Multi-speed Transmission Using Nested Planetary Gears
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Solution Overview
Problem
Current multiple speed transmissions face challenges in achieving improved performance, efficiency, responsiveness, smoothness, reduced size, and weight, while maintaining cost-effectiveness.
Innovation Solution
The transmission employs a configuration of four planetary gear sets with permanent mechanical connections and selectively engageable torque-transmitting mechanisms, including clutches and brakes, to achieve multiple gear ratios and incorporates latches for engine start/stop functionality, optimizing gear engagement through a hydraulic control system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a typical multiple speed transmission uses a combination of planetary gear arrangements and fixed interconnections to achieve multiple gear ratios, then the transmission can provide multiple speed ratios, but the size and weight of the transmission increase
Solution Approach 1:
The patent employs nested planetary gear sets where smaller planetary gears are positioned within the spaces of larger planetary gear sets. This nesting arrangement allows multiple gear ratios to be achieved while significantly reducing the overall size and weight of the transmission compared to conventional parallel planetary gear arrangements.
Solution Approach 2:
The invention transitions from a two-dimensional planar arrangement of planetary gears to a three-dimensional nested configuration. By stacking planetary gear sets vertically and utilizing the space between different sized gears, the patent achieves multiple speed ratios without proportionally increasing the transmission's footprint and weight.
2Adaptability or versatility
If more planetary gear sets are added to achieve more speed ratios, then the gear ratio range increases, but the packaging space and weight increase
Solution Approach 1:
The patent achieves an extended speed ratio range by nesting additional planetary gear sets within the existing structure. The fourth planetary gear set is positioned within the space created by the first three sets, allowing the transmission to provide more speed ratios without proportionally increasing volume.
Solution Approach 2:
The nested planetary gear sets share common components and housing space. Multiple gear sets utilize the same input and output shafts, and the nested arrangement allows each planetary set to contribute to different speed ratios, maximizing the utility of each added component while minimizing volume increase.
3Weight of moving object
If the transmission is designed to be more compact, then the size and weight are reduced, but the complexity of achieving multiple gear ratios increases
Solution Approach 1:
While the nested configuration appears complex, it actually simplifies the overall structure by eliminating the need for separate housing and mounting structures for each planetary gear set. The nested arrangement allows multiple gear sets to share common support elements and housing space, reducing the total number of discrete components compared to conventional parallel arrangements.
Data Source
AI summary
A transmission includes an input member, an output member, a plurality of torque-transmitting mechanisms that are selectively engageable to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member, and one or more latches associated with one or more of the torque-transmitting mechanisms. The one or more latches engages the respective torque-transmitting mechanisms during or prior to a start event.