The Application Research On Valve Train Noise And Vibration Of Automobile Engine

Valve train noise is one of the major structure radiated noise of engine. Thispaper studies the generation mechanism and the main influencing factors of valvetrain noise. Both the finite element method and the multi-body dynamics method areadopted to study the surface vibration characteristics of engine in the excitation ofvalve train. And radiated noise from the surface of engine in the excitation of valvetrain is researched by the boundary element method.This paper focused on the studying of the surface vibration characteristics ofengine in the excitation of valve train and the prediction of structure radiated noise tocarry on the research at following several respects:1. This paper studied the generation mechanism and the main route of valve trainnoise. The analysis revealed that the noise excitation forces of the valve train whichthis paper studied include the force of the valve seated, the contact stress betweencam and follower and the force of camshaft bearing, etc. The radiated noise wasmainly spreading through the surface of the cylinder head cover.2. The evaluation of the measured cam profile and the kinematics simulation ofvalve train were done. The numerical results showed that the cam profile met thedesign requirements, the working of valve train was stable and there was no irregularmovement.3. This paper established the dynamic model of the whole valve train and did thedynamic simulation of valve train. The main driving forces of valve train acquiredfrom the dynamic simulation were processed for the load condition of the surfacevibrations analysis of the cylinder head cover.4. On the basis of the finite element model, the multi-body analysis model wasestablished. The forms of the connection between components and the constraintswere a reference to the methods of vibration and noise test bench. The valve trainexciting force and cylinder pressure of the gas were imposed as the boundary load.The surface vibration of the cylinder head cover in the excitation of valve train at therated speed of engine (5000rpm) was acquired from the calculation. Compared withthe vibration test results to verify the reliability of the calculated results, and analyzedthe causes of error. The results showed that the vibration displacement in the cylinderhead cover at1000Hz which close to the cylinder head cover non-rigid body modal second-order natural frequency was biggest and caused the resonance. The frequencywas the focus of the valve train noise control. Through the structure optimization ofcylinder head cover to improve the natural frequency was an effective way to reducethe radiated noise of cylinder head cover.5. Used the boundary element method to predict the radiated noise of cylinderhead cover in the exciting force of valve train and identify the main noise radiationarea of cylinder head cover. And the structural improvements were made to reduce theradiation noise.