Research On Vibration Analysis And Prediction Of Radiating Noise Of Gasoline Engine

As the main power system of the vehicle,the attention degree of vibration and noise related problems is gradually improved.In the engine design and development stage,it can analyze the vibration characteristics and radiation noise of the structure and optimize the design,which is of great significance to enhance the engine product force.In this paper,a three-cylinder gasoline engine as the research object,at home and abroad on the engine vibration and noise on the basis of research based on multi-body dynamics theory and analysis of the engine load and load under the action of vibration characteristics,the use of acoustic boundary element The method is used to predict the radiation noise,and it is compared with the experiment,which provides the basis for the structural optimization design.The finite element model of each component of the engine is established,and the finite element model is combined into the whole machine model by means of contact surface binding or node sharing according to the different contact surface.The finite element model of the whole machine can better reflect the engine Actual assembly state.The main parts and the whole machine for a modal analysis,master the machine and the main parts in the excited after the energy distribution.The finite element modal parameters are compared with the modal test data,which verifies that the model is accurate,reasonable and accurate.Based on the GUYAN reduction method,the main DOF reduction of the finite element model is carried out,and the multi-body dynamics model of the whole machine and the substructure is established.The main excitation load of the engine at different rotational speeds is obtained,and under the action of the excitation load The vibration speed of the engine surface,the analysis of the engine vibration characteristics.The dynamic response of the whole structure provides the boundary condition for the structural radiation noise calculation.The vibration velocity of the surface of the whole structure is mapped to the acoustic model based on the Maximum Distance interpolation method.The acoustic noise of the engine structure is predicted by the acoustic boundary method.The surface acoustic pressure distribution at different rotational speeds is analyzed.It is concluded that the thin-walled parts such as the engine oil pan,the timing cover and the cylinder head cover are the main noise sources,and the engine noise is greatly increased in each peak frequency band.Compared with the experimental data,the acoustic boundary element model is reasonable and the calculation result is reliable,which provides a reference for the engine acoustic optimization design.