| Automobile has already penetrated into all aspects of all our life today. Though the structure of the tradition transmission is simple and the engine doesn't move in economical region and better exhaust because of the interrupted ratio. With the development of the society and the change of our living condition, people's demands for protecting environment, saving fuel and comfort are more and more high. The automatic transmission arises at such a particular situation. Among several type of car's transmissions. The metal pushing V-belt continuously variable transmission (CVT) is regarded as the ideal transmission because of its ideal power transmitting character, its compact structure, easy performance and perfect functions. CVT is regarded as one of the key technology in the development of automobile. Many famous auto companies strive to the first to research and develop CVT, and there are several productions come to the market. In recent years the CVT is accepted by people and has been developed greatly.This thesis studies on CVT of EQ6480 bus .The concrete research contents as following:1. The strap kinematics relations and the transmission mechanism are the CVT structural design foundation. This article has analyzed the greatest velocity ratio, the small velocity ratio, the belt transmission diagonal movement angle, the belt and a turn of included angle and the velocity ratio scope relations, Inferred has been allowed the movement belt pulley to move is away from and the velocity ratio formula, Finally obtains in the strap for long decides, under the center distance invariable restraint, uses the straight generator wheel, the strap can have the axial displacement, must carry on the control to the strap axial displacement. Embarked from the strap transmission mechanism, has analyzed relational, the strap transmission strength balance relations which the strap thrust force and the extension was apart from, produced the transmission wheel to clamp the strength formula.2. The hydraulic system is the execution of the control system whose working factor has a great effect on the CVT system. In order to realizethe dynamic characteristic of the hydraulic control system deeply, this paper analyze the working factor of the basic parts to begin with carry on theoretical analysis and build the model. Based on these, this paper analyzes the characteristic of the hydraulic system, which shows that the structural characteristic of the hydraulic system, such as the area of velocity ratio valve and current capacity of pump have effect on the velocity ratio change. The analysis provides for later research.3. Based on the experimenter data. We have established, the numerical model of EQ491 engine, also have found the best economical and dynamic control. We have got the arithmetic of goal velocity ratio and establish the goal velocity ratio under the best economical and dynamic control, which provides for the design of velocity ratio controller, after analyses the enlistment with one damper and establishing the biggest and smallest velocity ratio of EQ6480.4. According to the complexity of the CVT variable transmission system, this paper design fuzzy velocity ratio control, and do the accessorial design of velocity ratio control, with Fuzzy Logic Toolbox under the Mat lab. At the same time, this paper build the simulation model of fuzzy velocity ratio control compared with, the there typical situation. We build the simulation analysis of actual velocity ratio to goal velocity ratio following, and shows follow the nature to be good.5. In order to save the fund, this paper builds the mathematical model of EQ6480 transmission system and the simulation model with Simulink. In the start operating mode, the acceleration operating mode, receives the grade resistance operating mode. We do the simulation analysis of actual velocity ratio to goal velocity ratio following, with shows that the design of controller and the theoretical analysis of the adjustment are reasonable and provides for later research.
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