Five-Gearset Planetary Transmission With Selective Coupler Ratio Expansion
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Solution Overview
Problem
Existing multi-speed transmissions face limitations in achieving a wide range of forward and reverse speed ratios using conventional planetary gearsets and selective couplers, often requiring complex configurations and limited flexibility.
Innovation Solution
A multi-speed transmission design incorporating five planetary gearsets and seven selective couplers, including clutches and brakes, which allows for the establishment of at least nine forward and four reverse speed ratios through strategic engagement of these components to optimize torque transfer and gear ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional planetary gearsets and selective couplers are used, then the transmission can achieve basic speed ratios, but the range of forward and reverse speed ratios is limited
Solution Approach 1:
The transmission system is divided into multiple independent planetary gearsets (first, second, third planetary gearsets) that can be selectively engaged. Each planetary gearset can provide different speed ratios, and by segmenting the overall transmission into these modular units connected through selective couplers, the system achieves a broader range of forward and reverse speed ratios without requiring a single complex geartrain
Solution Approach 2:
The transmission employs dynamic engagement and disengagement of selective couplers to change the active gear path. The selective couplers can dynamically connect or disconnect between input shaft, output shaft, and different planetary gearsets based on the desired speed ratio and direction, enabling flexible adaptation to various operating conditions and achieving multiple forward and reverse ratios
2Adaptability or versatility
If more planetary gearsets and selective couplers are added to expand speed ratio range, then the adaptability improves, but the device complexity increases
Solution Approach 1:
Each planetary gearset is designed to serve multiple functions: they can all be engaged with the input shaft and output shaft, and each can provide both forward and reverse speed ratios. The selective couplers serve universal coupling functions, able to connect any planetary gearset to the input or output shaft. This multi-functionality allows the system to achieve a wide range of speed ratios using a relatively compact arrangement of reusable components
Solution Approach 2:
The planetary gearsets are arranged in a nested or cascaded configuration where the output of one planetary gearset can be coupled to the input of another through selective couplers. This nesting allows the system to compound speed ratios by series connection while maintaining a compact physical footprint, effectively multiplying the number of achievable ratios without proportionally increasing the overall system size or complexity
Data Source
AI summary
A multi-speed transmission may include a plurality of planetary gearsets and a plurality of selective couplers. The plurality of planetary gearsets may include a first planetary gearset, a second planetary gearset, a third planetary gearset, a fourth planetary gearset, and a fifth planetary gearset. The plurality of selective couplers may include a number of clutches and a number of brakes. The multi-speed transmission may have five planetary gearsets and seven selective couplers. The seven selective couplers may include two clutches and five brakes or three clutches and three brakes.