Aircraft Turbine Reducer With Symmetrical Chevron Satellites
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Solution Overview
Problem
Double-stage mechanical reduction gears in turbomachines, particularly in aircraft, face issues with asymmetry leading to significant moments at satellite bearings, which complicates assembly and manufacturing, and axial forces at interfaces, limiting compactness and efficiency.
Innovation Solution
The use of satellites with symmetrical herringbone teeth, where each toothing has two series of teeth inclined relative to each other, forming chevrons, and separated by an annular groove, to optimize compactness and reduce axial forces and moments, allowing for a more symmetrical and efficient gear design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If double-stage reduction gears are used to achieve higher reduction ratios, then the reduction capability is improved, but asymmetry generates significant moments at satellite bearings and axial forces at interfaces
Solution Approach 1:
The patent applies asymmetry principle by designing the satellite toothing with non-symmetrical tooth distributions relative to the satellite center. The first toothing has teeth distributed asymmetrically to engage with the sun gear, while the second toothing has a different asymmetric distribution to engage with the crown gear. This deliberate asymmetric design balances the moments and axial forces generated during operation, resolving the harmful effects of asymmetry through controlled asymmetric configuration.
2Productivity
If helical teeth are used to improve meshing quality and compactness, then the meshing efficiency is improved, but significant axial forces are generated at the interfaces
Solution Approach 1:
The satellite toothing is segmented into two distinct toothings: the first toothing for engagement with the sun gear and the second toothing for engagement with the crown gear. Each toothing can be optimized independently - the first toothing may use helical teeth for high meshing efficiency, while the second toothing uses a different configuration to counterbalance axial forces. This segmentation allows simultaneous optimization of meshing quality and axial force management.
3Object-affected harmful factors
If herringbone teeth are used to eliminate axial forces, then the axial force problem is solved, but bearing moments remain and assembly/manufacturing complexity increases
Solution Approach 1:
Different local qualities are applied to different parts of the satellite toothing. The first toothing may use helical teeth optimized for sun gear engagement, while the second toothing uses herringbone or other configurations optimized for crown gear engagement and axial force balance. This local differentiation allows each toothing to have properties specifically suited for its function, achieving overall system optimization without uniformly increasing complexity.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
Mechanical reducer (60) of turbomachine (1), in particular of aircraft, this reducer comprising a sun (70) having an axis of rotation (X), a ring (90) which extends around the sun and which is configured to be stationary in rotation about said axis, satellites (80) which are meshed with the sun and the ring and which are held by a satellite carrier (100) which is configured to be stationary or in rotation about said axis, each satellite comprising a first set of teeth (82) of average diameter D1 for meshing with the sun, and a second set of teeth (84) of average diameter D2, different from D1, for meshing with the ring, stationary or in rotation, characterized in that the first and second sets of teeth of each satellite comprise chevron teeth and have a symmetry with respect to a plane (H) perpendicular to said axis and passing substantially through the middle of the satellite.