Multi-speed Transmission with Four Planetary Gear Sets
Solution Overview
Problem
Current multiple speed transmissions face challenges in achieving improved efficiency, responsiveness, smoothness, reduced size, and weight while maintaining cost-effectiveness, primarily due to limitations in packaging and desired speed ratios.
Innovation Solution
A transmission design incorporating four planetary gear sets and multiple torque transmitting devices, including clutches and brakes, with specific interconnections between the gear sets to achieve ten or more speeds, allowing for various gear ratios and a reverse speed ratio through selective engagement of torque transmitting mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional planetary gear arrangements and fixed interconnections are used to achieve multiple speed ratios, then the transmission can provide the desired gear ratios, but the size and weight of the transmission increase
Solution Approach 1:
The patent combines multiple planetary gear sets (first, second, third, and fourth planetary gear sets) into a single integrated transmission system where gear sets share common components such as carriers and rings. This merging approach allows the transmission to achieve multiple speed ratios while reducing overall size and weight compared to separate gear sets for each ratio.
Solution Approach 2:
The transmission system uses a universal architecture where the same planetary gear sets and torque transmitting devices serve multiple functions across different operating modes. The first carrier member and third ring gear member, for example, serve as both input and output members depending on the engaged torque transmitting devices, allowing one component to perform multiple roles and reduce total component count.
2Adaptability or versatility
If more planetary gear sets and torque transmitting devices are added to achieve ten or more speeds, then the number of available gear ratios increases, but the device complexity increases
Solution Approach 1:
The patent merges four planetary gear sets into a compact arrangement where they share common carriers and ring gears. This consolidation allows the system to achieve ten or more forward speed ratios and reverse speed ratios without proportionally increasing the number of independent components, thereby managing complexity while expanding functionality.
Solution Approach 2:
The transmission employs seven torque transmitting devices (clutches and brakes) that can be selectively engaged and disengaged to dynamically reconfigure the gear ratios. This dynamic control system allows a single mechanical architecture to provide multiple speed ratios by changing the engagement state of torque transmitting devices rather than requiring separate mechanical paths for each ratio.
3Volume of moving object
If the transmission is designed to be compact with reduced size, then packaging efficiency improves, but achieving the desired speed ratios becomes more difficult
Solution Approach 1:
The planetary gear sets are arranged in a nested configuration where the first and second planetary gear sets share a common first carrier member, and the third and fourth planetary gear sets share a common third carrier member. This nesting allows multiple gear sets to occupy overlapping spatial volumes, achieving a compact transmission design that still provides ten or more forward speed ratios and reverse speed ratios.
Solution Approach 2:
The patent utilizes the radial dimension by arranging planetary gears around central sun gears, allowing multiple gear sets to be stacked and interconnected in three-dimensional space. This spatial arrangement enables compact packaging while maintaining the mechanical pathways needed for multiple speed ratios through selective engagement of torque transmitting devices.
Data Source
AI summary
A transmission is provided having 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 actuatable in combinations of two to establish a plurality of forward gear ratios and one reverse gear ratio.