Study On Design And Performance Of Many Kinds Of Muffler Structures

With the continuous and vigorous development of the global automobile industry,the automobile,as an important means of transportation,brings convenience and efficiency to people's production and life.At the same time,the problem of automobile noise pollution caused by it is also troubling people all over the world.In particular,the noise problem in the automobile intake and exhaust system has increasingly become the focus of the majority of experts and scholars.In order to effectively eliminate and reduce automobile noise,improve automobile acoustic quality,improve ride comfort,and reduce automobile noise pollution,this paper has designed a variety of noise elimination structures based on the acoustic-electric analogy method,Helmholtz resonator theory and expansion tube theory,and conducted an in-depth study on their noise elimination performance.First of all,based on the acoustoelectric analogy method,according to the electrical filter circuit diagram of the electrical components and acoustic acoustic component in a circuit diagram one-to-one correspondence matching principle,this paper has designed the third order,five order butterworth band-stop filter with performance highly close to the third order,five order acoustic filter structure.And the simulation analysis to the transmission loss characteristics has been carried on them through Comsol software.The structure optimization aiming at the defect of these two kinds of silencing structure on the performance has been conducted with good results having been achieved.And the correctness of the simulation method of this paper has been verified by applying the model in reference.The results reveal that the transmission loss characteristics of the designed third-order and fifth-order acoustic filter structure are highly consistent with the attenuation characteristics of the corresponding electrical filter,and the errors are small.Then,on a single Helmholtz resonator characteristics and its diameter axial periodic research,on the basis of the theory that combining with Helmholtz axial parallel resonators with different resonant frequencies of can widen the dead band,composite silencing structure has been designed which was based on Helmholtz resonators,and its axial periodic has been carried on the detailed research.The results indicate that the transmission loss characteristic curve of the composite silencer structure is in the shape of Chinese character “?”,which is fairely close to the ideal band-stop filter.With the increase of the number of axial period,the muffler ability of the composite muffler structure is improved greatly.Finally,based on the common extension tube,the formula of transmission loss has been deduced and the common extension pipe transmission loss characteristics has been analyzed in this paper.In allusion to the defect of the muffler performance,A and B type silencing structure has been designed by adding Helmholtz resonators and fixed elongation of the pipe,respectively from the angle of changing the shape of the transmission loss curve trough and the angle of removing the troughs.Especially,the sound transmission loss characteristics of the structure of B type presents the shape of arch,and is highly close rational band-stop filter features.Two types of noise elimination structures have improved the original average transmission loss characteristics of the expansion pipe.Furthermore,the effects of periodic and ultra-fine glass wool absorbing materials on the acoustic properties of A and B type muffler structures were further studied.The study suggests that periodicity can greatly improve the muffler performance of A and B type muffler structures,and the addition of sound absorbing materials can not only optimize the shape of the characteristic curve of transfer loss,but also further improve the muffler performance.