Reduction of Engine Noise by Close-Fitting Enclosure

Abstract

Close-fitting acoustical enclosure is an effective technique for reducing sound radiation. But, the reduction level is sometimes far from expectation at design stage. This paper describes a new concept for the closefitting enclosure as well as some examination on characteristics of that of present engines. The concept is as follows; air is fully enclosed, vibration of mounting point is minimized by high rigidity of engine block design. Effectiveness of the concept is shown by both exciter test and running engine test.