Geared Turbofan Flexible Ring Gear Mounts for Misalignment
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Solution Overview
Problem
Gas turbine engines face misalignment issues in gear systems due to operational forces, which can be mitigated by increasing the static structure's strength, but this adds weight, detracting from efficiency gains.
Innovation Solution
The implementation of a geared turbofan engine design with flexible ring gear mounts that are at least 5 times stiffer in the torsional direction, allowing ring gears to flex radially and angularly, and an integral carrier and fan shaft structure, along with a planetary gear system and oil collector system to capture and reuse oil, reducing misalignment and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the static structure's strength is increased to accommodate misalignment, then the gear system's ability to handle misalignment is improved, but the engine weight increases, detracting from efficiency gains
Solution Approach 1:
The patent applies the dynamics principle by making the ring gear mounts flexible rather than rigid, allowing the ring gears to move and flex dynamically to accommodate misalignment. This flexible mounting system enables the gear system to adapt to operational forces and misalignment without requiring a heavier static structure, thus resolving the contradiction between reliability and weight.
Solution Approach 2:
The patent changes the stiffness parameter of the ring gear mounts, making them at least 5 times stiffer in the torsional direction while allowing flexibility in other directions. This selective parameter change enables the mounts to accommodate misalignment while maintaining sufficient structural integrity, avoiding the need for increased overall structure strength that would add weight.
2Reliability
If multiple separate oil collection systems are used for ring gears and planet gears, then complete oil capture is improved, but device complexity increases
Solution Approach 1:
The patent merges the separate oil collection systems for ring gears and planet gears into a single integrated oil collection system. This unified system reduces device complexity while maintaining complete oil capture functionality, as the combined system collects oil from both the ring gears and planet gears through a coordinated structure rather than requiring multiple independent systems.
Solution Approach 2:
The oil collection system is designed with multi-functionality, serving both to collect oil from ring gears and planet gears, and to direct it to a common return line. This universal design allows a single system to perform multiple oil collection functions that would otherwise require separate dedicated systems, reducing 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
This design enhances the gear system's ability to accommodate misalignment while maintaining efficiency by reducing weight and part count, improving thermal, transfer, and propulsive efficiencies, and capturing a significant portion of oil for reuse.
Implementation Method 1
the flexible ring gear mounts enable the ring gears to flex in the radial direction and angular direction with respect to an engine centerline
Implementation Method 2
oil is transported by one or more tubes to an oil collector system
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A geared turbofan engine (120) includes a fan (122) rotatable about an engine axis (A). A compressor section (124) compresses air and delivers the compressed air to a combustor (126) where the compressed air is mixed with fuel and ignited to drive a turbine section (128) that in turn drives the fan (122) and the compressor section (124). A gear system (148) is driven by the turbine section (128) for driving the fan (122) at a speed different than the turbine section (128). The gear system (148) includes a carrier (192) attached to a fan shaft (140). A plurality of planet gears (182) are supported within the carrier (192). Each of the plurality of planet gears (182) includes a first row of gear teeth (184) and a second row of gear teeth (186) supported within the carrier (192). A sun gear (176) is driven by a turbine section (128). The sun gear (176) is in driving engagement with the plurality of planet gears (182). At least two separate ring gears (198A, 198B) circumscribe the plurality of planet gears (182). Each of the at least two ring gears (198A, 198B) are supported by a respective flexible ring gear mount (200A, 200B) that enables movement relative to an engine static structure (136). A fan drive gear system (148) for a gas turbine engine (120) is also disclosed.