Research Of Performance On Automotive8-Speed Automatic Transmission

Automatic Transmission (AT for short) is the main strength of transmission, the trendof the high gear AT is more obvious. The high gear AT can improve all aspects of vehicleperformance, because of its greater scope of gear ratio and more detailed ratio between thegear ratio distribution.Many automobile manufacturers in China have taken developing a higher gear ATequipped car into the direction, more research on higher AT systematic has an importantvalue and theoretical significance to promote technological progress and the developmentof the domestic auto industry.In this paper, there are six main working contents:1. Analysis of the8AT structure and make its structure diagram, and their works havebeen summarized based on the analysis in the structure. Analysis of power transmissionline of the8AT every gear, and make power transmission line diagram. The transmissionratio of every gear is derived and calculated based on characteristic equation of the generallaw of motion of single-line planet-gear;2. Established a mathematical model of the engine steady-state torque characteristics,and the engine model has been amended. Established mathematical models of thehydraulic torque converter original characteristics, the transmission power losses andtransmission and drive axle universal transmission efficiency, the transmission power lossis divided into cylindrical gear mesh power loss, bevel gear mesh power loss, the clutchfriction power loss, bearing friction power loss, stirred oil power loss, oil seal power loss;3. According to the mathematical model in MATLAB/Simulink platform toestablish a simulation model of the engine, torque converter simulation model,8AT powerloss simulation model,8AT transmission efficiency simulation model, automobiletransmission efficiency simulation model;4. At different engine input speed continuously variable gear case, get8AT transmission efficiency of the simulation results, recorded the various speeds at differentstalls of the sTable transmission efficiency results, find the average. Based on all thesimulation data, make the three-dimensional view of the engine speed, simulation time, theresults of the transmission efficiency, using the same method to get the simulation resultsand the three-dimensional view of the automobile transmission efficiency;5. Established the simulation mathematical models of vehicle powers, including thecalculation mathematical model of the vehicle maximum speed, the vehicle accelerationperformance, the vehicle power factors of every gear and the vehicle maximum climbablegradient, based on these calculation mathematical model established a vehicle powerssimulation model. Through the model get the vehicle speed under different gear, the powerfactor and climbable gradient of every gear based on8AT transmission efficiency, then getthe maximum speed, the maximum power factor and the maximum climbable gradient;6. Established the powers simulation model of the vehicle matching6AT, find thevehicle matching this6AT simulation results of the maximum speed, power factor andclimbable gradient. To compare the power results between the vehicles matching6AT andmatching8AT, obtained the influence of the different gears and different transmission ratioto the vehicle under the same conditions, description8AT outperforms6AT to the vehiclepowers performance.