Gas-Retaining Surface Covering for Stable Underwater Air Layers

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Solution Overview

Problem

Existing technologies fail to permanently separate a submerged body from surrounding liquid using a layer of air, as air escapes and dissolves in the water, limiting the immersion time and effectiveness in technical applications.

Innovation Solution

A gas-retaining layer is designed for a body that can be immersed in a liquid, featuring a hydrophobic surface with recesses or projections, and a gas-permeable layer connected to a gas supply device, maintaining a constant gas volume and separating the body from the liquid.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If a natural surface structure is used to trap air, then buoyancy and breathing are improved, but the air layer diminishes over time due to gas detachment and dissolution

Engineering Contradiction:
Improveair layer stabilityVSAvoidair loss
Core Design Contradiction:
Duration of action of moving objectVSLoss of substance

Solution Approach 1:

The surface is divided into numerous hydrophobic recesses or cavities that individually trap air pockets. This segmentation prevents complete air loss by providing multiple isolated reservoirs, extending the duration the air layer can maintain separation from the liquid.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The surface structure incorporates regions with different properties: hydrophobic surfaces for air retention in recesses, and potentially hydrophilic regions for controlled gas exchange. This local differentiation allows the surface to simultaneously retain air for buoyancy while managing gas dissolution rates.

Inventive Principle:
Principle #3Local quality

2Reliability

If a gas-retaining layer with hydrophobic surface is used, then permanent separation from liquid is achieved, but device complexity increases

Engineering Contradiction:
Improvepermanent separationVSAvoidlayer structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The gas-retaining layer is implemented as a thin film or coating with integrated hydrophobic recesses, rather than a thick rigid structure. This thin-film approach provides reliable liquid separation while minimizing added complexity and weight, making the system practical for various applications.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The surface covering combines multiple materials or structures: a base material providing mechanical strength, hydrophobic coatings or treatments for air retention, and potentially porous structures for gas permeability. This composite approach achieves reliable separation without requiring each component to be overly complex.

Inventive Principle:
Principle #40Composite materials

3Stability of the object's composition

If gas is continuously supplied through a gas-permeable layer, then constant gas volume is maintained, but energy consumption increases

Engineering Contradiction:
Improvegas volume stabilityVSAvoidgas supply energy
Core Design Contradiction:
Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

The system uses the body's own movements or environmental conditions to drive gas exchange. For example, flexing of the body or pressure changes during operation naturally force gas through the permeable layer, eliminating or reducing the need for active pumping and associated energy consumption.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

Instead of continuous gas supply, the system utilizes periodic pressure changes or movement cycles that naturally drive gas through the permeable layer at appropriate intervals. This periodic action maintains gas volume stability while significantly reducing average energy consumption compared to continuous supply.

Inventive Principle:
Principle #19Periodic action

4Productivity

If hydrophobic projections are used to retain gas, then flow resistance is reduced, but manufacturing precision requirements increase

Engineering Contradiction:
Improveflow efficiencyVSAvoidprojection geometry
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The invention specifies ranges for projection parameters (size, spacing, shape) rather than requiring exact dimensions. By defining acceptable parameter ranges that all provide sufficient flow resistance reduction, the manufacturing precision requirements are relaxed while maintaining the functional benefit.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

Rather than requiring perfectly optimized projection geometry, the system uses sufficiently dense or pronounced projections that provide adequate flow resistance reduction even with manufacturing variations. This partial optimization approach achieves acceptable flow efficiency without demanding extreme manufacturing precision.

Inventive Principle:
Principle #16Partial or excessive action

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 maintains a permanent separation between the body and liquid, reducing corrosion and fouling, while minimizing flow resistance and extending immersion time by maintaining a stable gas layer.

Implementation Method 1

the gas-retaining layer (10) has, at least partially, recesses or depressions (30) on the liquid-facing side (10a), the surfaces of which are at least partially hydrophobic

Methodology Applied
Scientific EffectHydrophobe: Hydrophobe

Implementation Method 2

a gas layer (5) held in the immersed region of the gas-retaining layer (10) separates the liquid (4) and the immersed region of the body (2) from each other at least partially

Methodology Applied
Scientific EffectPhysical separation by gas layer:

Implementation Method 3

a gas-permeable layer (12) which is arranged on the gas-retaining layer (10) on a body-facing side (10b) opposite the liquid-facing side (10a)

Methodology Applied
Scientific EffectGas permeability: Permeation

Data Source

PatentEP3791968A1Gas containing surface covering, assembly and use
Publication Date: 2021.03.17 BADEN WURTTEMBERG STIFFUNG GMBH
  • EP3791968A1 patent drawingFigure 1
  • EP3791968A1 patent drawingFigure 2
  • EP3791968A1 patent drawingFigure 3a~3f

AI summary

The invention relates to a gas-retaining surface covering for a body contactable with a liquid, as well as a corresponding arrangement and use.