Multi-speed countershaft transmission with planetary gear set
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Solution Overview
Problem
Traditional multi-speed transmissions are limited in their ability to provide a wide range of gear ratios efficiently, leading to increased engine size and fuel consumption, and they often require a large number of components and a heavy countershaft, which increases weight and reduces packaging efficiency.
Innovation Solution
A multi-speed transmission design that combines a planetary gear set with a countershaft configuration, utilizing a main shaft and two shaft members arranged in a triangular formation, with a minimal number of co-planar intermeshing gear sets and torque-transmitting mechanisms, including a two-way dog clutch and a lock-up clutch, to achieve at least seven forward and one reverse speed ratio with reduced length and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional multi-speed transmissions use a large number of components and a heavy countershaft to achieve multiple speed ratios, then the gear ratio coverage is improved, but the weight and length of the transmission increase
Solution Approach 1:
The patent merges the planetary gear set with the countershaft configuration into a single integrated transmission system. The planetary gear set (including sun gear, ring gear, and planet gears) is combined with the main shaft and range shaft, allowing multiple speed ratios to be achieved through a unified structure rather than separate components, thereby reducing overall weight while maintaining gear ratio coverage.
Solution Approach 2:
The planetary gear set serves multiple functions within the transmission system. It provides both direct drive capability (when planet carrier is engaged) and reduced gear ratios (when ring gear or sun gear is held), while the same gear set also serves as the foundation for the countershaft configuration. This multi-functionality eliminates the need for separate dedicated components for each function, reducing weight.
2Adaptability or versatility
If traditional multi-speed transmissions use a large number of components and a heavy countershaft to achieve multiple speed ratios, then the gear ratio coverage is improved, but the length and packaging efficiency of the transmission worsen
Solution Approach 1:
The transmission components are arranged in a nested configuration where the planetary gear set is integrated within the countershaft structure. The sun gear, ring gear, and planet gears are positioned concentrically, and the main shaft and range shaft are arranged to share common mounting points and support structures. This nesting allows the transmission to achieve multiple speed ratios within a compact radial and axial envelope, improving packaging efficiency.
Solution Approach 2:
The patent combines the planetary gear set with the countershaft configuration into a single integrated transmission system. The planetary gear set (including sun gear, ring gear, and planet gears) is combined with the main shaft and range shaft, allowing multiple speed ratios to be achieved through a unified structure rather than separate components, thereby reducing overall length and improving packaging efficiency.
3Adaptability or versatility
If traditional multi-speed transmissions use a heavy countershaft to achieve multiple speed ratios, then the gear ratio coverage is improved, but the fuel efficiency worsens
Solution Approach 1:
The patent merges the planetary gear set with the countershaft configuration into a single integrated transmission system. The planetary gear set (including sun gear, ring gear, and planet gears) is combined with the main shaft and range shaft, allowing multiple speed ratios to be achieved through a unified structure rather than separate components, thereby reducing overall weight and improving fuel efficiency.
Solution Approach 2:
The planetary gear set serves multiple functions within the transmission system, providing both direct drive and reduced gear ratios while serving as the foundation for the countershaft configuration. This multi-functionality eliminates the need for separate dedicated components for each function, reducing weight and parasitic losses, thereby improving fuel efficiency.
4Adaptability or versatility
If traditional multi-speed transmissions use many co-planar intermeshing gear sets to achieve multiple speed ratios, then the gear ratio coverage is improved, but the device complexity increases
Solution Approach 1:
The patent merges the planetary gear set with the countershaft configuration into a single integrated transmission system. The planetary gear set (including sun gear, ring gear, and planet gears) is combined with the main shaft and range shaft, allowing multiple speed ratios to be achieved through a unified structure rather than separate components, thereby reducing device complexity while maintaining gear ratio coverage.
Data Source
AI summary
A transmission is provided that combines first and second shaft members in a countershaft configuration with a planetary gear set and first and second head gear sets to provide ratios. Each of the shaft members includes gears in no more than four co-planar, intermeshing gear sets (and in some embodiments no more than three co-planar, intermeshing gear sets) and two sets of radially nested clutches, thus minimizing the overall length of the shaft members. At least one gear concentric with each shaft member is supported by a bearing on the adjacent gear rather than on the shaft member, thereby minimizing the weight of each shaft member. The transmission provides at least seven forward speed ratios and a reverse speed ratio and utilizes at most eight torque-transmitting mechanisms. A method of reducing the length and weight of a transmission package is also provided.