Compact Planetary Gear Train for Efficient Transmissions
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Summary
Problems
Current automatic transmissions with eight or more shift-stages face challenges in achieving better fuel efficiency and drivability due to increased complexity, length, and weight, which complicates installability and power flow efficiency.
Innovation solutions
A planetary gear train design with four planetary gear sets and two transfer gears, arranged in parallel on input and output shafts, along with strategically placed clutches and brakes, to achieve at least nine forward speeds and one reverse speed, optimizing gear ratios and reducing length while improving installability and fuel efficiency.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If the number of planetary gear sets and engagement elements is increased to achieve more shift stages, then the fuel consumption and drivability are improved, but the device complexity, length, and weight increase
Why choose this principle:
The patent combines multiple planetary gear sets (first, second, third, and fourth planetary gear sets) into a single integrated transmission assembly where rotation elements from different gear sets are selectively interconnected. This merging approach achieves nine forward speeds and reverse speed functionality without requiring separate independent gear sets, thereby reducing overall device complexity while maintaining the desired shift stages for improved fuel consumption.
Principle concept:
If the number of planetary gear sets and engagement elements is increased to achieve more shift stages, then the fuel consumption and drivability are improved, but the device complexity, length, and weight increase
Why choose this principle:
The engagement elements (clutches and brakes) are designed to perform multiple functions by selectively interconnecting rotation elements across different planetary gear sets. For example, the first clutch can connect rotation elements from both the first and fourth planetary gear sets, allowing a single engagement element to control multiple gear ratios and shift stages, thus reducing the total number of parts needed.
Application Domain
Data Source
AI summary:
A planetary gear train design with four planetary gear sets and two transfer gears, arranged in parallel on input and output shafts, along with strategically placed clutches and brakes, to achieve at least nine forward speeds and one reverse speed, optimizing gear ratios and reducing length while improving installability and fuel efficiency.
Abstract
A planetary gear train may include first to fourth planetary gear sets having first to third, fourth to sixth, seventh to ninth, and eighth to twelfth elements, the first to third gear sets being mounted on an input shaft, the fourth gear set being mounted on an output shaft, first shaft connected to the first and fourth elements, second shaft connected to the second and ninth elements, third shaft connected to the third element and the input shaft, fourth, fifth, sixth, and seventh shaft connected to the fifth, sixth, seventh, and eighth elements respectively, eighth shaft connected to the tenth element and externally gear-meshed with the fifth shaft, ninth shaft connected to the eleventh element and the output shaft, tenth shaft connected to the twelfth element, and externally gear-meshed with the seventh shaft, and two transfer gears each forming external gear-engagement between a corresponding pair of shafts.