Planetary Gearbox Layout for High-Ratio Turbomachine Drives
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Solution Overview
Problem
Existing gearbox assemblies for open rotor engines and three-stream turbomachine architectures face challenges in providing adequate gear ratios, compatibility with high-speed turbine inputs, and space constraints, leading to inefficient operation and size limitations.
Innovation Solution
A gearbox configuration featuring a ring gear, first and second sun gears, and planet gears with specific meshing arrangements allows for high gear ratios while reducing the size and weight, enabling compatibility with high-speed inputs and constrained engine dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If known gear assemblies are scaled to provide adequate gear ratios, then the gear ratio is improved, but the size and weight of the gearbox increases
Solution Approach 1:
The patent employs a planetary gear system where planet gears are nested around a sun gear, and the entire planetary assembly is contained within a ring gear. This nested configuration allows multiple gear stages to be compacted into a single modular unit, achieving high gear ratios without proportionally increasing gearbox size and weight.
Solution Approach 2:
The patent transitions from conventional parallel-axis gear arrangements to a radial planetary configuration, utilizing the radial dimension around the sun gear to accommodate multiple planet gears. This dimensional reorganization enables compact high-ratio gearing by distributing gear engagement around the circumference rather than along a linear axis.
2Power
If known gear assemblies are scaled to provide adequate gear ratios, then the gear ratio is improved, but the length and diameter of the engine increases
Solution Approach 1:
The planetary gear assembly with sun gear, planet gears, and ring gear creates a compact nested structure that fits within a small axial envelope. This allows high gear ratios to be achieved without increasing the engine's axial length, as all gear stages are contained within the radial space of a single planetary module.
Solution Approach 2:
By arranging gears in a radial planetary configuration rather than a linear parallel arrangement, the patent compresses the gear train in the axial direction. The radial distribution of planet gears around the sun gear enables high reduction ratios to be achieved within a compact axial footprint, preserving engine length constraints.
3Device complexity
If conventional gear assemblies are used, then the structure is simple, but they are inadequate for receiving single input-speed shafts from high-speed turbines
Solution Approach 1:
The planetary gear system is designed to universally accept single-input shafts from high-speed turbines while providing adaptable gear ratios. The sun gear serves as a universal input interface that can receive torque from various turbine configurations, and the planetary arrangement allows the same basic structure to achieve different gear ratios by varying planet gear count, size, or arrangement.
Solution Approach 2:
The patent employs a dynamic planetary gear configuration where the carrier, planet gears, and ring gear can be selectively fixed or rotated to achieve different gear ratios and operational modes. This dynamic adaptability allows the gearbox to efficiently handle high-speed turbine inputs across varying operating conditions while maintaining a relatively simple base structure.
Data Source
AI summary
A gearbox for an engine includes a rotating element and a turbomachine, the turbomachine includes a shaft, and the rotating element is driven by the shaft across the gearbox. The gearbox includes a ring gear, a first sun gear and a second sun gear each configured to be driven by the shaft of the turbomachine, a first planet gear comprising a first gear portion and a second gear portion, and a second planet gear comprising a first gear portion and a second gear portion.