Planetary Reduction Gearbox With Split Ring Gears for Misalignment
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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 for propeller drive, leading to inefficiencies and potential misalignment issues.
Innovation Solution
A planetary gear arrangement within a reduction gearbox is designed with a sun gear, planet gear assemblies, and independent fore and aft ring gears, allowing for adjustable widths and channel configurations to achieve a rotational speed reduction ratio of 6:1 to 22:1, while accommodating axial and radial movement to mitigate misalignment and enhance torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a reduction gearbox is used to reduce rotational speed and increase torque, then the turbine can drive the propeller effectively, but the gearbox adds weight and complexity to the engine
Solution Approach 1:
The gearbox is divided into two independent ring gears (fore ring gear and aft ring gear) that can be adjusted relative to each other, allowing the system to be segmented into adjustable modules rather than a single rigid structure. This segmentation enables complexity reduction through modular adjustment while maintaining the torque multiplication function.
Solution Approach 2:
The ring gears are made adjustable rather than fixed, allowing dynamic reconfiguration of the gear arrangement. The fore and aft ring gears can be positioned at different widths and orientations, enabling the system to adapt to different operational requirements without requiring multiple complete gearbox designs.
2Ease of manufacture
If the ring gears have fixed dimensions, then manufacturing is simpler, but the gearbox cannot accommodate misalignment and axial/radial movement
Solution Approach 1:
The ring gears are designed with adjustable dimensions and positions rather than fixed specifications. The fore and aft ring gears can be repositioned axially and radially to accommodate misalignment, and their widths can be adjusted to optimize engagement with the planet gear assemblies while maintaining manufacturability.
Solution Approach 2:
The geometric parameters of the ring gears (width, position, orientation) are made variable rather than constant. This allows the system to change parameters in response to alignment conditions and operational requirements, improving reliability without requiring completely custom-manufactured components for each configuration.
3Ease of manufacture
If the ring gears have uniform width throughout, then manufacturing is easier, but the gear arrangement cannot be optimized for different radial positions
Solution Approach 1:
The ring gears are designed with non-uniform width distributions, where different radial positions have different widths optimized for their specific functions. The fore and aft ring gears can have varying widths at different locations to optimize torque transmission efficiency at each radial position, while still being manufacturable using standard gear fabrication techniques.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces the weight and complexity of the gearbox while effectively managing rotational speed and torque, improving the efficiency and reliability of turboprop engine operations by allowing for optimized propeller drive and reduced stress on components.
Implementation Method 1
The planetary gear arrangement includes a sun gear, a plurality of planet gear assemblies, a fore ring gear and an aft ring gear. The sun gear is configured in communication with a cantilevered end of an input. Each planet gear assembly has a main gear meshed with the sun gear, a fore lateral gear and an aft lateral gear disposed on opposite sides of the main gear and rotating therewith.
Data Source
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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 a fore and aft ring gears. The sun gear is configured in communication with a cantilevered end of an input. Each planet gear assembly has a main gear meshed with the sun gear, a fore lateral gear and an aft lateral gear 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 have 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.