An Experiment Study On The Ratio Control Of Metal Belt CVT

The Metal Belt CVT is a type of ideal transmission for passengercars.Compare with the widely used Automatic Transmission (AT) currently, ithas many advantages, such as the function is good, the structure issimple and the price is low, etc. Along with the technological advance,The Metal Belt CVT is acquiring bigger and bigger development with itsexcellent no class characteristic. The control strategy of CVT affectsthe quality of transmission, the fuel economy, the dynamic performanceand the emission. To exert the excellences of CVT fully, it has becomea kind of inevitable choice to control the engine and the transmissionsynthetically. Ratio control is the core of the control system of CVT,and it is very important to the vehicle's performances. So this papermakes some study on the integrated control for an engine and a CVT,especially on the ratio control of CVT.(1) The no class transmission is an old concept, it has been atarget for the people from the automobile appeared. The ratio of theMetal Belt CVT can change continuously within the scope of design,enable the engine work in the best appearance, prolong its service life,improve the fuel economy and dynamic performance, reduce exhaust, andcarry out integrated control of the engine and CVT.(2)To study on the integrated control strategy of the engine andCVT, firstly, the data model of the engine was built up according tothe steady experiment data; secondly, the model of the power and thetransmission system was built up, and the effect of ratio change rateon the vehicle dynamic performance are analyzed. Controlling CVT'sratio according to the engine division door open degree and current carspeed, enable the engine work in the best appearance, thus is thematching principle of the engine and CVT. Confirming the division door'sopen degree of the engine and the ratio of CVT to change under a certainprinciple according to the driver's request and the running state ofthe car, consequently enable the car in best performance, thus is theengine and CVT's integrated control strategy.(3) The ratio control strategy of CVT was studied. CVT's targetratio is confirmed according to the engine division door's open degreeand current car speed, the ratio control must enable the real ratioachieve the target ratio as soon as possibly, and undulate near thetarget ratio. This test-bed adopts the method of rotate speed instead,carries out ratio control through controlling the voltage of theelectromagnetic valve. A PID controller was designed according to thisCVT.(4) The CVT test-bed was built up. On the foundation of integratedcontrast, according to the actual circumstance of our laboratory, thepower system, load system, test and control systems, and accessorialsystem were selected and designed here. The software system of the CVT...