Oil Reservoir Vent Valve for Shutdown Pressure Release
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Solution Overview
Problem
Existing aircraft engine oil tank de-pressurization systems using passive bleed orifices can result in pressure drops below acceptable levels at high altitudes and slow de-pressurization during engine shut-down, complicating tank servicing.
Innovation Solution
An oil reservoir assembly with a vent valve and pressurization system that includes a restrictor, scavenge pump, and a vent valve with a bleed orifice, allowing controlled airflow to escape during shut-down, maintaining sufficient pressure for tank access and servicing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a passive bleed orifice is used for de-pressurization, then the tank can be serviced, but the pressure drops below acceptable levels at high altitudes and de-pressurization is slow
Solution Approach 1:
The patent transitions from a static passive bleed orifice to a dynamic active vent valve system that responds to operational conditions. The vent valve opens or closes based on engine operation status, allowing controlled de-pressurization only when needed, while maintaining pressure during operation. This dynamic control resolves the contradiction by making the system adaptive rather than fixed.
Solution Approach 2:
The system incorporates feedback through pressure sensors and engine operation detection to control the vent valve. The valve responds to pressure conditions and engine status, opening to de-pressurize when the engine stops and closing when the engine runs to maintain proper pressure. This feedback mechanism ensures both reliable pressure maintenance and effective de-pressurization for servicing.
2Device complexity
If a passive bleed orifice is used, then the structure is simple, but de-pressurization speed is slow
Solution Approach 1:
The active vent valve provides dynamic control over the de-pressurization process, allowing rapid opening when needed to achieve fast pressure reduction. Unlike a fixed passive orifice, the controllable valve can fully open to maximize flow rate during de-pressurization, then close to maintain pressure, thus achieving both speed and control.
Solution Approach 2:
The system prepares for de-pressurization by detecting engine shutdown conditions and automatically activating the vent valve before servicing is needed. This preliminary action ensures rapid pressure reduction is already underway when the technician approaches, reducing waiting time while maintaining system simplicity through automation.
3Reliability
If pressure is maintained during operation, then lubrication is effective, but the tank cannot be accessed for servicing
Solution Approach 1:
The vent valve operates periodically based on engine operation cycles - closed during engine operation to maintain pressure for lubrication, and open during shutdown for de-pressurization and servicing. This periodic switching between pressure maintenance and de-pressurization modes resolves the contradiction by separating these conflicting requirements into distinct operational phases.
Solution Approach 2:
The system uses feedback from engine operation status to automatically switch between pressure maintenance and de-pressurization modes. When the engine runs, the valve closes to maintain pressure for effective lubrication; when the engine stops, the valve opens to enable safe tank access. This feedback-based control ensures both lubrication performance and servicing accessibility are achieved at appropriate times.
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 system effectively depressurizes the tank upon engine shut-down, ensuring safe and easy access for servicing by maintaining positive pressure under all operating conditions and preventing excessive oil flow to the gearbox, enhancing lubrication pump performance.
Implementation Method 1
the restrictor prevents backflow of air and oil into the return passage during operation
Implementation Method 2
Air and oil are drawn out of the return passage into the oil reservoir tank
Implementation Method 3
Air is vented from the return passage into a bleed orifice in a vent valve
Data Source
AI summary
An oil reservoir assembly includes a tank, a return passage, a pressurization valve, a first passage, and a vent valve. The tank includes a canister, a fill port, an first oil outlet, an second air outlet, and an inlet. The inlet is disposed in the canister and is connected to a restrictor. The return passage is connected to the inlet of the tank and to a scavenge pump. The pressurization valve is fluidly connected to the second air outlet of the tank. The first passage is connected to the pressurization valve and to an accessory gearbox of the engine. The vent valve is disposed in the return passage and includes a body, a channel extending through the body, an inlet orifice, and an outlet orifice. The inlet orifice is disposed in an end of the body. The outlet orifice is fluidly connected to the inlet orifice via the channel.