Fuel Cell Stack Case Thermal Expansion Mounting

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Solution Overview

Problem

The existing supporting structure for fuel cell stacks in vehicles fails to effectively manage the thermal expansion and contraction of fuel cell stacks, leading to deformation of rubber mounts and reduced durability due to shear forces, which compromises the vibration-blocking function and longevity of the mounts.

Innovation Solution

A fuel cell assembly design that includes a case housing the fuel cell stack, allowing for expansion and contraction, supported by an elastic member, and utilizing bolts to secure the supporting members to the case, with coil springs and high-tensile strength bolts to absorb and distribute loads, ensuring the rubber mounts are not subjected to deformation-causing forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the fuel cell stack is rigidly fixed to the vehicle using rubber mounts, then the vibration-blocking function is effective, but the rubber mount deforms due to thermal expansion shear forces reducing durability

Engineering Contradiction:

Improvevibration-blocking functionVSAvoiddurability of rubber mount

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent divides the support structure into multiple independent rubber mounts positioned at different locations on the fuel cell stack. Each rubber mount independently absorbs vibration and displacement, preventing concentrated stress on a single mount. This segmentation allows the stack to expand and contract thermally while maintaining overall stability and protecting individual mounts from excessive deformation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The rubber mounts serve as intermediary elements between the fuel cell stack and the vehicle chassis. These elastic intermediaries absorb the shear forces generated by thermal expansion, isolating the rigid stack from the vehicle structure while maintaining positional stability. The intermediary rubber components deform elastically to accommodate dimensional changes, protecting the primary structural elements.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If the fuel cell stack is allowed to expand and contract freely, then thermal stress is reduced, but the vibration-blocking function is compromised

Engineering Contradiction:

Improveresistance to thermal stressVSAvoidvibration-blocking function

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent utilizes the elastic properties of rubber mounts to accommodate parameter changes in the fuel cell stack dimensions during thermal cycling. The rubber mounts are designed with specific durometer and geometry to allow controlled deformation within certain displacement limits, absorbing thermal expansion forces while maintaining sufficient rigidity to block vibrations. This parameter-based design enables simultaneous achievement of thermal stress relief and vibration isolation.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If multiple rubber mounts are used to support the fuel cell stack, then vibration isolation is improved, but the complexity of the supporting structure increases

Engineering Contradiction:

Improvevibration-blocking functionVSAvoidcomplexity of supporting structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs multiple identical or similar rubber mount designs positioned at different locations on the fuel cell stack. This homogeneous approach simplifies manufacturing, installation, and maintenance while achieving distributed vibration isolation. Each mount has the same material properties and geometric characteristics, allowing for standardized production and easy replacement, thus reducing overall system complexity despite the increased number of components.

Inventive Principle:

Principle #33Homogeneity

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 design allows for the fuel cell stack to expand and contract without deforming the rubber mounts, maintaining their vibration-blocking function and extending their durability, while ensuring efficient distribution of loads and preventing gas or coolant leaks.

Implementation Method 1

The fuel cell stack generates heat due to a power generating reaction, and expands or contracts according to the temperature variation

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

an elastic member which supports the case in the vehicle

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS8771853B2Fuel cell assembly

Publication Date: 2014.07.08 NISSAN MOTOR CO LTD

AI summary

A fuel cell assembly (1) for mounting in a vehicle comprises a fuel cell stack (2) comprising two stack units (2a, 2b) arranged in parallel. Each of the stack units (2a, 2b) comprises a number of fuel cells stacked in a fixed direction. The fuel cell stack (2) is housed in a case (3). The case (3) is supported in the vehicle via a rubber mount (36). The case (3) permits expansion and contraction of the fuel cell stack (2) in the fixed direction so that the expansion and contraction of the fuel cell stack (2) does not exert a force on the rubber mount (36).