Epicyclic Gearbox Carrier Stiffness for Gear Misalignment Control
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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
An epicyclic gearbox design with a planet carrier having specific radial bending, tilt, and torsional stiffness ranges (e.g., radial bending stiffness ≥ 1.20×10^9 N/m and ≤ 1.00×10^12 N/m, tilt stiffness ≥ 6.00×10^8 Nm/rad) to compensate for misalignment and ensure even load sharing, thereby reducing gear mass while maintaining efficiency and life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the planet carrier stiffness is increased to maintain gear alignment, then gear misalignment compensation improves, but the risk of distortion and reduced reliability increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the planet carrier stiffness within a specific range (1.20×10^9 to 1.00×10^12 N/m for radial bending stiffness, and ≥6.00×10^8 Nm/rad for tilt stiffness). This optimized stiffness parameter allows the carrier to compensate for gear misalignment while preventing excessive distortion, thereby resolving the contradiction between manufacturing precision and reliability
Solution Approach 2:
The patent implements dynamics by allowing the planet carrier to have controlled flexibility rather than being completely rigid. The carrier can dynamically adjust and accommodate variations in gear positioning and wear conditions, enabling it to maintain proper gear alignment while absorbing misalignment stresses, thus improving both precision and reliability
2Manufacturing precision
If the planet carrier stiffness is increased to ensure even load sharing, then load distribution improves, but the gear mass increases
Solution Approach 1:
The patent optimizes the planet carrier stiffness parameters to achieve even load distribution across planet gears without excessive mass increase. By setting radial bending stiffness between 1.20×10^9 and 1.00×10^12 N/m and tilt stiffness ≥6.00×10^8 Nm/rad, the design achieves balanced load sharing while controlling the weight of moving components
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.