Modeling Of Synchronization Process And Research Of Control Strategy In Wet Dual Clutch Transmission

With the development of Chinese automotive industry,wet DCT has become more and more popular as a new type of automatic transmissions.Wet DCT depends on the control system in TCU to actuate the synchronizer for a successful preselect shift which is used to be completed by the driver.Thus the modeling and control strategy of synchronization process have been the core technologies of wet DCT.They could help optimize design parameters of synchronizer and decrease the design cycles,and then analyze dynamical characteristics of synchronization process,and also develop the control strategy to decrease the impact and noise in synchronization process and improve the performance of synchronizer.Currently the research on modeling of wet DCT synchronization process is still in infancy.The research on the mechanism how clutch drag torque affects the synchronization process is still less though clutch drag torque is one of main factors affecting the synchronizer of wet DCT.And there is still no research on online estimation method of clutch drag torque for wet DCT.The lack of studies on the synchronization process and effect of clutch drag torque leads to the difficulty to develop the control strategy of synchronization process in wet DCT.And the performance of controller could not be improved greatly.This paper focuses on the working phases of synchronization process,and constructs its dynamical model,and then analyzes the main factors affecting the synchronization process,and also discusses the second bump phenomenon by the model.Based on the model of synchronization process,this paper develops two synchronization position estimation methods and compares these methods with current method which provide valuable tools for the synchronization position estimation.This paper also discusses the clutch drag torque models and develops online estimation method of clutch drag torque based on the model of synchronization process.At last this paper develops adaptive supervisor control strategy for synchronization process based on above studies.For this purpose,works of this paper are as follows:(1)According to the working process of synchronizer in wet DCT,a dynamic model is established in Matlab\Simulink environment.The main factors affecting the synchronization process are analyzed in detail.The dislocation between sleeve and travel sensor during synchronization phase and variable friction coefficient between ring and cone of target gear are also discussed in detail.In order to ensure that the model can reproduce the true synchronization process and show the working characteristics,and establish a platform for research on synchronization position estimation,clutch drag torque estimation and control strategy,experiments are processed by test vehicle.The displacement signals of sleeve,the rotation speed signals of input and output shafts are used to verify and improve the dynamic model.(2)Current synchronization position estimation method is analyzed and two new estimation methods are developed to compensate the disadvantage of current method.One method is based on the sleeve velocity and angular acceleration of input shaft.And another is based on the dislocation.For evaluating these three methods,they all are applied in synchronizer model and experiments.By analysis and comparison of experimental results,this paper provides a reasonable basis for how to choose the best synchronization position estimation method.(3)Current popular clutch drag torque models are discussed.According to the clutch drag torque model,the discrete dynamic equations during synchronization phase are derived and rewritten into the form for least square method.Forgetting factor is introduced to accelerate the convergence rate.Finally online estimation method of clutch drag torque is established.Then the effect of longitudinal vehicle dynamics is taken into consideration to improve the accuracy of the estimation method.At last the estimation method is verified by the model of synchronization process.(4)According to the analysis of synchronization process,it is a hybrid dynamical system.Currently the research on control strategy of synchronization process in wet DCT is still at the start stage.The classic control methods have poor performance on the hybrid dynamical system.For improving the performance of synchronizer,this paper develops adaptive supervisor control strategy which is suitable for hybrid dynamical system.And the switch conditions between different phases are discussed in detail.At last the adaptive supervisor control strategy of synchronization process is verified by the simulation model and experiments,and evaluation is also presented.