Planetary Transmission Layout for Multi-Ratio Gear Shifting
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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 limited flexibility in gear ratio adjustments.
Innovation Solution
A multi-speed transmission design incorporating four planetary gearsets and six selective couplers, including clutches and brakes, which allows for the engagement of various combinations to achieve at least nine forward and one reverse speed ratio through a systematic truth table approach, enabling flexible gear ratio adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple planetary gearsets and selective couplers are used to achieve multiple forward and reverse speed ratios, then the number of speed ratios is increased, but the device complexity increases
Solution Approach 1:
The transmission system is divided into multiple planetary gearsets (first, second, third, and fourth planetary gearsets) with distinct configurations. Each gearset can be independently engaged or disengaged through selective couplers, allowing the system to achieve multiple speed ratios by activating specific segments rather than requiring a single complex geartrain.
Solution Approach 2:
Selective couplers are employed to dynamically engage and disengage specific planetary gearsets based on the desired speed ratio. This dynamic configuration allows the transmission to adapt its structure in real-time, achieving versatility in speed ratios without permanently fixing a complex multi-gearset arrangement.
2Adaptability or versatility
If complex configurations of planetary gearsets and selective couplers are used to achieve multiple speed ratios, then the gear ratio flexibility is improved, but the ease of operation deteriorates
Solution Approach 1:
Each selective coupler is designed to serve multiple functions: engaging specific planetary gearsets, disengaging others, and enabling different speed ratio configurations. This multi-functionality reduces the need for separate control mechanisms for each gear ratio, simplifying the overall operation despite the system's versatility.
Solution Approach 2:
Selective couplers act as intermediaries between the operator's gear selection input and the complex planetary gearset configurations. By providing a standardized interface for engaging/disengaging gearsets, the couplers shield the operator from the underlying complexity of multiple planetary gear interactions.
3Adaptability or versatility
If multiple selective couplers are engaged to achieve various speed ratios, then the flexibility in gear ratio adjustments is improved, but the device complexity increases
Solution Approach 1:
The control system is segmented into multiple independent selective couplers, each responsible for specific gearset engagements. This segmentation allows for modular control logic where each coupler can be managed independently, reducing the perceived complexity of coordinating multiple couplers simultaneously.
Solution Approach 2:
The patent includes a systematic truth table that pre-defines the required coupler engagement states for each desired speed ratio. This preliminary organization of control logic allows operators or control systems to simply follow predetermined patterns rather than calculating complex engagement combinations in real-time.
Data Source
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AI summary
A multi-speed transmission (1100) including a plurality of planetary gearsets (1108, 1110, 1112, 1114) and a plurality of selective couplers (1162, 1164, 1166,1168, 1170,1172) is disclosed. The plurality of selective couplers (1162, 1164, 1166, 1168, 1170, 1172) are operatively coupled to the plurality of planetary gearsets (1108, 1110, 1112, 1114) and each have an engaged configuration and a disengaged configuration. The multi-speed transmission (1100) further comprises a first interconnector (1180), a second interconnector (1182), and a third interconnector (1184).