Pylon Mounted Accessory Drive for Gas Turbine Engine
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Solution Overview
Problem
Conventional gas turbine engine accessory gearbox arrangements require significant space and multiple shafts, leading to suboptimal nacelle performance, especially when powering larger generators.
Innovation Solution
Locating the accessory gearbox within an engine pylon with a geartrain driven by a towershaft arrangement that extends through the core and fan nacelles, allowing direct drive of accessory components and optimizing core nacelle space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the accessory gearbox is mounted underneath the engine axially near the diffuser case with multiple shafts, then the power can be transferred to accessory components, but the space and weight within the core nacelle increases
Solution Approach 1:
The accessory gearbox is extracted from its conventional location underneath the engine and relocated to the engine pylon. This separation removes the bulky gearbox and multiple shaft arrangement from the core nacelle, significantly reducing the space required while maintaining the power transfer function through a simplified direct drive configuration
Solution Approach 2:
The accessory gearbox is relocated from the vertical axis under the engine to the horizontal pylon structure. This dimensional shift moves the accessory drive system out of the core nacelle volume constraint, allowing the core nacelle to be optimized for cruise performance while the pylon accommodates the accessory components
2Power
If multiple shafts and gearboxes are used to transfer power from the towershaft to the accessory gearbox, then the power can be distributed to various accessory systems, but the device complexity increases
Solution Approach 1:
The intermediate angle gearbox and layshaft are extracted from the power train, eliminating the complex multiple-shaft arrangement. The towershaft is directly coupled to the accessory gearbox input, reducing the number of moving parts and simplifying the mechanical power transfer path while maintaining full power distribution capability
Solution Approach 2:
The function of multiple shafts and intermediate gearboxes is merged into a single direct drive connection. The towershaft directly drives the accessory gearbox, consolidating the power transfer mechanism into one simple mechanical link that reduces complexity while preserving all accessory power distribution functions
3Volume of moving object
If the accessory gearbox is relocated to the engine pylon with direct drive, then the core nacelle space is optimized, but the towershaft arrangement must extend through both core and fan nacelles
Solution Approach 1:
The accessory gearbox is extracted from the core nacelle and mounted on the pylon, which eliminates the need for complex intermediate shafting within the core nacelle. Although the towershaft must extend longer to reach the pylon-mounted gearbox, this trade-off is acceptable because it frees up significant core nacelle space and simplifies the overall drive train architecture
Solution Approach 2:
The accessory drive system is relocated from the vertical dimension under the engine to the horizontal pylon structure. This allows the towershaft to extend horizontally through the nacelles to reach the pylon-mounted gearbox, optimizing the core nacelle volume while accommodating the extended shaft length in a different spatial configuration
Data Source
AI summary
A gas turbine engine includes an accessory gearbox within an engine pylon. The accessory components may be mounted within the engine pylon to save weight and space within the core nacelle as well as provide a relatively lower temperature operating environment.