Static Curvic Joint Assembly for Planet Carrier Alignment
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Solution Overview
Problem
Epicyclical gear systems in dynamic applications like geared turbofan engines face excessive wear and potential failure due to relative movement between components, which existing designs fail to adequately address, leading to misalignment and uneven load sharing among planet gears and bearings.
Innovation Solution
A planet gear housing assembly with a static curvic joint is introduced, comprising an aft and forward planet carrier assembly with curvic structures that form a static connection, reducing relative movement and misalignment by coupling the assemblies through a curvic joint, thereby maintaining precise alignment and load distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a dynamic connection is used between planet carrier assemblies to allow relative movement, then the system can accommodate misalignment and thermal expansion, but excessive wear and potential failure occur due to unwanted relative movement
Solution Approach 1:
The curvic joint employs a dynamic design where the forward and aft planet carrier assemblies are allowed to move relative to each other in a controlled manner. The curvic teeth engage to transmit torque while permitting axial movement and angular misalignment, thus accommodating thermal expansion and manufacturing tolerances without causing excessive wear or failure.
2Reliability
If rigid coupling is used between planet carrier assemblies to prevent relative movement, then misalignment is reduced, but the system cannot accommodate thermal expansion and manufacturing tolerances
Solution Approach 1:
The curvic joint changes the geometric parameters of the connection between planet carrier assemblies. The curvic teeth profile is specifically designed to allow controlled movement in certain directions while maintaining torque transmission. This parameter change enables the system to accommodate thermal expansion and manufacturing tolerances while preventing excessive misalignment that would lead to failure.
3Ease of manufacture
If traditional coupling methods are used to connect planet carrier assemblies, then assembly is simple, but fore-to-aft misalignment occurs leading to uneven load sharing among planet gears
Solution Approach 1:
The curvic joint acts as an intermediary element between the forward and aft planet carrier assemblies. It provides a specialized connection interface that simultaneously achieves precise alignment through curvic tooth engagement and maintains assembly simplicity through a straightforward bolting process. The curvic structure self-aligns the assemblies, eliminating fore-to-aft misalignment and ensuring even load distribution among planet gears.
Data Source
AI summary
A planet gear housing assembly in an epicyclical gear assembly comprises an aft planet gear assembly and a forward planet gear assembly. The aft planet carrier assembly comprises an aft flange defining a central aperture and an annular mounting flange positioned forward of and coaxial with said central aperture, said mounting flange forming a forward facing mounting surface comprising a curvic structure. The forward planet carrier assembly comprises a forward flange defining a central aperture and an annular mounting flange positioned aft of and coaxial with said central aperture, said mounting flange forming an aft facing mounting surface comprising a curvic structure. The curvic structures of the mounting surfaces are positioned relative to each other to thereby form a static curvic joint.