Fuel Cell Stack Boss Arrangement for Structural Stability
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Solution Overview
Problem
Fuel cell stacks with a skip cooling structure face issues in retaining the structure of components between power generation units, leading to deformation of electrolyte electrode assemblies and metal separators under load and pressure changes, which affects electrical conduction and stack integrity.
Innovation Solution
The fuel cell stack design alternates power generation units with evenly spaced electrolyte electrode assemblies and metal separators, featuring uneven buffers at flow field inlets and outlets, with bosses in the buffers arranged in the same phase to prevent shearing forces and ensure structural integrity, allowing the stack to withstand load and pressure changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a skip cooling structure is adopted with coolant flow field formed at intervals of unit cells, then the device complexity is reduced and manufacturing is simplified, but the structural stability deteriorates causing deformation of electrolyte electrode assemblies and metal separators under load and pressure changes
Solution Approach 1:
The fuel cell stack is divided into repeating units, each comprising a power generation unit and an adjacent coolant flow field. This segmentation ensures that every other unit cell has cooling capability, providing distributed structural support throughout the stack while maintaining the simplified skip cooling approach. The regular patterning of these units creates a stable alternating structure that prevents deformation.
2Reliability
If metal separators are used with grooves for gas flow fields, then the electrical conductivity is improved, but the mechanical strength deteriorates causing deformation under load and pressure changes
Solution Approach 1:
The metal separators are designed with locally differentiated properties: regions containing grooves for gas flow maintain high electrical conductivity for fuel cell operation, while regions forming the uneven buffer and boss structures provide enhanced mechanical strength for structural stability. This local quality differentiation allows simultaneous optimization of both electrical and mechanical properties in different areas of the same component.
Solution Approach 2:
The metal separator functions as a composite structure combining conductive metal material with strategically positioned reinforcing features (ridges, uneven buffers, bosses). This composite approach integrates the electrical conductivity function with mechanical support function, allowing the separator to withstand load and pressure changes while maintaining efficient electrical conduction across the fuel cell stack.
3Productivity
If the power generation units are stacked alternately to form coolant flow field, then the productivity is improved through simplified assembly, but the manufacturing precision deteriorates due to difficulty in retaining component structure
Solution Approach 1:
The metal separators are pre-formed with integrated uneven buffers and boss structures at specific locations before assembly. These pre-positioned features guide the stacking process and automatically align power generation units during assembly, ensuring precise retention of component structures without requiring complex assembly procedures. The preliminary formation of these structural features enables both high productivity and manufacturing precision.
Solution Approach 2:
The uneven buffers and boss structures on metal separators serve dual functions: they provide mechanical support for structural stability while simultaneously acting as self-aligning features during assembly. When power generation units are stacked alternately, these features automatically position components correctly, enabling the assembly process to self-correct and maintain manufacturing precision without external intervention or complex tooling.
Data Source
AI summary
There has been a problem that the cell units cannot bear the load exerted on the units while being stacked since a fuel cell stack including a refrigerant channel formed between cell units each having an even number of electrolyte/electrode structures (MEA) and metal separators which are alternated does not have any structure supporting the separators forming the refrigerant channel in a stacking direction. In order to solve the above problem, in each of a first power generating unit and a second power generating unit, projections formed at the buffer portions of the separators are disposed in the same positions in the stacking direction with the MEA interposed therebetween. Since between the first and second power generating units, the projections of the buffer portions are staggered, the projections of the first and second power generating units are thereby disposed in the same positions in the stacking direction.