Reconstruction of Indicated Pressure Waveform in a Spark-Ignition Engine From Block Vibration Measurements

Abstract

Knowledge of the pressure waveform in each cylinder of a spark-ignition engine may provide useful diagnostic information concerning engine operation. This paper presents a method for the reconstruction of the indicated pressure waveform for each cylinder of a multicylinder internal combustion engine using engine block vibration signals. The method permits the reconstruction of the cylinder pressure waveform, cycle by cycle, during free accelerations. The procedure has good potential for application in end-of-assembly diagnostic tests, using a noncontacting laser velocimeter. The same signal processing method may be applicable on-board an automobile to perform an on-line cylinder-by-cylinder diagnostics, using the same vibration sensor used for knock detection in many production vehicles.