Identification of Diesel Engine Cycle Events using Measured Surface Vibration

In this paper cycle events of a single cylinder diesel engine are identified by the separation of engine surface vibration sources. The engine vibration due to the following forces: exhaust valve close, inlet valve close, fuel injection, combustion, piston slap, exhaust valve open and inlet valve open are simulated as if it is acquired with a single channel accelerometer. Vibration signal of diesel engine is acquired in time domain with a single channel accelerometer as blind sources. The simulated and measured vibration signals are separated by segmentation independent component analysis (ICA). The technique is based on time-frequency analysis (TFA) and filtering of segmented parts of the original signal. The independent components (ICs) of the simulated and measured signals are analyzed by fast Fourier transform (FFT) and short time Fourier transform (STFT). The time is replaced by crank angle in the time-frequency plane in order to investigate engine events. From crank angle-frequency analysis the engine exhaust valve close, inlet valve close, fuel injection, combustion, piston slap, exhaust valve open and inlet valve open within the engine cycle are identified from the measured signal as well as from the simulated one. As predicted, the results show that the engine events obtained from vibration signal are well correlated with the engine design specifications.