Study On Valve Movement Disciplinarian Of SI Engine With Fully Variable Valve Hydraulic Actuation System

Valve system as one important part of the engine,has been designed to realize the engine's discharging:in order to deliver air-fuel mixture or clear air into the cylinder and to discharge the exhaust gas from the cylinder. The intake valve and exhaust valve were opened or closed according to the cylinder working order. 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 on fully variable valve train is of great practical significance.The intake valve of fully variable valve train studied in this paper is controlled open by intake cam, while the hydraulic mechanism controls it down at an appropriate time. This control is continuous variable in order to achieve the full-variable valve movement. In this paper, K157FMI engine is for experimental prototype, a series of simulation studies of valve movement with fully variable valve train is carried out. The main contents are as follow:First, we proposed a series of basic assumptions for model of two-chamber to calculate the movement of hydraulic fully variable valve train, and the work process is divided into three-stage:valve unopen stage, open stage and off stage. For each stage, we set out boundary conditions, and establish a series of basic equations.Second, we set up the correct engine cycle simulation model with AMESim according to the real situation. Analysis the parameters of every parts of model, including cam model, hydraulic oil; sub-model selection of pressure source module and the parameter; tappet cavity sub-model and parameter; valve piston chamber sub-model determination and parameter; circulation area of export control determination; throttle flow area determination. To simulate the hydraulic model and to compare the simulation results and experimental results to see whether the trend fit, it verify the accuracy and reliable of the simulation.Third, finishing the experimental date, analyzing and comparing the results under various circumstances to select the best program, under the optimal program analysis we obtained:FVVT agencies can achieve the full-variable valve lift and valve timing; seated speed of valve is affected not only by the speed of the engine, but also with the valve lift of the increase. Verified the seated speed and rebound height, we obtained the seated speed and rebound height of optimal solution were within the allowable range.