Bidirectional Fan Gear Lubrication Using Dual Pumps and Check Valves
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Solution Overview
Problem
Gas turbine engines face challenges in lubricant distribution due to reverse rotation of the fan section during downwind conditions, causing unintended lubricant drainage from journal bearings, which can lead to reduced operational efficiency and component wear.
Innovation Solution
A windmill assembly with interconnected gears and check valves is designed to pump lubricant to the gear assembly, utilizing various pump types (gerotor, rotary vane, lobe, etc.) and check valves (ball, diaphragm, swing) to ensure lubricant flow in both forward and reverse fan rotations, preventing backflow and maintaining lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pump is used to lubricate the gear assembly, then the device complexity is reduced, but the reliability of lubrication is compromised during reverse fan rotation
Solution Approach 1:
The single pump is divided into two separate pumps (first pump and second pump), each dedicated to handling one rotation direction. This segmentation allows each pump to be optimized for its specific function while collectively providing reliable lubrication for both forward and reverse rotations, resolving the contradiction between device complexity and lubrication reliability.
Solution Approach 2:
Instead of using a single pump that must handle both rotation directions, the system uses two pumps where the second pump is configured to operate in reverse relative to the first pump. This inversion approach ensures that when the fan rotates in either direction, there is always a pump configured to deliver lubrication in the correct direction, thereby maintaining reliability without excessive complexity.
2Reliability
If check valves are added to prevent lubricant backflow, then the lubrication reliability is improved, but the device complexity increases
Solution Approach 1:
Check valves are introduced as intermediary components between the pumps and the gear assembly. These valves act as mediators that automatically control the direction of lubricant flow based on pump operation, ensuring that lubrication is delivered only in the correct direction. This intermediary approach maintains lubrication reliability while keeping the overall system design straightforward and manageable.
3Reliability
If two pumps with multiple gears and check valves are implemented, then the lubrication reliability in both rotation directions is ensured, but the device complexity increases
Solution Approach 1:
The two pumps, their respective gear systems, and check valves are merged into a single integrated windmill assembly that couples to the fan shaft. This combining approach allows both pumps to share a common mounting structure and coordinate their operations through the shared rotational input, thereby achieving bidirectional lubrication reliability while minimizing the overall device complexity through unified design.
Solution Approach 2:
The windmill assembly is designed as a universal system that performs multiple functions: the first pump handles forward rotation lubrication, the second pump handles reverse rotation lubrication, and both are driven by the same fan shaft through their respective gear trains. This multi-functionality ensures reliable lubrication in both rotation directions while avoiding the need for separate independent systems, thus managing device complexity effectively.
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 pumps lubricant to the gear assembly in both directions of fan rotation, ensuring continuous lubrication and reducing wear, thereby enhancing the operational life and efficiency of gas turbine engine components.
Implementation Method 1
the first pump can include a first pump idler gear and a first driven gear directly connected to the first pump gear and to the first pump idler gear, the second pump can include a second pump idler gear and a second driven gear directly connected to the second pump gear and to the second pump idler gear
Implementation Method 2
A first check valve can be positioned between the first pump and the gear assembly and allow flow of the lubricant from the first pump to the gear assembly. A second check valve can be positioned between the second pump and the gear assembly and allow flow of the lubricant from the second pump to the gear assembly
Data Source
Figure 1
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AI summary
What is described is a system for pumping lubricant to a component of a gas turbine engine (20). The system includes a fan gear (200; 600) coupled to a fan shaft (98) of the gas turbine engine (20) and configured to rotate in a forward direction and in a reverse direction based at least partially on a direction of wind relative to a fan (42) of the gas turbine engine (20). The system also includes a first pump (206; 606) coupled to the fan gear (200; 600) and configured to pump lubricant to the component in response to the fan (42) rotating in the forward direction. The system also includes a second pump (208; 604) coupled to the fan gear (200; 600) and configured to pump lubricant to the component in response to the fan (42) rotating in the reverse direction.