Nested Planetary Transmission Layout for Nine Forward Speeds
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current multi-speed transmissions face limitations in achieving a sufficient number of forward and reverse speed ratios using planetary gearsets and selective couplers, as they often require complex configurations and may not efficiently provide the desired range of gear ratios.
Innovation Solution
A multi-speed transmission design incorporating four planetary gearsets and six selective couplers, where the gearsets and couplers are arranged and interconnected to achieve at least nine forward speed ratios and one reverse speed ratio, utilizing a combination of clutches and brakes to selectively couple gear components and interconnectors to vary the rotation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a plurality of planetary gearsets and selective couplers are used to achieve multiple forward and reverse speed ratios, then the transmission capability is improved, but the device complexity increases
Solution Approach 1:
The patent employs nested planetary gearsets where the ring gear of one planetary gearset serves as the sun gear of another planetary gearset. This nesting arrangement allows multiple gearsets to be compactly integrated, achieving multiple speed ratios without proportionally increasing overall device complexity. The selective couplers are similarly nested within the gearset structure, enabling efficient space utilization.
Solution Approach 2:
The selective couplers are designed to perform multiple functions: they can couple different gearset components together in various combinations to achieve forward speeds, reverse speeds, and neutral positions. Each coupler can engage with multiple components, allowing a single coupler to control multiple transmission states, thereby reducing the total number of components needed.
2Measurement precision
If selective couplers are used to control gear engagement, then the control precision is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple control functions into a single selective coupler assembly. Each selective coupler is capable of engaging with multiple gearset components simultaneously or sequentially, allowing one coupler to perform what would otherwise require multiple separate coupling mechanisms. This merging reduces the number of control elements while maintaining precise control over gear engagement.
Solution Approach 2:
The selective couplers are designed to automatically engage and disengage specific gear components based on their actuation state, providing self-contained control functionality. When actuated, a selective coupler inherently performs the correct coupling action without requiring additional control mechanisms, simplifying the overall control system while maintaining precision.
Data Source
Figure 1
Figure 2
AI summary
A multi-speed transmission (100) including a plurality of planetary gearsets (108, 110, 112, 114) and a plurality of selective couplers (162, 164, 166, 168, 170, 172) to achieve at least nine forward speed ratios is disclosed. The plurality of planetary gearsets (108, 110, 112, 114) may include a first planetary gearset (108), a second planetary gearset (110), a third planetary gearset (112), and a fourth planetary gearset (114). The plurality of selective couplers (162, 164, 166, 168, 170, 172) may include a number of clutches (162, 164, 168) and a number of brakes (166, 170, 172). The multi-speed transmission (100) may have four planetary gearsets (108, 110, 112, 114) and six selective couplers (162, 164, 166, 168, 170, 172). The six selective couplers (162) may include three clutches (162, 164, 168) and three brakes (166, 170, 172).