Gearbox Spline Lubrication via Scupper and Annular Dam
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Solution Overview
Problem
Gas turbine engine gearboxes face inefficiencies in lubricating splines due to continuous lubrication requirements, which can lead to unnecessary lubricant flow and potential leaks during operation, and existing systems may not effectively manage lubrication when the engine stops and restarts.
Innovation Solution
A gearbox assembly with a scupper and annular dam system that collects and directs lubricating liquid to splines only when the shafts stop rotating, providing a single shot of lubrication that is retained between the splines and the dam during operation, reducing continuous lubricant flow and minimizing leakage risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous flow of lubricating liquid is supplied to the splines during operation, then the splines are continuously lubricated to reduce friction and wear, but unnecessary lubricant flow occurs and potential leaks are increased
Solution Approach 1:
The system switches from continuous lubrication to periodic lubrication by using a scupper to collect lubricant and deliver it in discrete amounts only when the shafts are stationary, eliminating continuous flow and associated losses
Solution Approach 2:
The system uses the existing lubricant already present in the gearbox housing, collected by the scupper, rather than requiring an external continuous supply system, making the system self-sufficient and reducing waste
2Reliability
If a continuous lubrication system is used during engine operation, then the splines remain lubricated, but the system cannot effectively manage lubrication when the engine stops and restarts
Solution Approach 1:
The scupper collects and stores lubricant in advance during operation, preparing it for delivery when the shafts stop, ensuring lubrication is available at the critical moment without requiring a complex control system
Solution Approach 2:
The system dynamically adapts its lubrication delivery based on the operational state of the shafts, providing lubrication only when stationary and withholding it during rotation, optimizing performance for different operating conditions
3Reliability
If lubricating liquid is continuously supplied to the splines, then friction and wear are reduced, but the risk of leakage increases
Solution Approach 1:
The system extracts only the necessary amount of lubricant from the housing via the scupper and delivers it precisely where needed through the shaft cavity, removing excess lubricant that would otherwise be prone to leakage
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
This solution effectively lubricates splines with a single shot of lubricant at shutdown, reducing the need for continuous lubrication systems and minimizing the risk of leaks, enhancing operational efficiency and reliability by using the collected lubricant to service the splines during the entire operating period.
Implementation Method 1
A scupper is positioned on an inner surface of the gearbox housing proximate the first shaft so as to direct liquid from the scupper through the central cavity of the first shaft to the first and second sets of splines
Implementation Method 2
Lubricating liquid flows from the scupper through the first shaft to the splines when the first and second shafts stop rotating
Implementation Method 3
Such splines are typically lubricated to reduce friction and wear between the splines
Data Source
AI summary
A gearbox assembly for use in a gas turbine engine includes a gearbox housing and first and second shafts. The first shaft is rotatably mounted in the gearbox housing. The first shaft has a first set of splines and defines a central cavity. The second shaft has a second set of splines engaged with the first set of splines. A scupper is positioned on an inner surface of the gearbox housing proximate the first shaft so as to direct liquid from the scupper through the central cavity of the first shaft to the first and second sets of splines.