燃烧过程对轻型车用柴油机怠速噪声的影响  

Influence of In-cylinder Combustion on Idling Noise of Light-duty Vehicle Diesel Engine

作　　者：罗福强[1] 丁鑫华 吴少喆 金天宇 王楚翘 伍子旭 LUO Fuqiang;DING Xinhua;WU Shaozhe;JIN Tianyu;WANG Chuqiao;WU Zixu(School of Automotive and Traffic Engineering,Jiangsu University,Zhenjiang 212031,China;School of Energy and Power Engineering,Jiangsu University,Zhenjiang 212031,China)

机构地区：[1]江苏大学汽车与交通工程学院,江苏镇江212031 [2]江苏大学能源与动力工程学院,江苏镇江212031

出　　处：《车用发动机》2023年第3期59-66,72,共9页Vehicle Engine

摘　　要：发动机噪声是车辆怠速噪声的主要来源。为研究某轻型卡车怠速开空调时车内噪声增大的问题,进行了发动机台架试验,试验对象为一台4缸、四冲程、涡轮增压中冷、电控高压共轨柴油机。试验测量了柴油机的气缸压力、声功率及近场噪声,通过比较声功率级,分析了柴油机在不同工况下的噪声变化。基于气缸压力计算了放热率、压力升高率等燃烧特性参数,基于近场噪声信号计算了近场噪声频谱,进一步研究了燃烧特性参数变化对不同频率近场噪声的影响。结果表明:冷却液温度小幅度降低时喷射策略确定的喷油正时提前,导致气缸最高燃烧压力及预喷燃油燃烧引起的压力升高率峰值显著增大,怠速噪声增大;750 r/min时喷射策略确定的喷油正时较早,压力升高率较大,最高燃烧压力在更靠近上止点的位置出现且持续时间较长,燃烧过程较780 r/min与820 r/min时更为剧烈,这是该转速下噪声较高的主要原因。开空调时循环供油量增加,燃烧过程更加剧烈,产生更高的压力升高率及最高燃烧压力,也会导致怠速噪声增大。此外,频率在1000 Hz左右噪声的变化对该柴油机整体噪声水平的影响最大。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,four-stroke,turbocharging and intercooling,electronically controlled common-rail 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 1000 Hz made the greatest influence on the idling noise of diesel engine.

关 键 词：柴油机 怠速 噪声 燃烧过程 频谱分析 

分 类 号：TK421.2[动力工程及工程热物理—动力机械及工程] TK421.6