Multi-speed Transmission with Shared Planetary Gear Components
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Solution Overview
Problem
The development of power transmissions with more than five forward speed ratios and a reverse speed ratio is hindered by complexity, size, and cost, limiting their adoption in passenger vehicles despite offering improved acceleration and fuel economy.
Innovation Solution
A family of transmissions utilizing three planetary gear sets with up to seven torque-transmitting devices, including clutches and brakes, to achieve at least five forward speed ratios and one reverse speed ratio, with specific interconnections and selective engagements of gear members to optimize speed ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of forward speed ratios is increased to six or more, then vehicle acceleration and fuel economy are improved, but transmission complexity, size, and cost increase
Solution Approach 1:
The patent merges multiple planetary gear sets into a unified transmission system where gear sets share common components. Specifically, the first and second planetary gear sets share a common sun gear, and the second and third planetary gear sets share a common ring gear, reducing overall component count and complexity while achieving six forward speed ratios and one reverse speed ratio
Solution Approach 2:
Individual gear members serve multiple functions across different speed ratios. The common sun gear and ring gear participate in multiple gear sets, allowing a single component to contribute to multiple speed ratio configurations. This multi-functionality reduces the total number of components needed while maintaining the capability to provide six forward speed ratios and one reverse speed ratio
2Adaptability or versatility
If three planetary gear sets with multiple torque-transmitting devices are used, then at least five forward speed ratios and one reverse speed ratio are achieved, but transmission size and cost increase
Solution Approach 1:
The planetary gear sets are arranged in a nested configuration where gear sets share common components. The first planetary gear set is nested with the second gear set through a shared sun gear, and the second gear set is nested with the third gear set through a shared ring gear, creating a compact nested structure that reduces transmission volume
Solution Approach 2:
Multiple planetary gear sets are merged into a single integrated transmission system with shared components. The common sun gear and ring gear serve multiple gear sets simultaneously, reducing the total volume required compared to separate gear sets while providing six forward speed ratios and one reverse speed ratio
Data Source
AI summary
The family of transmissions has a plurality of members that can be utilized in powertrains to provide at least five forward speed ratios and one reverse speed ratio. The transmission family members include three planetary gear sets having up to seven torque-transmitting mechanisms and three interconnecting members. The powertrain includes an engine that is selectively or continuously connectable to at least one of the planetary gear members and an output shaft that is continuously connected with another one of the planetary gear members. The torque-transmitting mechanisms provide interconnections between various gear members, the input shaft and the transmission housing, and are operated in combinations of two to establish at least five forward speed ratios and at least one reverse speed ratio.