Battery Cell Stack End Caps for Draft-Angle Compression Interfaces
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traction battery packs face challenges in securely interfacing cell stacks with enclosure structures, particularly due to draft angles in the side walls, which can lead to inadequate compression and structural integrity.
Innovation Solution
The use of end caps that square draft angles and apply compressive loads, combined with foam structures and adhesives, to enhance the interface between cell stacks and enclosure walls, thereby improving structural integrity and accommodating battery expansion forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the side wall includes a draft angle for ease of manufacturing, then the enclosure assembly is easier to manufacture, but the compression interface between the end cap and cell stack becomes inadequate
Solution Approach 1:
The end cap is divided into two distinct sections: a first side section with a substantially flat surface that interfaces with the cell stack, and a second side section with a sloped surface that interfaces with the draft angle side wall. This segmentation allows each section to be optimized for its specific function while maintaining overall structural integrity.
Solution Approach 2:
The end cap acts as an intermediary component between the draft angle side wall and the cell stack. It translates the sloped draft angle interface into a flat compression surface, mediating between the manufacturing requirements of the enclosure and the structural requirements of the battery cell support.
2Strength
If the end cap is designed to square the draft angle for structural integrity, then the compression interface is improved, but the device complexity increases
Solution Approach 1:
The end cap merges multiple functions into a single component: it provides structural support, squares the draft angle, applies compression to the cell stack, and interfaces with both the enclosure wall and battery cells. This consolidation reduces overall device complexity despite the increased geometric complexity of the end cap itself.
Solution Approach 2:
The end cap serves multiple purposes simultaneously: it acts as a structural beam support, a compression applicator, a draft angle translator, and an interface between different components. This multi-functionality justifies the increased geometric complexity by eliminating the need for separate components.
3Strength
If foam structure is added between the end cap and side wall for compression, then the structural integrity is enhanced, but the device complexity and manufacturing steps increase
Solution Approach 1:
The foam structure is pre-positioned between the end cap and the side wall before final assembly. This beforehand cushioning ensures that compression forces are distributed evenly and that the foam is properly compressed to the correct density, enhancing structural integrity while simplifying the assembly process.
Solution Approach 2:
The foam structure acts as a flexible compression element that can conform to slight variations in the interface between the end cap and side wall. This flexibility allows for effective compression without requiring extremely precise manufacturing tolerances, thereby managing complexity.
Data Source
AI summary
Cell stack end caps are provided for use within traction battery packs. An end cap may be positioned to at least partially fill a volume of space between a cell stack and an enclosure structure (e.g., an enclosure tray) inside the traction battery pack. The end cap may be configured to square a draft angle of a side wall of the enclosure structure in order to impart a compressive load to the cell stack and/or the enclosure structure. A foam structure may be positioned between the end cap and the enclosure structure or within a hollow passageway of the end cap for increasing the structural integrity of the traction battery pack.