Aircraft Wastewater Control Module Fail-Safe Valve Design
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Solution Overview
Problem
Conventional wastewater control modules for aircraft vacuum disposal systems are unreliable due to issues with foreign bodies, vibrations, and temperature sensitivity, leading to uncontrolled valve operation and potential backflow, and are not fail-safe or suitable for aviation environments.
Innovation Solution
A wastewater control module with a storage container, inlet, and outlet connected to a vacuum suction line, featuring a valve with a membrane-sealed valve body and a control chamber that can be actively closed by pneumatic support, ensuring reliable operation and preventing backflow, even in the absence of negative pressure, with a pilot valve and mechanical spring for fail-safe closure, and a conical design for easy ice removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional vacuum disposal system is used, then the system is simple in structure, but the noise level becomes excessively high at the end of emptying
Solution Approach 1:
The system is divided into two functional parts: a buffer storage container that accumulates wastewater and a separate vacuum disposal system that empties it. This segmentation allows the noisy emptying operation to occur separately from the usage phase, reducing noise impact during normal operation.
Solution Approach 2:
Wastewater is collected and stored in the buffer container before being emptied by the vacuum system. This preliminary accumulation allows the system to handle multiple small amounts of wastewater in one controlled emptying cycle, reducing the frequency and intensity of noisy operations.
2Extent of automation
If a float-controlled valve is used in the intermediate store, then automatic emptying is achieved, but the valve becomes unreliable due to foreign bodies, vibrations, and temperature changes
Solution Approach 1:
The float-controlled mechanical valve system is replaced with a valve actuated by negative pressure from the vacuum system. This substitution eliminates the reliability issues associated with float valves in mobile applications, including sensitivity to foreign bodies, vibrations, and temperature changes.
Solution Approach 2:
Negative pressure from the vacuum system serves as an intermediary to actuate the valve, replacing the direct mechanical float control. This intermediary mechanism provides more reliable valve operation under the challenging conditions of mobile applications.
3Extent of automation
If negative pressure is used to hold the valve closed, then automatic emptying is enabled, but the system becomes non-fail-safe and allows backflow when vacuum fails
Solution Approach 1:
A mechanical spring provides a counteracting force to the negative pressure that holds the valve closed. This spring force ensures the valve closes reliably even when vacuum pressure is insufficient or fails, making the system fail-safe and preventing backflow.
4Object-affected harmful factors
If an intermediate storage container is added, then noise is reduced by separating accumulation from emptying, but the device complexity increases
Solution Approach 1:
The buffer storage container is integrated with the existing vacuum disposal system components, merging the storage function with the disposal mechanism. This integration minimizes the increase in overall system complexity while achieving noise reduction through separated accumulation and emptying operations.
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 reliable and fail-safe operation, preventing backflow and ensuring the module remains functional in varying pressure conditions and temperatures, with the ability to manually or automatically empty the storage container, maintaining hygiene and operational reliability.
Implementation Method 1
the valve body is slidably sealed in relation to the valve housing by means of a membrane
Implementation Method 2
a control chamber which is delimited by the valve housing and the valve body and can be connected to the vacuum suction line via a control line which can be shut off by means of an actively switchable pilot valve
Implementation Method 3
the contents of the relevant washing, rinsing, toilet or other basin is conveyed into the collection container due to the pressure drop
Implementation Method 4
on the side of the valve body facing away from the working chamber there is a control chamber
Data Source
Figure 1
Figure 2
AI summary
A wastewater control module in a vacuum disposal unit on board a vehicle has an intermediate store and comprises a storage tank (1), an inlet pipe (2) leading into said tank, and an outlet pipe (3) which can be connected to a vacuum suction line; a valve (19) which comprises a valve seat (10) and a valve body (12) which can be moved relative to said seat is arranged in the bottom region of the storage tank, in the flow path between the storage tank and the outlet pipe; a valve housing (11) is arranged on the intermediate store, below the storage tank (1), and the valve body (12) bears on its side facing away from the storage tank against the valve seat; the valve body is sealed by means of a membrane (20) with respect to the valve housing such that it can be displaced therein; the outlet pipe (3) leads into a working chamber (23) defined by the valve body, the valve housing, the membrane and the valve seat; on the valve body acts a switchable actuating device (34) which lifts the valve body downwardly off the seat; on that side of the valve body (12) facing away from the working chamber (23) is provided a control chamber (25) which is defined by the valve housing (11) and the valve body and which can be connected to the vacuum suction line via a control line (29) which can be shut off by means of an actively switchable pilot valve (31).