Thermally Foamable Protective Member for Hydrogen Tank Head

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Solution Overview

Problem

Existing pressure vessels storing hydrogen face issues with increased mass and volume due to protective layers, requiring downsizing, cost reduction, resource conservation, simplified manufacturing, and improved usability.

Innovation Solution

A pressure vessel design that uses a thermally foamable material to protect the tank head section with a double-layer protective member, where the inner layer provides impact protection and the outer layer, containing expanded graphite, enhances heat insulation without increasing the vessel's outer diameter, and includes a production method using mold forming to reduce material costs and ensure bonding between layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protective layer is added to protect the tank head section, then impact protection is improved, but mass and volume increase

Engineering Contradiction:

Improveimpact protectionVSAvoidmass of pressure vessel

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The protective member utilizes thermally foamable material that changes density and volume through foam expansion, creating a lightweight yet effective protective structure. The foam expansion ratio and density distribution are controlled to achieve optimal protection-to-weight ratio.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The protective member is constructed as a composite structure combining thermally foamable material with heat insulating material, creating a multi-functional protective layer that provides both impact protection and thermal insulation while maintaining low mass.

Inventive Principle:

Principle #40Composite materials

2Reliability

If a protective layer is added to protect the tank head section, then impact protection is improved, but volume increases

Engineering Contradiction:

Improveimpact protectionVSAvoidvolume of pressure vessel

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The thermally foamable material undergoes controlled expansion to increase protective volume only where needed for impact absorption, while the overall outer diameter of the pressure vessel is maintained within specified limits through precise foam expansion control.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The protective member is designed to expand in the radial dimension through foam expansion, providing protection without increasing the axial length or overall volume of the pressure vessel beyond acceptable limits.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Temperature

If thermally foamable material is used for protection, then heat insulation is improved, but heat release performance may deteriorate

Engineering Contradiction:

Improveheat insulationVSAvoidheat release performance

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The protective member applies heat insulation only to the tank head section where impact protection is needed, while leaving other portions of the pressure vessel with different thermal characteristics, thus maintaining overall heat release performance while providing localized insulation.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The protective member is designed as a thin-walled foam structure that provides adequate insulation without creating excessive thermal resistance, allowing heat to dissipate through the protective layer without significantly impeding overall heat release performance.

Inventive Principle:

Principle #30Flexible shells and thin films

4Reliability

If the protective member covers the shell plate section, then protection is improved, but outer diameter increases

Engineering Contradiction:

Improveprotection coverageVSAvoidouter diameter

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The protective member is designed to cover only the tank head section rather than the entire pressure vessel, segmenting the protection coverage to the specific area requiring impact protection while avoiding increase in overall outer diameter caused by covering the shell plate section.

Inventive Principle:

Principle #1Segmentation

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 solution effectively reduces the mass and volume of the pressure vessel while maintaining heat release performance and impact protection, ensuring the protective member does not interfere with safety valves and allows for efficient hydrogen filling without slowing down the filling rate.

Implementation Method 1

a thermally foamable material to protect the tank head section with a double-layer protective member, where the inner layer provides impact protection and the outer layer, containing expanded graphite, enhances heat insulation

Methodology Applied

Scientific EffectThermal foaming: Phase Change

Data Source

PatentEP2905527B1Pressure vessel and production method therefor

Publication Date: 2017.10.25 TOYOTA JIDOSHA KK

AI summary

A second protective member (62) is provided to cover a thin wall portion and its periphery of a second tank head section (92), so as to protect the thin wall portion. The thin wall portion is a region of the second tank head section (92) in which a reinforcing layer (20) has a smaller wall thickness. The second protective member (62) has a double layer structure including an inner layer made of polyurethane and an outer layer made of a material mixture of polyurethane and expanded graphite. This structure suppresses the mass and the volume of a pressure vessel from being increased by the presence of a protective layer.