Aircraft Waste Tank Drain Cap With Pressure Balancing
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Solution Overview
Problem
The existing drainage devices in aircraft waste water tanks face difficulties in opening the cap due to pressure imbalances, leading to potential leakage and operational challenges during drainage operations.
Innovation Solution
A pressure balancing system is integrated into the drainage device, featuring a cap with through-orifices and a balancing valve that allows communication between inner and outer zones, balancing pressures and facilitating easier cap opening by adjusting the peripheral edge's contact with the cap face.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cap is used to close the downstream end of the drainage duct, then leakage is prevented, but the cap becomes difficult to open due to pressure imbalance
Solution Approach 1:
A pressure equalization valve is introduced as an intermediary mechanism between the inner and outer zones. This valve allows controlled pressure equalization through a passage, mediating the pressure imbalance that makes cap opening difficult while maintaining the seal when closed. The valve acts as a mediator that temporarily relieves the pressure differential without compromising the overall sealing function.
Solution Approach 2:
The system changes the pressure parameter dynamically by introducing a pressure equalization valve that can open and close. When the valve opens, it changes the pressure condition from imbalanced to balanced, making cap opening easy. When closed, it maintains the pressure imbalance needed for reliable sealing. This parameter change allows the system to switch between contradictory states as needed.
2Reliability
If the cap is designed to seal tightly, then leakage is prevented, but the force required to open the cap increases
Solution Approach 1:
The pressure equalization valve serves as an intermediary that reduces the force needed to open the cap. By allowing pressure equalization through its passage when open, it mediates the force requirement, enabling the cap to be opened with minimal effort while maintaining tight sealing when closed through the coordinated action of the valve and cap.
3Device complexity
If a simple cap design is used, then device complexity is reduced, but pressure balancing capability is lost
Solution Approach 1:
The system is segmented into distinct functional components: the cap and the pressure equalization valve. This segmentation allows the cap to maintain its simple sealing function while the valve handles the pressure balancing task. The through-orifice is also a separate element that enables communication between zones. This segmentation resolves the contradiction by distributing functions across multiple simple components rather than complicating the cap itself.
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 pressure balancing system effectively balances pressures on either side of the cap, making it easier to open and ensuring a secure seal, thereby preventing leakage and simplifying the drainage process.
Implementation Method 1
a pressure balancing system having at least one through-orifice connecting the inner and outer faces of the cap and at least one balancing valve supported by the cap and configured to occupy an open state in which the balancing valve allows the inner and outer zones to communicate with each other via the (one or more) through-orifice(s)
Data Source
AI summary
A drainage device for a tank of an aircraft comprising a drainage duct that has an upstream end, configured to open into the tank, and a downstream end, a drainage valve positioned between the upstream and downstream ends of the drainage duct, a cap configured to occupy a closed position in which it closes off the downstream end of the drainage duct, a pressure balancing system configured to balance the pressures on either side of the cap when the latter is in the closed position. Also an aircraft having at least one such drainage device.