Recently, the quietness of the passenger compartment has become an important quality for a vehicle, and as a result, various improvements have been made to reduce the passenger compartment noise level. Particularly engine noise, a major source of interior noise, has been studied for many years and has recently been reduced to an acceptable level. As a result, air intake noise, which was a relatively minor noise source in the past, has rapidly become a noticeable noise source.
This paper describes a newly developed air intake system testing apparatus, which enables us to evaluate intake noise at an early stage of engine development and also describes how the new apparatus and approach was used to develop a low-noise air intake system.
This apparatus, called the PULSATION SIMULATOR, reproduces intake pulsations in the actual engine using its cylinder head and reproduces intake air flow precisely. Generally, in the past, intake system development was conducted by giving priority to engine volumetric efficiency. By the use of the apparatus, however, study for intake noise reduction can be started at an early stage of engine development and in parallel with the study of volumetric efficiency. Thus, the apparatus enables us to establish intake system designs which satisfy both the volumetric efficiency and intake noise requirements at an earlier stage than ever before.