Effects of structural parameters on the motion variability of the continuously variable valve mechanism

Abstract

Facing the significant demand for energy saving and emission reduction in the internal combustion engine industry, a new continuous variable valve mechanism (CVVM) is designed for marine medium and high-speed internal combustion engines. By building a single-degree-of-freedom mathematical model, the influence of eccentric shaft position, eccentricity, and input rocker arm ratio on the variable characteristics of the mechanical motion is studied. The results show that the single-degree-of-freedom mathematical model is accurate and can be used to research mechanism motion variability. Under different vital structural parameters, the mechanism exhibits four variable motion modes with the adjustment of the phase of the eccentric wheel. For the continuously variable Miller mode, when the input rocker arm of the mechanism is constant, and the initial position is the same, the valve motion interference phenomenon is more serious when the eccentric shaft position is farther away from the camshaft, the eccentricity is more extensive, and the input rocker arm ratio is larger. The maximum lift of the valve is unchanged under the influence of eccentricity, and the larger the input rocker ratio, the greater the maximum lift of the valve.