Epicyclic Gearbox Planet Carrier Stiffness for Gear Load Sharing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing aircraft engine gearboxes face challenges in maintaining gear alignment and load distribution due to manufacturing tolerances and wear, leading to potential distortion and reduced gearbox reliability.
Innovation Solution
The use of an epicyclic gearbox with a planet carrier having specific stiffness ranges, including radial bending stiffness between 1.20×10^9 N/m and 1.00×10^12 N/m, tilt stiffness greater than 6.00×10^8 Nm/radian, and torsional stiffness between 1.60×10^8 Nm/rad, to compensate for misalignment and ensure even load sharing across gears.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the planet carrier stiffness is increased to maintain gear alignment, then gear misalignment is reduced, but the gear mass must be increased to achieve the required stiffness
Solution Approach 1:
The patent applies parameter changes by optimizing the planet carrier stiffness to specific ranges (radial bending stiffness: 1.20×10^9 to 1.00×10^12 N/m, tilt stiffness: ≥6.00×10^8 Nm/radian, torsional stiffness: ≥1.60×10^8 Nm/rad). This allows the carrier to maintain gear alignment within acceptable tolerances while avoiding excessive stiffness that would require heavier gears, thus resolving the contradiction between alignment precision and mass.
2Stability of the object's composition
If the planet carrier is made more rigid to prevent distortion, then structural stability is improved, but the ability to compensate for manufacturing tolerances and wear is reduced
Solution Approach 1:
The patent resolves this contradiction by defining optimal stiffness ranges rather than maximizing rigidity. The planet carrier stiffness parameters are set to specific ranges that provide sufficient structural stability while maintaining enough flexibility to accommodate manufacturing tolerances and wear. This balanced approach ensures both structural integrity and long-term reliability.
3Use of energy by moving object
If the gear mass is reduced to improve efficiency, then energy consumption is decreased, but the load distribution and alignment stability are compromised
Solution Approach 1:
The patent enables light-weighting of gears by optimizing the planet carrier stiffness parameters. The carrier acts as a compliant support that compensates for variations in gear mass and dimensions, maintaining even load distribution across planet gears. This allows gear mass to be reduced for energy efficiency without compromising load distribution stability.
4Duration of action of stationary object
If the planet carrier stiffness is optimized within specific ranges, then gearbox lifetime is extended, but the design complexity increases
Solution Approach 1:
The patent extends gearbox lifetime by defining specific stiffness ranges for the planet carrier rather than using arbitrary values. The optimized parameters (radial bending: 1.20×10^9 to 1.00×10^12 N/m, tilt: ≥6.00×10^8 Nm/radian, torsional: ≥1.60×10^8 Nm/rad) ensure even load distribution and minimize stress concentrations, thereby extending component life despite the increased precision required in design.
Data Source
AI summary
An engine for an aircraft includes an engine core having a turbine, a compressor, and a core shaft connecting the turbine to the compressor; a fan located upstream of the engine core, the fan having a plurality of fan blades; and a gearbox. The gearbox is an epicyclic gearbox and comprises a sun gear, a plurality of planet gears, a ring gear, and a planet carrier on which the planet gears are mounted. The radial bending stiffness of the planet carrier is equal to or greater than 1.20×109 N/m, and/or the tilt stiffness of the planet carrier is greater than or equal to 6.00×108 Nm/rad. A method of operation of such an engine is also disclosed.