Abstract: Automatic mechanical transmission(AMT) is the core plant of a single shaft parallel hybrid electric system, whose acceleration, economy, lifetime and reliability largely depend on the rapid, accurate control of AMT’s shifting process. The shifting process control of AMT based on virtual clutch technology is proposed and above all, the five sequential process of the mentioned method are expounded in detail, in which the primary control problems of every stage are put forward. According to the system’s structure, the dynamic model considering the driving shaft’s torsional vibration in the drivetrain is built up and the approximate mathematical model of the transmitted torque in AMT that can be used in shifting process control is deduced. This model is validated in trial that it can control the torque transmitted in AMT and weaken the oscillation of the output shaft’s rotate speed after shifting into neutral gear. Vehicle trial shows that virtual clutch technology aimed at zero torque transmitted in transmission is able to apply on the shifting process control of AMT. The application of this technology can realize the gear shift of AMT without clutch manipulation, effectively decrease the time of power interrupt during shifting process, reduce the oscillation of vehicle speed and improve the shifting quality of AMT system.

Key words: virtual clutch;hybrid electric system;shifting process;automatic mechanical transmission;transmitted torque