Windmill Pump Gear Train for Bidirectional Turbofan Lubrication
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Solution Overview
Problem
Gas turbine engines with geared architectures face challenges in lubricating journal bearings during both normal operation and windmilling conditions, as existing lubrication systems fail to provide consistent lubricant flow across rotational directions.
Innovation Solution
A lubrication system incorporating an input gear train with forward and reverse clutches and gears, which drives a pump to supply lubricant unidirectionally in response to shaft rotations in both forward and reverse directions, ensuring continuous lubrication to geared architectures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional lubrication system is used in geared architectures, then the system structure remains simple, but the lubrication effectiveness deteriorates during windmilling conditions due to inability to maintain unidirectional pump rotation
Solution Approach 1:
The system dynamically adapts its configuration based on rotational direction. The input gear train automatically engages different gear paths (forward gear for clockwise rotation, reverse gear for counter-clockwise rotation) to maintain unidirectional pump rotation, transforming a static system into a dynamic one that responds to operational conditions
Solution Approach 2:
The input gear train is segmented into multiple independent gear paths (forward path with forward gear and reverse path with reverse gear). Each path is optimized for a specific rotational direction, allowing the system to maintain simplicity within each segment while achieving overall functionality through selective engagement
2Reliability
If the pump is directly coupled to the shaft gear, then the device complexity is reduced, but the lubrication reliability deteriorates during reverse rotation as the pump cannot rotate unidirectionally
Solution Approach 1:
The input gear train acts as an intermediary mechanism between the shaft gear and the pump. It converts bidirectional shaft rotation into unidirectional pump rotation through intermediate gears (forward gear, reverse gear, idler gear), allowing the pump to receive rotation in only one direction regardless of shaft rotation direction
Solution Approach 2:
Instead of coupling the pump directly to rotate with the shaft, the system inverts the approach by using the gear train to drive the pump in a consistent direction opposite to one of the shaft rotation directions. This ensures the pump always rotates the same way regardless of which direction the shaft rotates
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 ensures effective lubrication of journal bearings during both normal operation and windmilling conditions, prolonging the operational life of geared architectures by maintaining lubricant flow irrespective of rotational direction.
Implementation Method 1
an input gear train coupled to the shaft gear and configured to drive the pump with a unidirectional rotation in response to a forward rotation and an reverse rotation of the shaft gear
Implementation Method 2
a pump configured to supply a flow of lubricant to a component benefiting from lubrication
Data Source
AI summary
A lubrication system may comprise a shaft including a shaft gear, a pump configured to supply a flow of lubricant to a component benefiting from lubrication and an input gear train coupled to the shaft gear and configured to drive the gear pump with a unidirectional rotation in response to a forward rotation and an reverse rotation of the shaft gear. The input gear grain may comprise a primary gear coupled to a common shaft. The input gear train may further comprise a forward shaft and a forward gear about the common shaft, wherein the forward gear is coupled to the forward shaft.