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The paper presents a new method for assessment of combustion process correctness taking place in CI engines, based on the expanded vibroacoustic signal analysis. The method uses chosen non-linear, spectrum and time-frequency analyses of the signal. Diagnostics of the correctness of the above main engine process and misfire detection for engines at exploitation conditions with the use of the various methods of the accompanying processes analysis was the aim of the presented analyses. Possibility of the method application to combustion process assessment of the CI engines was verified, algorithms of misfire detection for the each method are described, quantity point estimators of processes and conditions of the OBD diagnostics realization were obtained, methodology of the measurement process, limits of the methods use and their diagnostic accuracy in the point of view of the combustion OBD III engine monitor design are also presented.

The paper describes the problem of the combustion process diagnostics dedicated for CI engines with direct injection of HDV vehicles in the aspect of misfire detection monitor application for OBD and EOBD systems. The monitor is based on the vibroacoustic signal utilization. Because of that, frequency method and the method of time-frequency parameterization map a(t,f) of vibration accelerations generated by combustion engine were used. The above article is directed to get a diagnostic monitor that would detect faults and incorrect runs in the combustion process (including also its lack) in the real time with the help of vibration accelerations estimators. Point estimators of the process and research stages and conditions are presented. The signal analyses and limits of a method use, criteria of the process qualification and its accuracy were also write down.

The paper presents a new method of misfire identification for a Diesel engine, based on results of parameterizations of a time-frequency a(t, f) map of an engine vibration signal. The Joint Time-Frequency Analysis (JTFA) methods have been proposed as a tool for a time-frequency selection of a vibration signal. An algorithm of the method has been outlined and an example application of a synchronous averaged Short Time Fourier Transform (STFT) for extracting vibration signal components related to combustion process has been shown. Parameterization of a(t, f) map gives measures covariable with misfire in a cylinder of an internal combustion engine. The method and analyses of the chosen characteristics and parameters were used in on-line diagnostics of the combustion process lack, what gave the necessary bases for application of the new method in OBD system.

The paper concerns the assessment possibilities of use of chosen vibration signal parameters to detect misfires in diesel locomotives engines (non-road vehicles). Methodological assumptions, stages of measurements and vibration signal analyses for a compression-ignition engine of a locomotive have been presented in the paper. Measurement results and concepts of further research regarding the use of vibration methods in on-board diagnostic systems have been presented as well.