Planetary Transmission Layout for Nine-Speed Ratio Control
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Solution Overview
Problem
Current multi-speed transmissions face challenges in achieving a sufficient number of forward and reverse speed ratios efficiently using planetary gearsets and selective couplers, limiting their versatility and performance.
Innovation Solution
A multi-speed transmission design incorporating multiple planetary gearsets and selective couplers, including clutches and brakes, that allows for the engagement of various combinations to achieve at least nine forward and one reverse speed ratio through a system of interconnectors and truth tables, enabling flexible torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple planetary gearsets and selective couplers are used to achieve more speed ratios, then the versatility and performance of the transmission is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple planetary gearsets (first, second, third planetary gearsets) into a single integrated transmission system where the gearsets share common components such as the stationary member, sun gears, and ring gears. This merging approach allows the system to achieve multiple speed ratios (at least nine forward and one reverse) without proportionally increasing the number of discrete components, thereby improving versatility while controlling complexity.
Solution Approach 2:
The selective couplers are designed to perform multiple functions by selectively coupling different components of the planetary gearsets. The same couplers can engage different planetary gearsets at different times to achieve various speed ratios, and can also provide reverse gear functionality. This multi-functionality allows a limited number of couplers to control a large number of speed ratios, resolving the contradiction between versatility and complexity.
2Adaptability or versatility
If selective couplers are used to achieve multiple speed ratios, then the adaptability is improved, but the ease of operation deteriorates due to complex engagement control
Solution Approach 1:
The transmission system employs dynamic control of selective couplers that can be engaged or disengaged to change the operational state of the planetary gearsets. The system transitions between different operational modes (direct drive, overdrive, reverse, etc.) by dynamically activating specific couplers, allowing the transmission to adapt to different driving conditions while maintaining operational simplicity through automated or pre-programmed control sequences.
Solution Approach 2:
The selective couplers act as intermediaries between the input member and the various planetary gearsets. Rather than requiring direct control of each gearset component, the couplers mediate the power flow by selectively connecting the input member to specific gearsets or stationary members. This intermediary mechanism simplifies operation by reducing the number of direct control points needed while still achieving versatile speed ratio selection.
Data Source
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AI summary
A multi-speed transmission (100, 300) including a plurality of planetary gearsets (108, 110, 112, 114, 308, 310, 312, 314) and a plurality of selective couplers (162, 164, 166, 168, 170, 172, 362, 364, 366, 368, 370, 372) to achieve at least nine forward speed ratios is disclosed. The plurality of planetary gearsets (108, 110, 112, 114, 308, 310, 312, 314) may include a first planetary gearset (108, 308), a second planetary gearset (110, 310), a third planetary gearset (112,312), and a fourth planetary gearset (114, 314). The plurality of selective couplers (162, 164, 166, 168, 170, 172, 362, 364, 366, 368, 370, 372) may include a number of clutches (166, 168, 170, 172, 366, 368, 370, 372) and a number of brakes (162, 164, 362, 364). The multi-speed transmission (100, 300) may have four planetary gearsets (108, 110, 112, 114, 308, 310, 312, 314) and six selective couplers (162, 164, 166, 168, 170, 172, 362, 364, 366, 368, 370, 372). The six selective couplers (162, 164, 166, 168, 170, 172, 362, 364, 366, 368, 370, 372) may include four clutches (166, 168, 170, 172, 366, 368, 370, 372) and two brakes (162, 164, 362, 364).