach 1:
The patent employs composite material structures including aluminum alloy sheets combined with foam core materials and honeycomb structures. This allows the battery box to achieve high strength-to-weight ratio, maintaining crash resistance while reducing overall weight. The composite construction provides both structural integrity and weight reduction benefits simultaneously.
Solution Approach 2:
The patent implements varying wall thicknesses and reinforcement strategies at different locations of the battery box. Critical areas experiencing higher impact forces receive enhanced structural support through localized thickening or reinforcement, while non-critical areas use thinner walls to reduce weight. This selective approach optimizes the balance between weight reduction and crash resistance.
2Length of moving object
If the aluminum alloy sheet thickness is reduced to achieve a thinner design, then weight is reduced and formability is improved, but intrusion resistance and structural integrity worsen
Solution Approach 1:
The patent combines thin aluminum alloy sheets with foam core materials or honeycomb structures to create a composite panel system. This allows the use of thinner aluminum sheets while maintaining intrusion resistance through the combined structural properties of the composite assembly, achieving both weight reduction and protective functionality.
Solution Approach 2:
The patent specifies precise compositional parameters for the aluminum alloy, including controlled ranges of Mg (2.5-4.0%), Mn (0.1-0.8%), Si (≤0.4%), Fe (≤0.5%), and Cu (≤0.5%). These parameter optimizations enhance the mechanical properties and formability of thin sheets, enabling thinner designs that still meet intrusion resistance requirements.
3Strength
If magnesium content is increased to improve strength and corrosion resistance, then mechanical properties are enhanced, but manufacturing complexity and alloy control difficulty increase
Solution Approach 1:
The patent defines specific parameter ranges for alloy composition, particularly Mg content (2.5-4.0%) and interactions with other elements like Mn and Si. These controlled parameter changes optimize strength and corrosion resistance while maintaining manufacturability. The specified ranges balance performance enhancement with practical alloy production and quality control considerations.
Data Source
AI summary
The present invention is directed to a bottom part of a battery box for electric or hybrid motor vehicles made from an aluminium alloy sheet having a thickness between 2 and 6 mm, wherein said aluminum alloy comprises 2.5 to 4.0 wt. % of Mg, 0.1 to 0.8 wt. % of Mn, 0.4 wt. % or less of Si, 0.5 wt. % or less of Fe, 0.5 wt. % or less of Cu, 0.1 wt. % or less of Cr, 0.1 wt. % or less of Zn, 0.1 wt. % or less of Ti, rest aluminium and unavoidable impurities up to 0.05 wt. % each and 0.15 wt. % total. Another object of the invention is a method to make a bottom part of battery box according to the invention comprising casting said aluminium alloy into a rolling ingot; homogenizing and/or reheating said rolling ingot; hot rolling and optionally cold rolling said rolling ingot to obtain a sheet with a thickness between 2 mm and 6 mm. The bottom part of battery box of the invention is simultaneously light, resistant against intrusion, sufficiently formable and leak tight, corrosion resistant, able to accommodate temperature variations and sufficiently stiff and strong.