Epicyclic Gear Carrier Flexpin Compensation for Distortion
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Solution Overview
Problem
Epicyclic gear systems experience carrier distortion under heavy loads, leading to improper meshing of planet pinions with sun and ring gears, resulting in excessive wear, friction, heat generation, and noise due to uneven torque sharing and stress concentration in flexpins.
Innovation Solution
The epicyclic gear system employs planet pinions arranged in two arrays on flexpins with angular offset and varying tooth widths or flexpin flexibility to compensate for carrier distortion, ensuring even torque sharing and reduced stress by aligning flexpins and adjusting load paths to maintain even meshing with sun and ring gears.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If planet pinions are arranged in two arrays on flexpins with angular offset and varying tooth widths to compensate for carrier distortion, then even torque distribution and alignment are achieved, but device complexity increases
Solution Approach 1:
The patent applies asymmetry by introducing angular offsets between the two arrays of planet pinions and varying the tooth widths of pinions in different arrays. This asymmetric configuration compensates for carrier distortion under load, ensuring that pinions in both arrays maintain proper meshing alignment with the sun and ring gears, thereby achieving even torque distribution across all pinions.
Solution Approach 2:
The patent segments the planet pinion system into two distinct arrays, each with specifically designed characteristics (angular offset and varying tooth widths). This segmentation allows each array to be optimized for its specific load path and distortion compensation requirements, enabling the system to handle carrier distortion more effectively while distributing torque evenly across all pinions.
2Power
If heavy loads are applied to the carrier, then power transfer capacity increases, but carrier distortion occurs causing improper meshing
Solution Approach 1:
The patent applies preliminary action by pre-configuring the planet pinions with angular offsets and varying tooth widths before the carrier undergoes distortion. This preliminary asymmetric arrangement is specifically designed to compensate for the expected distortion under heavy loads, ensuring that even when the carrier distorts, the pinions maintain proper meshing alignment with the sun and ring gears, thereby preserving both power transfer capacity and meshing precision.
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
This configuration reduces wear, friction, and noise by ensuring even torque distribution and alignment of planet pinions with sun and ring gears, enhancing the system's operational efficiency and longevity.
Implementation Method 1
The cantilevers produce high stresses in the flexpins, and to have more moderate stresses, some carriers have two walls with flexpins anchored in each of the walls
Data Source
Figure 1~2
Figure 3~5
Figure 6~6B
AI summary
An epicyclic gear system (A) includes sun and ring gears (2, 4) and planet pinions (6, 8) arranged in two side-by-side arrays (a, b) between the sun and ring gears, there also being a carrier (10, 50) to which planet pinions are coupled through flexpins (30). The carrier has primary and secondary walls (20, 22) between which the pinions are located and webs (24) connecting the walls. The flexpins for one array of pinions are cantilevered from the primary wall and the flexpins for the other array of pinions are cantilevered from the secondary wall. When the gear system operates, the carrier along its primary wall is subjected to an externally applied torque which transfers through the system at the planet pinions of the two arrays. The load path (pa) for the pinions at the primary wall is shorter than the load path (pb) for the pinions at the secondary wall, and this disparity causes the carrier to distort. To compensate for this distortion so that the pinions of the two arrays will mesh more evenly with the sun and ring gears, the flexpins of the first array are offset angularly with respect to the flexpins of the second array, or the teeth of the pinions in the first array are narrower than the teeth of the pinions of the second array, or the primary wall of the carrier has areas (40, 44) of weakness where the flexpins of the first array are cantilevered from it, or the flexpins of the first array are more flexible than the flexpins of the second array. As a consequence, the pinions of the two arrays mesh better under load with the sun and ring gears and share the transfer of torque more evenly.