Motorcycle Intake Noise Control

The noise is an important performance to evaluate the quality of motor vehicles. As one kind of the motor vehicles, the noise of motorcycle plays an important role in the noise pollution. Because of the more stringent statutory pass-by noise requirements at home and abroad, the developed country furnished funds for researching the noise control of motorcycle. Our country paid great attention to the research gradually after 1980'.This paper expounds the special generating mechanism of the motorcycle noise and the technique of distinguishing the motorcycle noise sources simply. Basing on these theories, we measured one representative motorcycle engine and induction noise spectrum by means of the Beamforming and SONAH measurement. The induction noise was one of the main noise sources, and it did an important contribution to the pass-by noise. Engine induction noise is mostly in the low frequency region. The conclusion can be got that the improvement of acoustic performance of air-in filter below 1000Hz is very important to reduce the induction noise. This paper designed the air-in filter with only one expand chamber according to enter creation mechanism of annoy the voice and extend type filter of a machine a principle into the spirit. The CAD model and the boundary element model were founded. The transmission loss was calculated based on the boundary element method.According the result of numerical simulation the CAD model was founded, then the physical model. The new air-in filter showed good acoustic performance in the pass-by noise tests, the pass-by noise descends 1.1dB, and do not to the power and the induction efficiency of the engine. Finally, it has inherent characteristics in reducing low frequency, small pressure loss and simple geometry, the methods and principles used in the course of filter design are correct and workable.