Research On Clutch Control And Optimization In Wet DCT Shifting Process

Because of its high transmission efficiency and uninterrupted power transmission,wet DCT(Dual Clutch Transmisson)stands out from various automatic transmissions and becomes the main development direction of my country’s automatic transmission market.The shift quality of the wet DCT is mainly affected by the shift control strategy and whether the clutch actuator can accurately execute the control commands.Therefore,it is necessary to formulate an appropriate target torque trajectory of the dual clutch in the shifting process and ensure that the actual transmission torque of the wet clutch can accurately follow the target transmission torque,so as to achieve the goal of improving the shifting quality.This paper takes a certain wet DCT as the object,and conducts in-depth research on the dual-clutch control in the shifting process.The main research contents are as follows:The first chapter expounds the background and significance of this topic,briefly introduces the classification and working principle of dual-clutch automatic transmission,summarizes the research status of dual-clutch control in wet DCT shifting process at home and abroad,and proposes the research of this paper Content and technical route.The second chapter studies the wet DCT clutch hydraulic control system,analyzes the structure and working principle of the components of the system,and establishes the mathematical model and system dynamic simulation model of each hydraulic component in the wet DCT clutch hydraulic control system.Simulation analysis of its system characteristics.Finally,the established model is verified by experiments.The results show that the model can accurately reflect the dynamic characteristics of the system and its working performance,which lays a foundation for the in-depth study of clutch control in the subsequent wet DCT shifting process.In the third chapter,the torque transfer model of the wet clutch is established by using the average Reynolds equation and the G-W elastic contact model.And a dynamic friction coefficient model is proposed to represent the change of friction coefficient during wet clutch engagement.Based on the established correlation model,the influence of the temperature of the wet clutch cooling lubricating oil on its torque transmission characteristics is studied.Finally,the wet clutch torque transfer model is coupled with the wet DCT clutch pressure control system simulation model,and the co-simulation analysis is carried out.The fourth chapter establishes the wet DCT shifting dynamics model based on the analysis of the wet DCT shifting process,and formulates the dual-parameter shifting law and the pre-shifting law.Secondly,the NSGA-II algorithm is used to optimize the target torque trajectory of the dual clutch in the shifting process.According to the shifting quality evaluation index and shifting dynamics model,the objective function and constraint conditions are determined.The dual-clutch target torque trajectory with good shifting quality can be selected in combination with the actual situation and the preference for shifting quality during the actual vehicle shifting process.The fifth chapter establishes the clutch pressure adaptive control algorithm by using RBF neural network and fuzzy RBF neural network respectively.In order to fully consider the influence of the wet clutch viscous torque,the wet clutch dynamic friction coefficient is introduced into the calculation of the clutch expected control oil pressure,and compared with the case where the wet clutch viscous torque is ignored in the shift control,it effectively improves the wet clutch viscous torque.Shift quality of the DCT shift process.Finally,the influence of control algorithm performance on shift quality is analyzed.The sixth chapter summarizes the research results of the full text,and looks forward to the future work.