Flexible Stack Compression for Lightweight Fuel Cells

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Solution Overview

Problem

Conventional compression methods for fuel cell and electrolyser stacks, such as using rods, bolts, or straps, are not suitable for lightweight applications due to their high mass and cost, and scaling down these components is difficult, while springs are not ideal for longer lifetime applications.

Innovation Solution

A compression hardware system using flexible elements, such as cables or ropes, to compress electrochemical unit cells, providing mechanical advantage and accommodating length variations, replacing traditional rods and straps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional rods, bolts, or straps are used to compress fuel cell and electrolyser stacks, then the compression strength and structural stability are sufficient, but the mass and cost increase significantly

Engineering Contradiction:
Improvecompression strengthVSAvoidmass of compression hardware
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent changes the fundamental parameter of the compression element from rigid (rods, bolts, straps) to flexible (cables, ropes, springs). This parameter change enables the use of lighter materials while maintaining compression capability through elastic deformation and mechanical advantage principles.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the conventional rigid mechanical compression system with a flexible element-based system that utilizes elastic potential energy storage and mechanical advantage. The flexible elements can be arranged in configurations that amplify force while reducing the mass of the compression hardware.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Stability of the object's composition

If rods and bolts are used for compression, then the structural stability is maintained, but the adaptability to different stack configurations and power levels is reduced

Engineering Contradiction:
Improvestructural stabilityVSAvoidadaptability to stack configurations
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent introduces dynamic flexibility into the compression system by using flexible elements that can adapt their configuration. The flexible elements can be arranged in various patterns (parallel, series, combinations) and can accommodate different stack lengths and compression requirements, enabling the same basic compression hardware design to serve multiple stack configurations and power levels.

Inventive Principle:
Principle #15Dynamics

3Duration of action of stationary object

If compression springs are added to compensate for material compression set, then the lifetime is extended, but the device complexity and assembly difficulty increase

Engineering Contradiction:
Improvelifetime of stackVSAvoidcomplexity of compression hardware
Core Design Contradiction:
Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent merges the compression function with the lifetime extension function by using flexible elements that inherently provide both compression force and compensation for material compression set. The flexible elements themselves act as the springs that compensate for GDL and seal compression, eliminating the need for separate spring components and reducing overall device complexity.

Inventive Principle:
Principle #5Merging (Combining)

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 flexible elements offer a lightweight and cost-effective solution that maintains compression and stiffness, allowing for power optimization and accommodating length changes, enhancing gravimetric power density and dimensional stability.

Implementation Method 1

Using the principle of mechanical advantage, the at least one flexible element can apply more compressive force than that of an equivalent rod under the same tensile stress

Methodology Applied
Scientific EffectMechanical advantage: Mechanical Advantage

Implementation Method 2

With the at least one flexible element, variations in the fuel cell and/or electrolyser stack length can be simply compensated

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4651247A1Compression hardware for compressing several electrochemical unit cells of a fuel cell and/or electrolyser stack for lightweight applications
Publication Date: 2025.11.19 AVL LIST GMBH
  • EP4651247A1 patent drawingFigure 1
  • EP4651247A1 patent drawingFigure 2
  • EP4651247A1 patent drawingFigure 3

AI summary

The invention is related to a compression hardware (10) for compressing several electrochemical unit cells (110) of a fuel cell and/or electrolyser stack (100), wherein the compression hardware (10) comprises two end elements (14, 16) for exerting pressure on the several electrochemical unit cells (110) of the fuel cell and/or electrolyser stack (100), wherein the two end elements (14, 16) are arrangeable on two opposite sides of the several electrochemical unit cells (110), and at least one flexible element (18) for mechanically connecting the two end elements (14, 16), wherein the at least one flexible element (18) is configured to exert a compressive force on the two end elements (14, 16) for compressing the several electrochemical unit cells (110) of the fuel cell and/or electrolyser stack (100).