Engine noise is the main source of vehicle idling noise. Engine bench test was conducted to investigate the high noise problem of a light-duty vehicle when the air conditioner was turned on at idle. Test engine was a four-cylinder, fourstroke, turbocharging and intercooling, electronically controlled commonrail diesel engine. The cylinder pressure, sound power level and near-field noise of diesel engine were measured. The noise variations of diesel engine under different conditions were analyzed by comparing the sound power level. The heat release rate and cylinder pressure rise rate were calculated based on the cylinder pressure. The near-field noise spectrum were calculated based on the near-field noise signals. The influences of in-cylinder combustion parameters on the near-field noises of different frequencies were studied. The results show that the injection timing determined by the injection strategy advances when the coolant temperature decreases slightly. The peak pressure rise rate caused by the peak cylinder pressure and the combustion of pilot fuel increases significantly so as to increase noticeably the idling noise. Besides, the injection timing determined by the injection strategy is earlier at 750 r/min, and a higher pressure rise rate hence produces. The peak cylinder pressure occurs closer to top dead center and lasts longer at 750 r/min, the combustion process is more intense than that at 780 r/min and 820 r/min, which is the main reason of higher noise. When the air conditioner turns on, the cycle fuel injection quantity increases, the combustion process becomes more intense, a higher pressure rise rate and peak cylinder pressure produces, and a significant increase of idling noise comes true in the end. In addition, the noise around 1 000 Hz made the greatest influence on the idling noise of diesel engine.
LUO Fuqiang
,
DING Xinhua
,
WU Shaozhe
,
JIN Tianyu
,
WANG Chuqiao
,
WU Zixu
. Influence of In-cylinder Combustion on Idling Noise of Light-duty Vehicle Diesel Engine[J]. Vehicle Engine, 2023
, 0(3)
: 59
-66
.
DOI: 10.3969/j.issn.1001-2222.2023.03.010
