Planet Carrier Geometry for Lightweight High-Torque Gearboxes
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Solution Overview
Problem
High-power turbine engines require gearbox assemblies with high gear ratios to efficiently transfer torque from low-pressure turbines to propellers, leading to increased stress on planet carriers, which affects reliability and weight optimization, while existing planet carriers struggle to balance torque absorption and weight reduction.
Innovation Solution
The design of a planet carrier with a specific planet carrier envelope, defined by the relationship (Dp/L) * (D/aw), which optimizes the planet gear pocket aspect ratio and carrier radial ratio to absorb torque efficiently, reducing the size and weight of the gearbox assembly and turbine engine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high gear ratios are used to transfer torque efficiently, then torque transfer efficiency is improved, but stress on planet carriers increases
Solution Approach 1:
The patent optimizes geometric parameters of the planet carrier including the planet gear pocket aspect ratio (Dp/L) and carrier radial ratio (D/aw) to achieve an optimal planet carrier envelope value between 2.70 and 4.50. This parameter optimization allows the planet carrier to withstand high stress conditions while maintaining efficient torque transfer through modified structural dimensions and configuration.
2Weight of moving object
If planet carrier size is reduced to decrease weight, then weight optimization is improved, but torque absorption capability deteriorates
Solution Approach 1:
The patent employs parameter optimization by establishing specific ranges for the planet gear pocket aspect ratio (Dp/L between 0.8-1.5) and carrier radial ratio (D/aw between 2.5-3.5) to achieve an optimal planet carrier envelope. This allows significant weight reduction through compact design while maintaining adequate torque absorption capability through optimized geometric proportions.
Solution Approach 2:
The patent introduces flexibility considerations in the planet carrier design, allowing controlled deformation under load through optimized structural parameters. The planet carrier is designed to flex within acceptable limits to absorb torque variations dynamically, enabling weight reduction while maintaining strength through intelligent structural design rather than brute-force sizing.
3Weight of moving object
If planet carrier size is reduced to decrease weight, then weight optimization is improved, but reliability deteriorates
Solution Approach 1:
The patent establishes an optimal planet carrier envelope range (2.70-4.50) through optimization of geometric parameters including planet gear pocket aspect ratio and carrier radial ratio. This parameter optimization ensures that even in compact, lightweight designs, the planet carrier maintains sufficient structural integrity and reliability by preventing excessive stress concentrations and ensuring adequate load distribution across the gear mesh.
Data Source
AI summary
A gearbox assembly includes a plurality of planet gears and a planet carrier including a plurality of planet gear pockets. Each planet gear is mounted in a respective planet gear pocket about a pin. The planet carrier is characterized by a planet carrier envelope in a range of 2.7 and 4.50. The planet carrier envelope is equal to a product of a planet gear pocket aspect ratio multiplied by a planet carrier radial ratio. The planet gear pocket aspect ratio is Dp/L. The planet carrier radial ratio is D/aw. Dp is a planet gear pocket diameter of the plurality of planet gear pockets, L is a planet gear pocket length of the plurality of planet gear pockets, D is a planet carrier diameter of the planet carrier, and aw is a pin center distance from a longitudinal axis of the planet carrier to an axis of the pin.