Of Cg125 Motorcycle Noise Source Identification And Exhaust Noise Control

The noise level is an important index in the process of evaluating the quality of motor vehicles. As a kind of the motor vehicles, the noise of motorcycle plays an important role in the noise pollution. With more stringent statutory establishments to the pass-by noise in home and abroad, the noise control of motorcycle has became more urgent, but, in China, it's still at a primary stage.In this paper, the generating principle of noise and the identification of noise source of motorcycle are introduced, respectively. Based on these principles, the test of the noise source identification of a typical 125cc motorcycle is carried out using Beamforming and SONAH technologies, simultaneously, the frequency spectrum of the exhaust noise is analyzed. According to the above test results, the exhaust noise of the engine is considered as the main noise source of the motorcycle. Based on the test and the muffling principle, the optimizing program to the exhaust noise is determined. Firstly, the CAD modeling and the acoustic numerical modeling of the muffler of the motorcycle are established; secondly, the transmission loss of the muffler is calculated by SYSNOISE. In terms of the test and simulation results, the muffler acoustic units of the labyrinthic chamber and perforated pipe are employed to improve the muffling performance of the muffler.The new exhaust muffler shows good acoustic performance in the pass-by noise test, and does not reduce the engine power, which validate the rationality of the optimization methods to the muffler and make the exhaust noise of the motorcycle satisfy the latest national standards,...