Fuel Cell Stack Retensioning for Stable Compression Sealing
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Solution Overview
Problem
Existing fuel cell stacks face challenges in maintaining consistent compression over time due to aging elastic tensioning elements, which can lead to reduced sealing effectiveness and potential damage from excessive tension or slackening, particularly in varying stack heights and temperatures.
Innovation Solution
A fuel cell stack design incorporating a rotatable mounting shaft with torsion springs that automatically retension elastic tensioning elements by storing potential energy, allowing for adjustable torque to maintain optimal compression force, preventing over-tensioning and ensuring consistent sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If elastic tensioning elements are used to compress the fuel cell stack, then the stack can be compressed and sealed, but the elasticity of the tensioning elements decreases over time leading to loss of compression force
Solution Approach 1:
The mounting shaft is designed to be rotatable, allowing dynamic adjustment of the tensioning element length. This enables the system to adapt to changes in stack height and compensate for aging effects by rewinding the tensioning element onto the shaft, thereby maintaining compression force throughout the service life.
Solution Approach 2:
The system allows changing the effective length of the tensioning element by winding it onto the mounting shaft. This parameter change compensates for the degradation of elasticity over time and accommodates thermal expansion/contraction of the stack, maintaining optimal compression force.
2Reliability
If the fuel cell stack is permanently compressed to ensure sealing, then sealing effectiveness is improved, but the stack cannot accommodate operational height variations caused by temperature and moisture changes
Solution Approach 1:
The rotatable mounting shaft provides a dynamic adjustment mechanism that allows the tensioning element length to be modified in response to stack height variations. This maintains sealing effectiveness while accommodating thermal and moisture-induced dimensional changes.
Solution Approach 2:
The system provides a mechanism for monitoring and adjusting compression force in response to changing conditions. The ability to rewind the tensioning element creates a feedback loop that maintains optimal sealing pressure despite operational variations.
3Reliability
If the mounting shaft is rotated to retension the tensioning element, then compression force is restored, but the system requires manual intervention and adjustment
Solution Approach 1:
The system is designed to be largely self-regulating. The rotatable mounting shaft can be adjusted by the operational team as needed, and the design inherently accommodates stack expansion through the rotational freedom of the shaft, reducing the need for frequent manual interventions.
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 solution ensures permanent and adjustable compression of the fuel cell stack, maintaining sealing effectiveness over extended periods by automatically retensioning tensioning elements, thus preventing damage from excessive tension or slackening, and accommodating operational height variations.
Implementation Method 1
at least one torsion spring connected to the mounting shaft and the fuel cell stack in a tensioned state
Implementation Method 2
torsion spring connected to the mounting shaft and the fuel cell stack in a tensioned state
Data Source
AI summary
A fuel cell stack is provided comprising a first end plate and a second end plate between which a plurality of fuel cells is arranged. At least one elastic tensioning element is tensioned in the stack direction between the end plates. Furthermore, the fuel cell stack has at least one rotatably mounted mounting shaft. At least one end section of at least one tensioning element is fixed to the rotating mounting shaft. Moreover, the rotatable mounting shaft is connected to the fuel cell stack via a tensioned torsion spring. The torsion spring brings about an automatic retensioning of the tensioning element.