Multi-speed planetary transmission with nested gearsets
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Solution Overview
Problem
Current multi-speed transmissions face challenges in achieving a sufficient number of forward and reverse speed ratios using planetary gearsets and selective couplers, as they often require complex configurations and additional elements to meet the desired performance.
Innovation Solution
A multi-speed transmission design incorporating four planetary gearsets and six selective couplers, including a combination of clutches and brakes, to achieve at least nine forward speed ratios and one reverse speed ratio, with specific interconnections and configurations of gearsets and couplers allowing for varied torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple planetary gearsets and selective couplers are used to achieve multiple speed ratios, then the number of forward and reverse speed ratios increases, but the device complexity increases
Solution Approach 1:
The patent employs nested planetary gearsets where the sun gear of one planetary gearset serves as the ring gear of another planetary gearset. This nesting arrangement allows multiple gearsets to be compactly integrated, achieving nine forward and two reverse speed ratios without proportionally increasing device complexity, as the nested structure shares common components across gearsets.
Solution Approach 2:
Selective couplers (clutches and brakes) are designed to serve multiple functions across different planetary gearsets. The same selective coupler can engage different components in different operating modes to achieve various speed ratios, reducing the total number of selective couplers needed and simplifying the overall control system while maintaining versatility.
2Adaptability or versatility
If additional elements are added to achieve sufficient speed ratios, then the performance requirements are met, but the manufacturing complexity increases
Solution Approach 1:
The patent merges multiple functional elements into integrated components. Planetary gearsets are combined with selective couplers such that the couplers are directly attached to gearset components, eliminating the need for separate mounting structures and reducing assembly steps. This merging approach meets performance requirements while simplifying manufacturing processes.
3Volume of moving object
If a compact transmission design is used, then the transmission size is reduced, but the configuration of gearsets and couplers becomes more complex
Solution Approach 1:
Planetary gearsets are nested within each other, with the sun gear of one gearset forming the ring gear of the next gearset. This nested configuration achieves compact transmission size by eliminating radial space between gearsets, while the systematic nesting pattern provides a regular structure that manages configuration complexity through repetition rather than arbitrary complexity.
Data Source
AI summary
A multi-speed transmission including a plurality of planetary gearsets and a plurality of selective couplers to achieve at least nine forward speed ratios is disclosed. The plurality of planetary gearsets may include a first planetary gearset, a second planetary gearset, a third planetary gearset, and a fourth planetary gearset. The plurality of selective couplers may include a number of clutches and a number of brakes. The multi-speed transmission may have four planetary gearsets and six selective couplers. The six selective couplers may include four clutches and two brakes.