Reaserch On Shift Schedule Of Power Hydromechanical Automatic Transimission

Automatic transmission’s shift schedule is a core technology in the design of the automatic transmission, and the quality of shift schedule have a significant influence to the vehicle’s power, fuel consumption, shift quality, shift smooth and rapidity, automatic transmission technology applications. The subject comes from “the design of the automatic transmission in high-power vehicles”, which is developed by IEST (Institute of Electro-hydraulic Servo Simulation&Test System) of Harbin Institute of Technology and Guizhou Winstar Hydraulic Transmission Machinery. The research is hydromechanical automatic transmission’s shift schedule in high-power vehicles, and the main contents are as follows: First of all, the composition and characteristics of automotive driveline isdescribed clearly. And it includes characteristics and mathematical models of diesel engine, gear pump, steering pump, hydraulic torque converter, gear transmission and so on. At the same time, the dynamics of automotive driveline including the driving force and the driving resistance (rolling resistance, air resistance, gradient resistance and acceleration resistance) is analyzed. This establishs the theoretical foundation for the study of automatic shift schedule and computer simulation. Secondly, the optimal dynamic shift schedule is researched. It contains twoparameters optimal dynamic shift schedule and dynamic three-parameter optimal dynamic shift schedule. Finally, considering the impact of the slope of the ramp on shift schedule on the basis of the dynamic three-parameter optimal dynamic shift schedule above, a improved dynamic three-parameter optimal dynamic shift schedule is raised. Thirdly, the optimal fuel economy shift schedule is explored. It outlines theevaluations of automotive fuel economy, calculation, load characteristics of the engine and automobile fuel consumption equation. And it briefly introduces the development of a general three-parameter optimal fuel economy shift schedule. In addition, it also puts forward a improved three-parameter optimal fuel economy shift schedule, which involves the theoretical analysis, formula analysis, model analysis and competes surface fitting of three-parameter optimal fuel economy shift schedule. Finally, computer simulation about shift schedule is achieved with the MATlab/simulink software. It establishs engine model, clutch model, transmission model, vehicle dynamics model and shift schedule model (including the shift schedule module and the shift logic module), and add input and output modules and initialization module to build the overall model about the optimal shift schedule. Different shift schedules are stored in the shift schedule module. These different schedules contain two parameters optimal dynamic shift schedule, dynamic three-parameter optimal dynamic shift schedule and three-parameter optimal fuel economy shift schedule. After the simulation experiments, the results are analyzed and compared.