| The power-cycling variable transmission(PCVT) system is a new transmission system. Compared with CVT, it has a relative wide ratio range and rather high efficiency. Compared with AT, its efficiency is higher than the unlocked-up automatic transmission. Moreover, the continuous speed ratio is achieved fully in the whole ratio changing range. Therefore, the new transmission will be very promising for research and application.The research based on the project of National Natural Science Foundation of China(51375505) “Design theory and control method of a new power-cycling variable transmission”. In view of the structure and operation principle of automatic transmission with reflex power, the main research work is as follows:① Firstly based on the structure and operation principle of PCVT system, its speed ratio characters and efficiency characters are analyzed. Considering the powertrain structural characteristics and aiming for improving efficiency and increasing speed ratio range, the determination method of structural parameter is put forward according to the analysis of the relationship of the various parameters. Take the AMT car of changan SC7130 as the design prototype, design on structural parameters of automatic transmission with reflux power is given under the guarantee of the power.② The engine model has been established based on the spline interpolation of the engine test data. The clutch torque model is set up by the way of analysis of various states of clutch. In consideration of the torque converter changes as the change of gear transmission ratio in the progress of shifting, the torque converter model, the efficiency of system model and the vehicle resistance model is established. For analysis of the process of shifting, the shifting dynamic model of PCVT system is set up. It will lay foundation for the formulation of shift control strategy and simulation.③ According to the shifting requirements of PCVT system, the main factors that influences the shifting quality is analyzed and the shifting evaluation index is put forward. In view of the shifting characteristics of automatic transmission with reflux power, the gears switch process of the whole transmission system and related parameters in the shifting process are analyzed. Therefore, this paper proposes the control strategy of every shifting process, the judgements and switch conditions are established.④ In order to solve the problem of automatic transmission’s efficiency mutation in the shifting process and realize the smooth shifting, the clutches and engine need to be controlled well and the controller of the oil pressure of clutch and the throttle opening of engine are designed respectively. The simulation test is set up to verify feasibility of the scheme through the Matlab/Simulink software. |
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