Research On Control Characteristics Of DSG Clutches During Slipping Process

In this paper,the studied object is the direct shift gearbox(DSG),which is used in a tracked armoured vehicle.Considering the working environment of high speed,overloading,complex road conditions,and requirements of dynamic property,reliability,high power density,a dynamic model for DSG launching and shifting process is built.The characteristics of clutches during the slipping process are analyzed,and launching and shifting control strategies are proposed.The theory and simulation study is used to analyze the influence of control quality with the change of parameter,and the experiment is conduct as well to verify the results.Main conclusions are shown as follows:(1)A vehicle system model is built,including engine model,clutch model,load model.Several different engine models are analyzed and the influence of friction coefficient on control quality is investigated.Launching and shifting models are built by analyzing the DSG's working process.(2)In order to evaluate the performance of dynamic,fuel economy,riding comfort,reliability comprehensively and objectively,several indexes such as jerk,friction work,engagement time,thermal load,engine speed fluctuation are introduced to build a complete assessment system.(3)The launching control strategy is proposed.Considering the driver's intention,engine running state and clutch engagement state during launching process,fuzzy PID control is used to obtain the oil pressure and PI control is adopted to track the target engine speed.The shifting process is divided into two stages: engine torque is transferred between two clutches during the torque phase,which needs control oil press precisely.The speed of clutch's driven side should accord with the driving side during the inertia phase,which needs intergrate control of engine and clutch.(4)The influence of initial speed difference,load and oil pressure characteristics on launching quality is analyzed.Furthermore,the effect of the transmission ratio,engine speed regulating,shifting speed on shifting quality is analyzed through simulation,which is verified by experimental test.This study provides good basis for making control strategy and optimizing control quality.