Aircraft Turbine Sun Gear Stepped Profile for Oil Evacuation
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Solution Overview
Problem
Current mechanical reduction gears in turbomachines, particularly in aircraft, face challenges in efficient oil circulation and evacuation, leading to potential overpressure issues that can affect the alignment and lubrication of components.
Innovation Solution
A sun gear with a stepped profile and internal splines that allows for axial centering and lubrication, featuring annular grooves and holes for oil supply and evacuation, along with a lubricating oil distributor system that includes oil deflectors to project oil jets tangentially, ensuring effective oil circulation and retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional sun gear design is used, then the structure is simple, but oil circulation and evacuation are inefficient leading to overpressure issues
Solution Approach 1:
The sun gear is segmented into multiple axial sections (first section with centering surface, second section with splines, third section with evacuation holes) to enable different functions in different zones. This segmentation allows efficient oil circulation through dedicated supply and evacuation paths while maintaining structural integrity.
Solution Approach 2:
Different axial sections of the sun gear have different local structures optimized for specific functions: the first section has a centering surface for alignment, the second section has splines for torque transmission and oil supply, and the third section has evacuation holes for oil drainage. This local quality approach resolves the contradiction by making the structure complex only where necessary.
2Manufacturing precision
If the sun gear has stepped profile with multiple sections, then centering and lubrication are improved, but manufacturing complexity increases
Solution Approach 1:
The stepped profile is achieved by segmenting the sun gear into axial sections with different diameters and features. This segmentation enables precise centering through the first section's centering surface while maintaining manufacturability by using standard machining operations for each section.
Solution Approach 2:
The centering surface is provided in advance in the first section to ensure proper alignment before the sun gear is fully assembled. This preliminary centering action prevents misalignment issues during assembly and operation, improving manufacturing precision without requiring complex post-assembly adjustments.
3Reliability
If oil jets are projected tangentially, then splashing is reduced and lubrication is improved, but the system complexity increases
Solution Approach 1:
Instead of projecting oil jets axially or radially as in conventional designs, the oil jets are projected tangentially to the sun gear rotation. This inverted approach uses the rotational motion of the sun gear to distribute oil more effectively along the tooth flanks, reducing splashing and improving lubrication effectiveness.
Solution Approach 2:
The tangential oil jet system utilizes the existing rotational motion of the sun gear to achieve oil distribution. The rotating sun gear itself serves as the distribution mechanism, eliminating the need for separate complex distribution components and reducing overall system complexity while improving lubrication.
4Stress or pressure
If multiple axial sections are used for oil supply and evacuation, then overpressure is prevented, but assembly complexity increases
Solution Approach 1:
The sun gear is divided into axial sections with dedicated oil supply (second section) and evacuation (third section) functions. This segmentation creates pressure differential paths that prevent overpressure buildup while maintaining a relatively simple monolithic structure that can be assembled as a single piece, reducing assembly complexity.
Solution Approach 2:
The sun gear structure serves multiple functions simultaneously: torque transmission through splines, oil supply through the second section, oil evacuation through the third section, and centering through the first section. This multi-functionality reduces the need for separate components, simplifying assembly while achieving pressure control.
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 design simplifies assembly, enhances centering, and improves lubrication by allowing for efficient oil supply and evacuation, reducing the risk of overpressure and splashing, thereby maintaining optimal operating conditions for the reduction gear components.
Implementation Method 1
a lubricating oil distributor system that includes oil deflectors to project oil jets tangentially, ensuring effective oil circulation and retention
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
Solar (7) for a mechanical turbomachine reducer, in particular for aircraft, the solar having a general annular shape around an axis (X) and having at its external periphery a meshing tooth with satellites of the reducer, and at its internal periphery splines (7a) for coupling with an input shaft (3) of the reducer, characterized in that the solar has in axial section a stepped profile and preferably includes an annular groove (60) opening radially inwards and configured to receive at least one oil jet (39).