Sacrificial Battery Case Attachments for Vehicle Impact Loads
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Solution Overview
Problem
High voltage battery cases in vehicles are prone to damage from impact loads due to tight packaging and may fracture if made from conventional brittle materials like aluminum, necessitating a solution to protect the battery case integrity.
Innovation Solution
A high voltage battery case assembly with a sacrificial attachment system featuring sacrificial pockets with thin-walled sections that break away upon impact, combined with non-sacrificial attachments that remain secure to the vehicle body, absorbing and redirecting impact loads to prevent damage to the battery case.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the battery case is made from conventional aluminum using high pressure die cast process, then cost and weight effectiveness is improved, but the case becomes brittle and may fracture under impact loads
Solution Approach 1:
The attachment system is divided into two distinct segments: sacrificial attachments with thin-walled sections designed to break, and non-sacrificial attachments with thick-walled sections designed to remain intact. This segmentation allows the system to provide both weight effectiveness and impact protection by distributing the impact load across multiple attachment points with different failure characteristics.
Solution Approach 2:
Different wall thicknesses are applied to different sections of the attachment brackets. The sacrificial attachments have thin-walled sections (0.03-0.06 inches) that are intentionally weak, while the non-sacrificial attachments have thick-walled sections (0.125-0.25 inches) that are structurally strong. This local quality differentiation enables the system to achieve both weight reduction and impact resistance in specific locations where needed.
2Volume of moving object
If the battery case is tightly packaged inside the vehicle, then space utilization is improved, but the case becomes subject to loading from surrounding components during impact events
Solution Approach 1:
The sacrificial attachments act as intermediary elements between the battery case and the vehicle body. During impact events, these intermediaries are designed to fail first, absorbing the harmful impact loads before they can be transmitted to the battery case. This mediator approach allows tight packaging while protecting against impact forces from surrounding vehicle components.
Solution Approach 2:
The thin-walled sacrificial sections are pre-designed with controlled weakness to serve as predetermined failure points. This beforehand cushioning ensures that during impact events, the sacrificial attachments will break at predictable energy levels (5-50 Joules), cushioning the battery case from the full force of the impact before the load is fully transmitted.
3Strength
If sacrificial attachments with thin-walled sections are used to protect the battery case, then impact protection is improved, but the attachment system complexity increases
Solution Approach 1:
The sacrificial and non-sacrificial attachments are merged into a single integrated attachment system that uses the same basic bracket geometry and mounting methodology. Both attachment types are integrally formed with the battery case using the same die cast process, and both use identical fastening mechanisms. This merging reduces system complexity compared to using entirely different attachment systems, while still providing the protective function of sacrificial elements.
Data Source
AI summary
A high voltage battery case assembly for a vehicle includes a battery case having a plurality of walls at least partially defining a cavity configured to receive one or more high voltage battery modules, a sacrificial pocket formed on an exterior of the battery case and including a thin-walled section, and an attachment bracket configured to couple between the sacrificial pocket and a body of the vehicle. The thin-walled section is configured to intentionally break away from the sacrificial pocket when the attachment bracket receives an impact load of a predetermined energy level to thereby facilitate protecting the high voltage battery case assembly from the impact load.