Fuel Cell Separator Weld Layout for Sealing Pressure Retention

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Solution Overview

Problem

The uniformity of reaction force across the bead portions of fuel cell separators is challenging due to variations in stiffness caused by through-holes, embossed portions, and ribs, leading to excessive heat input at weld meeting points, which can reduce the sealing property.

Innovation Solution

Form the weld meeting points at high-stiffness areas away from the bead portions to prevent thermal contraction and maintain the required surface pressure for sealing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a metal substrate is used as a fuel cell separator, then electrical conductivity and mechanical strength are improved, but susceptibility to stress cracking and corrosion increases

Engineering Contradiction:
Improvemechanical strengthVSAvoidresistance to stress cracking
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent applies composite materials by coating a metal substrate with a porous layer comprising a porous inorganic backbone and an organic-inorganic composite coating. This composite structure combines the high strength and electrical conductivity of metal with the corrosion and stress cracking resistance of ceramic and polymer materials, resolving the contradiction between mechanical strength and reliability.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent uses porous materials by forming a porous inorganic backbone layer and an organic-inorganic composite porous coating on the metal substrate. The porous structure provides pathways for reactant gas flow while maintaining mechanical integrity and providing barrier protection against corrosion and stress cracking, thus improving reliability without sacrificing strength.

Inventive Principle:
Principle #31Porous materials

2Use of energy by moving object

If a metal substrate is used as a fuel cell separator, then electrical conductivity is improved, but corrosion resistance deteriorates

Engineering Contradiction:
Improveelectrical conductivityVSAvoidcorrosion resistance
Core Design Contradiction:
Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies composite materials by coating a metal substrate with a porous layer comprising a porous inorganic backbone and an organic-inorganic composite coating. This composite structure combines the high strength and electrical conductivity of metal with the corrosion and stress cracking resistance of ceramic and polymer materials, resolving the contradiction between mechanical strength and reliability.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent uses porous materials by forming a porous inorganic backbone layer and an organic-inorganic composite porous coating on the metal substrate. The porous structure provides pathways for reactant gas flow while maintaining mechanical integrity and providing barrier protection against corrosion and stress cracking, thus improving reliability without sacrificing strength.

Inventive Principle:
Principle #31Porous materials

3Reliability

If organic-inorganic composite porous coating is applied, then corrosion and stress cracking resistance are improved, but manufacturing complexity increases

Engineering Contradiction:
Improveresistance to stress crackingVSAvoidcoating structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the protective coating into two distinct functional layers: a porous inorganic backbone layer and an organic-inorganic composite porous coating layer. This segmented structure allows each layer to perform its specific function (structural support and corrosion/stress cracking protection) while simplifying the overall manufacturing process through sequential application of standardized layers.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies parameter changes by controlling the pore size, porosity, and compositional parameters of each coating layer to optimize both protective performance and manufacturability. By adjusting these parameters within defined ranges, the patent achieves reliable stress cracking and corrosion resistance without requiring overly complex multi-layer or gradient structures.

Inventive Principle:
Principle #35Parameter changes

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

Prevents reduction in sealing property by ensuring consistent bead height and maintaining high reaction force through strategic weld placement at high-stiffness areas.

Implementation Method 1

a porous coating layer covering the surface of the metal substrate and having a water retention function

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Implementation Method 2

an anodized layer formed on a metal substrate

Methodology Applied
Scientific EffectAnodizing: Anodising

Implementation Method 3

a porous inorganic backbone and an organic-inorganic composite coating formed on the porous inorganic backbone

Methodology Applied
Scientific EffectStress distribution through porous structure: Porosity

Data Source

PatentEP4343899B1Fuel cell separator manufacturing method and fuel cell separator
Publication Date: 2026.05.06 NOK CORP
  • EP4343899B1 patent drawingFigure 1~2
  • EP4343899B1 patent drawingFigure 3
  • EP4343899B1 patent drawingFigure 4

AI summary

Provided is a manufacturing method of a fuel cell separator and a fuel cell separator that can prevent a reduction of a sealing property. The manufacturing method of the fuel cell separator includes an overlaying step of overlaying a first metal separator (21) and a second metal separator (22) together, the first metal separator (21) and the second metal separator (22) each including a flat portion (30) and a bead portion (31) protruding from the flat portion (30), a welding step of welding along the bead portion (31) overlaid flat portions (30), and in the welding step, a weld meeting point (Z) where welded portions meet is formed at an area which is away from the bead portion (31) and/or which is to be a high stiffness part (U) with a high stiffness on a welding path.