Biconical Planet Carrier Shafts for Turbomachine Gear Alignment
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Solution Overview
Problem
Mechanical reduction gears in turbomachines, particularly in dual-flow turbomachines, face challenges with satellite misalignment due to deformations under load, leading to increased contact pressures and tooth overload, which existing designs struggle to fully mitigate without compromising stiffness or balancing loads.
Innovation Solution
A planet carrier with a biconical internal periphery and frustoconical surfaces that can adjust ±10% in length to rebalance the assembly and reduce misalignment, optimizing stiffness and minimizing overload on satellite teeth, compatible with various gearbox types and tooth configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the planet carrier is made stiffer to reduce misalignment, then alignment precision improves, but the load bearing capacity and flexibility are compromised
Solution Approach 1:
The patent changes the geometric parameters of the guide shaft by introducing a biconical internal periphery with frustoconical surfaces instead of a cylindrical shape. This geometric parameter change allows the shaft to have variable stiffness along its length, with the conical surfaces providing alignment precision while the overall structure maintains load bearing capacity through optimized stress distribution.
2Strength
If the planet carrier is made more flexible to absorb deformations, then load bearing capacity improves, but satellite alignment precision deteriorates
Solution Approach 1:
The patent applies local quality by creating different structural characteristics at different locations of the guide shaft. The biconical internal periphery with frustoconical surfaces provides localized stiffness where alignment is critical, while other portions of the structure maintain flexibility to absorb deformations and bear loads, thus resolving the contradiction between precision and load capacity.
3Stability of the object's composition
If the raceways are made more rigid to reduce deformation, then alignment stability improves, but the risk of bearing pinch and contact pressure increase
Solution Approach 1:
The patent introduces curved frustoconical surfaces with specific cone angles (10-50°) instead of straight cylindrical surfaces. This curvature allows the raceways to gradually accommodate bearing deformations and misalignments, distributing contact pressures more evenly along the bearing contact area, thus reducing the risk of bearing pinch while maintaining alignment stability.
Data Source
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AI summary
Satellite carrier (10) for a mechanical turbomachine reducer, in particular for aircraft, this satellite carrier having an axis of rotation (X) and comprising satellite guidance axes (10b) which are arranged around and parallel to the axis of rotation (X), each of said guidance axes having a general tubular shape whose external periphery comprises only two coaxial and adjacent cylindrical tracks (11b) for the respective rolling of two annular rows of bearings (11a), characterized in that each of said axes has a substantially biconical internal periphery and comprising two coaxial and adjacent frustoconical surfaces (10e, 10f), these internal frustoconical surfaces converging towards each other and extending respectively radially inside said tracks.