Research On Improvement Of Sound Quality In Vehicle Adjusted By Intake Noise

Over the past few decades,with the continuous development of NVH(Noise,Vibration,Harshness)technology,the inteor noise of vehicle has been well controlled.However,as consumers put forward higher demands on the comfort of vehicles,the sound quality of vehicles has become a hot research.Integrating the key project of Automotive Technology Research Center ‘Acoustical Quality Control Technology in Vehicle’,the thesis made a SUV as a sample vehicle to improve the sound quality of the vehicle adjuested by intake noise.Firstly,based on the detailed analysis of the transfer path principle and the experimental test method,the time-domain transfer path analysis(TPA)was used to analyze the vibration and noise of the vehicle.Acoustic source acquisition test,acoustic transfer test and hammer test were finished in Vehicle semi anechoic room.Based on the test date,the transfer path analysis model was built in PROGNO[I]SE software,and the noise in the vehicle was simulated and decomposed,to find the main contribution of the air intake system.Secondly,the dissertation studied the mechanism of the engine intake noise in detail,based on the result of the transfer path decomposition,the frequency adjustment of the engine intake noise was used to adjust the interior sound quality.In the stage of frequency adjustment,the paper made the research of coupled muffler,studied the effect of eliminating the broadband noise,and designed a good coupled muffler with high function of eliminating noise.At the same time,order adjustment was also used to control the engine intake noise,the paper studied the effect of manifold length to the order consist of the engine intake noise.A theoretical method for adjusting the length of the intake manifold by using the engine ignition sequence is proposed and used as an optimization for the intake manifold of the experimental vehicle engine.After optimization,the ignition order of intake noise were strengthened,and the half-order and other full-order subsonic pressures were suppressed,which changed the order consist of the intake noise and improved the acoustic quality of engine intake noise.Finally,a well-designed coupled muffler and optimized engine intake manifold were added to the engine intake system model to capture virtual intake noise and replaced the intake noise collected by the test.It was fitted with other vibrations and noises collected in TPA to synthesis the interior noise in PROGNO[I]SE software.The interior noise was evaluated by objective sound quality parameters.The analysis results showed that based on the transfer path decomposition,the frequency and order adjustment of engine intake noise can improve the sound quality of the vehicle and enhance the hearing comfort of the vehicle.