摘要: The misfiring fault of internal combustion engine was detected by using the vibration signals of cylinder-head. Based on the data acquisition system built with LabVIEW, the cylinder-head vibration signals were detected with an accelerometer while the engine was rapidly accelerating from idle speed to high speed, at which time the engine was running under four working conditions of normal and single cylinder misfiring, double cylinders continuously misfiring and double cylinders alternately misfiring. After decomposing the vibration signals with db3 wavelet, whether the engine was misfiring or not, and what type of misfiring, were judged by comparing the decomposing results. The resultd showrf that, the low-frequency vibration of the engine cylinder head was related to the rotation of the principal shaft, and the high-frequency vibration was related to the combustion in the cylinder. There were certain corresponding relationships between wave crests of high-frequency vibration and wave crests of low-frequency under the four conditions of normal and faults when engine runs in idle segment, accelerating segment, and high-speed segment. Thus, the misfiring fault and type can be detected by analyzing the corresponding relations. Detection of the misfiring fault by using wavelet analysis was effective and feasible.