Fuel Cell Tightening Structure for Uniform Stack Pressure
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Solution Overview
Problem
Existing fuel cells face challenges in applying uniform surface pressure to the cell stacked body due to deflection of tightening plates, leading to non-uniform contact resistance and potential damage from stress concentration.
Innovation Solution
A tightening structure comprising a first tightening plate with a planar portion in surface contact with an insulating plate and a second tightening plate that presses against the insulating plate, featuring a convex-shaped inside pressing part to ensure uniform surface pressure application despite deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an integrally molded tightening plate with a projection is used to maintain rigidity, then rigidity is improved, but surface pressure uniformity deteriorates due to varying pressure between the projection and surroundings
Solution Approach 1:
The tightening plate incorporates a recessed portion at the center position, creating a local structural feature that specifically addresses the floating issue without affecting the overall plate rigidity. This local modification allows the plate to maintain sufficient rigidity while preventing excessive tightening force concentration at the center, thereby achieving uniform surface pressure distribution across the entire plate surface.
2Strength
If the plate thickness is increased to suppress floating, then rigidity is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
Instead of uniformly increasing the entire plate thickness, the invention segments the plate structure by introducing a recessed portion only at the center position. This segmentation approach allows the plate to maintain adequate rigidity through the overall thickness while locally reducing material at the center to prevent floating, thereby simplifying the structure compared to a uniformly thick plate and reducing manufacturing complexity.
3Strength
If a projection is added to the tightening plate to ensure rigidity, then rigidity is improved, but stress concentration increases causing potential damage
Solution Approach 1:
Instead of adding a projection (outward extension) to maintain rigidity, the invention uses the opposite approach by creating a recessed portion (inward indentation) at the center position. This inverted structure prevents the center of the tightening plate from floating during tightening operations while distributing the tightening force more evenly, thereby avoiding stress concentration and potential damage to the cell stacked body.
4Ease of manufacture
If the tightening plate is made thinner for easier processing, then ease of manufacture is improved, but rigidity deteriorates causing floating during tightening
Solution Approach 1:
The tightening plate is manufactured with a uniform thin thickness for ease of processing, but a recessed portion is locally created at the center position. This local modification provides the necessary structural support to prevent floating during tightening operations without requiring the entire plate to be thicker, thereby maintaining both ease of manufacture and sufficient rigidity.
Data Source
AI summary
According to an embodiment, a fuel cell includes: a cell staked body 10 including a plurality of single unit fuel cells stacked one on another; a collecting plate 20 located on the cell stacked body 10 in a stacking direction; an insulating plate 30 located on the collecting plate 20; and a tightening structure 40 located on the insulating plate 30 and configured to hold the collecting plate 20 and the insulating plate 30 on the cell stacked body 10 by being tightened toward the cell stacked body 10. The tightening structure 40 includes a first tightening plate 41 including a planar portion in surface contact with the insulating plate 30, and a second tightening plate 42 located on the first tightening plate 41 and configured to press the first tightening plate 41 against the insulating plate 30 by being tightened toward the cell stacked body 10.