Planetary Transmission Coupler Layout for Nine-Speed Ratio Range
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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 system incorporating four planetary gearsets and six selective couplers, including clutches and brakes, which are actively or passively controlled to achieve at least nine forward and one reverse speed ratio by varying the engagement of these couplers, allowing for efficient torque transfer and rotation speed variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple planetary gearsets and selective couplers are used to achieve more forward and reverse speed ratios, then the transmission capability and adaptability are improved, but the device complexity increases
Solution Approach 1:
The transmission system is divided into multiple independent planetary gearsets (first, second, third, and fourth planetary gearsets) that can be selectively engaged through individual selective couplers. This segmentation allows each gearset to contribute to specific speed ratios independently, enabling the system to achieve at least nine forward and one reverse speed ratio through selective combination rather than requiring a single complex geartrain.
Solution Approach 2:
The transmission system employs six selective couplers that can be dynamically engaged or disengaged to change the operational configuration. This dynamic control allows the system to adapt between different speed ratios and operational modes (including reverse gear) by selectively activating specific planetary gearsets, providing versatility without permanently fixing the system in a complex static configuration.
2Adaptability or versatility
If selective couplers are engaged to achieve different speed ratios, then the adaptability is improved, but the control complexity increases
Solution Approach 1:
Each selective coupler is designed to perform multiple functions: it can engage to connect specific planetary gearsets for forward speed ratios, disengage to allow relative motion for different ratio selection, and work in combination with other couplers to achieve reverse gear operation. This multi-functionality reduces the need for separate dedicated mechanisms for each speed ratio, simplifying the overall control architecture despite the wide speed ratio range.
Solution Approach 2:
The selective couplers act as intermediaries between the input member and the various planetary gearsets, mediating the torque flow and motion transmission. By engaging or disengaging these intermediate couplers, the system can route power through different planetary gearset combinations to achieve the desired speed ratios, including reverse gear, without requiring direct complex control of each gearset component.
Data Source
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AI summary
A multi-speed transmission (100) including a plurality of planetary gearsets (108, 110, 112, 114) and aplurality 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 (168, 170, 172) and a number of brakes (162, 164, 166). 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, 164, 166, 168, 170, 172) may include three clutches (168, 170, 172) and three brakes (162, 164, 166).