Nested Double Epicyclic Reducer for Aircraft Landing Gear Wheels
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing mechanical reducers for aircraft landing gear wheels face space constraints and require large reduction ratios due to high-speed electric motors, which current epicyclic and planetary gears cannot adequately provide in restricted spaces.
Innovation Solution
A double epicyclic gear train with a first and second epicyclic gear train, utilizing first and second satellites with different toothings and planet carriers, to achieve a large reduction ratio within a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional epicyclic or planetary gear reducer is used, then the structure is simple and space is saved, but the reduction ratio is insufficient for high-speed electric motors
Solution Approach 1:
The patent divides the single epicyclic gear train into two separate epicyclic gear trains connected in series. The first epicyclic gear train includes a first sun gear, first satellites, and a crown, while the second epicyclic gear train includes a second sun gear, second satellites, and the same crown. This segmentation allows each stage to contribute to the overall reduction ratio, achieving a cumulative effect that satisfies the high reduction ratio requirement without requiring an excessively complex single-stage design.
Solution Approach 2:
The patent implements a nested configuration where the first epicyclic gear train and second epicyclic gear train are arranged concentrically around the same crown gear. The first satellites and second satellites are distributed around the same circular path, with the first planet carrier and second planet carrier nested within the same spatial envelope. This nesting allows both gear trains to share common components (the crown and mounting structure), achieving high reduction ratio while minimizing the overall footprint and maintaining structural compactness.
2Power
If a high-speed electric motor is used, then power density is improved, but the required reduction ratio increases the space requirement
Solution Approach 1:
The patent employs a nested dual-epicyclic gear train configuration where both gear trains share the same crown gear and operate within the same radial space. The first and second planet carriers are arranged concentrically, allowing the reducers to achieve a cumulative reduction ratio without proportionally increasing the outer diameter. This nested arrangement enables high power density motors to be paired with compact reducers that provide the necessary large reduction ratio while maintaining a small overall volume.
Solution Approach 2:
The patent utilizes the axial dimension by stacking two epicyclic gear stages along the same radial plane. Instead of increasing the radial or tangential dimensions to accommodate higher reduction ratios, the design stacks gear stages axially, with the first and second planet carriers positioned at different axial locations but sharing the same crown gear. This dimensional approach allows the reducer to achieve high reduction ratios without significantly increasing the overall footprint, maintaining compatibility with compact high-power-density motor assemblies.
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 double epicyclic gear train provides a high reduction ratio while maintaining a small footprint, suitable for aircraft landing gear applications.
Implementation Method 1
The role of a mechanical reducer is to modify the speed and torque ratio between the input shaft and the output shaft of a mechanical system
Implementation Method 2
second satellites distributed around the X axis and meshed with a crown and with external teeth of said first planet carrier
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Mechanical speed reducer (28), in particular for a device (10) for driving at least one wheel (12) of an aircraft landing gear (14), this reducer comprising: - a first sun gear (32) having an external toothing (32a), - first satellites (34) meshed with the external toothing (32a) of the first sun gear (32), these first satellites (32) being carried by a first satellite carrier (36), - a fixed ring gear (38) meshed with the satellites (34), and - second satellites (46) meshed with a ring gear (38) and with an external toothing (36a) of said first satellite carrier (36), these second satellites (46) being carried by a second satellite carrier (48).