Control Of DCT Shift Process Based On Negative Engine Torque

DCT （Dual Clutch Transmission） is the study focus of vehicle automatictransmission field. For DCT can transmit power continuous during shift process, thecomfortable and drive-ability could be improved. Besides, for its high transmissionefficiency of gear as MT, DCT transmission vehicle economic could be improved.What’s more, as the structure and component of DCT are same as MT, the factory costcould be decreased. So, DCT has become an important program in vehicle field,especially in China.For the key technology problems of DCT, the main research works in this paperare as follows:①Based on engine experiment data and vehicle parameters, the optimal powershift schedule and economic schedule has been calculated. The uniform recognition ofboth driver intention and driving conditions has been carried out and then the standardshift schedules have been amended. The finally shift schedule model has beenestablished.②For the dry DCT, research of diaphragm has been carried out. The relationshipbetween release bearing displacement and diaphragm load has been build out.Combined to tribology theory, this paper build the clutch control model.③The engine model has been established based on the spline interpolation ofengine test data. By the analysis of DCT powertrain, the powertrain system dynamicmodel has been established. And it convenient to the DCT control strategy beenformulated and simulated.④Based on the operation of positive engine torque, this paper analysed the processof DCT shift. For the characteristic of shift process, this paper proposed the clutchcontrol strategy of each shift process stage combined to the control of engine torque.And the recognition methodology of each stage has been proposed.⑤The comparison of power-on shift and power off shift has been carried out, theengine speed condition of clutch torque switch has been proposed. Based on theoperation of negative engine torque, this paper analysed the process of DCT up shift anddown shift. And the brake torque of engine must be switch when engine speed is higherthan each clutch speed. The recognition methodology of each stage has been formulated.And this paper proposed the clutch control strategy to keep engine operating stable. Based on Matlab/Simulink, the DCT powertrain system model and the strategy has beensimulated. Results indicate the strategy could satisfy the shift demand.