Compound Planetary Gearbox with Split Helical Pinions for Axial Load Balance
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Solution Overview
Problem
Traditional compound planetary gear systems face issues such as excessive axial loads on bearings, large gear deflections, complex assembly, and limited heat transfer due to flexure ring gears, which affect performance and durability, especially in space-constrained applications like aircraft systems.
Innovation Solution
The enhanced compound planetary gear system incorporates a multi-section carrier with differently angled helical gears to balance axial loads, uses a split bearing bore for easier assembly, and implements a flexible high-temperature seal to enhance heat transfer, thereby reducing weight and improving operational efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional compound planetary gear systems are used, then power transmission is achieved, but excessive axial loads are imposed on bearings
Solution Approach 1:
The planet pinion is segmented into two distinct gears (first gear and second gear) with different helical angles, allowing independent optimization of load distribution. This segmentation enables the first gear to engage with the sun gear at one helical angle while the second gear engages with the ring gear at a different helical angle, thereby balancing axial loads on bearings while maintaining power transmission capability.
2Power
If traditional compound planetary gear systems are used, then gear reduction is achieved, but large gear deflections occur
Solution Approach 1:
Different regions of the planet pinion are assigned different local qualities through varying helical angles. The first gear portion has a first helical angle optimized for sun gear engagement, while the second gear portion has a second helical angle optimized for ring gear engagement. This local quality differentiation allows each gear portion to independently manage its deflection characteristics, reducing overall gear deflection while maintaining gear reduction function.
3Adaptability or versatility
If flexure ring gears are used, then adaptability is improved, but heat transfer capability is reduced
Solution Approach 1:
A flexible high-temperature seal acts as an intermediary element that bridges the gap between the flexure ring gear and the housing. This seal maintains the adaptability benefits of the flexure ring gear while providing a thermal conduction path for heat transfer, effectively mediating between the conflicting requirements of flexibility and heat dissipation.
4Manufacturing precision
If complex assembly procedures are used, then manufacturing precision is achieved, but assembly time increases
Solution Approach 1:
The carrier is segmented into multiple sections that can be assembled independently and then joined together. This segmentation allows for simplified assembly procedures where each section can be manufactured and assembled separately with standard precision requirements, then combined to achieve the overall complex structure, thereby reducing total assembly time while maintaining manufacturing precision.
Data Source
AI summary
An improved compound planetary gear system. In embodiments, a compound planetary gear system includes at least one planet pinion including a main shaft having a first gear for meshing with a sun gear and a second gear for meshing with a ring gear, and a carrier for supporting the at least one planet pinion. Teeth of the first gear are configured with a first helical angle with respect to a longitudinal angle of the at least one planet pinion, teeth of the second gear are configured with a second helical angle with respect to the longitudinal angle of the at least one planet pinion, the first helical angle different from the second helical angle.