Bearing Chamber Pressure Control via Parallel Venting Valve
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Solution Overview
Problem
Gas turbine engines face oil leakage issues due to excessive wear or failure of seals in bearing chambers, as the positive pressure differential across the seals can be reduced or reversed, leading to potential oil loss.
Innovation Solution
An apparatus comprising a scavenge pump and a venting valve that controls the pressure differential across the seals by pumping oil from the bearing chamber and venting the chamber in parallel to the scavenge pump, with the venting valve opening when the pressure differential falls below a predetermined threshold to prevent oil leakage, and a non-return valve to prevent backflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a positive pressure differential is maintained across the seals to prevent oil leakage, then oil loss is reduced, but the system becomes vulnerable to oil leakage when seal wear or failure occurs
Solution Approach 1:
The patent introduces a venting valve as an intermediary component that provides an alternative path for air to enter the bearing chamber when seals fail. This mediator allows the system to maintain positive pressure differential across the seals while providing a backup mechanism that prevents oil leakage in case of seal wear or failure, thus resolving the contradiction between reducing oil loss and maintaining reliability
Solution Approach 2:
The venting valve is configured in advance to provide a protective function before seal failure occurs. By pre-positioning the venting valve in the air path, the system is cushioned against the harmful effect of oil leakage that would occur upon seal failure, allowing the positive pressure differential to continue protecting against oil loss while the venting valve stands ready to prevent catastrophic failure
2Loss of substance
If the scavenge pump capacity is increased to maintain pressure differential, then oil leakage prevention is improved, but the device complexity increases
Solution Approach 1:
The patent segments the oil leakage prevention function into two parts: the scavenge pump handles normal operation by maintaining pressure differential, while the venting valve handles abnormal conditions by providing an alternative air path. This segmentation allows the scavenge pump to be sized for normal operation without needing excessive capacity for worst-case scenarios, thus reducing device complexity while maintaining effective oil leakage prevention
Solution Approach 2:
The venting valve acts as an intermediary that relieves the scavenge pump from needing to handle all pressure differential maintenance alone. By providing an alternative path for air to enter the bearing chamber, the venting valve reduces the burden on the scavenge pump, allowing it to be smaller and simpler while still achieving effective oil leakage prevention
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 desired pressure differential across the seals, preventing oil leakage even in cases of excessive wear or failure, thereby reducing the risk of oil loss and potential in-flight shutdowns.
Implementation Method 1
a scavenge pump in fluid communication with an interior of the bearing chamber for pumping oil from the bearing chamber
Implementation Method 2
a venting valve configured to controllably vent the interior of the bearing chamber in parallel to the scavenge pump based on the pressure differential across the one or more seals
Implementation Method 3
The venting valve may comprise a biasing member urging the valve member toward an open position to cause venting of the interior of the bearing chamber
Data Source
AI summary
Apparatus and methods for controlling a pressure differential across one or more seals of a bearing chamber in a gas turbine engine are disclosed. In some embodiments, the apparatus comprises a scavenge pump in fluid communication with an interior of the bearing chamber for driving oil from the bearing chamber; and a venting valve. The venting valve is configured to cause venting of the interior of the bearing chamber in parallel to the scavenge pump based on the pressure differential across the one or more seals.