Aircraft Propulsion Gearbox With Dual Planetary Stages
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Solution Overview
Problem
Existing aircraft propulsion system gearboxes lack efficiency and flexibility in adjusting rotational speeds, leading to suboptimal performance and potential mechanical stress.
Innovation Solution
A gear assembly with a sun gear and planet gears featuring double helical patterns, along with fixed ring gears and lateral gears, configured to drive rotational loads at reduced speeds, enhancing power output and accommodating axial movement through splined connections and journal bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional single-stage planetary gear assembly is used, then the device complexity is low, but the adaptability for different rotational speed requirements is insufficient
Solution Approach 1:
The gear assembly is divided into two independent planetary stages, each capable of providing different reduction ratios. The first planetary stage includes a sun gear, planet gears, and a first ring gear, while the second planetary stage includes another set of planet gears and a second ring gear. This segmentation allows each stage to be optimized for specific speed reduction requirements, thereby improving adaptability without requiring a complete redesign of the entire system.
Solution Approach 2:
The dual planetary stage configuration enables the single gear assembly to provide multiple reduction ratios and accommodate various rotational speed requirements. By fixing different elements (sun gear, ring gears, or carrier) in different operating modes, the assembly can function as a single-stage or two-stage planetary gearbox, providing universal applicability across different propulsion scenarios.
2Power
If higher loading capacity is achieved through increased gear size, then the power transmission capability improves, but the axial space requirement increases
Solution Approach 1:
The patent transitions from a single-plane gear arrangement to a multi-stage planetary configuration that utilizes radial and axial dimensions more efficiently. The first and second ring gears are arranged concentrically with different diameters, allowing the gear assembly to achieve higher loading capacity through increased effective gear area without proportionally increasing the overall axial length. The compact planetary arrangement distributes loads across multiple contact points in three-dimensional space.
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 gear assembly achieves higher loading capacity and reduced torque fluctuations, improving propulsion system efficiency and mechanical stability.
Implementation Method 1
The sun gear includes a first double helical gear pattern. Each planet gear of the plurality of planet gears includes a main gear, a first lateral gear, and a second lateral gear. The main gear includes a second double helical gear pattern engaged with the first double helical gear pattern.
Implementation Method 2
The planet carrier may include a plurality of journal bearings, with each journal bearing positioned between a respective shaft of the plurality of shafts and a respective planet gear of the plurality of planet gears.
Data Source
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AI summary
An assembly for an aircraft propulsion system includes an output shaft (56) and a gear assembly (62). The gear assembly (62) is configured to drive rotation of the output shaft (56). The gear assembly (62) includes a sun gear (66), a plurality of planet gears (68), a first ring gear (70), and a second ring gear (72). The sun gear (66) is rotatable about a rotational axis (38). The sun gear (66) includes a first double helical gear pattern (74). Each planet gear (68) of the plurality of planet gears (68) includes a main gear (80), a first lateral gear (82), and a second lateral gear (84). The main gear (80) includes a second double helical gear pattern (92) engaged with the first double helical gear pattern (74). The first lateral gear (82) is engaged with the first ring gear (70). The second lateral gear (84) is engaged with the second ring gear (72). The first ring gear (70) is axially spaced from the second ring gear (72) relative to the rotational axis (38).