Planetary Ring Gear Flange Geometry for Precise Centering
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Solution Overview
Problem
Current turbine engine reduction gears, particularly planetary and epicyclic types, face challenges in ensuring optimum centering and axial alignment of ring gear elements, leading to misalignments and inefficient force transmission due to existing centering solutions that either hinder mechanical behavior or fail to maintain precise angular adjustment.
Innovation Solution
The design features angled peripheral portions on the flanges of the ring gear elements, allowing for direct force paths and stress distribution, reducing misalignments, and incorporating an inter-element annular cavity for oil passage to prevent stagnation, with the angled surfaces facilitating easier assembly and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional centering solutions (peripheral rim and annular recess) are used to center the ring gear elements, then centering is achieved, but the transmission of forces in the elements is hindered and misalignment of teeth sets occurs
Solution Approach 1:
The invention removes the traditional peripheral rim and annular recess centering features from the ring gear elements. Instead, centering is achieved through the geometry of the flanges themselves, specifically through the angled peripheral portions that guide axial positioning without interfering with force transmission paths in the teeth sets.
Solution Approach 2:
The flanges of the ring gear elements serve multiple functions: they provide structural support, enable force transmission from the teeth sets, and simultaneously achieve centering through their angled peripheral portions. This eliminates the need for separate centering features that would compromise force transmission.
2Manufacturing precision
If traditional centering solutions are used, then centering is achieved, but precise angular adjustment between elements cannot be maintained
Solution Approach 1:
The flanges incorporate asymmetric angled peripheral portions that provide precise angular positioning. The angles are specifically designed to guide the elements into correct angular alignment during assembly, ensuring that the teeth sets of different elements are properly oriented relative to each other without requiring separate adjustment mechanisms.
3Ease of operation
If radial oil passages are provided through the ring gear, then oil discharge is enabled, but radial notches are created that increase flexibility and reduce centering function
Solution Approach 1:
The invention provides oil discharge functionality through localized features that do not compromise the overall centering function. Oil passages are provided through the flanges in a controlled manner, with careful positioning to avoid creating radial notches in the angled peripheral portions that are critical for centering. This allows oil discharge while maintaining the structural integrity and centering capability of the flanges.
Data Source
AI summary
A ring gear for an epicyclic or planetary reduction gear of a turbomachine, in particular of an aircraft, said ring gear extending about an axis X and comprising first and second coaxial annular elements and comprising, respectively, two inner annular toothing sets of different orientation, each of said toothing sets having a pitch diameter and a median plane substantially perpendicular to said axis and with an intersection point designated Y in an axial cross-section of the ring gear, said first and second annular elements further comprising, respectively, first and second radially outer annular flanges for attaching said first and second elements to each other, wherein each of said first and second flanges comprises a peripheral portion extending in a plane that is angled with respect to said axis X and that passes substantially through said intersection point Y.