Axial Accessory Gearbox With Crossover Gears for Compact Drive Layout
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional gas turbine engine accessory gearboxes require complex mounting arrangements and additional structures, leading to increased weight, complexity, and reduced reliability due to the need for separate angled gearbox housings and layshafts, which complicate the efficient operation of accessory components at different speeds and power requirements.
Innovation Solution
An axial housing assembly with a towershaft and integrated geartrain that allows accessory components to straddle the engine case, eliminating the need for a separate angled gearbox housing by using a crossover gear set to drive accessory components, reducing component complexity and weight, and improving reliability by operating in a cooler environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional accessory gearbox with separate angled gearbox housing and layshaft is used, then the accessory components can be driven at different speeds, but the gearbox size, weight, and complexity increase
Solution Approach 1:
The patent merges the accessory gearbox functionality directly into the engine case structure. The engine case itself serves as the gearbox housing, eliminating the need for a separate angled gearbox housing and layshaft. This integration maintains the capability to drive multiple accessory components at different speeds through integrated gear sets while significantly reducing structural complexity and component count.
Solution Approach 2:
The engine case is designed to serve multiple functions simultaneously: it acts as both the engine structural housing and the accessory gearbox housing. The engine case incorporates mounting surfaces, gear sets, and drive mechanisms directly within its structure, allowing it to perform both engine containment and accessory power transmission functions.
2Adaptability or versatility
If a conventional accessory gearbox with separate angled gearbox housing is used, then the accessory components can be mounted, but the overall weight increases
Solution Approach 1:
The accessory gearbox is merged with the engine case structure, eliminating the weight of separate housing components. The engine case material and structure are utilized to provide both engine containment and gearbox housing functions, thereby reducing the total weight while maintaining full accessory mounting capability.
3Power
If a layshaft and angled gearbox housing are used, then power transmission to accessories is enabled, but reliability decreases due to more components and bolted flanges
Solution Approach 1:
The power transmission path is simplified by merging the gearbox functions into the engine case. The elimination of the layshaft and separate housing removes potential failure points associated with these components and their connections. Power is transmitted directly through integrated gear sets mounted on the engine case, reducing the number of bolted flanges and connection points that could compromise reliability.
4Adaptability or versatility
If a conventional accessory gearbox configuration is used, then accessory components can be driven, but the gearbox size increases
Solution Approach 1:
The accessory gearbox volume is merged with the engine case volume. By utilizing the existing engine case structure as the gearbox housing, the additional volume required for a separate gearbox is eliminated. The gear sets and drive mechanisms are integrated within the engine case boundaries, maintaining accessory drive capability without increasing overall gearbox volume.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An accessory system (60) for a gas turbine engine includes an accessory gearbox which defines an accessory gearbox axis (L). A crossover gear set (92) generally along the accessory gearbox axis (L) interconnects a first gear set (84C) and a second gear set (84E).