Battery Pack Structural Connections for Cell Expansion Forces
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Solution Overview
Problem
Existing traction battery packs face challenges in effectively containing battery cell expansion forces, which can lead to structural integrity issues and potential risks such as the 'jack-out' of threaded inserts.
Innovation Solution
The proposed traction battery pack design incorporates a cell stack configuration with cross-member assemblies featuring a ladder frame, threaded rods, and pultruded reinforcement beams. These components work together to provide structural connections between cell stacks and a structural plate member, effectively containing battery cell expansion forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional connection structures are used in battery packs, then the device complexity is reduced, but the structural integrity deteriorates due to inability to contain battery cell expansion forces
Solution Approach 1:
The connection structure is divided into modular components: ladder frames, threaded rods, nuts, and reinforcement beams. Each component serves a specific function in containing expansion forces, allowing the system to manage structural complexity through functional segmentation while maintaining overall integrity.
Solution Approach 2:
The connection system combines multiple material types and structural forms (metal ladder frames, threaded rods, nuts, and pultruded reinforcement beams) to create a composite connection structure that can withstand battery cell expansion forces while distributing stress across different components.
2Reliability
If simple threaded rod connections are used, then the ease of manufacture is improved, but the reliability deteriorates due to jack-out risk of threaded inserts
Solution Approach 1:
Reinforcement beams act as intermediary elements between the threaded rods and the battery cell stacks. These beams distribute the expansion forces across a larger area, preventing concentrated loads that would cause threaded inserts to jack out, thereby improving reliability without significantly complicating manufacturing.
Solution Approach 2:
The reinforcement beams are installed beforehand to cushion and distribute expansion forces before they reach the threaded rod connections. This preventive measure protects the threaded inserts from excessive stress during battery operation, enhancing connection reliability.
3Strength
If reinforcement beams are added to the connection structure, then the strength is improved, but the device complexity increases
Solution Approach 1:
The reinforcement beams are integrated with the existing ladder frame structure, combining multiple functions into unified components. This merging approach increases connection strength while minimizing the addition of separate discrete parts, thereby limiting the increase in overall device complexity.
Data Source
AI summary
Battery structural connections are provided for containing battery cell expansion forces within a traction battery pack. An exemplary traction battery pack may provide structural connections between each of a plurality of cell stacks and a structural plate member that is arranged to span the plurality of cell stacks. Each cell stack may include a pair of cross-member assemblies, and each cross-member assembly may include a threaded rod that is receivable through an opening of the structural plate member. A nut may be secured to the threaded rod for containing battery cell expansion forces.