Rotating Carrier Gear Assembly for Stronger Epicyclic Fan Drives
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Solution Overview
Problem
Existing fan drive gear systems for gas turbine engines face challenges in achieving improved strength and rigidity, particularly in the assembly of epicyclic gear trains with rotating carriers, which require efficient lubrication and secure mounting of components to ensure reliable operation.
Innovation Solution
A method for assembling a fan drive gear system using a unitary carrier with circumferentially spaced mounts and apertures, where intermediate gears and a sun gear are inserted and engaged, and a torque frame is attached to facilitate rotation, with a ring gear and bearing assemblies positioned to support the fan shaft and provide lubrication, enhancing structural integrity and lubrication distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a two-part carrier housing is used, then assembly is easier, but strength and rigidity are reduced
Solution Approach 1:
The patent merges the two-part carrier housing into a single unitary carrier housing structure. This integration eliminates the joint between housing halves, providing improved strength and rigidity while maintaining ease of assembly through the simplified monolithic structure.
2Strength
If a unitary carrier housing is used, then strength and rigidity are improved, but assembly complexity increases
Solution Approach 1:
The patent segments the assembly process into distinct stages: first inserting intermediate gears through the central opening, then inserting the sun gear, and finally placing the ring gear. This systematic segmentation of the assembly sequence simplifies the overall process despite the unitary housing structure.
Solution Approach 2:
The patent employs a nested assembly approach where intermediate gears are inserted first and positioned within the carrier, then the sun gear is inserted and meshed with the intermediate gears, and finally the ring gear is placed to complete the epicyclic gear train. This nested sequencing reduces assembly complexity.
3Ease of manufacture
If intermediate gears are inserted through the central opening, then assembly is simplified, but precise positioning becomes more difficult
Solution Approach 1:
The patent incorporates preliminary positioning features in the unitary carrier housing, including gear pockets and locating surfaces that guide the intermediate gears and sun gear into correct positions during insertion. These pre-built features ensure precise gear meshing and alignment without requiring complex adjustment procedures.
Data Source
AI summary
A method of assembling a gear system for a gas turbine engine according to an example of the present disclosure includes the steps of providing a unitary carrier, positioning baffles between side walls of the carrier such that an end of each of the baffles abuts a respective mount of the carrier, inserting intermediate gears through a central opening of the carrier, and then moving the intermediate gears radially outwardly into respective gear pockets of the carrier, inserting a sun gear through the central opening, moving the intermediate gears radially inwardly to engage the sun gear, coupling a shaft to the carrier, including attaching a torque frame to the carrier such that the torque frame interconnects the carrier and the shaft, placing first and second ring gear halves of a ring gear onto an outer periphery of the intermediate gears, and fixedly attaching the ring gear to an engine static structure. A gear system is also disclosed.