Two-Stage Planetary Gear Layout for High-Ratio Efficient Reduction
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Solution Overview
Problem
Conventional planetary gear mechanisms face challenges in designing small and lightweight gear devices with high reduction gear ratios exceeding 100:1, due to design restrictions and decreased power transmission efficiency with multiple gear stages.
Innovation Solution
A planetary gear device configuration featuring two-stage gear mechanisms with shared carriers, spur gear planetary gears, and optimized addendum modification coefficients to enhance power transmission efficiency, allowing for high reduction gear ratios while minimizing gear stages and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional planetary gear mechanisms use multiple gear stages to achieve high reduction gear ratios, then the reduction gear ratio increases, but the power transmission efficiency decreases
Solution Approach 1:
The patent combines two planetary gear mechanisms into a single integrated mechanism sharing a common carrier, achieving a high reduction gear ratio of approximately 1/50 without requiring multiple sequential gear stages. This merging approach reduces the number of meshing interfaces and minimizes cumulative power losses while maintaining compact structure
Solution Approach 2:
The patent applies addendum modification to the planetary gears, changing the tooth profile parameters to optimize meshing characteristics. This parameter modification improves power transmission efficiency by reducing sliding friction and enhancing contact conditions between gear teeth, thereby minimizing energy loss while achieving the target reduction ratio
2Power
If planetary gear mechanisms use special gear structures to achieve high reduction gear ratios, then the reduction gear ratio increases, but manufacturing costs increase and productivity deteriorates
Solution Approach 1:
The patent employs addendum modified spur gears with standardized tooth profiles and manufacturing parameters. By modifying only the addendum portion of standard gears rather than adopting completely specialized gear forms, the invention achieves high reduction ratios while maintaining compatibility with conventional gear manufacturing processes, thereby controlling production costs and preserving manufacturing productivity
Solution Approach 2:
The planetary gears in the patent serve multiple functions simultaneously: they provide the primary gear reduction, accommodate addendum modification for efficiency optimization, and maintain standardization for ease of manufacture. This multi-functionality allows a single standardized component design to achieve high performance without requiring multiple specialized parts, thus reducing manufacturing complexity and cost
Data Source
AI summary
A planetary gear device configured by combining a plurality of planetary gear mechanisms includes first and second planetary gear mechanisms sharing a carrier, wherein each planetary gear mechanism is composed of an internal gear Ik (k is an integer equal to or larger than 2) and a planetary gear Pk which is engaged with the internal gear Ik and revolves in a circumferential direction of the internal gear, the planetary gear Pk of each planetary gear mechanism is composed of a spur gear in the form of an external gear, the planetary gears Pk of the planetary gear mechanisms share a central axis or have central axes integrally connected to integrally rotate on a common rotation central axis line or are integrated with each other to integrally rotate on the common rotation central axis line in order to configure the entire planetary gear device as a two-stage gear mechanism, the planetary gear device is configured such that the number of teeth zp1 of a first planetary gear constituting the first planetary gear mechanism and the number of teeth zp2 of a second planetary gear constituting the second planetary gear mechanism are different from each other, the number of teeth on the internal gear I1 is zi1, and the number of teeth on the internal gear I2 is zi2, an addendum modification coefficient of the first planetary gear is xp1, an addendum modification coefficient of an internal gear which is engaged with the first planetary gear and constitutes the first planetary gear mechanism is xi1, an addendum modification coefficient of the second planetary gear is xp2, an addendum modification coefficient of an internal gear which is engaged with the second planetary gear and constitutes the second planetary gear mechanism is xi2, a power transmission efficiency of the planetary gear device having the addendum modification coefficients xp1, xi1, xp2, and xi2 is η, an addendum modification coefficient of the internal gear I1 is xi1, and an addendum modification coefficient of the internal gear I2 is xi2, and the addendum modification coefficients have relationships in which values selected from combinations of the addendum modification coefficients which maximize or submaximize the power transmission efficiency η within an allowable range of design specifications given in advance are combined.