Press-Hardened Battery Tray With Soft Corners for Crack-Free Forming
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Solution Overview
Problem
Existing battery trays for electric vehicles are not optimized for geometric dimensions to accommodate batteries effectively, particularly in terms of capacity and crash safety, and require improved protection against environmental factors and fluid leakage.
Innovation Solution
A battery tray manufactured from a single sheet of hardenable steel alloy, with optimized corner areas having lower tensile strength and a mixed microstructure, combined with higher strength in other areas, allowing for thin-walled construction and enhanced crash safety through controlled material flow during forming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the battery tray is manufactured with high tensile strength throughout (Rm ≥ 1250 MPa), then crash safety and structural integrity are improved, but the forming process becomes difficult due to material cracking and excessive stretching in corner areas
Solution Approach 1:
The patent applies local quality by creating different material properties in different regions of the battery tray. The corner areas are selectively softened through controlled cooling to achieve lower tensile strength (550-800 MPa), while the remaining areas maintain high tensile strength (≥1250 MPa). This localized differentiation allows the corner regions to be formed without cracking while the rest of the structure maintains high strength requirements.
Solution Approach 2:
The patent changes the physical parameter of tensile strength in specific regions by controlling the cooling rate during hot forming. By selectively cooling corner areas at different rates than the rest of the tray, the material's tensile strength parameter is modified locally. This parameter change enables the forming process to proceed without material failure in corner regions while maintaining high strength elsewhere.
2Strength
If the battery tray uses uniform high tensile strength material throughout, then crash safety is improved, but geometric optimization for battery accommodation is limited due to forming constraints
Solution Approach 1:
The patent enables geometric optimization by applying local quality differentiation. Corner areas with softened material properties allow for optimized geometries such as sharper edges and better battery accommodation shapes, while the high-strength regions maintain structural integrity for crash safety. This localized approach resolves the conflict between geometric flexibility and structural strength.
3Weight of moving object
If the battery tray is made with thin wall thickness for low weight, then weight is reduced, but the risk of cracking and material failure during forming increases
Solution Approach 1:
The patent reduces material failure risk by applying local quality to corner regions. By softening the material in these high-stress forming areas through selective cooling, thin-walled sections can be formed without cracking. The rest of the tray maintains high strength properties, allowing overall weight reduction while ensuring reliability in critical corner areas during the forming process.
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
The solution provides high rigidity, crash safety, and weight reduction while preventing cracking and excessive stretching, enabling efficient battery accommodation and protection against fluid leakage.
Implementation Method 1
partial austenitizing or complete austenitizing and partial intercooling of the later corner areas
Implementation Method 2
inserting it into a hot forming and press hardening tool, and hot forming and press hardening
Implementation Method 3
inserting it into a hot forming and press hardening tool, and hot forming and press hardening
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3b
AI summary
The invention relates to a battery tray (1) for a battery carrier of an electric vehicle, wherein the battery tray (1) has a base (3) and extends in one piece and of a single material from the base (3) having a circumferential wall and optionally an externally circumferential flange (6) projecting from the wall, wherein the battery tray (1) is made from a hardenable sheet steel blank (13) as a hot-formed and press-hardened component, with a tensile strength Rm greater than or equal to 1250 MPa, characterized in that in a respective corner region (10) of the side walls (4, 5) the tensile strength Rm is less than 1100 MPa.