Compact Accessory Gearbox Layout for Smaller Turbine Nacelles
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Solution Overview
Problem
Gas turbine engines have large accessory systems that increase the size of the engine nacelle, leading to increased drag on mobile platforms, such as aircraft, which is undesirable for efficiency and performance.
Innovation Solution
A compact accessory system with a gearbox configuration that includes multiple bevel gears and a bearing housing assembly, allowing for a reduced size nacelle by optimizing the arrangement and orientation of accessories within the engine nacelle, including a towershaft, primary shaft, secondary shaft, tertiary shaft, and quaternary shaft, with adjustable contact patterns to accommodate manufacturing tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional accessory systems are used, then the accessories can be positioned within the engine nacelle, but the size of the engine nacelle increases leading to increased drag
Solution Approach 1:
The patent employs multiple shafts (towershaft, primary shaft, secondary shaft, tertiary shaft, quaternary shaft) arranged in three-dimensional space with transverse and parallel axis orientations. This spatial arrangement allows accessories to be distributed across multiple dimensions within the nacelle, optimizing space utilization and reducing the overall nacelle volume required while maintaining all necessary accessory functions.
Solution Approach 2:
The accessory system implements a nested configuration where multiple shafts and gears are arranged concentrically and in overlapping spatial relationships. The towershaft with its bevel gear at the distal end, primary shaft with first and second bevel gears, secondary shaft with third and fourth bevel gears, and tertiary shaft with fifth bevel gear create a compact nested structure that maximizes space efficiency within the nacelle.
2Productivity
If accessories are arranged within the engine nacelle, then the engine operation is assisted, but the nacelle size increases which affects aerodynamic efficiency
Solution Approach 1:
By arranging shafts and gears in three-dimensional space with transverse and parallel orientations, the patent accommodates all necessary accessories for engine operation within a reduced nacelle volume, thereby maintaining productivity while minimizing aerodynamic drag.
Solution Approach 2:
The bearing housing assembly with movable lock mechanism allows dynamic adjustment of the contact pattern between the towershaft bevel gear and first bevel gear, enabling the system to adapt to manufacturing tolerances and maintain optimal gear engagement for efficient operation.
3Volume of stationary object
If a compact accessory gearbox is designed, then the nacelle size can be reduced, but the manufacturing precision requirements increase due to adjustable contact patterns
Solution Approach 1:
The bearing housing assembly incorporates a movable lock that enables adjustment of the contact pattern between gears. This dynamic adjustment capability compensates for manufacturing tolerances, allowing the compact gearbox design to achieve proper gear engagement without requiring extremely tight manufacturing precision.
Solution Approach 2:
The system allows adjustment of the contact pattern parameters between the towershaft bevel gear and first bevel gear through the movable lock mechanism. By changing the contact pattern parameters, the system can accommodate variations in manufacturing precision while maintaining proper gear meshing in the compact nacelle configuration.
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 system reduces the size of the engine nacelle by approximately 2.5%, enhancing aerodynamic efficiency and allowing for a more balanced and lightweight design, while maintaining the functionality of the gas turbine engine accessories.
Implementation Method 1
The towershaft includes a towershaft bevel gear at a distal end. The accessory system includes a primary shaft including a first bevel gear and a second bevel gear that each revolve about a primary shaft axis of rotation. The first bevel gear is coupled to the towershaft bevel gear to drive the primary shaft.
Data Source
AI summary
An accessory system for a gas turbine engine having a drive shaft with an axis of rotation is provided. Also provided is a bearing housing assembly for coupling the drive shaft of an accessory having a first gear to a gear associated with the accessory system. The bearing housing assembly includes a mount including an interface to be coupled to the accessory and defining a central bore, and a lock cylinder configured to receive the drive shaft. The lock cylinder is movable relative to the central bore and the drive shaft to adjust a contact pattern between the first gear of the drive shaft and the gear of the accessory system.