Planetary Differential Speed Reducer Compact Reliability
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Solution Overview
Problem
Differential mechanisms employing spur gears and bevel gears are complex and lack reliability for shifting between synchronously rotating and differentially rotating states.
Innovation Solution
A planetary differential reduction device comprising a first and second sun gear, planetary gears, and internal gears, with a common planetary carrier, allowing for synchronous and differential rotation states through a reduction mechanism that integrates a planetary reduction part for enhanced reliability and compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If differential mechanisms are constituted by assembling spur gears and bevel gears, then the rotational state can be changed from synchronous to differential, but the structure becomes complicated and reliability decreases
Solution Approach 1:
The patent combines two planetary reduction mechanisms into a single integrated differential mechanism. The first planetary mechanism (with first sun gear, first planetary gears, and first internal gear) and the second planetary mechanism (with second sun gear, second planetary gears, and second internal gear) share a common planetary carrier and are merged into one compact structure. This merging eliminates the need for separate spur gear and bevel gear assemblies, reducing structural complexity while maintaining reliability through the inherent robustness of planetary gear design.
Solution Approach 2:
The common planetary carrier serves multiple functions: it supports both the first and second planetary gears, transmits motion from both sun gears to their respective internal gears, and enables the differential action when the second sun gear rotates. This multi-functionality reduces the number of separate components needed, simplifying the overall structure while maintaining the ability to achieve both synchronous and differential rotation states.
2Reliability
If differential mechanisms are constituted by assembling spur gears and bevel gears, then the rotational state can be changed from synchronous to differential, but the device size increases
Solution Approach 1:
The patent employs a nested arrangement where the second planetary mechanism is positioned adjacent to and integrated with the first planetary mechanism. The common planetary carrier acts as a shared structure that houses both sets of planetary gears. The second sun gear is arranged concentrically with the first sun gear, and the second internal gear is positioned within the overall structure. This nesting allows the differential mechanism to achieve compact dimensions while maintaining high reliability through the robust planetary gear configuration.
Solution Approach 2:
The patent utilizes the axial dimension by arranging the first and second planetary mechanisms side-by-side along the device axis. Rather than stacking components radially or requiring excessive axial space, the mechanisms are positioned adjacent to each other, efficiently utilizing the available volume. This dimensional arrangement contributes to the compact overall size of the differential mechanism while preserving the reliability benefits of planetary gear design.
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
When a first output shaft (5) of a planetary differential reduction device (1) is driven to rotate, a first internal gear (24) of a first planetary reduction part (20) and a second internal gear (34) of a second planetary reduction part (30) are rotated in the same direction at the same speed, and a planetary carrier (63) of a third planetary reduction part (40) is also rotated in the same direction at the same speed, whereby a second output shaft (6) connected to the planetary carrier (63) is rotated synchronously with the first output shaft (5). When differential rotation is inputted to the second sun gear (31), a reduced rotational output is output to the planetary carrier (63) of the third planetary reduction part (40). The second output shaft (6) is added with the reduced rotational output for differential rotation, whereby the second output shaft (6) is shifted to a differential rotating state. It is possible to realize a small, compact and highly reliable differential mechanism compared to a case in which spur gears and bevel gears are used.