Development of a camless engine valve actuator system for robust engine valve timing control

Abstract

In this paper, a camless engine valve actuator (CEVA) system for robust engine valve timing control is presented. A particularly challenging control obstacle, shown in hydraulic actuation system for camless engine valve actuators, is the sluggish response of valve actuators at a cold operating condition. This is mainly due to the characteristics of oil viscosity with respect to temperature changes. At a low temperature condition, CEVA shows the very sluggish response. The retarded valve opening and closing timing, by CEVA's slow response at low temperature, causes an increase in pollutant emission and cylinder temperature during engine operation. In order to avoid these adverse effects by retarded timing, the new valve timing controller is proposed to control opening timing and closing timing, which is robust against temperature variations. A proposed valve timing controller is for guaranteeing the valve timing repeatability without using expensive position sensors. Experimental results indicate the feasibility of a fully variable valve timing control and CEVA system which can be constructed at a low cost. © 2012 Inderscience Enterprises Ltd.