中文摘要：

为了探究瞬时转速法的诊断机理,以5S50ME型二冲程柴油机为研究对象,测得柴油机在正常状态和故障状态时不同工况下的瞬时转速信号,得到不同工况下瞬时转速的变化规律,在此基础上,通过分析各工况下的瞬时转速波形图和频谱图,提出谐波幅值比和波动率峰值两种能有效反应柴油机故障状态的特征参数。以5缸机为研究对象,若1次谐波分量和5次谐波分量的谐波幅值比大于某一阈值,则说明柴油机存在单缸故障,并且故障缸为波动率峰值最小的缸。

英文摘要：

Taking a 5S50ME dual-stroke diesel engine with 5 cylinders as the object, the diagnosis mechanism of theinstantaneous speed method is studied. The instantaneous speed signals in normal operation state and fault operation state ofthe engine are measured. The variation law of the instantaneous speed in different operation conditions is obtained. On thisbasis, by analyzing the instantaneous speed waveform diagram and spectrum diagram, two characteristic parameters,volatility peak and harmonic amplitude ratio, are proposed which can effectively reflect the fault status of the engine. If theharmonic amplitude ratio of the 1st-order harmonic component to the 5th-order harmonic component is greater than a certainthreshold, there is a single-cylinder fault in the diesel engine, and the cylinder which has the minimum volatility peak is thefaulty cylinder.