Compound Planetary Gear Carrier Layout for Bearing Load Balance
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Solution Overview
Problem
Current compound planetary gear systems suffer from issues such as excessive axial loads on bearings, large gear deflections, complex assembly processes, and limited heat transfer capabilities, which affect their performance and reliability, especially in applications like aircraft where space and weight are critical.
Innovation Solution
The enhanced compound planetary gear system incorporates a multi-section carrier with upper and lower sections, split bearing bores, and a flexible high-temperature seal to address the issues of axial loads, assembly complexity, and heat transfer. The carrier's design balances axial loads through helical angles on the planet pinion gears and facilitates easier assembly by allowing the ring gear to be installed without overlapping large bearings. Additionally, the flexible seal enhances thermal conductivity during lubrication loss events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a compound planetary gear system is used to achieve high reduction ratios in limited space, then the reduction ratio is improved, but excessive axial loads are applied to the bearings
Solution Approach 1:
The planet pinion is divided into two separate gears (first gear and second gear) mounted on the same shaft, allowing independent optimization of each gear's helical angle to balance axial loads while maintaining high reduction ratio
Solution Approach 2:
The helical angles of the first and second gears are specifically configured with different values to balance the axial loads applied to the bearings, resolving the contradiction between high reduction ratio and excessive axial loads
2Strength
If large bearings are used to support the planet pinions, then the bearing capacity is improved, but the assembly process becomes complex due to overlapping components
Solution Approach 1:
The carrier is divided into upper and lower sections that can be assembled separately and then joined together, allowing the ring gear to be installed without needing to pass over the large bearings, thus simplifying the assembly process while maintaining bearing capacity
3Strength
If a rigid ring gear is used, then the structural strength is improved, but the heat transfer capability during lubrication loss events is reduced
Solution Approach 1:
A flexible high-temperature seal is incorporated into the ring gear design, which enhances thermal conductivity during lubrication loss events while maintaining the structural strength of the ring gear
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.