| CVT(Continuously Variable Transmission) can make the engine work ate optiimmi condition, and adapt the various car speed or driving conditions relying on its steplespeed iegulation. not only 1 the engine,s combustion best, but also exhaust min. Limited by the mechanical structure, tranditional metal v-belt CVT has defects in transmission efficiency and maximum transmiion torque. The thesis is based on Hangzhou Donghua compys resech project: development of metal chain-belt CVT,s test bench,includig the in-depth Ksearch on hydraulic system and electrical control system A better understanding on metal chain-belt CVT scontrol characteristics and transmission performance has been acquired. The specific studies are as follows:(1)The development process of CVT and its electro-hydraulic control system at home and abroad is summed up on the basis of the subject background, then the significance of this thesis is pointed out(2)The mechanical structure and speed ratio changing theory of metal chainbelt CVT are introduced. The mathematical models of speed ratio and clamping foice have been bui Besides,the overall trol strategy is determined.(3) The hydraulic system has been designed accordig the bench control requirements,which is divided into three subsystems: speed and clamping force control:lubrication and cooling, temperature control. The integration of the hydraulic system is completed, and the mathematics models of major hydraulic elements are also built.(4)The metal chain-be CVT,s speed ratio changing eory and control tasks are systematically studied. The author design the hardware circuit of PLC control system, and complete the control program.(5)At last,a bench is conducted verify the performance of the CVT,including the control characteristics and transmission performance. The bench results show that the electro-hydraulic control system and control strategies can the speed ratio requirements,and the CVT has better performance on the transmission efficiency and maximum transmission torque aspects.Finally,summary and forecast of this paper,s work are provided. |
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