The Research Of Power-shifting Process Base On The Structure Of Dual-clutch Transmission

As a new type transmission, DCT(Dual Clutch Transmission) combines the advantages of AMT and AT. As the abbreviation of Automatic Manual Transmission, AMT has the traits of high efficiency , simple structure, excellent technology inheritance, low manufacture cost. Whereas as the abbreviation of Automatic Transmission, AT has the traits of power-shift. For these reasons, DCT has high quality of shift, fantastic power performance and fuel-economy, which is especially available for the markets in which manual transmission takes the dominant role. It can improve our R&D ability on the automobile components and promote the development of automatic transmission industry for us to study the process of engagement as well as the control strategy of shift.Funded by Chongqing Municipal Education Commission(project NO:KJ080619), in this paper, an AMESim model for the simulation is established and the power shift of DCT is studied, the hydraulic pressure traits of the clutch during the process of shift overlap are obtained, and shift schedule of DCT is worked out. The main research includes:(1)Based on the analysis of dynamic model of DCT, power shift simulation model has been set up using AMESim. This simulation model not only establishes a simulation platform for further researching comprehensive control strategy between two clutches and engine during shifting process, but also lays a foundation for cutting down control system development cycle of DCT.(2)The shift process of DCT is simulated based on the AMESim simulation model. Some valuable conclusions are obtained by analyzing the relationship between the hydraulic pressure of clutch during the shift process and three parameter (lag time, start and end pressure and slope of positive pressure) by using the simulation results . Based on the above results, the conclusion that the slope of positive pressure is the key factor influencing the jerk and slipping work through Orthogonal Distributing Design of Experiments(DOE). Finally the method of controlling the slope of positive pressure is presented by reducing slipping time and work.(3)Based on the analysis of a car's engine map, the fuel consumption of constant speed 100 kilometers was obtained directly through the transformation of car's engine map by MATLAB. Through this method, the computing process is simplified, a car's engine map is directly perceived and readable, an important significance is developed for theoretical research and practical application of fuel-economic shift profile. (4)According to transformed engine map, fuel-economic shift profile is acquired by drawing resistance power surface and external characteristic power surface on the engine map.(5)Based on the concept of economic speed, the concept of comprehensive economic speed of a motor vehicle are put forward. The relationship between fuel consumption and travel speed is balanced, fuel consumption is saved as well as time. The solution methods are also introduced.(6)Based on the concept of comprehensive economic speed of a motor vehicle, comprehensive economic rotational speed of engine is put forward. The fuel-economic range of engine is easily knew, which provides a reference basis for engineers during process of establishing reasonable fuel-economic shift profile, which also provides a reason of shifting for drivers who chose fuel-economy especially the fresh ones.