Pole Cap Pressure Connection for Leak-Tight Composite Vessels

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Solution Overview

Problem

Current fiber-reinforced pressure vessels with plastic liners face challenges in maintaining leak-tightness due to deformation under high pressures, requiring a reliable and easy-to-assemble fitting that remains secure throughout the vessel's service life.

Innovation Solution

A pole cap with a conically designed sealing cone and bushing, where the sealing cone is pressed into the bushing from the inside and secured by a fixing means, creating a high sealing effect by distributing pressure over a larger area, preventing deformation and leakage, and an attachment element to prevent radial deformation of the bushing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a metal connection piece is used to connect the pressure vessel valve to the CFRP pressure vessel with plastic liner, then the connection remains leak-tight under high pressure, but the assembly becomes more complex and difficult to install

Engineering Contradiction:
Improveleak-tightnessVSAvoidconnection complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces a connection piece with a conical pressing surface that acts as an intermediary between the sealing cone and the plastic liner. This intermediary component distributes the pressing force over a larger conical surface area, preventing material flow while maintaining leak-tightness. The connection piece simplifies the overall assembly by providing a standardized interface that combines sealing and mechanical connection functions.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the geometric parameters of the connection interface by using conical surfaces instead of cylindrical or threaded connections. The conical pressing surface with specific angle and dimensions transforms the pressure distribution, converting concentrated point loads into distributed area loads, which prevents plastic material flow while maintaining connection integrity under high pressure.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If high pressing force is applied to ensure tight sealing, then leak-tightness is improved, but the plastic material deforms and flows away under the connection surface

Engineering Contradiction:
Improvesealing effectVSAvoidmaterial deformation
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the geometric parameters of the connection interface by using conical surfaces instead of cylindrical or threaded connections. The conical pressing surface with specific angle and dimensions transforms the pressure distribution, converting concentrated point loads into distributed area loads, which prevents plastic material flow while maintaining connection integrity under high pressure.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent transitions from a one-dimensional point or line contact to a two-dimensional conical surface contact. By expanding the sealing interface from a narrow ring to a broad conical surface, the pressing force is distributed over a much larger area, reducing the pressure intensity at any given point and preventing material flow while maintaining effective sealing.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Weight of moving object

If the plastic liner is used for type 4 pressure vessels to reduce cost and weight, then manufacturing cost and weight are reduced, but the connection reliability under high pressure becomes problematic

Engineering Contradiction:
Improvevessel weightVSAvoidconnection reliability
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

The patent changes the geometric parameters of the connection interface by using conical surfaces instead of cylindrical or threaded connections. The conical pressing surface with specific angle and dimensions transforms the pressure distribution, converting concentrated point loads into distributed area loads, which prevents plastic material flow while maintaining connection integrity under high pressure.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite connection system combining metal components (sealing cone, connection piece) with the plastic liner. The metal components provide the rigid structural framework and sealing surfaces, while the plastic liner provides corrosion resistance and weight reduction. The conical interface design ensures compatible deformation characteristics between the metal and plastic materials under high pressure.

Inventive Principle:
Principle #40Composite materials

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 ensures a pressure-tight connection that remains leak-tight under high pressures, extending the service life of the pressure vessel and allowing for the storage of gases like hydrogen with low losses, suitable for high-pressure applications without compromising the fiber reinforcement.

Implementation Method 1

creating a high sealing effect by distributing pressure over a larger area, preventing deformation and leakage

Methodology Applied
Scientific EffectPressure distribution: Pascal's Law

Implementation Method 2

The cone-shaped contour of the sealing body makes it possible for a sealing cone inserted into the passage from the inside of the pole cap to assume a press fit in the inner contour of the neck-shaped passage

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 3

secured by a fixing means, creating a high sealing effect

Methodology Applied
Scientific EffectMechanical fastening: Mechanical Fastener

Implementation Method 4

an attachment element to prevent radial deformation of the bushing

Methodology Applied
Scientific EffectRadial constraint:

Data Source

PatentEP3366975B1Pole cap with pressure connection element for pressure vessels
Publication Date: 2021.12.29 NPROXX BV
  • EP3366975B1 patent drawingFigure 1
  • EP3366975B1 patent drawingFigure 2
  • EP3366975B1 patent drawingFigure 3

AI summary

The invention relates to a pole cap (1) made of a plastic material for pressure-tight sealing of a pressure vessel (100), a pressure vessel (100) with such a pole cap (1) and methods (200, 300) for manufacturing such a pole cap (1) and such a pressure vessel (100).The pole cap (1) comprises an inner side (11) for later closure of the pressure vessel (100), an outer side (12) for wrapping with a fiber composite material (3) after closure of the pressure vessel (100), and a neck-shaped open passage (13) projecting outwards from the outer side with an inner contour (13i), each made of plastic material, and a pressure connection element (2) connected to the passage (13) for closure of the passage (13), wherein the pressure connection element (2) comprises a sealing cone (21) made of metal with a first section (21a) projecting outwards through the passage (13) and with a second section (21b) tapering conically towards the first section (21a), at least in the area of ​​the passage (13), which is held in a pressure-tight press fit in the inner contour (13i) by means of a fixing means (22) arranged from the outside on the first section (21a).