Epicyclic Gearbox Carrier Stiffness for Load Sharing and Alignment
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Solution Overview
Problem
Gas turbine 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 gearbox incorporates an epicyclic design with a planet carrier having specific radial bending, tilt, and torsional stiffness ranges to compensate for misalignment and ensure even load distribution, allowing for flexibility to accommodate minor misalignments while maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the planet carrier is made with high stiffness to maintain gear alignment, then gear misalignment is reduced, but the gearbox becomes more sensitive to manufacturing tolerances and wear
Solution Approach 1:
The patent applies parameter changes by optimizing the stiffness values of the planet carrier within specific ranges (radial bending stiffness: 0.5-2.0×10^9 N/m, tilt stiffness: 0.2-0.8×10^9 Nm/rad, torsional stiffness: 0.1-0.5×10^9 Nm/rad). This allows the carrier to maintain sufficient rigidity for gear alignment while having enough flexibility to accommodate manufacturing tolerances and wear, thereby resolving the contradiction between stability and reliability.
2Strength
If the planet carrier is made with high stiffness to ensure even load distribution, then load distribution is improved, but distortion risk increases under varying operational conditions
Solution Approach 1:
The patent uses parameter changes by defining specific stiffness ranges for the planet carrier that balance load distribution capabilities with distortion resistance. The radial bending stiffness (0.5-2.0×10^9 N/m), tilt stiffness (0.2-0.8×10^9 Nm/rad), and torsional stiffness (0.1-0.5×10^9 Nm/rad) are optimized to ensure even load distribution across planet gears while preventing excessive distortion under varying operational loads.
3Manufacturing precision
If the planet carrier stiffness is increased to accommodate manufacturing tolerances, then misalignment compensation is improved, but the gearbox structure becomes more complex
Solution Approach 1:
The patent resolves this contradiction through parameter changes by optimizing the stiffness characteristics of the existing planet carrier structure rather than adding complex compensation mechanisms. The specific stiffness ranges (radial bending: 0.5-2.0×10^9 N/m, tilt: 0.2-0.8×10^9 Nm/rad, torsional: 0.1-0.5×10^9 Nm/rad) enable the carrier to passively compensate for manufacturing tolerances and wear through controlled elastic deformation, maintaining manufacturing precision without increasing structural complexity.
Data Source
AI summary
An engine for an aircraft comprises an engine core comprising a turbine, a compressor, and a core shaft connecting the turbine to the compressor; a fan located upstream of the engine core, the fan comprising 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.