| By the support of National Nature Science Foundation, some key problems of CVT were investigated, and some useful results were obtained as follows: (1) The relations between metal-belt misalignment in axial direction and transmission parameters were studied. By designing curved generating line pulley or adjusting the axial displacement of pulley, the degree of misalignment of the metal belt was decreaed. (2) Mechanics model of multi-layers metal ring and the model of transmission slip ratio were established. The relation between parameters and transmitting torque or efficiency were studied, and the way how to improve the transmitting capacity of CVT and transmission efficiency were also investigated. (3) A new method of measuring slip ratio of CVT was proposed, and test device was also developped. Some experiments were done on the CVT test bench. The relation of transmission ratio, clipped force of pulley and transmission torque was investigated by experiment. The effects of transmission parameters on the performance and transmission efficiency of CVT were studied. (4) The characteristic of continuously variable transmission fluid was analysised. The performance of hydraulic transmission fluid No. 8, hyper automatic transmission fluid(ATF), continuously variable transmission fluid(CVTF) were compared. The compared results are the reference of chosing the right fluid in CVT. The mechanism of ZnDDP additive how effects on the performance of CVTF is investigated by X-ray photoelectron spectroscopy(XPS). By analysing the scar of Four Ball Friction Test and XPS photoelectron spectrum. The mechanism of ZnDDP additive effect on friction performance was disclosed. (5) The principle of CVT hydraulic control is studied. A CVT test box , CVT ratio control hydraulic pump station and electric control system based on personal computer(PC) were developped. A CVT performance test bench was also established. (6) A performance test of torque converter has been done,and the control strategies of torque converter lock and unlock control were proposed. The performance of hydraulic control valves has been tested on the bench. A CVT controller was proposed based on fuzzy logic alrithmetic. The control parameters were calibratted on the test bench, and the control effections of PID controller and fuzzy controller were compared.(7) The electro-hydraulic control scheme has been designed. Some sensors in the CVT system were calibratted. A wire bale of CVT control system and original vehicle wire were designed and revised. A CVT prototype was manufactured and successfully equipped on the car which brand is duiker. Some matching bench test and road test has been finished. And test results are generally well.
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