Battery Stack Fastening Structure for Cell Expansion Loads
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Solution Overview
Problem
The increasing capacity of secondary battery cells leads to stress concentration and potential screw breakage in power supply devices due to expansion, compromising the stability of the battery stack fastening.
Innovation Solution
A power supply device design featuring flat plate-shaped fastening members with through holes and pipe portions that disperse stress, reducing the load on fastening members and enhancing durability by avoiding stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the capacity of secondary battery cells is increased to meet higher demand, then the energy storage capability is improved, but the expansion amount increases causing stress concentration and screw breakage
Solution Approach 1:
The invention divides the fastening function into multiple components: bind bars for basic fastening, and additional plate-shaped fastening members with pipe portions for stress distribution. This segmentation allows each component to handle specific aspects of the fastening requirement, with the pipe portions specifically addressing stress concentration from battery expansion.
Solution Approach 2:
The invention adds pipe portions that extend in the stacking direction (vertical dimension) beyond the plane of the bind bars. This dimensional extension creates a three-dimensional fastening structure where the pipe portions penetrate through the battery stack, distributing stresses in multiple directions and preventing screw breakage from planar expansion forces.
2Device complexity
If bind bars are used to fasten the battery stack, then the assembly is simplified, but stress concentration occurs at the fastening points leading to screw breakage
Solution Approach 1:
The plate-shaped fastening members with pipe portions act as intermediary elements between the bind bars and the battery cells. These intermediaries distribute the contact stresses from the bind bars over larger areas and in multiple directions, preventing direct stress concentration at the screw fastening points while maintaining the overall simplicity of the bind bar structure.
3Quantity of substance
If a large number of secondary battery cells are stacked to increase capacity, then the energy storage is improved, but the expansion load on the battery stack increases causing fastening failure
Solution Approach 1:
By extending the fastening structure into the stacking direction with pipe portions that penetrate through multiple battery cells, the invention distributes expansion forces vertically across the stack rather than concentrating them at the horizontal fastening points. This three-dimensional distribution capability allows the system to handle larger total expansion loads from increased cell numbers.
Solution Approach 2:
The fastening system is segmented into multiple independent fastening members distributed across the battery stack. Each plate-shaped member with pipe portions handles local expansion forces independently, allowing the overall system to scale with the number of cells while maintaining consistent fastening performance at each segment.
Data Source
AI summary
Power supply device includes a plurality of secondary battery cells having a flat rectangular parallelepiped shape, a pair of end plates covering both end faces of battery stack having the plurality of secondary battery cells stacked on each other, and a plurality of fastening members for fastening end plates to each other. Each of the plurality of fastening members has a plate shape extending along the stacking direction of the plurality of secondary battery cells and is disposed on a corresponding one of opposite surfaces of battery stack. Through holes are formed in both ends of each plate shape. Each of the pair of end plates includes pipe portions inserted into the through holes of a pair of fastening members disposed on opposite surfaces of battery stack among the plurality of fastening members.