Planetary Ring Gear With External Centering Rim for Tooth Alignment
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Solution Overview
Problem
Current turbomachine reduction gears, particularly epicyclic and planetary types, face challenges in ensuring optimal centering and alignment of crown elements, leading to misalignment of teeth due to vibratory modes and force transmission, which affects mechanical and vibratory behaviors, and existing centering solutions are not entirely satisfactory.
Innovation Solution
The implementation of a cylindrical centering rim on the outer periphery of one annular flange to cooperate with the other flange's outer periphery for centering, allowing for improved stress distribution, axial alignment, and oil passage design with radial notches and orifices for efficient lubrication and torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a peripheral rim centering solution is provided at the internal periphery of the flange, then centering of elements is achieved, but the presence of the flange and centering recess interferes with force transmission and causes misalignment of teeth
Solution Approach 1:
The patent inverts the conventional centering approach by moving the centering rim from the internal periphery to the external periphery of the flange. This external centering rim cooperates with a corresponding recess in the crown holder, eliminating the interference between internal centering features and force transmission paths while maintaining precise centering functionality.
Solution Approach 2:
The patent relocates the centering function to a different spatial dimension - from the internal radial dimension to the external radial dimension of the flange. This dimensional relocation allows the centering rim to function independently without interfering with the internal force transmission pathways.
2Manufacturing precision
If internal centering recesses are provided, then element centering is enabled, but the axial position of webs cannot be brought closer to the median plane
Solution Approach 1:
The patent inverts the centering location from internal to external, allowing the web structures to be positioned more favorably axially closer to the median plane between teeth, optimizing the structural configuration and force distribution.
3Quantity of substance
If radial oil passages are provided through the ring gear, then oil evacuation is enabled, but radial notches are created in the centering flange which increase its flexibility and reduce centering function
Solution Approach 1:
The patent segments the oil passage system by providing axial oil passages through the crown elements rather than radial passages through the centering flange. This segmentation allows oil evacuation functionality to be maintained while preserving the integrity and stiffness of the centering flange structure.
Solution Approach 2:
The patent introduces axial oil passages as an intermediary solution that achieves oil evacuation without compromising the centering flange. The oil passages are routed through the crown elements themselves, acting as mediators between the lubrication requirement and the centering precision requirement.
Data Source
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AI summary
A ring gear (114) for an epicyclic or planetary reduction gear (110) of a turbomachine, in particular of an aircraft, said ring gear extending about an axis and comprising first and second coaxial annular elements (114a, 114b) and comprising, respectively, two inner annular toothing sets (150) of different orientation, said first and second annular elements further comprising, respectively, first and second radially outer annular flanges (114ab, 114bb) for attaching said first and second elements to each other, characterised in that one of said first and second flanges comprises, at its outer periphery, a cylindrical centring rim (164) configured to cooperate with the outer periphery of the other of said first and second flanges.