The Simulation Analysis And Test Research On Metal Belt CVT

Automobile is one of the symbols of human civilization, it'sdevelopment must conform to the requirements of the society. The twomain themes of the contemporary world are economizing energy andprotecting environment. However, millions of autos running in thestreet are the major subjects of energy consumption and environmentalpollution. Therefore, one of the directions of future automobiledevelopment is to take effective measures and apply new technology toreduce the fuel consumption and minimize exhaust gas. Because thecharacteristic of Internal-combustion Engine is different from that ofthe Ideal engine, So a transmission is needed to improve the performanceof powertrain. And the most effectual and promising way is CVT( Continuously Variable transmission ). The metal pushing V-belt typecontinuously variable transmission (CVT) has the advantages of simpleand compact structure, easy operation, excellent performance, low costand fuel economy. As an advanced technology to develop passenger car,it can meet the demands of developing transmission in our country. Sothis technology attracts much more attention in recent years. Thedissertation mainly focused on the speed ratio control of CVT andmatching with engine, which based on the science and technology majorresearch emphasis item of The Ministry of Education ——"The researchof car's continuously variable transmission dynamic matching rule andthe electrohyraulic control systems integration exploitation" andChangchun City science and technology bureau tackle key problems item——"The hydraulics building block design means very combinationcontrol characteristic of Car's continuously variabletransmission(CVT)".The main research contents as follows:Firstly, the dissertation reviews the development process and thetechnique of CVT briefly. Through the comparison with othertransmission, showing that the metal pushing V-Belt type CVT can meetthe currently demand of drivability, economics and emission etc, andstating that the CVT is the ideal transmission which will be thedeveloping tendency for the transmission of passenger car. In the paperthe background and the necessity of this theme in science and practiceare given.Secondly, the dissertation introduces the CVT's basic structureand critical components, which makes we know clearly that the V-modemetal belt possess unique feature, therefore V-mode metal belt'stransmission mechanism is different from apron belt. The stess analyseof metal belt is extraordinary intricacy, whereas the transmissionmechanism of metal belt is the rational of its transmission and control,thereby educes three critical technologies of CVT's control system——clamp force control,ratio speed control and fist time step processcontrol.Thirdly, to different engine,load bearing characteristic and speedcharacteristic is different, therefore CVT's ratio speed is differenttoo. The dissertation utilized the mating motor's test data, usingformula fitting process to found torque numerical model,oil wearnumerical model and magnitude of power model of the motor. Therebygotten universal characteristic and speed adjustment characteristic ofthe mating motor, which eatablished foundation of continuously variabletransmission system's achieving the best economy and the great powermatching, consequently supply clearly gist for CVT system control.Fourthly, according to lumped mass method, continuously variabletransmission system is boiled down to two rotating mass model system,then based on the motor numerical model, we got the vehicle's best powerand optimal economy ratio speed. Using PID control method to controlratio speed rate of change, thereby achieve the aim of speed ratiocontrol. I did some simulation analyses before test for prove thefeasibility of control method. In the dissertation, founding simulationmodle of vehicle with CVT system under simulink environment of matlabsoftware, which include engine submodel,CVT-automobile submodel,target ratio speed submodel and ratio speed control submodel, then madesimulation analysis to three different working condition: fist timestep process,starting-up to speed process and accelerate came in forroad resistance process. The simulation result indicate that ratiospeed following condition of this model is in order which explain thePID control design is reasonable, and it made a favorable foundationfor the next bench test.In the end, we did bench test under the test condition we have todemonstrate the control-theory right or not. The test included constantspeed ratio follow,step speed ratio follow ,simulate fist time stepworking condition and deceleration , from the test resule we can seethis control system effect all right and possess definitefeasibility,but owing to limitation of test condition, we can'tproceed the next bench test and auto-test.In a word, CVT is the most newfashioned automatic transmissiongearing which have multitude mechanism,hydraulic pressure,eletron andcomputrerized technology. This kind of transmission now is on researchphase in our country, there are some challenge problems in transmissionmechanism,system design and test. So maste these theories and criticaltechnology have importmant practical meaning in advancing independenceexploitation ability of our national made car and shorting the gap withdeveloped country, certainly it is the common goal of each largeautomobile corporate.