Planetary Ring Gear Assembly With External Centering Rim
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Solution Overview
Problem
Current turbine engine reduction gears, particularly planetary and epicyclic types, face challenges in ensuring optimum centring and alignment of ring gear elements, leading to misalignment of teeth sets and inefficient force transmission due to existing centring methods that either hinder mechanical behavior or fail to maintain axial position effectively.
Innovation Solution
The proposed solution involves a ring gear design with cylindrical centring rims on the outer periphery of flanges, allowing for external centring and precise angular adjustment, which improves the distribution of stresses and facilitates better assembly and lubrication oil passage, ensuring correct orientation of teeth sets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a peripheral rim is provided at the inner periphery of the flange to engage in an annular recess for centring, then centring of the elements is achieved, but the transmission of forces is hindered and misalignment of teeth sets occurs
Solution Approach 1:
The patent moves the centring mechanism from the inner periphery (radial dimension) to the outer periphery of the flange (external dimension). The cylindrical centring rim on the outer periphery of one flange engages with a corresponding recess on the outer periphery of the other flange, achieving centring without interfering with the internal force transmission paths through the teeth sets.
Solution Approach 2:
The patent separates the centring function from the force transmission function by placing the centring mechanism on the outer periphery of the flange, distinct from the inner periphery where the teeth sets transmit forces. This segmentation allows both functions to operate independently without interference.
2Manufacturing precision
If centring is performed via the interior of the elements, then centring is achieved, but the axial position of the webs cannot be brought closer to the median plane
Solution Approach 1:
The patent relocates the centring mechanism to the outer periphery of the flange, enabling the webs to be positioned axially closer to the median plane while maintaining centring capability through the external cylindrical rim and recess engagement.
3Ease of operation
If radial oil passages are provided through the ring gear, then lubrication is enabled, but the centring rim flexibility increases and centring function deteriorates
Solution Approach 1:
The patent provides oil passages through the flange structure rather than through the centring rim itself, maintaining the rigidity and precision of the centring rim while enabling lubrication through alternative paths in the flange body.
Data Source
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.