The Control Of Intake And Exhaust System Noise Of A0 Gasoline Engine

With the increasing of automobiles in city, noise pollution has greatly disturbed people's life. Currently more and more tightening environment noise legislations have been imposed on the vehicles in many countries. Vehicle is a integrative noise source comprising noises with various characteristics. According to the study of MIRA, the engine noise is the dominant part of the whole vehicle noises. And the air dynamic noises consisting of intake and exhaust noise is one of the main noise sources of engine. Therefore, optimizing the intake and exhaust system to reduce the intake and exhaust noises has a great effect in reducing the whole vehicle noises.In this thesis, the intake and exhaust noise was studied with emphasis for a gasoline engine of a certain A0 car. Since intake and exhaust system and engine system are connected together, and the parameters of the three systems are interactive, thus, considering them together can optimize the individual subsystem. At first, therefore, a coupled complete engine model consisting of intake and exhaust system and engine system was established using the software of GT-POWER to conduct performance simulation and model calibration for meeting the requirement of model accuracy. The model can be used for the sequent calculation simulation. As a result, it improved the conventional method of designing the intake and exhaust system respectively. Second, based on Helmholtz resonance theory, a resonant cavity was designed. The result of simulation shows that, the optimized intake system can remarkably improve the intake noise of engine, which also has a special reference to the development of intake system. Then, the acoustic characteristics of exhaust muffler were analyzed by finite element method of three dimensions, and the improvements of exhaust muffler were proposed for the motivation of reducing exhaust noise. Finally, the sequent experiment plans for testing intake and exhaust noise were proposed using the discriminating methods of noise source.