Dynamic Analysis and Adaptive Valve Timing Controller Design of Camless Engine Valve Actuators

Abstract

Camless Engine Valve Actuation (CEVA) technologies have been known for improving fuel efficiency, enhancing power output, and reducing emissions of Internal Combustion(IC) engine. Electro-Hydraulic valve actuators are used to eliminate the camshaft of an existing Internal Combustion(IC) engine and to control the valve timing and valve duration independently. This thesis presents a research activity like hydraulic actuator design, dynamic simulations, analysis and adaptive valve timing control of a CEVA. Electro-Hydraulic valve actuator’s main function is to provide fully variable open/close valve timing. The CEVA system has been modeled by means of a powerful hydraulic simulation tool, AMESim, which is useful for the dynamic simulations and analysis of hydraulic systems. The designed model has been validated through comparisons with mathematical model and experimental results obtained in a prototype test bench. A proposed CEVA system controls valve landing velocity through a mechanically designed snubber. The dynamic analysis and performance results of a CEVA with hydraulic snubber are verified by comparing simulation in AMESim with experimental results on a prototype test bench. This research is also focused on the adaptive valve timing control of a CEVA system. A particular challenging control obstacle expected is the performance of valve actuators at cold operating condition. This is mainly due to the extremely nonlinear characteristics of fluid viscosity to temperature change. At a low temperature condition, CEVA’s response is very sluggish. The valve timing control algorithm proposed in this thesis is used to robustly control opening timing and closing timing regardless of fluid temperature variations. A proposed valve timing controller is to guarantee the valve timing and lift repeatability without using expensive linear position sensors. Test bench data and simulation results indicate that a CEVA system would verify the effectiven...