Study on Predicative Evaluation Method of Noise Generated by Engine

The engine noise accounts for a relatively large percentage among the noises generated by a motorcycle. Among the parts of the engine, the cover is important in design as well as a source of the engine noise, being at the end of the vibration transfer path.

This paper clarifies that the natural frequency of the cover with a flat surface clearly affects its vibration and noise radiation and that its vibration depends on this surface, by investigation of the effect of surface shape of the cover on its vibration and noise radiation and by a modal analysis of its vibration characteristics. In addition, we confirmed that the calculated value of the radiated noise from the cover agrees well with the measured value.