Multi-Planetary Transmission Gear Arrangement
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Solution Overview
Problem
Current multi-speed transmissions face challenges in achieving improved efficiency, responsiveness, smoothness, reduced size, and weight, while maintaining cost-effectiveness.
Innovation Solution
A transmission design incorporating at least four planetary gear sets, torque-transmitting devices such as clutches and brakes, and a transfer mechanism that allows for selective engagement to achieve multiple forward and reverse gear ratios, including a torque converter for input torque and a differential assembly for front-wheel and all-wheel drive modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple planetary gear sets are used to achieve multiple speed ratios, then the number of gear ratios increases, but the size and weight of the transmission increase
Solution Approach 1:
The patent combines multiple planetary gear sets (first, second, third planetary gear sets) into a single integrated transmission structure where gear sets share common components such as the input shaft and various planetary carriers. This merging approach enables multiple speed ratios to be achieved while reducing overall transmission size and weight compared to using separate gear sets for each ratio.
Solution Approach 2:
The patent employs a nested arrangement where the second planetary gear set is positioned within or adjacent to the first planetary gear set, and the third planetary gear set is integrated with the previous sets. This nesting allows compact packaging of multiple gear sets, reducing the overall footprint and weight while maintaining the capability to achieve multiple forward and reverse speed ratios through selective engagement of clutches and brakes.
2Adaptability or versatility
If multiple planetary gear sets and torque transmitting devices are used to achieve multiple speed ratios, then the adaptability increases, but the device complexity increases
Solution Approach 1:
The patent designs the planetary gear sets and torque transmitting devices (clutches and brakes) to serve multiple functions. For example, the first planetary carrier serves as both a support for planet gears and a connection point for clutches and brakes. The same structural components are used across different gear sets, reducing the number of unique parts needed and simplifying the overall device complexity while maintaining adaptability for multiple speed ratios.
Solution Approach 2:
The transmission is segmented into distinct functional modules (first, second, third planetary gear sets with associated clutches and brakes) that can be independently controlled. This segmentation allows complex multi-speed functionality to be achieved through modular combinations of simpler units, making the overall system more manageable and less complex than a fully integrated single-unit design.
3Volume of moving object
If compact packaging is pursued to reduce size, then the volume decreases, but the arrangement of gear sets becomes more constrained
Solution Approach 1:
The patent implements a nested configuration where the second planetary gear set is arranged within the spatial envelope of the first planetary gear set, and the third planetary gear set is similarly integrated. This nesting enables compact packaging that minimizes transmission volume while the flexible clutch and brake arrangement provides the necessary operational freedom to manage gear engagement despite the constrained physical layout.
Solution Approach 2:
The patent utilizes three-dimensional spatial arrangement to pack multiple planetary gear sets into a compact volume. Rather than arranging gear sets in a simple linear sequence, the design employs vertical and radial stacking, with planetary carriers positioned at different heights and radii around the input shaft. This dimensional optimization reduces overall transmission volume while maintaining adequate clearance and accessibility for torque transmitting devices.
Data Source
AI summary
A transmission includes an input member, an output member, at least four planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. The torque transmitting devices include clutches and brakes that are actuated in various combinations to establish a plurality of forward gear ratios and a reverse gear ratio.