Planetary Reduction Gearbox Using Independent Fore and Aft Ring Gears
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Solution Overview
Problem
Aircraft gas turbine engines require reduction gearboxes to manage the high rotational speed of turbines for propeller drive, but existing gearboxes add weight and complexity, offering room for improvement.
Innovation Solution
A reduction gearbox with a planetary gear arrangement, including a sun gear, planet gear assemblies, and independent fore and aft ring gears, which are mechanically engaged with the casing to optimize rotational speed reduction and torque generation, while minimizing weight and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a reduction gearbox is used to reduce turbine rotational speed and increase torque, then the propeller can be driven effectively, but the gearbox adds weight and complexity to the engine
Solution Approach 1:
The planetary gear assembly is divided into multiple independent planet gear assemblies, each with its own planet gear, carrier, and bearing. This segmentation allows for modular manufacturing and assembly, reducing overall system complexity while maintaining the torque multiplication function.
Solution Approach 2:
The planet gears are nested within the annular gear, with multiple planet gears arranged radially around the sun gear. This nested configuration achieves compact design, reducing the overall footprint and complexity of the gearbox while providing effective torque reduction.
2Power
If a reduction gearbox is used to reduce turbine rotational speed and increase torque, then the propeller can be driven effectively, but the gearbox adds weight to the engine
Solution Approach 1:
The gearbox components, including the sun gear, planet gears, and annular gear, are manufactured using composite materials or optimized alloy structures. This reduces the weight of individual components while maintaining the structural integrity and load-bearing capacity required for torque transmission.
Solution Approach 2:
The nested planetary gear configuration allows multiple gears to occupy the same radial space, creating a compact structure that minimizes the overall volume and weight of the gearbox while achieving the required torque multiplication ratio.
3Power
If multiple planet gear assemblies are used to reduce rotational speed, then torque generation is improved, but the number of components and complexity increases
Solution Approach 1:
Each planet gear assembly is designed as a universal module that performs multiple functions: torque transmission, speed reduction, and load distribution. The standardized design of each module allows them to be replicated and combined, achieving high torque generation without proportionally increasing system complexity.
Solution Approach 2:
Multiple planet gear assemblies are merged into a single integrated planetary gear system that shares common components such as the sun gear, annular gear, and planet carrier. This merging approach allows the system to achieve high torque multiplication while avoiding the complexity of completely independent gear trains.
Data Source
AI summary
A reduction gearbox is provided that includes a planetary gear arrangement disposed in a casing. The planetary gear arrangement includes a sun gear, planet gear assemblies, and fore and aft ring gears. The sun gear is configured for communication with an input. Each planet gear assembly has a main gear meshed with the sun gear, fore and aft lateral gears disposed on opposite sides of the main gear and rotating therewith. The main gear has a main gear pitch diameter and the fore and aft lateral gears having a lateral gear pitch diameter. The fore ring gear is meshed with the fore lateral gears. The aft ring gear is meshed with the aft lateral gears. The aft ring gear is independent of the fore ring gear. The planet gear assemblies are in communication with an output. The fore and aft ring gears are mechanically engaged with the casing.