摘要
本文中针对搭载1. 5L自然吸气汽油机的某SUV在加速过程中急收油门出现异响的问题进行了排查与诊断.首先利用动力总成台架试验重现了异响,排除了车身作为噪声源的怀疑;随后在整车转鼓台架上进行了发动机声强和其他NVH测试,通过对机舱内异响信号进行滤波和音频回放,确认异响所处频段为6 - 8 kHz,并通过发动机各个端面的声强试验确认异响为扩散声源,符合燃烧噪声特性;然后对缸压和振动与噪声信号进行自适应广义 S变换,结果表明,缸压同时存在6 - 8 kHz异常激励,且在时域上与异响完全吻合;为进一步确认噪声源,对收油时刻的ECU点火提前角map图进行调整,使点火时刻变化幅度减小,缸压平稳下降,主观判断的异响已经消失,同时时频图中6 - 8 kHz缸压激励明显减弱;最后通过对缸压曲轴转角曲线进行放大发现,6 - 8 kHz缸压激励出现的时刻与上止点后带快速波动的第2 个峰对应,可能由轻微爆震引起.
Troubleshooting and diagnosis are proceeded on the abnormal sound appearing at tip-out mo m e n tin the acceleration process of a S U V with a 1. 5 L naturally aspirated gasoline engine in this paper. Firstly, theabnormal sound is reconstructed by the bench test of powertrain to exclude the suspicion on car body as noisesource. Then the sound intensity of engine and the N V H of other parts are measured on dynamometer,the abnormalsound signals in engine compartment are ascertained by filtering and audio playback to be at a frequency band of 6 8k H z ,and are confirmed to be diffuse sound source and accord with the features of combustion noise by the soundintensity test on all end planes of engine. Furthermore, the adaptive generalized S transform is performed oncylinder pressure and vibration and noise signals. The results show that there are abnormal excitation of 6- 8 k H z incylinder pressure as well,which agree well with abnormal sound in time domain. For further confirming the sourceof noise,the E C U ignition advanced angle m a p is adjusted at tip-out m o m e n t . A s a result,the variation amplitudeof ignition timing reduces, cylinder pressure steadily falls, the abnormal sound by subjective judgment disappearsand the cylinder pressure excitation of 6 - 8 k H z in time-frequency chart obviously weakens. Finally it is found bymagnifying cylinder pressure-crank angle curve that the m o m e n t the cylinder pressure excitation of 6 - 8 k H z appearscorresponds to the rippled second peak after T D C ,caused by trace knock possibly.
出处
《汽车工程》
EI
CSCD
北大核心
2016年第10期1252-1257,1263,共7页
Automotive Engineering
关键词
整车异响
燃烧噪声
时频分析
缸压
vehicle abnormal sound
combustion noise
time-frequency analysis
cylinder pressure
