Modeling And Simulation Of Hydraulic Control System Of Continuously Variable Transmission

Continuously Variable Transmission is an ideal automatic transmission for vehicles. Theengine can work in the best operating area by changing the speed ratio continuously. The fueleconomy and dynamic performance can be improved.The metal pushing V-Belt CVT is one of the widely used CVTs currently. It hasadvantages of good performance and simple structure. And the CVT has a bright developmentprospects in our country. The electro-hydraulic control system is one core part of CVT. Thereis a big gap between china and developed countries on CVT technology. This article has madea research on the electro-hydraulic control technology of CVT. The main contents are asfollows.The CVT’s develop history and research situation are discussed in this article. Thestructure and working principle of metal pushing V-Belt CVT are also been introduced.The engine output torque model has been established by cubic spline interpolation basedon the experimental data of engine. And then the optimal dynamic operating line has been got.The main components of the hydraulic control system have been analyzed and themathematical model of these components has been built.The control of the CVT includes the clutch control, the speed ratio control and theclamping force control. The clamping force and speed ratio calculating formula have beenobtained based on the force analysis of CVT and the relationship between working radius andspeed ratio respectively. Aiming at the control of speed ratio and clamping force, the speed ratiocontroller and clamping force controller were designed.The models of the hydraulic control system and vehicle powertrain system have beenestablished by AMESim. The control effects in the different driving modes have been verifiedthrough simulation experiments. The results of simulation show that the control strategy andalgorithms of the speed ratio and clamping force are effective and applicable.