Semi-Permeable Drain Valve for Aircraft Light Pressure Venting
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Solution Overview
Problem
Exterior aircraft light units face issues with excessive water accumulation due to air pressure changes during flight, leading to potential damage and reduced functionality, as existing venting solutions fail to effectively prevent liquid water entry while allowing air and water vapor exchange.
Innovation Solution
A drain valve with a movable plunger and semi-permeable membrane that allows air and water vapor to pass while preventing liquid water entry, using an elastic element to automatically switch between sealing and venting positions based on pressure differences, ensuring reliable and cost-effective drainage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a drain valve allows air and water vapor to pass through for pressure equalization, then venting effectiveness is improved, but liquid water may enter the enclosed space
Solution Approach 1:
The patent employs a semi-permeable membrane with microporous structure that allows air and water vapor to pass through while blocking liquid water. The membrane's pore size is specifically designed to permit gas molecules while preventing liquid droplets from penetrating, thus resolving the contradiction between effective venting and water prevention.
Solution Approach 2:
The drain valve combines multiple materials with different properties: a hydrophobic coating on the membrane surface, the semi-permeable membrane itself, and a movable plunger mechanism. This composite structure leverages the complementary properties of each material to achieve both gas permeability and liquid blocking functionality.
2Object-affected harmful factors
If a drain valve uses a movable plunger to block liquid water, then water prevention is improved, but air and water vapor exchange is restricted
Solution Approach 1:
The plunger is designed with a localized hydrophobic coating only on its outer surface that contacts the membrane, while the interior surface and passage remain open. This local differentiation allows the plunger to block liquid water through surface tension at the interface while maintaining an open channel for gas molecules to pass through the hydrophobic surface.
Solution Approach 2:
The hydrophobic coating is applied uniformly across the plunger's outer surface, creating a consistent barrier property that reliably repels liquid water while allowing gas permeability. The homogeneous treatment ensures predictable performance across the entire sealing interface.
3Productivity
If a drain valve provides a wide opening for water drainage, then drainage efficiency is improved, but the risk of liquid water entering during normal operation increases
Solution Approach 1:
The plunger is designed to be movable rather than fixed, allowing it to dynamically adjust its position and the effective opening size based on the pressure differential and water accumulation level. During normal operation, the plunger maintains a restricted opening that prevents water entry, while during drainage events, the opening can expand to accommodate water flow.
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 drain valve effectively vents and drains exterior aircraft light units and power supply boxes, preventing liquid water entry while allowing air and water vapor exchange, thereby maintaining unit functionality and safety without external control, and reducing the risk of explosions from hot gases.
Implementation Method 1
Said at least one duct is sealed by a semi-permeable medium, which is permeable for air and water vapor in case a predetermined pressure difference is exceeded, and which is impermeable for liquid water even if the predetermined pressure difference is exceeded
Implementation Method 2
Due to temperature differences, water vapor comprised in air flowing into the exterior aircraft light unit may condense within the exterior aircraft light unit
Implementation Method 3
an elastic element, which is configured to urge the movable plunger into its closed position
Implementation Method 4
the elastic element urges the plunger back into its closed position sealing the valve
Data Source
AI summary
A drain valve for draining liquid from an enclosed space comprises a movable plunger, which is movable between a closed position in which the plunger does not allow liquid to flow through the drain valve, and at least one open position, in which the plunger allows liquid to flow through the drain valve; and an elastic element, which is configured to urge the movable plunger into its closed position. The plunger is provided with at least one duct extending through the plunger and allowing fluid to flow through the drain valve when the plunger is positioned in its closed position, wherein said at least one duct is closed by a semi-permeable medium, which is permeable for air and water vapor and impermeable for liquid water.