Fuel Cell Stack Sealing Mounting Holes
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Solution Overview
Problem
Conventional fuel cell stacks experience leakage of reaction gases, particularly hydrogen gas, through gaps between unit cells, leading to potential corrosion due to water ingress into the casing, especially at the interface between end plates and coupling bars.
Innovation Solution
Incorporation of seal members within the mounting holes of the end plates and coupling bars, where the fastening member is inserted, to prevent gas leakage and water ingress, ensuring close contact with the inner surfaces of the mounting holes and the cylindrical knock, thereby blocking gas flow and water entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the end plates and coupling bar are fastened using mounting holes and fastening members, then the structural integrity of the fuel cell stack is improved, but reaction gas leaks through the mounting holes and water can ingress causing corrosion
Solution Approach 1:
A seal member is introduced as an intermediary component between the end plate, coupling bar, and fastening member. The seal member fills the mounting hole and creates a barrier that prevents hydrogen gas leakage and water ingress while allowing the fastening member to maintain structural integrity of the joint
Solution Approach 2:
The seal member is implemented as a flexible sealing element (such as an O-ring or gasket) that is inserted into the mounting hole. This flexible component deforms to conform to the mounting hole geometry and creates an effective seal against gas and liquid penetration while maintaining the mechanical fastening function
2Reliability
If seal members are added to prevent gas leakage and water ingress, then sealing reliability is improved, but device complexity increases
Solution Approach 1:
The seal member serves multiple functions simultaneously: it prevents hydrogen gas leakage from the fuel cell stack, blocks water ingress that would cause corrosion of the cylindrical knock and fastening members, and maintains the sealing interface between the end plate and coupling bar. This multi-functionality achieves improved reliability without proportionally increasing complexity
Data Source
AI summary
A fuel cell stack includes a pair of end plates disposed on opposing sides of a fuel cell stacked body in a first direction, a coupling bar that bridges between the end plates, a fastening member that connects the end plates and the coupling bar in the first direction, and a cylindrical knock disposed inside an end plate side mounting hole and a coupling bar side mounting hole of the end plates and the coupling bar in the first direction, and being externally fitted to the fastening member inside the end plate side mounting hole and the coupling bar side mounting hole. A first seal member in close contact with at least an inner circumferential surface of the end plate side mounting hole and the fastening member is disposed in a portion located between the cylindrical knock and the fastening member inside the end plate side mounting hole.