Abstract
Keywords - CVT, pressure control, ratio control, model based PID, robustness
Abstract - Ratio control of CVT (Continuously Variable Transmission) can be classified as flow control and pressure control type according to how to control belt and pulley displacement for shift. In conventional flow control type, required speed ratios are obtained by controlling the opening area of the ratio control valve. In pressure control type, as required speed ratios are obtained by directly controlling the thrusts of the pulleys, it is effective in preventing belt slip, shift response and stability compared to flow control type. Because of these merits, pressure control types are attempted for recently developed CVTs, but few papers are published for its shift characteristics and details of the control algorithm. In this study, pressure control valves and low level controllers (PID, model based PID) for shift control were designed and it was found that an excellent and stable shift performance is possible to be obtained by only linearized model-based control.
-design of pressure control type ratio control valve
-design of controller for CVT shift control and development of test rig
-characteristic comparison of control valves/controllers
-development of control algorithm for pressure control type ratio control