Planetary Gear Support Structure for Reduced Shaft Moment
Solution Overview
Problem
The existing planetary gear devices, such as those disclosed in PTL 1, suffer from durability issues due to the large moment acting on the planetary shaft, which can lead to damage and reduced durability.
Innovation Solution
A planetary gear device configuration with a carrier portion featuring first and second facing portions and supporting portions that cooperate to rotatably support the planetary portion, distributing the moment more evenly and reducing stress on individual components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single long planetary shaft is used to support the planetary gear, then the structure is simpler, but the moment acting on the shaft increases causing damage and reduced durability
Solution Approach 1:
The single long planetary shaft is divided into multiple shorter shaft segments (first planetary shaft and second planetary shaft). Each shaft segment is supported by separate bearing portions, distributing the mechanical load and reducing the moment acting on any single shaft segment, thereby improving durability while maintaining structural simplicity.
2Device complexity
If a single long planetary shaft is used, then fewer components are needed, but the moment concentration causes component damage
Solution Approach 1:
The planetary shaft is segmented into multiple shorter sections with intermediate support points. This segmentation reduces the span length of each shaft segment, thereby reducing the bending moment and stress concentration, which improves the strength and load-bearing capacity of the shaft system.
Solution Approach 2:
Bearing portions are strategically positioned at specific locations along the planetary shaft to provide localized support where moments are generated. This local reinforcement approach strengthens critical areas without requiring a complete redesign of the entire shaft structure.
Data Source
AI summary
A planetary gear device include: a carrier portion including a first facing portion and a second facing portion that face with each other, a planetary portion disposed between the first facing portion and the second facing portion; and a first supporting portion and a second supporting portion formed on the first facing portion and the second facing portion or the planetary portion, respectively, and cooperating with each other so as to support the planetary portion rotatably on the second facing portion.