Turbomachine Shaft Splines With Radial Locking for Modular Maintenance
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Solution Overview
Problem
The modularity of aircraft turbomachines is compromised during maintenance due to complex tool access and risk of engine damage, particularly when a reduction gear is present, as existing solutions either require disassembling the lubrication enclosure or increasing the gearbox size, which affects performance.
Innovation Solution
A set of shafts with radial screws for axial locking and unlocking, allowing for modular separation without disassembling the lubrication enclosure, enabling easier maintenance by providing a smaller gearbox diameter and facilitating tool access through radial orifices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the nut is accessed from the inside of the reducer, then the lubrication enclosure remains closed, but the reducer internal diameter must be increased which penalizes size and performance
Solution Approach 1:
Instead of accessing the nut from the inside of the reducer through the input shaft, the invention inverts the approach by providing access from the outside through radial orifices in the reducer casing. This allows the lubrication enclosure to remain closed while maintaining a compact reducer design.
Solution Approach 2:
The invention changes the access dimension from axial (through the input shaft) to radial (through the reducer casing). This dimensional shift enables tool access to the locking nut without increasing the reducer's internal diameter or opening the lubrication enclosure.
2Ease of operation
If complex tools are used to access the nut, then the nut can be accessed, but the risk of mishandling and damage to the engine increases
Solution Approach 1:
The invention segments the access path by providing multiple radial orifices distributed around the reducer circumference, allowing standard tools to access the locking nut from convenient directions without requiring complex elongated tools that penetrate through the entire engine assembly.
3Productivity
If the fan diameter is increased to improve propulsive efficiency, then bypass ratio increases, but access to the LP shaft nut becomes even more complex
Solution Approach 1:
By changing the access dimension from axial (through the long LP shaft) to radial (through the reducer casing), the invention eliminates the problem of increasing tool length complexity that would result from larger fan diameters and higher bypass ratios.
4Adaptability or versatility
If the LP body is divided into two modules, then modularity is achieved, but the first module cannot be independently maintained when it includes a reducer
Solution Approach 1:
The invention further segments the first module by providing independent access to the locking nut through radial orifices, allowing the reducer-containing module to be independently maintained without requiring disassembly of the lubrication enclosure or other modules.
Data Source
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AI summary
A set of shafts (34, 72) for an aircraft turbomachine, this set comprising: a first shaft (72) having external splines (76) oriented parallel to an axis of rotation (A) of the shaft, a second shaft (34) having internal splines (74) complementary to said external splines, this second shaft being fitted axially on the first shaft and these shafts rotating as one by engagement of their splines, and a system for axially locking the shafts with respect to one another, characterized in that said system comprises screws (78) that are oriented radially with respect to said axis, each of these screws being screwed into a first orifice (80) in one of the shafts and having a free end for engaging a second orifice (82) in the other of the shafts.