Identification of combustion timing based on the vibration acceleration of diesel engines

A method for identification of combustion timing for diesel engines, based on the cylinder head's vibration acceleration, is presented in this paper. A finite element model of a 195 diesel engine is established to study the correlation between the cylinder head's vibration acceleration and the second derivative of the in-cylinder pressure. Simulation results show that the vibration acceleration and the second derivative of the in-cylinder pressure have similar trends before the peak pressure, and the combustion timing therefore can be identified by the zero-crossing point before the peak vibration acceleration. Experiments are also conducted on 195 and 495 diesel engines, and the combustion timing is predicted by the cylinder head's vibration acceleration. Results verify that the combustion timing can be determined by the cylinder head's vibration acceleration with an average error of less than 1.2 degrees crank angle.