Aircraft Turbine Spline Lubrication via Injection Cavity
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Solution Overview
Problem
Aircraft turbomachines face inadequate lubrication due to increased torque transmission intensity, leading to high contact pressures and energy dissipation issues, compounded by relative axial movements caused by differential thermal expansion between rotating shafts and follower elements.
Innovation Solution
The implementation of a spline connection with radial centering connections that allow axial sliding, lubricant inlet and discharge passages, and a lubricant collection cavity to manage lubrication effectively, ensuring efficient lubrication and energy dissipation across the splines and radial centering connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional immersion lubrication is used, then device simplicity is maintained, but lubrication effectiveness deteriorates under high torque conditions
Solution Approach 1:
The patent introduces a lubricant injection system that delivers lubricant to the spline connection before critical wear occurs. The injection means are positioned to supply lubricant directly to the lubrication cavity, ensuring lubrication is established in advance of high-stress contact conditions.
Solution Approach 2:
The patent introduces a lubricant as an intermediary substance between the spline surfaces. The lubricant collection cavity and injection system serve as intermediaries to deliver this lubricant precisely where needed, mediating the contact between splines to reduce friction and wear under high torque.
2Device complexity
If radial centering is performed by splines, then structural simplicity is maintained, but lubrication effectiveness deteriorates due to insufficient lubricant flow
Solution Approach 1:
The patent separates the radial centering function from the spline connection. Dedicated radial centering connections are provided independently of the splines, allowing the splines to focus on torque transmission while the centering connections handle alignment. This segmentation enables better lubrication flow paths.
Solution Approach 2:
The patent introduces axial sliding capability to the radial centering connections, adding an axial dimension to the centering mechanism. This allows the centering connections to accommodate thermal expansion while maintaining radial alignment, and the axial clearance provides additional pathways for lubricant flow.
3Stability of the object's composition
If fixed axial positioning is used, then positional stability is maintained, but adaptability to thermal expansion deteriorates
Solution Approach 1:
The patent makes the axial positioning dynamic rather than fixed. The radial centering connections are designed to slide axially, allowing automatic adjustment to accommodate thermal expansion and contraction of the shaft and follower element. This dynamic capability maintains stability during operation while adapting to temperature changes.
4Manufacturing precision
If small radial clearances are provided at centering connections, then centering precision is improved, but lubrication flow deteriorates
Solution Approach 1:
The patent segments the clearance distribution: small radial clearances at the centering connections for precision, and larger radial clearances at the spline ends for lubricant flow. The lubrication cavity connects these regions, allowing lubricant to flow from the high-clearance spline region through the cavity to the low-clearance centering regions.
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 solution effectively addresses lubrication insufficiencies by accommodating thermal expansion and enhancing lubricant flow, ensuring satisfactory lubrication of splines and radial centering connections, thereby improving the turbomachine's operational efficiency and reliability.
Implementation Method 1
since radial centering is no longer carried out by the splines, significant radial clearances can be provided at the end of these splines, promoting the passage of a flow of lubricant capable of evacuating the part of the power dissipated at the level of the contacts between these splines
Implementation Method 2
the arrangement according to the invention makes it possible to cope with relative axial displacements between the rotating shaft and the follower element, for example following differential thermal expansion
Data Source
Figure 1
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AI summary
The invention relates to an arrangement (60) for an aircraft turbine engine, comprising a shaft (11) and a follower element (52) rotatably coupled to the shaft (11) by a spline connection (62), the arrangement comprising: - upstream and downstream connections (68a, 68b) for radially centring the follower element (52) relative to the shaft (11); - means (36) for spraying a lubricant into a collection cavity (74); - a passage (86) for receiving lubricant, which passage opens into the collection cavity (74) and into a cavity (66) for lubricating the splines which is partially defined by the upstream and downstream radial centring connections (68a, 68b); and - a passage (88) for discharging lubricant, which passage opens into the cavity (66) for lubricating the splines and outside the arrangement.