Accessory Gearbox Radial Layout for Nacelle Airflow and Alignment
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Solution Overview
Problem
Existing accessory gearbox assemblies for gas turbine engines often protrude through the aerodynamic nacelle, disrupting air flow and requiring complex adjustments, and the alignment of bevel gears is time-consuming and difficult.
Innovation Solution
A novel accessory gearbox assembly with a gear train and V-shaped shaft arrangement, where spur gears and bevel gears mesh to drive accessories, allowing the gearbox to be mounted radially between the core engine casing and nacelle, eliminating protrusion and simplifying alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the accessory gearbox is mounted on the core engine casing with accessories arranged axially, then the accessories can be driven efficiently, but the accessory gearbox protrudes through the aerodynamic nacelle disrupting air flow
Solution Approach 1:
The patent transitions from axial arrangement of accessories to a radial arrangement where accessories are mounted on the periphery of the gearbox, extending radially outward. This dimensional change allows the gearbox to be positioned within the nacelle without axial protrusion, eliminating air flow disruption while maintaining driving efficiency through the radial gear train configuration
2Object-affected harmful factors
If the accessory gearbox is positioned to avoid protrusion, then air flow is maintained, but the alignment of bevel gears becomes time-consuming and difficult
Solution Approach 1:
The patent changes the geometric parameters of the gear arrangement by using a radial layout with standardized gear positions and spacing. This parameter standardization enables the use of modular components with predetermined alignment features, reducing the complexity and time of alignment during assembly while maintaining the non-protruding configuration
3Adaptability or versatility
If larger accessories are accommodated, then functional requirements are met, but the aerodynamic nacelle shape must be adjusted affecting air flow
Solution Approach 1:
The patent employs a nested configuration where larger accessories are positioned radially outward from the gearbox center, with smaller accessories arranged in the inner radial zones. This nested radial arrangement accommodates accessories of varying sizes within the available radial space without requiring axial extension or nacelle shape modification, thereby maintaining smooth air flow through the bypass duct
Data Source
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AI summary
A gas turbine engine (10) comprising an accessory gearbox assembly (28). The accessory gearbox assembly (28) comprising an accessory gearbox (46) and a plurality of accessories (48) arranged to be driven by the accessory gearbox (46). The accessory gearbox (46) comprises a gear train (70) and an accessory gearbox casing (56) enclosing the gears of the gear train (70). Each accessory (48) is driven by a shaft (72) and the shaft (72) of each accessory (48) has a spur gear (74). The gear train (70) comprises the spur gears (74) of the accessories (48). The shaft (72A, 72B) of at least one of the accessories (48A, 48B) has a bevel gear (76) and the bevel gear (76) is arranged to mesh with a further bevel gear (42) and the further bevel gear (42) is arranged to drive the accessory gearbox assembly (28). The accessories (48) may be arranged in V-shape on the core engine casing (50) within an aerodynamic core nacelle (52).