Flexible Coupling Shaft Layout for Compact Turbine Gearboxes
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Solution Overview
Problem
Turbine engines face challenges in increasing efficiency, reducing fuel consumption, and minimizing noise while managing torque and power output variations, which can lead to deformations and overspeed conditions, and existing gearbox configurations often increase packaging dimensions.
Innovation Solution
A flexible coupling shaft connects the engine core to the gearbox, featuring splines and a star gear arrangement that allows for axial and radial deformation, separating torque and speed sensing paths, and incorporating bearings and sensors to improve response to intermittent changes and reduce packaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a reduction gearbox is introduced between engine core and fan/propeller to increase efficiency, then turbine engine efficiency improves, but turbine engine packaging increases
Solution Approach 1:
The flexible coupling shaft is positioned within the hub of the rotor, nesting the coupling mechanism inside the existing rotor structure. This eliminates the need for additional external packaging space while maintaining the torque transmission function and flexibility benefits.
Solution Approach 2:
The invention transitions from a traditional external gearbox configuration to an internal coupling arrangement where the flexible coupling shaft operates within the rotor hub's internal volume. This dimensional repositioning reduces external packaging requirements while preserving the reduction gearbox functionality.
2Device complexity
If a rigid connection is used between engine core and gearbox, then structural simplicity is maintained, but response to intermittent torque changes and deformations is poor
Solution Approach 1:
The flexible coupling shaft changes the mechanical parameter of stiffness, transitioning from a rigid connection to a flexible one. This allows the system to accommodate intermittent torque changes and deformations while maintaining reliable power transmission.
Solution Approach 2:
The flexible coupling shaft introduces dynamic compliance to the connection between engine core and gearbox, allowing the system to adapt to varying torque conditions. This dynamic flexibility improves reliability by preventing stress concentrations and deformation-related failures.
3Productivity
If torque path is optimized for speed, then power transmission is efficient, but response time to overspeed conditions is reduced
Solution Approach 1:
The flexible coupling shaft acts as an intermediary element between the engine core and gearbox, serving dual functions: maintaining efficient torque transmission while providing a detectable interface for overspeed monitoring. This mediator role allows both productivity and safety response requirements to be met.
4Volume of moving object
If flexible coupling shaft extends within hub radially and axially, then packaging is reduced, but manufacturing complexity increases
Solution Approach 1:
The flexible coupling shaft incorporates segmented splines that can be manufactured as separate elements and then assembled or formed into the final structure. This segmentation approach reduces manufacturing complexity compared to creating a fully integrated complex-shaped shaft, while still achieving the desired compact packaging.
Data Source
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AI summary
The present disclosure is directed to a turbine engine (10) defining an axial direction and a radial direction. The turbine engine (10) includes a fan or propeller assembly (14) comprising a gearbox (45); an engine core (20) comprising one or more rotors (32), wherein at least one of the rotors (32) defines an axially extended annular hub (34); and a flexible coupling shaft (100) defining a first end (101) and a second end (102) along the axial direction, wherein the first end (101) is connected to the engine core (20) and the second end (102) is connected to the gearbox (45), and further wherein the flexible coupling shaft (100) extends from the one or more rotors (32) to the gearbox (45) in the axial direction and inward of the hub (34) in the radial direction.