Research On Shifting Control Strategy Of Vehicle Automatic Transmission

From the perspective of improving the vehicle dynamic quality,based on a depth analysis on the characteristics of engine torque,this paper has studied on the strategy of shifting control of vehicle automatic transmission and thus obtained the method to control the strategy of shifting for the optimum dynamic quality and rele vant theories.The main research contents of this paper includes:(1)Through theoretical analysis,by the use of mathematical methods like interpolation and fitting,the engine performance curve and vehicle driving force——running resistance balance diagram and other relevant diagrams have been plotted,the driving experience of “downshift is needed when climbing uphill” had been verified and explained from the theoretical perspective,based on the torque characteristic curve of engine after fitting,a geometric construction method to determine the position of maximum power point and maximum torque point on torque characteristic curve of engine has been put forward.(2)The evaluation index of vehicle dynamic quality has been analyzed,the engine test data was used to investigate the gear-shift at the point of intersectio n of vehicle driving power curve at the intersection;The equation of the engine speed of the driving force intersection point is inferred.Through the graph comparison analysis,it was proposed in this paper that,shifting at point of intersection of vehicle driving power curve was the strategy of gear shift that can achieve the best dynamic quality,the law of gear shift having the best dynamic quality had been formulated.(3)The difference in dynamic quality between maximum power point and maximum torque point controlling strategies had been compared and analyzed based on Matlab software,the method to determine the initial gear of shifting with the optimum dynamic quality during the running of vehicle having a step down variable transmission had been proposed.(4)The features of shifting at the equipower point had been analyzed to draw a conclusion that,the engine had a better chance to use the high power to output when gear-shifting was made at the equipower point;Based on the shifting strategy of step down variable transmission with optimum dynamic quality and the feature of equipower point,the transmission ratio and speed controlling method having an optimum dynamic control of speed had been proposed,based on which,the speed-controlling strategy of Continuously Variable Transmission with the optimum vehicle dynamic quality had been formulated.The method to determine the initial gear of shifting with the optimum dynamic quality during the running of vehicle having a step down variable transmission had been proposed.(5)The simulation model of starting with single clutch and dual clutch had been built with Matlab/simulink software,based on the strategy of constant revolving speed control,this paper proposed to reduce the combining pressure before the synchronization of clutch and to optimize the shock degree during the starting by single clutch,the difference in shock degree,slipping friction work and shifting between the two starting patterns had been compared and analyzed.