Aircraft Wheel Reducer Layout for High Ratio in Limited Rim Space
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Solution Overview
Problem
Existing technologies face challenges in achieving high reduction ratios for electric motor-driven aircraft landing gear wheels due to space constraints and the need for high-speed reduction within a limited wheel rim and hub diameter, which current epicyclic and planetary gears cannot satisfy.
Innovation Solution
A mechanical reducer system with a sun gear, fixed and mobile crowns, and satellites carried by a planet carrier, allowing for a double-stage reduction configuration that increases the reduction ratio within the constrained space of an aircraft landing gear wheel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a mechanical reducer is used to transmit power from the electric motor to the wheel, then the reduction ratio can be increased to match the low rotational speed of the wheel, but the space constraints within the wheel rim and hub prevent achieving the required reduction ratio with conventional epicyclic or planetary gears
Solution Approach 1:
The patent divides the single-stage reduction into two separate meshing stages: a first meshing stage between the sun gear and planet gears, and a second meshing stage between the planet gears and the fixed crown. This segmentation allows each stage to contribute to the overall reduction ratio, enabling a higher total reduction (product of both stages) within the same spatial envelope, thus resolving the contradiction between achieving high reduction ratio and maintaining compact size.
2Power
If the electric motor rotates at high speeds, then the motor can be more compact and efficient, but the wheel requires low rotational speed, necessitating a reduction gear with large reduction ratio that cannot fit in the limited space
Solution Approach 1:
The patent utilizes the radial dimension by arranging the double-stage epicyclic gear system with the sun gear at the center, planet gears in the intermediate radial zone, and the fixed crown at the outer radial position. This radial arrangement allows the two meshing stages to be stacked in the radial direction rather than requiring additional axial length, thereby achieving high reduction ratio within the limited radial space between the hub and rim while maintaining motor efficiency.
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 proposed reducer system effectively increases the reduction ratio, optimizing power transmission for electrically driven aircraft landing gear wheels while accommodating the spatial limitations of the wheel rim and hub.
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
a sun gear integral in rotation with the motor shaft, this sun gear being centered on the axis and comprising external teeth, a fixed crown centered on the axis and which comprises internal teeth, this fixed crown being configured to be fixed to a stator of the device, a mobile crown centered on the axis and which comprises internal teeth, this mobile crown being integral in rotation with the rim, and satellites which are meshed with the sun gear
Data Source
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AI summary
Device (10) for driving at least one wheel (12) of an aircraft landing gear (14), this device (10) comprising: - at least one wheel (12) having a rim (16), - an electric motor (20) having a shaft, - a mechanical transmission system (22) between the shaft of the motor (20) and the rim (16), this mechanical transmission system (22) comprising a mechanical reducer comprising: - a sun gear fixed in rotation to the shaft and having external teeth, - a fixed ring gear having internal teeth, - a movable ring gear fixed in rotation to the rim and having internal teeth, and - planet gears which are meshed with the sun gear and which each have two external teeth meshed respectively with the teeth of the fixed and movable rings.