Electro-Mechanical Control Devices for Continuously Variable Transmissions

Electronic hydraulic control system adopted in the conventional vehicle continuously variable transmissions needs to consume energy incessantly for its oil pump driven by engine working continuously. As a result we can reduce the fuel consumption of the engine by removing the pump and replacing the control system with electro-mechanical one. The paper introduces two types of electro-mechanical controlled CVT (EM-CVT). One of them use gear train which is driven by a motor, and the other applies a planetary gear control device which uses spring to provide clamping force and electromagnetism clutches to control the planetary gears. The former is mainly applied to small torque CVT, for its clamping force brought from spring is limited. The latter can offer larger clamping force, and can be applied to prevalent CVT nowadays. The paper compares the electro-hydraulic control system of CVT with electro-mechanical one, and makes the conclusion that the electro-mechanical controlled CVT will be the center of the research and development in the future, for it's potential to improve fuel consumption.

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See papers presented at 2008 SAE International Powertrains, Fuels and Lubricants Congress, June 2008, Shanghai, CHINA, Session: Advanced Transmissions

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