Research On Sound Quality Of Gasoline Engine And Components

Along with the developing economy and better living standard,automobile is changing its social status quietly in China.In 2014,Chinese automobile market has had the largest sales volume and yield around the word with more than 23 million for six years,so there is no doubt that China is the first automotive market.The larger sales volume,the bigger inventory.Consequently,the requirements to NVH charaters are not limited to the sound insulation and comfort.People become picky about the external and internal sounds,they want the sounds bring better feelings.So the research on sound quality is more and more significant.In this paper,the youngsters especially the generator after 80 s and 90 s was selected as the juries in the subjective evaluation uniquely.This is basing on the problems in the sound quality research and the real situation of Chinese automotive market.In consideration of this crowd mainly focus on the entry-level automobiles whose price range from 100 thousand to 200 thousand,so the noise samples were all from the gasoline engines in the entry-level vehicles.The bench test was executed to acquire the 12 samples,then we got the subjective mertis and psychoacoustics parameters from the subjective evaluation and psychoacoustics analysis.In order to establish the prediction model of multiple linear regression,correlation analysis between subjective merits and psychoacoustics parameters was excuted to prepare for the multiple linear regression model.Then the prediction was established with Loudness,Sharpness and Roughness according to SPSS.Then a trilaminar BPNN model was estabilshed whose input data and training data were the psychoacoustics parameters and target data were subjective mertis.Then a comparison test was carried out between the two prediction models.The two models both can predict the subjective merits well especially the multiple linear regression model who has fewer inputs to avoid more errors and interference.To research on the influence from components to the sound quality,analysis on the influence to the engine NVH from timing driving system from 1.3T and turbocharger heat shield from 1.5T was executed.At last,the consequence is that the components can influence the sound quality through the amplitude-frequency characters and transfer functions.This can provide some thinkings and reference to the positive development of sound quality.