Compact Accessory Gearbox Layout for Reduced Engine Nacelle Volume
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Solution Overview
Problem
Gas turbine engines face challenges in reducing the size of accessory systems, leading to increased drag and nacelle volume, which affects efficiency and mobility, particularly in mobile platforms like aircraft.
Innovation Solution
A compact accessory gearbox system is designed with a unique gear train configuration that includes a towershaft and multiple accessory drive shafts with bevel gears, allowing for a reduced footprint by optimizing the arrangement of accessories around the gearbox, thereby minimizing the engine nacelle volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional accessory systems are used in gas turbine engines, then the accessories can be driven reliably, but the size of the accessory gearbox increases, leading to increased nacelle volume and drag
Solution Approach 1:
The patent applies dimensional change by introducing a towershaft that extends transverse to the engine axis and then vertically, creating a three-dimensional gear train arrangement. This vertical stacking of bevel gears on the towershaft allows compact packaging of multiple accessory drives in a reduced horizontal footprint, resolving the contradiction between small volume and reliable drive function
Solution Approach 2:
The patent implements nesting by arranging multiple bevel gears and accessory drives in a nested configuration around the towershaft. The first, second, and third accessory drives are positioned at different vertical levels and radial distances from the towershaft, creating a compact nested structure that minimizes overall gearbox volume while maintaining all necessary drive functions
2Volume of moving object
If the accessory gearbox size is reduced, then the nacelle volume and drag are reduced, but the complexity of the gear train arrangement increases
Solution Approach 1:
The patent applies segmentation by dividing the accessory drive system into multiple independent modules, each consisting of an accessory, adapter, and drive shaft assembly. These modular segments are then arranged around the towershaft, allowing the complex function to be achieved through standardized, repeatable units rather than a single complex integrated structure
Solution Approach 2:
The towershaft serves as an intermediary element that mediates between the engine's rotational power and multiple accessory drives. By introducing this intermediate vertical shaft with bevel gears, the patent simplifies the overall gear train configuration compared to direct horizontal gear arrangements, as the towershaft acts as a central hub for power distribution to multiple accessories
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 compact accessory gearbox system achieves a significant reduction in space requirements within the engine nacelle, enhancing mobility and efficiency by reducing the overall size of the accessory system while maintaining functionality.
Implementation Method 1
The towershaft includes a towershaft bevel gear at a distal end. The accessory system also includes a shaft including a first shaft bevel gear coupled to the towershaft bevel gear.
Data Source
AI summary
An accessory system for a gas turbine engine having a driveshaft is provided. The accessory system includes a towershaft coupled to the driveshaft and driven by the driveshaft. The accessory system also includes a shaft including a first shaft bevel gear coupled to a towershaft bevel gear. The shaft is rotatable by the towershaft. The accessory system includes a first accessory drive shaft having a first accessory bevel gear driven by the shaft. The accessory system also includes a second accessory drive shaft having a second accessory bevel gear driven by the shaft.