Abstract：By near-field sound pressure level methed, the near-field sound pressure levels of 14 parts were measured for the four-cylinder diesel engine including cylinder cover, fuel pump, oil pan, turbocharger, air filter and so on. The contribution of each part noise to overall noise was analyzed. The sound intensity scanning method was used to measure the sound intensities of fuel pump side, exhaust side, fan side and cylinder head side of the diesel engine, and the near field noise spectrum of main noise sources was collected. The results show that the contribution rate of fuel pump noise to overall noise is 37%, and the oil pan surface radiation noise energy accounts for 22% of whole noise energy at the declared working condition. The noise peaks of fuel pump appear at the frequencies of 630 Hz and 2 000 Hz, and the radiation noise peaks of oil pan appear at every frequency band. The noise of fuel pump and the radiation noise of oil pan are the main noise sources of diesel engine, and the radiation noises of cylinder head, accessory box and crankshaft are secondary noise sources. The results by two indentification ways are consistent.
2016, Vol. 37 
