Automotive Diesel Engine Performance and Condition Monitoring using Downpipe Acoustic Waveform Analysis

It would seem logical that acoustic signals measured from within a diesel engine’s exhaust pipe would contain useful information for engine monitoring. Preliminary experimental results, however, are found to be influenced significantly by changes in sensor positions and silencer configurations due to acoustic reflections inside the exhaust pipe. In order to suppress the contamination of reflection, this paper develops an effective acoustic method using two sensors mounted along the exhaust pipe. In addition to simulation modelling and theoretical study, experimental investigations are conducted to verify the reliability of this method. The experimental results show that using peak and shape indices of the incident waveforms, derived from measurements of the two sensors, accurate and reliable detection and diagnosis results are obtained for a range of realistic incipient faults under different operating conditions.