Technological Development for Active Control of Air Induction Noise 951301
In recent years, designers have attributed increasing importance to reducing noise in car interiors, and various improvements have led to a steady decrease each year in said interior noise. More recently, there has been abundant research on quantitative and qualitative approaches to interior noise, including studies on improving sound quality, such as elimination of rumbling noise and creating a feeling of linearity.
Particularly engine noise, one of the major causes of interior noise, has been studied from various angles and significantly reduced in recent years. This has led in turn to increased interest in air induction noise which was a relatively minor noise source in the past. One method of reducing induction noise is the addition of several resonators to the induction system.
Induction system components, including resonators, have a major effect on engine output and fuel consumption. Varied research was thus conducted on optimization of the induction system to reduce both of these influences as well as air induction noise. Thus, development of an induction system at an early stage of engine development was considered important. The results of those studies have already been presented in SAE paper 911042.
Nevertheless, further improvements in induction systems are required due to stricter fuel economizing regulations. This also applies to regulations in both Europe and Japan involving induction system noise and noise during acceleration. Further mention can be made here of demands for improvements in the sound characteristics of vehicle interiors.
Focusing on the active noise control method, which functions by using sound to eliminate undesired sound, the authors examined introduction of such a method into the induction system. The results of research appear below.