Bus Bar Projection Structure for Cell Swelling Flexibility
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Solution Overview
Problem
The increase in cell capacity leads to increased swelling, which applies a higher load on the connecting parts between the bus bar and the cell, causing gaps and instability in welding, increased electrical resistance, and higher production costs due to the need for multiple dies for different projection shapes.
Innovation Solution
A bus bar structure with inclined projections that align with a varying interval, allowing plates to overlap without gaps and using a single die, maintaining flexibility and reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If plates having a projection in the same shape are stacked, then production cost is reduced by using a single die, but gaps are created between the plates
Solution Approach 1:
The patent applies asymmetry by making the projection shapes asymmetric relative to each other when viewed from the stacking direction. Specifically, the distance between adjacent projections on different plates is made unequal, which prevents gaps from forming when plates are stacked, while still allowing all plates to be manufactured using a single die pattern.
2Adaptability or versatility
If projections are provided to increase flexibility of the bus bar, then flexibility is improved, but gaps between plates are created
Solution Approach 1:
The asymmetric arrangement of projections maintains the flexibility function while eliminating gaps. The projections are positioned at different distances from corresponding projections on adjacent plates, allowing the bus bar to flex while maintaining continuous plate contact throughout the stacking direction.
3Manufacturing precision
If different sized projections are used to prevent gaps between plates, then gap prevention is achieved, but production cost increases due to need for multiple dies
Solution Approach 1:
The patent resolves this contradiction by using asymmetric positioning rather than different sizes. All plates use the same projection size and shape, but the projections are positioned asymmetrically relative to each other in the stacking direction, eliminating the need for multiple dies while preventing gaps.
4Power
If cell capacity is increased, then power output is improved, but load on connecting parts increases due to increased swelling
Solution Approach 1:
The patent applies dynamics by making the bus bar structure flexible through the projection arrangement. This flexibility allows the bus bar to dynamically adapt to cell swelling forces, distributing the mechanical load across multiple plates and connection points rather than concentrating it at single rigid connection points.
Solution Approach 2:
The bus bar is segmented into multiple stacked plates connected by projections. This segmentation distributes the mechanical stress from cell swelling across multiple connection points and plates, reducing the load on any single connecting part while maintaining electrical connectivity.
Data Source
AI summary
A bus bar has: a first joint part connected to an output terminal of the first cell; a second joint part connected to an output terminal of the second cell; and a projection that is disposed between the first joint part and the second joint part and protrudes in a stacking direction in which the cells and the bus bar are stacked. The projection has a first inclined part extending from the first joint part and has a second inclined part extending from the second joint part. The first inclined part and the second inclined part are arranged in such a manner that the first inclined part and the second inclined part are aligned with a predetermined interval W and that the predetermined interval gradually becomes wider from a first end side toward a second end side.