Dynamic Simulation And Leakd-down Experiment Of Valve Train With Hydraulic Lash Adjuster

This thesis focus on the dynamic simulation on the valve train with Hydraulic Lash Adjuster (HLA) and the study of HLA's leak-down speciality.Based on the review of the reference literature ,the calculation formula for the oil force in the hydraulic model of HLA is deduced, the mathematical model for valve train with bucket type HLA was set up and in which the HLA is treated as a hydraulic element. A computer program be developed based on MATLAB language and which be used to calculate the dynamics of valve train of Santana Engine. The leak-down measurements under various loads for two Santana Engine's HLA are carried out on special designed measurement equipment. Values of leak-down damper are calculated from the measured results. Mastered the values of leak-down under various loads of HLA, got the damp parameters through the testing result and calculate formula.The result of calculation show that the hydraulic model can reflect the dynamic behavior of HLA effectively, and can get more info than the spring-mass model, which also can reflect the movement status of check valve globe. The program of this thesis could be used to simulate the movement rule of valve train of the common type .The results of simulation show that the variations of length of HLA is the mainly caused by the compressibility of oil in the high pressure chamber, the leakage and the compensation. when the valve is opening, the compressibility of oil is principal and the effect of leakage is relatively small, when the valve closed and the check valve open, the compensation of oil turned to be the chief cause.Finally, contrasted the result of calculation and the experiment result, analysed the effection on simulation result of the mainly frame parameters of HLA, carried out the sensitivity analysis, and pointed out the direction of the study in the future.