Noise Sources Identification And Reduction Of Diesel Engine Based On Principal Component Analysis

Noise level is considered as a significant performance index. For a hydraulic crawler excavator powered by a diesel engine primarily, the diesel engine is the main noise source. Therefore, it is of great theoretical meaning and practical value to research the noise characteristic of it. In this paper, noise identification and applications about noise reduction for a4B2-38M34type diesel engine equipped in SWE50G3has been researched.First of all, noise of4B2-38M34diesel engine was tested and collected by an acoustic camera during each rotate speed. Noise region, noise level and their amplitude map in frequency-domain was obained. Principal component analysis was applied in the collected noise signals and the most responsible noise signal was separated.Next, three-dimensional solid models of main diesel engine parts were built under Pro/E environment, and their modal analysis was performed to obtain main noise radiation points and resonance frequencies of surface parts. By means of comparing the result of principal component analysis with that of modal analysis, principal noise source was found.Then, The diesel engine noise was tested with sound intensity technique. From its three-dimensional sound intensity map, we observed the noise region and the approach of noise sources identification was proved valid and proper.Finally, proposals to reduce diesel engine noise were applied, reinforcing ribs to the oil pan, cylinder body, fly wheel and cylinder head to strengthen their rigidity; changing combustor size to improve combustion and emission; Torsional vibration damper was also adopted to reduce impact force transmission to the surface. Experiment shows that noise level of the improved diesel engine reduced by2.1dB(A).