Bidirectional Lubrication Pump for Geared Turbofan Windmilling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gas turbine engines face challenges in lubricating their geared architectures during non-operating conditions, particularly when windmilling occurs, as traditional lubricant pump systems only provide lubricant flow when the fan shaft rotates in one direction, leading to potential wear and maintenance issues due to back-driving of the geared architecture.
Innovation Solution
A lubrication system with an input gear train that includes both primary and reverse gear trains, coupled with overrunning clutches, drives a lubricant pump to generate lubricant flow regardless of the shaft's rotational direction, ensuring continuous lubrication to the geared architecture even during windmilling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional lubricant pump system is used that only operates in one direction, then the device complexity is reduced, but the reliability deteriorates during windmilling conditions when the shaft rotates in reverse
Solution Approach 1:
The input gear train is segmented into two independent subsystems: a primary gear train for forward rotation and a reverse gear train for backward rotation. Each subsystem is activated only when needed, allowing the system to maintain reliability in both rotation directions while keeping each individual subsystem relatively simple
Solution Approach 2:
Overrunning clutches are pre-configured in the gear trains to automatically engage the appropriate subsystem before reverse rotation occurs. This preliminary arrangement ensures that lubrication is immediately available during windmilling without requiring complex sensing or control systems
2Strength
If a single-direction lubricant pump system is used, then the manufacturing cost is reduced, but the wear resistance deteriorates during non-operating windmilling conditions
Solution Approach 1:
The gear train is divided into separate forward and reverse pathways, each equipped with its own overrunning clutch. This segmentation allows standard manufacturing processes to be applied to each simpler subsystem while ensuring comprehensive protection against wear during both operating and windmilling conditions
Solution Approach 2:
The overrunning clutches automatically select and activate the appropriate gear train based on rotation direction without external control. This self-service mechanism reduces manufacturing complexity by eliminating the need for complex control systems while ensuring wear resistance is maintained during windmilling
3Adaptability or versatility
If traditional single-direction pump control is used, then the device complexity is minimized, but the adaptability deteriorates when the engine operates in both forward and reverse windmilling conditions
Solution Approach 1:
The dual gear train system with overrunning clutches provides universal lubrication capability for both forward and reverse rotation directions. Each gear train is simple in structure but the combined system achieves multi-functionality, adapting automatically to any rotation direction without increasing overall complexity
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 provides lubrication to the geared architecture in both directions of rotation, reducing wear and maintenance complexity by ensuring consistent lubricant flow, thereby enhancing the reliability and efficiency of gas turbine engines.
Implementation Method 1
a primary overrunning clutch configured to couple the primary gear to the primary gear shaft during rotation in the first direction
Implementation Method 2
a reverse overrunning clutch for coupling the reverse gear to the reverse gear shaft during rotation of the shaft in the second direction
Implementation Method 3
a lubrication pump configured to supply a lubricant flow to the gear system
Data Source
AI summary
A lubrication system includes a shaft rotatable about an axis, a lubrication pump configured to supply a lubricant flow to a gear system, and a gear train coupled to the shaft and configured to drive the lubrication pump in a first direction responsive to rotation of the shaft in both the first direction and a second direction. A gas turbine engine and method are also disclosed.