Fuel Cell Stack Seal Integrity via Overmolded Grommet Seals
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Solution Overview
Problem
Existing fuel cell stack designs face issues with unbalanced forces leading to flexing and seal failure due to the use of mechanical fasteners, which result in leakage and inadequate seal compression, especially when insulating plates are bolted to aluminum end/frame plates.
Innovation Solution
The solution involves overmolding a seal, such as a grommet seal, onto an extruded frame plate with hollow cavities filled with a foam material, eliminating the need for mechanical fasteners by creating an integral unit with grommet-like seals that distribute seal forces effectively between the insulating and frame plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If mechanical fasteners are used to bolt insulating plates to aluminum end/frame plates, then the plates are securely connected, but unbalanced forces cause flexing and seal failure leading to leakage
Solution Approach 1:
The patent replaces the mechanical fastening system (bolts, nuts, and fasteners) with a compression-based sealing system. The seal is compressed between the insulating plate and the end/frame plate without mechanical fasteners, eliminating the unbalanced forces that caused flexing and seal failure. This substitution of the mechanical connection system with a direct compression sealing mechanism resolves the contradiction by maintaining connection strength while improving seal integrity.
Solution Approach 2:
The patent changes the physical parameters of the seal and compression mechanism to achieve balanced force distribution. By adjusting the compression force, seal material properties, and plate rigidity, the system achieves uniform stress distribution across the sealing interface, preventing localized flexing and seal failure while maintaining adequate connection strength.
2Strength
If mechanical fasteners are used to secure insulating plates, then connection is achieved, but many fasteners and parts are required increasing complexity
Solution Approach 1:
The patent merges the connection function and sealing function into a single integrated system. Instead of using separate mechanical fasteners and seals, the design combines these functions into a unified compression-based sealing mechanism that secures the insulating plate while creating the seal, thereby reducing the number of parts and simplifying the overall structure.
Solution Approach 2:
The patent extracts and eliminates the mechanical fastening components (bolts, nuts, washers, and other fasteners) from the assembly, retaining only the essential sealing elements. This extraction of unnecessary mechanical parts reduces device complexity while maintaining connection strength through the compression-based sealing system.
3Strength
If mechanical fasteners are used to attach insulating plates, then plates are secured, but seal compression is inadequate and seals are prone to leakage and failure
Solution Approach 1:
The patent replaces the mechanical fastening system with a dedicated compression sealing system that is specifically designed to apply uniform and adequate compression force to the seal. This substitution ensures proper seal compression without the interference of mechanical fasteners that created unbalanced forces, thereby improving manufacturing precision of the seal interface.
Solution Approach 2:
The patent applies local quality enhancements to the sealing interface, including optimized seal material properties, surface finish, and geometric features that concentrate and distribute compression forces appropriately. This localized optimization of the sealing zone ensures adequate and uniform seal compression while maintaining overall connection strength.
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
This approach enhances seal integrity and prevents flexing and seal offloading, reducing the number of parts and ensuring consistent seal compression without mechanical fasteners, thereby improving the reliability and efficiency of fuel cell stacks.
Implementation Method 1
The end frame plate may comprise an extruded piece comprising a plurality of hollow cavities. Such cavities may be filled with a cavity-filler material, which may comprise a foam material, which may facilitate the overmolding process.
Implementation Method 2
Overmolding a seal, such as a grommet seal, to an end frame plate of a fuel cell stack... creating an integral unit with grommet-like seals that distribute seal forces effectively between the insulating and frame plates.
Data Source
AI summary
Methods, apparatus, and systems for improving and/or simplifying one or more seals in a fuel cell stack, such as a vehicle fuel cell stack. In some implementations, a plate or assembly for the stack may be extruded through an extrusion die so as to create a plate comprising a top surface, a bottom surface, and a plurality of cavities disposed between the top and bottom surfaces. At least a subset of the cavities may be filled with a cavity-filler material distinct from a material used to form the plate, such as a foam material. One or more headers, such as grommet seals, may then be overmolded into the plate to form corresponding conduits between the top surface and the bottom surface of the plate/assembly.