大功率汽车自动变速机构档位切换机理研究机械电子工程专业论文.docx

Abstract Transmission is one of the most important part of the vehicle driving system, and it has much influence on the performance of the vehicle. Automatic transmission can not only alleviates the driver’s working intensity, but also greatly improves vehicle performance of power, efficiency and comfort. Optimum control of the automatic transmission can improves ride performance, also prolong service life of transmission system and clutch friction disk. The goal of this thesis is to study and develop some essential control technologies of the automatic transmission ALLISON4800SP. Simple analysis of the ALLISON4800SP automatic transmission is shown on this paper.The power transmission line and the solution of the ratio are also introduced.The types of shift schedule are briefly introduced and according to the kinetic equation of the vehicle, the formulating method of the tractive performance shift schedule is studied. The best shift dot of the tractive performance shift schedule under the maximum throttle is drafted based on the dynamic 3-parameter shift schedule. The influence of vehicle driving smoothness, drive system load and the life of the friction disk are analyzed and the objective evaluation criteria are introduced. The kinetic equation during shift 3 to shift 4 is built based on virtual displacement principle and Alembert Principle. Torque phase and inertial phase during the shift are also analyzed. This thesis build the engine and control unit model based on Simulink; the load, mechanical part and hydraulic part model of the automotive transmission are built based on AMESim. Co-simulation of the shift process during shift 3 up to shift 4 is given. This system uses sectional control. The first stage is an open-loop control for oil pressure of both clutches; the post stage is a closed-loop control uses the turbine acceleration as a feedback parameter. The influences of vehicle’s acceleration, jerk and slipping work upon the control parameters are analyzed.