Analysis of ICE Instantaneous Speed Signal Based on EMD and HHT

The basic method and principles of empirical mode decomposition(EMD) and Hilbert-Huang transform(HHT) were introduced.For a 4-cylinder gasoline engine,the instantaneous speed signal was decomposed under the 2 500 r/min and 83.6 N·m condition with empirical mode decomposition method.The intrinsic mode function(IMF) was transformed with Hilbert-Huang transform and fast Fourier transform,the instantaneous frequency and instantaneous amplitude relations with time were acquired and finally the IMFs were analyzed combining with internal combustion engine theory.The research result shows that EMD algorithm can identify different frequency information,which has its own physical significance,from the engine instantaneous speed signal.