Planetary Reduction Gearbox With Split Ring Gears for Turboprops
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Solution Overview
Problem
Aircraft engine gearboxes, particularly those used in turboprop engines, face challenges due to their weight and complexity, which are exacerbated by the need for a reduction gearbox to manage the high rotational speed of turbines while providing sufficient torque for propeller operation.
Innovation Solution
A reduction gearbox with a planetary gear arrangement is designed, featuring a sun gear, planet gear assemblies, and independent fore and aft ring gears with mechanical features for engagement, allowing for efficient torque transmission and rotational speed reduction, while minimizing weight and complexity through optimized mechanical engagement and lubrication systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a reduction gearbox is used to reduce turbine rotational speed and increase torque, then propeller operation becomes feasible, but weight and complexity of the engine increase
Solution Approach 1:
The patent employs a planetary gear arrangement where planet gears are nested around a sun gear, and ring gears enclose the planet gears. This nested configuration allows multiple gear stages to be compacted into a single integrated unit, achieving torque multiplication while minimizing the gearbox's overall weight and volume.
Solution Approach 2:
The reduction gearbox is divided into multiple independent planet gear assemblies, each containing sun gears, planet gears, and ring gears. This segmentation allows the torque reduction function to be distributed across several smaller components rather than requiring a single large gearbox, reducing overall weight while maintaining functionality.
2Power
If a reduction gearbox is used to reduce turbine rotational speed and increase torque, then propeller operation becomes feasible, but device complexity increases
Solution Approach 1:
The patent merges multiple gear reduction stages into a single planetary gear system where sun gears, planet gears, and ring gears work together in one integrated arrangement. This combining of functions into a unified mechanism reduces the number of separate components and assemblies needed, thereby reducing overall device complexity while achieving the required torque multiplication.
Solution Approach 2:
The planetary gear arrangement serves multiple functions simultaneously: it reduces rotational speed, multiplies torque, and provides structural support through the interconnected sun-planet-ring gear configuration. This multi-functionality eliminates the need for separate mechanisms for each function, reducing overall gearbox complexity.
Data Source
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AI summary
A reduction gearbox is provided that includes a planetary gear arrangement (42) disposed in a casing (44). The planetary gear arrangement (42) includes a sun gear (46), planet gear assemblies (48), and fore and aft ring gears (50A, 50B). The sun gear (46) is configured for communication with an input (52). Each planet gear assembly (48) has a main gear (58) meshed with the sun gear (46), fore and aft lateral gears (60, 62) disposed on opposite sides of the main gear (58) and rotating therewith. The main gear (58) has a main gear pitch diameter and the fore and aft lateral gears (60, 62) having a lateral gear pitch diameter. The fore ring gear (50A) is meshed with the fore lateral gears (60). The aft ring gear (50B) is meshed with the aft lateral gears (62). The aft ring gear (50B) is independent of the fore ring gear (50A). The planet gear assemblies (48) are in communication with an output (40). The fore and aft ring gears (50A, 50B) are mechanically engaged with the casing (44).