Bevel Gear Arrangement for Axial Accessory Box
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Historically, the radial envelope of accessory gearboxes in gas turbine engines has been undesirably large due to circumferential spacing of accessories, which is addressed by reconfiguring the drive arrangement to axially space accessories along the drive axis using a layshaft and bevel gear arrangements.
Innovation Solution
The drive arrangement features an input gear driving a first driven gear on one radial side, which in turn drives a bevel gear arrangement to power accessories on the opposed side of the drive axis, allowing for a tighter axial dimension by crossing the drive axis and reducing the overall radial envelope.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If accessories are spaced circumferentially about a central drive axis, then the drive arrangement is simple, but the radial envelope becomes undesirably large
Solution Approach 1:
The patent transitions from circumferential (radial) spacing of accessories to axial spacing along the drive axis. By moving accessories from a radial arrangement to an axial arrangement on the layshaft, the design reduces the radial envelope while maintaining accessory drive functionality through the bevel gear arrangement that crosses the drive axis.
2Area of stationary object
If accessories are spaced axially along the drive axis using a layshaft, then the radial envelope is reduced, but the device complexity increases
Solution Approach 1:
The patent introduces a layshaft as an intermediary shaft that runs axially and carries accessories at axially spaced locations. This layshaft works in conjunction with bevel gears (including a first bevel gear on the input shaft and second bevel gears on the layshaft) to transfer power from the circumferential input to the axial accessory positions, thereby achieving compact radial dimensions while maintaining a systematic drive structure.
3Length of stationary object
If a bevel gear arrangement is used to cross the drive axis, then the axial dimension is reduced, but the manufacturing complexity increases
Solution Approach 1:
The patent combines multiple functions into the bevel gear arrangement: the first bevel gear on the input shaft meshes with second bevel gears on the layshaft to both change the direction of power transmission (crossing the drive axis) and to drive the axially spaced accessories. This merging of power transmission and accessory drive functions into a single gear arrangement reduces the overall axial dimension while consolidating the mechanical complexity into standardized gear components.
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
This configuration enables a more compact accessory gearbox that can be positioned in smaller axial spaces, improving the spatial efficiency and allowing for cooler locations on the gas turbine engine, such as the compressor case.
Implementation Method 1
The second driven gear drives a bevel gear arrangement to drive a third driven gear on an opposed side of the drive axis. The bevel gear arrangement includes a first bevel gear driven to rotate on one radial side. The first bevel gear drives a second bevel gear, and the second bevel gear drives a third bevel gear.
Data Source
AI summary
An accessory box for a gas turbine engine has an input gear to be driven by an input shaft. The input gear is engaged to drive a first driven gear on one radial side of a drive axis of the input gear. The first gear drives at least a second driven gear on one radial side of the drive axis, with at least one accessory driven by one of the first and second driven gears. The second driven gear drives a bevel gear arrangement to drive a third driven gear on an opposed side of the drive axis of the input gear. The third driven gear drives at least a second accessory. The accessories are associated with a gas turbine engine.