Study On Integrated Control Of Passenger Vehicles Equipped With Dual Clutch Transmissions

Dual clutch transmissions (DCT) are a new and fastly developing technology in automatic transmission field. DCT combines the advantages of manual transmission (MT) and conventional automatic transmission (AT). DCT vehicles feature the convenience and comfort of AT vehicles and the fuel economy better than AT vehicles. In addition, dual clutch transmissions is less costly to manufacture since it shares similar structure and components with MT. Due to its advantages, DCT has attacted extensive development interests in the automotive industry in recent years.In this paper, the key technical problems and integrated control of DCT-powertrain systems have been investigated deeply through both theoretical and experimental means. The main research work is as follows:(1) The engine model has been established based on the test data. According to the principle of uniform wear of clutch, the static clutch torque has been formulated. The powetrain system model for DCT vehicles has been established and the dynamics of DCT launch and shift have been analyzed in detail.(2) According to the dynamic analysis of clutch actuator, the model of clutch torque control has been established. The calibration method for DCT clutch torque has been proposed based on the DCT vehicle dynamic model. The off-line calibration model of clutch torque has been built up using Matlab/Simulink software. This method has been applied to a test vehicle equipped with DCT. The correlation between clutch torque and control parameters has been validated on testing vehicle. This correlation realizes the requirement of actual control of clutch torque.(3) Based on the principle of partly constant engine speed, the control strategy of launch with two clutches has been proposed. During the each phase of launch, the clutch engaged speeds of both clutches have been designed. The launch model with two clutches has been established based on Matlab/Simulink software and the simulation have been carried out. The results show that this strategy can share the friction work between two clutches during launch and extend the clutch life.(4) The shift schedules for both the dynamic performance and fuel economy have been designed based on engine map data and vehicle parameters. The uniform recognition of both driver intention and driving conditions has been carried out and then the standard shift schedules have been amended. The simulation results show that the amended shift schedules are better satisfied the driver intention and driving conditions. The DCT intelligent shift system has been established and the algorithms of shift decision have also been proposed. It provides foundation for intelligent control of DCT.(5) The dymamic models of DCT shift have been built based on the analysis of the DCT shift characteristics. Considering the weakness of existing DCT shift control strategy, a shift control strategy based on driver intention and vehicle condition has been proposed. The controllers of engine throttle opening and two clutches have been designed. DCT shift modeling and simulation are carried out using Matlab/Simulink software. The effective of this strategy have been validated by a test vehicle during the process of both upshift and downshift.In this paper, Simulation and testing methods are both used for integrated control of DCT powertrain system. Testing results are highly agreeable with the research results of this work. It provides a theoretical and experimental foundation for the development of DCT vehicles.