Multi-Axis Accessory Gearbox for Gas Turbine Engines
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Solution Overview
Problem
Conventional accessory gearboxes in gas turbine engines are bulky, heavy, and difficult to package within the limited space of an engine nacelle due to their linear gear configurations, which complicates access and installation of accessory devices and increases the size and weight of the engine.
Innovation Solution
A multi-axis accessory gearbox design that uses a skewed drive shaft and bevel gear system, allowing each side bevel gear to rotate at a unique angle independent of others, enabling direct power transmission to accessory devices without a spur gear train, thus reducing the overall size and weight while improving accessibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional linear gear configurations are used in accessory gearboxes, then power transmission is straightforward, but the gearbox becomes bulky and heavy, increasing engine size and weight
Solution Approach 1:
The patent transitions from conventional linear gear arrangements to a multi-axis configuration where gears are arranged in three-dimensional space at different angles. The bevel gear set connects shafts at intersecting angles, and the side bevel gear set extends power transmission to side accessory devices at yet another orientation. This spatial reconfiguration reduces the linear footprint and overall size of the gearbox while maintaining effective power transmission to all accessory devices.
2Power
If conventional accessory gearbox arrangements are used, then power can be transmitted to accessory devices, but the gearbox requires a large amount of space within the engine nacelle
Solution Approach 1:
The multi-axis gear arrangement distributes power transmission in three dimensions rather than along a single linear path. The main drive shaft connects to the bevel gear set which transmits power at an angle to the drive shaft, and the side bevel gear set extends to side accessory devices. This spatial distribution reduces the projected area occupied by the gearbox in the engine nacelle while maintaining full power transmission capability to all accessory devices.
Solution Approach 2:
The side bevel gear set is positioned within the spatial envelope of the main gearbox housing, with side accessory devices mounted on the periphery. This nested arrangement allows multiple power transmission paths to coexist within a compact volume, reducing the overall space required in the engine nacelle while maintaining access to all accessory devices.
3Adaptability or versatility
If conventional accessory gearbox layouts are used, then accessory devices can be mounted, but access for installation and removal becomes difficult
Solution Approach 1:
By arranging accessory devices at different angular positions around the multi-axis gearbox rather than in a linear sequence, the design provides multiple access paths. Side accessory devices mounted on the periphery are accessible from the side of the engine, while drive shaft accessories are accessible from the front or rear, improving maintenance accessibility without compromising mounting versatility.
4Reliability
If conventional gear configurations are used, then power transmission is reliable, but the accessory gearbox and engine packaging becomes complicated
Solution Approach 1:
The multi-axis configuration consolidates multiple power transmission functions into a single integrated gearbox structure. The bevel gear set and side bevel gear set work together in a coordinated three-dimensional arrangement, reducing the number of separate components and mounting locations required compared to conventional linear arrangements. This simplifies the overall packaging of the engine and accessory gearbox assembly while maintaining reliable power transmission.
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 multi-axis gearbox design results in a more compact and lightweight accessory gearbox that can be positioned closer to the engine casing, simplifying packaging and access, reducing drag, and enhancing fuel efficiency by allowing for a more compact engine layout.
Implementation Method 1
A bevel pinion gear and bevel gear may be mounted on the towershaft and drive shaft, respectively, and mesh with one another
Implementation Method 2
A side bevel gear set may be provided that is operable to directly drive at least one side accessory device
Data Source
AI summary
Gas turbine engines including multi-axis accessory gearboxes of mechanical drive systems are provided. The gearbox comprises a housing, a drive shaft, bevel pinion and drive shaft bevel gears, and a side bevel gear set operable to directly at least one side accessory device. Housing is disposed about a towershaft operatively coupled to main engine shaft and operable to rotate about a first axis. Drive shaft is skewed to main shaft and operable to rotate about a second axis that intersects the first axis at a first angle. Bevel pinion gear is mounted on the towershaft. Drive shaft bevel gear is mounted on the drive shaft. Side bevel gear set comprises an input gear meshing with one or more side bevel gears each having a side bevel gear axis at a second angle to the first axis and independently positionable relative to input gear. Second angle is independent of other angles.