Arched Segmented End Members for Uniform Fuel Cell Stack Pressure
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Solution Overview
Problem
Conventional fuel cell stacks face challenges in achieving high performance due to uneven pressure distribution across the membrane electrode assembly (MEA), which is exacerbated by the difficulty in achieving both high strength and flatness in large end plates, leading to manufacturing cost issues and potential warping of resin materials.
Innovation Solution
A fuel cell stack design featuring a cell stack structure with arched end members and a fastener band that includes bendable coupling members, allowing for uniform pressure distribution and reduced manufacturing costs by eliminating the need for high flatness across the entire end plate area, while the fastener band's high bending strength prevents warping and ensures consistent power generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the end plate is made large to cover the entire MEA area, then the coverage area is improved, but the flatness and strength deteriorate
Solution Approach 1:
The end plate is divided into multiple plate members arranged in parallel, each having a small area that can maintain high flatness. The segmented structure allows each individual plate member to be manufactured with high precision while collectively covering the entire MEA area through their arrangement.
Solution Approach 2:
Instead of requiring the entire large end plate to have uniform high flatness, the invention applies local quality by ensuring only the contact surfaces of individual plate members have high flatness. The arched shape provides local structural reinforcement where needed while maintaining overall coverage.
2Area of stationary object
If the end plate area is increased to cover large MEA, then the coverage is improved, but the manufacturing cost increases due to required secondary processing
Solution Approach 1:
The end plate is segmented into multiple smaller plate members that can be manufactured using standard die-casting processes without requiring expensive secondary machining operations. Each small plate member can be produced cost-effectively while collectively providing the necessary large coverage area.
Solution Approach 2:
The arched shape of plate members provides structural strength and rigidity without requiring additional reinforcement features or secondary processing. The curved geometry naturally distributes stresses and maintains flatness where needed, eliminating the need for costly post-processing operations.
3Ease of manufacture
If resin material is used for end plate, then the manufacturing cost is reduced, but the flatness deteriorates due to warping
Solution Approach 1:
The resin end plate is divided into multiple small plate members, each with dimensions small enough to resist warping. The segmented structure allows each individual member to maintain flatness while the collective assembly provides large area coverage, overcoming the inherent warping tendency of resin materials.
Solution Approach 2:
The arched shape of resin plate members provides structural rigidity that counteracts warping forces. The curved geometry distributes internal stresses more evenly throughout the material, preventing the distortion and warping that typically occurs in large flat resin components.
4Strength
If the fastener band applies high pressure to ensure tight fastening, then the fastening strength is improved, but the pressure unevenness on MEA increases
Solution Approach 1:
The fastening force is distributed through multiple plate members that contact the MEA at different locations. This segmentation of the contact interface ensures that pressure is applied uniformly across the entire MEA area, preventing concentration of force at single points while maintaining overall fastening strength.
Solution Approach 2:
Each plate member is designed with specific local characteristics including arched shape and appropriate contact surface area, ensuring that pressure is distributed evenly at each contact point. The localized optimization of each plate member contributes to uniform overall pressure distribution on the MEA.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces unevenness in power generation distribution and improves fuel cell stack performance by ensuring uniform contact resistance and reducing manufacturing costs through simpler end member design and assembly.
Implementation Method 1
Adjacent plate members of the plurality of plate members are coupled to each other through a bendable coupling member
Implementation Method 2
a fastener band wrapped around a cell stack formed by stacking the cell stack structure, the pair of current collectors, and the pair of end members
Data Source
AI summary
A fuel cell stack includes: a cell stack structure formed by stacking a plurality of cells; a pair of current collectors; a pair of end members; and a fastener band wrapped around a cell stack formed by stacking the cell stack structure, the pair of current collectors, and the pair of end members. Each of the pair of end members includes a plurality of plate members. The plate members have a same arched shape in which a height from a surface to contacting a corresponding one of the pair of current collectors gradually increases toward a center portion from both ends, and are disposed in parallel while being apart from each other in a width direction of the fastener band. Adjacent plate members are coupled to each other through a bendable coupling member at part of facing surfaces.