Epicyclic Gear Housing Stiffening for Planet Carrier Alignment
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Solution Overview
Problem
Epicyclical gear systems in gas turbine engines face challenges in maintaining alignment and reducing relative movement between components, leading to misalignment and uneven load sharing, which can cause gear degradation and reduced bearing life due to differences in stiffness between forward and aft planet carrier assemblies.
Innovation Solution
A planet gear housing assembly with a stiffening member positioned between the forward and aft planet carrier assemblies, achieving a desired stiffness ratio to reduce misalignment and enhance torsional stiffness, thereby improving the alignment and operational stability of the epicyclical gear system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the forward planet carrier assembly is made stiffer to reduce misalignment, then gear alignment improves, but the stiffness imbalance between forward and aft assemblies worsens
Solution Approach 1:
The stiffening member is strategically positioned between the forward and aft planet carrier assemblies, providing localized reinforcement to the forward assembly. This creates non-uniform stiffness distribution where the forward assembly becomes stiffer than the aft assembly, directly addressing the alignment problem while maintaining overall system balance
Solution Approach 2:
The stiffening member acts as an intermediary component that couples the forward and aft planet carrier assemblies. It transfers and balances the torsional loads between the two assemblies, preventing excessive misalignment in the forward assembly while maintaining the necessary stiffness differential
2Reliability
If relative movement between planet carrier assemblies is reduced to prevent wear, then component life improves, but the system's ability to accommodate thermal expansion and manufacturing tolerances worsens
Solution Approach 1:
The stiffening member modifies the torsional stiffness parameters of the forward planet carrier assembly, creating a controlled stiffness differential. This allows the system to maintain reduced relative movement for wear prevention while the stiffness gradient accommodates thermal expansion and manufacturing tolerances through elastic deformation
3Manufacturing precision
If the forward torsional stiffness is increased to 60-80% of aft torsional stiffness, then misalignment is reduced, but the structural complexity increases
Solution Approach 1:
The stiffening member is designed as a segmented structure with multiple radial flanges that can be independently positioned and sized. This segmentation allows precise control over the stiffness characteristics while maintaining a relatively simple overall structure that integrates with the existing planet carrier assemblies
Data Source
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AI summary
A planet gear housing assembly is disclosed in an epicyclical gear system of a gas turbine engine having an engine casing. The planet gear housing assembly comprises an aft planet carrier assembly, a forward planet carrier assembly, and a plurality of planet gears. An aft flange of the aft planet carrier assembly is coupled to the engine casing to define a first torsional stiffness. A forward flange of the forward planet carrier assembly is coupled to the aft flange to define a second torsional stiffness. The second torsional stiffness may be between 60% and 80% of the first torsional stiffness. The planet gear housing assembly may further comprise a stiffening member positioned between the forward planet carrier assembly and the aft planet carrier assembly.