Noise Reduction Research And Development Of The Exhaust Muffler For Motorcycle

As the traffic noise pollution has been severer than before, people have paid much attention to the noise of motorcyle, The legislations for limiting noise of motorcyle is becoming more and more strict, 80dB(A) is the limitation of noise for motorcyle which displacement is 80-175mL at 2002, but it had become 77dB(A) because of GB16169-2005 at 2005. As a result, a lot of new motorcyles were unqualified in product quality test and can't be listed for sale because the noise isn't reach the standard. Noise has become a problem restricting sustainable development of China's motorcycle production enterprises.So how to reduce the noise of motoreycle has been more and more important.The exhausting noise of engine is one main source of vehicle noise, while designing and manufactering excellent Muffler is a great effect way to reduce noise in the actual project. Most of domestic general muffler design is"imitating design"or just according to designers' experience. Not only the method of which is out of date, but also the cost is high, and the design cycle is long.With the development of computer technology, muffler design will become digitization, visualization, and it will significantly shorten the design cycle and reduce the cost of inputs. Designing muffler will become convenient and credible through three-dimensional entity modeling, FEM analysis and BEM calculations.As far as domestic and overseas muffler research goes, by the combined way of using three kinds of software such as the"PROE","ANSYS"and"SYSNOISE", this paper analyzes the muffler numerically, and discusses key techniques such as the building of finite element model, the FE mesh demarcation, and the post-processing data analysis, etc. Furthermore, it analyzes the characteristics and application scope of muffler fundamental silencing structure. Then, given the condition as the project of decreasing some kind of motorcycle engine's noise, this paper put forward introducing numerical simulation technology into the muffler design process based on practical working situation, and the muffler has been successfully developed. The result of the experiment show that the muffler acoustic attenuation performance is accord with practical expectation and silimar to expectation through numerical simulation. The content in detail is as follows:At first, the spectrum of motorcycle engine's exhaust is determined through experiment. And the spectrum of amount of noise elimination is make sure based on the spectrum of motorcycle engine's exhaust and NR curve.Secondly, referring to the same type muffler structural form and experimental data,the muffler structural form and model size are initially determined based on the frequency response of motorcycle engine's exhaust and assembly requirements.Then, the muffler structural form and model size are numerical simulation analysed, improved, and predicted the muffler acoustic attenuation performance.At last, a muffler is made, and the acoustic attenuation performance is determined through experiment. The difference is very small when compared with the acoustic attenuation performance determined through numerical simulation. And they are all need the amount of noise elimination. It show that the muffler design process is effective.This design process can shorten the test-period of muffler and reduce its cost. And it is also convenient, fast and illustrated. It will be guiding significant and practical value to be applied in design and development of muffler.