Aircraft Wheel Reducer With Double-Stage Satellites for High Gear Reduction
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Solution Overview
Problem
Existing technologies face challenges in achieving a large reduction ratio for electric motor-driven aircraft landing gear wheels within the constrained space of the wheel rim and hub, as current epicyclic and planetary gears do not meet the required reduction levels.
Innovation Solution
A mechanical reducer system with symmetrical double-stage satellites is employed, featuring a sun gear, a crown gear, and satellites with specific tooth configurations, allowing for a high reduction ratio while minimizing space requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional epicyclic or planetary gears are used, then the structure is simple and well-known, but the reduction ratio is insufficient for the constrained space
Solution Approach 1:
The patent divides the single-stage satellite gear into multiple independent satellite gears, each with specific tooth configurations. The first satellite has teeth meshing with the sun gear, while the second satellite has teeth meshing with the crown gear, creating a segmented power transmission path that achieves higher reduction ratio within the same spatial envelope.
Solution Approach 2:
The patent utilizes the radial dimension by arranging satellites at different radii from the center axis. The first satellite operates at a larger radius meshing with the sun gear, while the second satellite operates at a smaller radius meshing with the crown gear, effectively using radial spacing to achieve additional reduction stages without increasing axial length.
2Power
If the reduction ratio is increased to meet wheel speed requirements, then the power transmission is sufficient, but the outer diameter of the reduction gear increases beyond the wheel rim dimension
Solution Approach 1:
The patent nests the second satellite gear within the radial space defined by the first satellite gear. The second satellite operates at a smaller radius and meshes with the crown gear, effectively nesting multiple reduction stages within the same outer diameter envelope, similar to nested dolls occupying different spatial scales.
Solution Approach 2:
Instead of increasing the outer diameter to achieve higher reduction ratio, the patent transitions to using the radial dimension by positioning satellites at different distances from the center. This allows multiple meshing stages to occur within the same circumferential space, preventing the outer diameter from exceeding the wheel rim dimension.
3Power
If the reduction ratio is increased to meet wheel speed requirements, then the power transmission is sufficient, but the inner diameter of the reduction gear increases beyond the wheel hub diameter
Solution Approach 1:
The patent segments the power transmission into two distinct paths: one through the sun gear and first satellite for the primary reduction, and another through the crown gear and second satellite for the secondary reduction. This segmentation allows each stage to operate independently with optimized radial positions, minimizing the required inner diameter while achieving the cumulative reduction ratio.
Solution Approach 2:
The patent uses the radial dimension to accommodate multiple satellite gears at different distances from the center axis. By positioning the second satellite at a smaller radius than the first satellite, the design achieves additional reduction without increasing the inner diameter, as the second satellite's meshing path occurs closer to the center where space is available.
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 achieves a large reduction ratio with a compact design, suitable for aircraft landing gear wheels, reducing space constraints and enabling efficient electric taxiing.
Implementation Method 1
a sun gear integral in rotation with the motor shaft, this sun gear being centered on the axis and comprising an external toothing, a crown gear centered on the axis and which comprises two internal toothings, and satellites which are carried by a planet carrier and which each have a median plane of symmetry perpendicular to the axis, each of the satellites comprising three external toothings
Data Source
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AI summary
A device (10) for driving at least one wheel (12) of an aircraft landing gear (14), this device (10) comprising: - at least one landing gear wheel (12), this 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 reduction gear (28) having: - a sun gear (32) fixed for rotation to the shaft of the motor (20), - a ring gear (38), and - planet gears (34) which are carried by a planet carrier (36) and which each have three external teeth (34a, 34b1, 34b2), including a central external tooth which meshes with a tooth (32a) of the sun gear, and two lateral external teeth (34b1, 34b2) which are respectively meshed with teeth (38d1, 38d2) of the crown (38).