Geared Transmission Unit with Dual Planetary Gear System
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Solution Overview
Problem
Conventional planetary gear units face limitations in increasing speed ratio and size restrictions due to the arrangement of gears, making it difficult to further enhance the speed reducing ratio.
Innovation Solution
The proposed geared transmission unit employs a carrier with multiple pinion gears and sun gears, allowing for a wider range of speed ratios without increasing the size of the transmission unit by utilizing a series of interconnected gears to amplify or reduce torque between two shafts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the input shaft and output shaft are arranged coaxially in a conventional planetary gear unit, then the structure is compact, but the speed reducing ratio is limited and arrangements of input and output mechanisms are restricted
Solution Approach 1:
The patent transitions from a coaxial arrangement to a non-coaxial arrangement where the input shaft and output shaft are positioned at different locations. The carrier rotates around the fixed sun gear, and the output shaft is positioned at the rotation center of the carrier, creating a dimensional change in the spatial relationship between input and output shafts. This allows for greater flexibility in speed ratio adjustment without being constrained by coaxial alignment.
2Productivity
If gears are arranged in the inner circumferential side of the carrier to increase speed ratio, then the speed reducing ratio increases, but the size and number of teeth of gears are restricted
Solution Approach 1:
The patent divides the gear system into multiple independent gear pairs: a first gear pair consisting of the fixed sun gear and first planet gear, and a second gear pair consisting of the second sun gear and second planet gear. This segmentation allows each gear pair to contribute independently to the overall speed reduction, enabling higher speed ratios without requiring excessively large individual gears. The modular structure also facilitates better space utilization within the transmission unit.
3Productivity
If the number of teeth difference between meshed gears is increased to achieve desired speed ratio, then the speed ratio is achieved, but the transmission unit size increases
Solution Approach 1:
The patent employs a dual planetary gear system where the carrier rotates around the fixed sun gear, creating a dynamic compound gear mechanism. This dynamic arrangement allows the speed ratio to be determined by the combined effect of two gear pairs rather than relying on a single large tooth difference. The system achieves flexible speed ratio adjustment through the interaction of multiple gears with moderate tooth differences, avoiding the need for excessively large gear dimensions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables an increased speed reducing ratio and flexible setting of speed ratios by using fewer teeth differences between gears, allowing for downsizing of the transmission unit while maintaining or enhancing torque transmission efficiency.
Implementation Method 1
a first pinion gear that is supported by the carrier in a rotatable manner; a first ring gear that is formed on a predetermined stationary member to be meshed with the first pinion gear; a first sun gear that meshes with the first pinion gear
Implementation Method 2
a second pinion gear that is supported in a rotatable manner by the carrier while being meshed with the second sun gear
Implementation Method 3
a second ring gear that is coupled to the second shaft while being meshed with the third pinion gear
Data Source
AI summary
A geared transmission unit in which a range of a speed ratio is widened without increasing a size of the transmission unit. The geared transmission unit comprises: a carrier coupled to the first shaft; a first pinion gear that is supported by the carrier; a first ring gear formed on a stationary member to be meshed with the first pinion gear; a first sun gear meshing with the first pinion gear; a second sun gear rotated integrally with the first sun gear; a second pinion gear supported by the carrier while being meshed with the second sun gear; a third pinion gear rotated integrally with the second pinion gear; and a second ring gear coupled to the second shaft while being meshed with the third pinion gear.