Technique for Front-loading Countermeasures against Deterioration of Sound Quality in Vehicle Interior due to Rapid Combustion in an SI Engine

This paper discusses a technique for the examination of countermeasures at the design stage of the prototype vehicle in order to realize efficient enhancement of the engine combustion noise quality in the vehicle interior. An existing sound quality evaluation method was applied as a simulation technology. The deterioration of the sound quality of combustion noise in the passenger compartment of a new vehicle was estimated from the in-cylinder pressures of a newly developed engine measured on a dynamometer test bench and the structural response functions obtained from the previous mass production vehicle. In addition, the level of reduction in structural response sensitivity necessary for the enhancement of combustion noise quality was estimated for each frequency band. Based on the results, effective countermeasures for the enhancement of combustion noise quality were selected and reflected in the drawings for the initial prototype vehicle. This made it possible to realize the target combustion noise quality in the initial prototype vehicle, which in turn eliminated the necessity for the additional combustion noise countermeasures that have often been applied at the later stages of conventional vehicle development.