Ring Gear Deflection Limiter for Turbine Gear Alignment
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Solution Overview
Problem
Gas turbine engines with geared architectures face challenges in maintaining alignment and reducing vibrations, particularly due to the cantilevered position of the geared architecture, which can lead to misalignment and increased deflection under load, necessitating a solution that allows for differential movement in radial and circumferential directions.
Innovation Solution
The implementation of a deflection limiter system with a flexible ring gear support and a combination of radial and circumferential clearances, along with a flexible input coupling and output shaft, to accommodate movement and maintain gear alignment, utilizing a deflection limiter that allows unequal amounts of movement in radial and circumferential directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the geared architecture is supported in a cantilever position, then the device complexity is reduced, but the gear alignment stability deteriorates under load due to increased deflection
Solution Approach 1:
The patent introduces differential clearance parameters between radial and circumferential directions, allowing the support structure to accommodate deflection while maintaining gear alignment. The radial clearance (0.030-0.050 inches) differs from circumferential clearance (0.030-0.250 inches), enabling the system to adapt to load-induced deflection without compromising alignment stability.
Solution Approach 2:
The deflection limiter transforms the static support structure into a dynamic system that can accommodate movement. By allowing controlled radial and circumferential clearance, the system adapts to deflection under load while maintaining gear mesh integrity, resolving the contradiction between simplified cantilever support and alignment stability.
2Manufacturing precision
If radial and circumferential clearances are equal, then the manufacturing precision is improved, but the ability to accommodate differential movement deteriorates
Solution Approach 1:
The patent deliberately introduces asymmetry by setting different clearance values for radial and circumferential directions. The radial clearance (0.030-0.050 inches) is smaller than the circumferential clearance (0.030-0.250 inches), creating an asymmetric clearance pattern that accommodates the specific deflection characteristics of the cantilever-supported geared architecture under operational loads.
3Stability of the object's composition
If the ring gear is rigidly supported, then the gear alignment is maintained, but the vibration increases due to inability to accommodate deflection
Solution Approach 1:
The patent employs a flexible support approach for the ring gear, incorporating controlled clearances that allow the support structure to flex and accommodate deflection. This flexibility absorbs vibrational energy while maintaining gear alignment, preventing the rigid support from transmitting excessive vibration through the system.
4Manufacturing precision
If the radial clearance is minimized, then the gear mesh precision is improved, but the ability to accommodate thermal expansion and deflection deteriorates
Solution Approach 1:
The patent optimizes the radial clearance parameter to a specific range (0.030-0.050 inches) that balances gear mesh precision with the ability to accommodate thermal expansion and deflection. This parameter selection ensures adequate clearance for operational variations while maintaining sufficient precision for effective gear meshing.
Data Source
Figure 1
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Figure 4A~6
AI summary
A gas turbine engine (20) includes a turbine section (28) that includes a fan drive turbine (46). A geared architecture (48) includes a sun gear (70) in driving engagement with the fan drive turbine (46). A plurality of planet gears (74) surrounds the sun gear (70). A ring gear (78) surrounds the plurality of planet gears (74). A deflection limiter (84A-D) mechanically attaches the ring gear (78) to an engine static structure (36). The deflection limiter (84A-D) includes a first support (86A-D) fixed to the ring gear (78) that has a first interlocking feature and a second support (88A-D) fixed to the engine static structure (36) that has a second interlocking feature. The first and second interlocking features define at least one of a radial clearance (94A-D) of between 0.005 inches (0.127 mm) and 0.080 inches (2.032 mm) or a circumferential clearance (96A-D)of between 0.005 inches (0.127 mm) and 0.250 inches (6.350 mm). A fan section (22) includes a plurality of fan blades (42) in driving engagement with the geared architecture (48) through a fan drive shaft (82).