10-Speed Transmission Using Four Planetary Gear Sets
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Solution Overview
Problem
Current power transmissions for passenger vehicles, particularly automatic transmissions, are limited by complexity, size, and cost, which restrict the development of higher gear ratios, resulting in suboptimal fuel efficiency and acceleration performance.
Innovation Solution
A power transmission system utilizing four planetary gear sets and six torque-transmitting devices to achieve at least ten forward speed ratios and one reverse speed ratio, with interconnecting members and selectively engageable torque-transmitting devices to enable efficient gear shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of forward speed ratios is increased to improve fuel economy and acceleration, then the transmission complexity and size increase
Solution Approach 1:
The transmission is divided into four separate planetary gear sets, each capable of independent operation. This segmentation allows the system to achieve multiple speed ratios through various combinations of engaged planetary sets, rather than requiring a single complex gear train. Each planetary set acts as an independent module that can be selectively activated to produce different gear ratios.
Solution Approach 2:
The planetary gear sets are arranged in a nested configuration where multiple planetary mechanisms are integrated within a compact housing. The interconnecting members link the planetary sets in series, allowing them to function as nested components that share common structural elements and torque paths, thereby reducing overall transmission size while maintaining multiple speed ratios.
2Speed
If the number of forward speed ratios is increased to improve acceleration performance, then the transmission size increases
Solution Approach 1:
Multiple planetary gear sets are merged into a single integrated transmission assembly that shares common input and output shafts. The interconnecting members combine the torque output of one planetary set with the input of the next, allowing the system to achieve the cumulative effect of multiple gear stages without requiring separate transmission housings for each planetary mechanism.
Solution Approach 2:
Each planetary gear set is designed to perform multiple functions: it can operate as a speed-reducing gear set, a speed-increasing gear set, or be disengaged entirely. The same planetary mechanism can provide different gear ratios depending on which torque-transmitting devices are engaged, allowing a single compact transmission to replace what would traditionally require multiple specialized gear sets.
3Adaptability or versatility
If more torque-transmitting devices are added to control four planetary gear sets, then the device complexity increases
Solution Approach 1:
The transmission employs six torque-transmitting devices that can be dynamically engaged and disengaged to provide ten forward speed ratios and one reverse speed ratio. This dynamic control system allows the transmission to adapt to different driving conditions by selectively activating specific planetary gear sets and torque-transmitting devices, rather than requiring fixed mechanical linkages for each possible gear ratio.
Data Source
AI summary
The transmission has a plurality of members that can be utilized in powertrains to provide ten forward speed ratios and one reverse speed ratio. The transmission includes four planetary gear sets having six torque-transmitting mechanisms and four fixed interconnections. The powertrain includes an engine and torque converter that is continuously connected to at least one of the planetary gear members and an output member that is continuously connected with another one of the planetary gear members. The six torque-transmitting mechanisms provide interconnections between various gear members, and the transmission housing, and are operated in combinations of three to establish at least ten forward speed ratios and at least one reverse speed ratio.