Effect of Basic Design Parameters of Automotive Engines on Their Sound Characteristics

During acceleration, engine combustion is the major sound source in passenger vehicles.[1] This sound characterizes the overall impression made by the vehicle. Automobile manufactures have been developing engines to have better sound characteristics since the late 1980s.[2] However, fundamental and systematic knowledge of the relationship between the basic structural dynamics of the engine and its sound characteristics has not yet been reported. In addition, in the design stage, engine designers were not previously able to listen to the sound generated by the engines. This paper introduces a tool that synthesizes engine combustion sound by specifying the combustion process and a basic engine structural dynamics model having a small number of parameters. Using this tool, the authors obtained important relationships between combustion process and subjective sound characteristics evaluation scores.