Method for identifying noise source of internal combustion engine

The invention relates to a method for identifying a noise source of an internal combustion engine, which comprises the steps of acquiring complete machine noise signals of the internal combustion engine under a standard working condition and a reverse towing working condition, and testing vibration signals and cylinder pressure signals of a cylinder cover, a piston knocking point main thrust side,an oil injection pump, a turbocharger, an air compressor, an oil pan, a gear cover cap and a cylinder cover cap under the standard working condition; performing DC removal, trend term removal and filtering preprocessing on the vibration signals and the noise signals to reduce signal acquisition errors; performing improved variational mode decomposition (IVMD) on the preprocessed noise signals, and adaptively obtaining signal components of different frequency bands; performing time-frequency analysis on the decomposed noise components by adopting wavelet transform, and determining the time-frequency and power spectrum