Fuel Cell Case Segmentation and Friction Stir Welding

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Solution Overview

Problem

Existing fuel cell configurations with draft angles in their cases tend to increase the size of the fuel cell, leading to larger dimensions and potential deformation issues during manufacturing and operation.

Innovation Solution

A fuel cell design featuring a case with opposing side walls having draft angles, where the edges of these walls are joined using friction stir welding, minimizing size expansion and reducing the risk of deformation by optimizing the length and arrangement of these walls, and incorporating intervening layers to manage external forces and maintain contact with the cell stacked body.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a case with draft angles is formed by attaching a plate to a concave member, then the case can be manufactured, but the size of the fuel cell increases due to the draft angles

Engineering Contradiction:

Improvecase manufacturabilityVSAvoidfuel cell size

Core Design Contradiction:

Ease of manufactureVSVolume of moving object

Solution Approach 1:

The case is divided into two separate cases (first case and second case) that are joined together. Each case has draft angles on its side walls, but by splitting the structure, the overall fuel cell size is reduced compared to a single large case with draft angles. The segmentation allows each component to be optimized independently while maintaining manufacturability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first case and second case are joined together by joining their respective side walls to form a complete case structure. This merging of two smaller cases with draft angles creates a functional equivalent to a single large case but with reduced overall size and improved manufacturing characteristics.

Inventive Principle:

Principle #5Merging (Combining)

2Ease of manufacture

If the first case and second case are joined by attaching plates, then the case structure is complete, but deformation may occur during manufacturing and operation

Engineering Contradiction:

Improvecase assemblyVSAvoidstructural stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The joining method is changed from mechanical plate attachment to friction stir welding, which creates a stronger, more integrated bond between the first and second cases. This substitution of joining technology eliminates the deformation issues associated with plate attachment while maintaining ease of manufacture.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The case structure combines the first case and second case into a composite assembly where the joined side walls form an integrated structure. This composite construction provides enhanced structural stability and resistance to deformation during manufacturing and operation.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If draft angles are extended to the outer side of the case, then the case can be manufactured, but the case size expands

Engineering Contradiction:

Improvecase fabricationVSAvoidcase dimensions

Core Design Contradiction:

Ease of manufactureVSLength of stationary object

Solution Approach 1:

By dividing the case into two separate cases, each with its own draft angles, the patent reduces the overall dimensional impact. The draft angles on each smaller case produce less size expansion than a single large case with equivalent draft angles would produce.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The draft angles are applied locally to specific side walls of the first and second cases rather than uniformly across the entire case structure. This localized application of draft angles minimizes overall size expansion while maintaining the necessary manufacturability of each component.

Inventive Principle:

Principle #3Local quality

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 design effectively suppresses size expansion and deformation of the fuel cell, maintaining efficient operation and reducing the risk of damage from external forces, while also simplifying the manufacturing process by using lower temperature friction stir welding.

Implementation Method 1

A first edge of each of the first opposed side walls on an opposite side that is opposite to the first case side wall is joined with a second edge of each of the second opposed side walls on an opposite side that is opposite to the second case side wall

Methodology Applied

Scientific EffectFriction stir welding: Friction Welding

Data Source

PatentUS10559841B2Fuel cell and manufacturing method of fuel cell

Publication Date: 2020.02.11 TOYOTA JIDOSHA KK

AI summary

There is provided a fuel cell comprising a cell stacked body and a case configured to surround at least stacked body side faces of the cell stacked body. The case comprises a first case configured to include a first case side wall and a pair of first opposed side walls that are arranged to rise from a circumference of the first case side wall such as to have a draft angle; and a second case configured to include a second case side wall and a pair of second opposed side walls that are arranged to rise from a circumference of the second case side wall such as to have a draft angle. A first edge of each of the first opposed side walls is joined with a second edge of each of the second opposed side walls. This configuration suppresses size expansion of the fuel cell.