Search Results

Using a 1D simulation that transforms the 3D shape of intake-exhaust systems into one dimension and calculates the thermodynamics and fluid gas dynamics of internal combustion engines, a prediction technology of the output power and intake-exhaust noise for small- displacement single-cylinder motorcycles was established. Output power can be calculated accurately for various engines with different displacements and cooling systems by adjusting the boundary conditions in the calculation model. The intake-exhaust noise can be calculated accurately by clarifying some important points for accuracy when transforming the 3D shapes of the intake-exhaust system into the 1D model and by reflecting them in the calculation model. As for mufflers that have complicated internal structures, the calculation of exhaust-noise cannot be made with sufficient accuracy because 1D simulation does not calculate spatial flow behavior. But, improvement of accuracy is expected using a 1D-3D coupled simulation.

In order to accurately estimate the intake sound pressure level, it is important to improve the accuracy of the air cleaner simulation model and precisely estimate the sound source of the intake. It has been confirmed that the modeling accuracy of an air cleaner can be improved by considering the vibro-acoustic coupling. Meanwhile, the sound source of the intake depends not only on the engine specifications, but on the intake system and even the exhaust system design. In this reported example, since it is difficult to estimate the sound source of the intake only by calculation, due to the aforementioned reasons, actual measurements were carried out to define the sound source. The method is such that the sound source is modeled by acoustic impedance and volume velocity in the engine, and the acoustic impedance is measured using an impedance tube. Then, the sound pressure at the intake opening is measured.

While on the one hand the development period to meet the market needs to be as short as possible and cost reduction of products is extremely important for manufacturers, the demands for environmental considerations and riders' comfort have recently been rapidly increasing in the area of motorcycle performance as well. Considering these arguments, this paper discusses how to establish technology to predict riders' vibration comfort of a motorcycle, starting from a computer aided design (CAD). So far, only a few papers on the prediction of motorcycle vibration have already been made public, but with regard to modeling the connection between component models even less literature is available and, as a result, empirical figures are widely used. Therefor this paper focuses on the modeling aspects of these connectors to make accurate virtual models that allow the assessment of motorcycle vibrations in operational conditions.