Turbine Engine Lubrication Overflow Routing for Scavenge Failures
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Solution Overview
Problem
Turbine engines face issues with oil overfilling in gearboxes due to scavenge system failures, leading to flooding, excess drag, and heat generation, which can damage components and degrade the oil.
Innovation Solution
A lubrication system with a scavenge arrangement that includes a conduit to transfer overflow oil from a failed sump to a secondary sump, utilizing various valve and cap configurations to prevent mist ingress and ensure continuous oil circulation, including axial and float valves, and radial heads to manage oil flow during failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a scavenge pump fails, then oil continues to accumulate in the sump, but this causes gearbox flooding and component damage
Solution Approach 1:
The overflow conduit is pre-configured to automatically activate when the scavenge pump fails, creating a backup drainage path that prevents oil accumulation and gearbox flooding before the failure becomes catastrophic
Solution Approach 2:
The overflow conduit acts as an intermediary component that transfers excess oil from the first sump to the second sump when the primary scavenge system fails, providing a secondary pathway that mediates between the oil supply and the gearbox
2Reliability
If oil is continuously circulated through the gearbox, then lubrication is maintained, but heat generation and oil degradation occur
Solution Approach 1:
The dual-sump system with overflow conduit ensures continuous oil circulation and lubrication by maintaining adequate oil levels in the gearbox even during scavenge pump failure, preventing interruption of the lubrication process
Solution Approach 2:
The system allows oil to be temporarily stored in the second sump when the first sump overflows, effectively discarding the problematic accumulation scenario and recovering the ability to maintain proper lubrication levels
3Device complexity
If a single sump system is used, then the structure is simple, but oil overfilling cannot be prevented during scavenge failure
Solution Approach 1:
The oil collection system is segmented into two separate sumps with an overflow conduit connecting them, dividing the single oil management function into multiple components that work together to prevent overfilling while maintaining structural organization
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
Prevents gearbox flooding and maintains efficient lubrication by ensuring continuous oil circulation, reducing heat generation and component damage, even in scavenge pump failure scenarios.
Implementation Method 1
a float valve assembly comprising a valve stop, a valve member that closes against the valve stop in a normally closed position, and a float that floats atop the first continuous liquid mass of oil, connected to the valve member via a linkage
Implementation Method 2
a flapper valve assembly comprising a torsion spring at the hinge, connected to the flapper and to the conduit, that holds the flapper against the valve stop in the normally closed position, the torsion spring twisting under hydrostatic pressure from the first continuous liquid mass of oil
Implementation Method 3
an axial valve assembly comprising an axial compression spring that holds the valve member against the valve stop in the normally closed position, the axial compression spring compressing under hydrostatic pressure from the first continuous liquid mass of oil at the threshold level
Data Source
AI summary
A turbine engine includes a first gearbox, lubricated by oil. A first sump, located below the first gearbox, collects the oil. A first scavenge element pumps the oil from the first sump in an operational state and does not pump the oil in a failure state. A second gearbox is also lubricated by oil. A second sump, located below the second gearbox, collects the oil. A second scavenge element pumps the oil from the second sump in both the operational state and in the failure state. A conduit connects the first sump to the second sump to transfer overflow oil from the first sump to the second sump in the failure state, the overflow oil combining with the oil in the second sump, upon the oil in the first sump reaching a threshold level.