Study On Intake Performance Of SI Engine With Fully Variable Valve Hydraulic Actuation System

With the social development of science and technology, environment, energy issues are increasingly prominent, studying the engine that has energy-efficient ,low pollution ,high performance and new structure must be imperative, in this context it has appeared a variable valve train. fixed valve train of Traditional engine can not take into account all the high-speed and low speed condition, therefore in most cases the engine does not work in the reasonable case phase, while in the gas exchange process pumping loss is larger, resulting in greater fuel consumption and engine emissions deterioration, therefore ,the studying of fully variable valve train is of great practical significance.This paper introduces a hydraulic fully variable valve train. This mechanism uses cam and hydraulic to control the motion of valve, directly to adjust the valve lift, continuous angle. Using cam opens valve ,at the appropriate time the hydraulic system controls valve down, this control is a continuous variable ,in order to achieve the full-variable valve movement. Valve can change in the 180°CA after TDC, directly to control air input, so as to achieve the purpose of the abolition of throttle. Since the structure has canceled the throttle, thus greatly reducing the pumping loss.In this paper, K157FMI engine of Qingqi Group is for experimental prototype, we carried out a series of studies of a hydraulic fully variable valve train, the main contents include the following:First, we uses mathematical model of two-chamber to calculate the movement of hydraulic fully variable valve train. The result shows that this design can achieve the direct control of valve movement ,can change the intake valve lift and opening duration in a wide range. this truly achieves fully variable of valve movement.Second, we establish One-dimensional fluid dynamics model, and use the BOOST software to analysis. The results also confirmed that the agency can charge for the engine cycle regulation, and greatly reduce the pumping loss.At the end, we trial-produce hydraulic fully variable valve train and conduct experiments, the compared that the experimental results with the calculate results verifies the correctness of mathematical model and the feasibility of this train.