Study On Key Technologies During The Shifting Process Of Wet Dual Cluth Transmission

With the rapid development of automatic control technology, automatic transmission has been developing vigorously. It has the virtues of reducing fuel consumption, improving emissions, enhancing the life of driveline and relieving labour intensity of drivers etc. Thus, it has been applied more and more frequently.Dual clutch transmission is a new type of transmission. It is based on the parallel axis type transmission. Odd and even gears are respectively arranged with two clutches and shift by exchanging the two clutches. It not only maintains the merits of simple structure, low cost and high mechanical efficiency compared with conventional manual transmission, but also attains shifting without power interruption, and improves power performance, fuel economy and shifting quality. So in recent years, DCT has been a focus of the research in the field of international transmission.This paper is based on the current situation of the research on DCT, combining with the national 863 Science Plan of China-Imlpementing Scheme on "the development of six-speed dual clutch transmission".The key technologies during the shifting process of wet dual cluth transmission are studied. The main contents of research are as follows:(1) Based on the analysis of the functions, compositions and operation principles of electrohydraulic system, the hydraulic characteristics of shifting force control and clutch pressure control are studied. The models of shifting force control module and clutch pressure control valve are established and simulations are carried out. And solenoid valve test is conducted on a hydraulic pressure colligation test-bed, the test results show that the simulating outcomes are in coincidence with the experimental data, reflecting the basic properties of electromagnetic pressure control.(2) Characteristics of pre-select gears and control technology of shifting force are researched. Mathematical model of synchronous process and resistance model of pre-select gears process are established based on the working process of synchronizer. The target position of shifting fork in the process of pre-select gears and the shifting force corresponding to the position are determined. The fuzzy control strategy of shifting force is proved to be effective by the vehicle test. (3) The determination method of cluth optimum target torque in the shifting process is studied. Staged shift strategy is formulated and shifting dynamical models in different stages are established based on analysis of dual clutch transmission in the shifting process of different working conditions. An optimal control trajectory of clutch pressure at every shift stage is obtained by optimal control algorithm in which longitudinal jerk and friction work are chosen to form quadratic performance index functions, and the optimal control of clutch pressure in the shift process is realized using optimal control trajectories. Jerk and friction during shifting process can be well equilibrated by adjusting weight coefficients.(4) The structure of wet dual clutch, its operating principles and torque transfer characteristics are analysed, then the troque model of wet clutch is established based on the analysis. Considering the accuracy of mathematical control model is not precise enough and the quality change after using for a long time, PSD control arithmetic is introduced into the single neuron PID control, and the single neuron adaptive PSD intelligent controller is formed and applied into wet clutch control system. The clutch pressure intelligent control algorithm is built and the real vehicle tests are done. Test results show that the wet clutch control arithmetic based on the single neuron adaptive PSD possesses good following performance and high control precision. Based on the optimal theory of the clutch target torque, the determination technique keeps slipping work and jerk well balanced and supplies the vehicle with good shift characteristics.(5) The DCT shift schedule based on driver type is studied. After identifying the driving style with BP neural network classifier, the data fusion decision is made based on the driving style identification result of manipulation and the driving style identification result of all different manipulation with bayesian fusion decision method, and the driver type is identified in final. DCT shift schedule based on driver type is established with the identification result, and the simulation is carried out. The validity of the shift schedule is verified by the simulation results.In this paper, the key technologies during the shifting process of wet dual cluth transmission are studied by theoretical analysis associated with experimental research. The results show that a good shifting quality is achieved, which has some reference value to the shifting technology development of wet dual cluth transmission.