Distributed Engine Accessory Drive Gearboxes
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Solution Overview
Problem
The limited space under the core engine cowl in gas turbine engines poses a challenge for efficiently arranging and maximizing the use of accessory drive gearboxes and accessories, due to restricted space and varying operating temperatures, which complicates maintenance and future design considerations.
Innovation Solution
The implementation of multiple accessory drive gearboxes, connected to remote accessories via flexible or power extension shafts, allowing for optimal spatial arrangement within the core engine envelope and potentially in the nacelle envelope, to maximize space utilization and accommodate varying accessory locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple accessories are mounted under the core engine cowl, then the number of driven accessories increases, but the available space becomes insufficient
Solution Approach 1:
The invention divides the accessory drive system into multiple separate gearboxes instead of using a single large gearbox. Each gearbox drives a specific subset of accessories, allowing them to be distributed in different spatial locations under the core engine cowl. This segmentation enables better space utilization and accommodates more accessories by placing them in previously unusable or less optimal locations.
2Volume of moving object
If accessories are mounted in downstream sections, then space utilization improves, but heat exposure increases
Solution Approach 1:
The invention assigns different accessories to different gearboxes based on their thermal environment requirements. Heat-sensitive accessories are connected to gearboxes positioned in cooler upstream sections, while heat-tolerant accessories can be served by gearboxes in warmer downstream sections. This local quality approach optimizes both space utilization and thermal management by matching each accessory's thermal requirements with its location.
3Volume of moving object
If gearbox and accessories are mounted under the core engine cowl, then space efficiency improves, but maintenance accessibility deteriorates
Solution Approach 1:
By dividing the accessory drive system into multiple smaller, independent gearboxes, the invention improves maintenance accessibility. Each gearbox can be accessed and serviced independently without requiring complete disassembly of a large integrated gearbox. The modular architecture allows maintenance personnel to work on individual gearboxes and accessories more easily, even when mounted in constrained spaces under the core engine cowl.
4Device complexity
If a single gearbox drives all accessories, then device complexity is reduced, but adaptability to different configurations decreases
Solution Approach 1:
The invention segments the accessory drive system into multiple independent gearboxes, each capable of driving specific accessories. This modular configuration provides greater adaptability and versatility, as different combinations of gearboxes and accessories can be selected and arranged to meet varying engine requirements. The system can be easily reconfigured by adding, removing, or repositioning individual gearboxes and accessories without redesigning the entire drive system.
Data Source
AI summary
An accessory drive system for an aircraft gas turbine engine is disclosed. The system may comprise an engine case including a core engine cowl and at least a first accessory drive gearbox disposed within the core engine cowl. The at least first accessory drive gearbox may be operatively connected to one or more accessories remotely located therefrom.