The Study On Control And Mechanism Of Noise In Valve Train Of Internal Combustion Engine

When valve-train of engine works, it brings intense vibration and impact. This makes it one of the main noise sources of engine. To improve the noise performance of engine valve train, the mechanic and control of valve-train noise of one certain 125 engine are studied with the way of experiment and analysis .With the requirement of experiment, bench for engine noise testing is designed and. With this bench,the every part of noise of valve train of engine in low revolve speed and in high revolve are tested,the acoustic power of each noise and their proportion in the whole noise of valve train are calculated after this. The result reveals that the main noise of is resulted from the impact due to the clearance of valve and the impact between the valve and valve seat. In the low revolve speed. the noise of valve clearance is dominated, while in high revolve speed, the noise of resulted from the impact between the valve and the valve seat is dominated. To study the noise mechanical of valve train furthermore, the accelerator of valve is tested also.The valve train kinetic and dynamic simulated model is founded based on the geometrical model. Multi body dynamics analysis is carried on. After contrasting, it is found that the valve acceleration of simulation is coincident with the valve acceleration from experimental result for its validity. It demonstrates the simulated model of valve train is accurate. By analysis of kinematics and dynamics of the valve train, it is found that the stiffness of the rockers and tappets are reasonable, the movement they transferred is accurate. It reveals that the influence factors to the impacting acceleration of valve and opening-hitting force of valve is the shape curve of cam. So the cam is optimized to reduce the acceleration of valve. After this, the dynamic analysis of simulation of valve train is carried on. The result reveals that the optimized cam dose good effect to reducing the impacting acceleration of valve. This will reduce the noise of valve train...