Maulevych V. Determination of the main diagnostic parameters of the working process of transport diesel engines in operation

The thesis is devoted to the actual problem of developing scientific methods for determining the main, most significant for diagnosing the technical state of the parameters of the working process of transport diesel engines in operation. The analysis showed that the existing methods need to be refined and improved. To determine the main parameters of the workflow, only analysis of indicator diagrams and vibration diagrams of high-pressure fuel equipment determined during operation is used. A method has been developed for calculating the phase of the onset of combustion in the cylinder of a transport diesel engine by refining the calculation of the maximum of the second derivative of the indicator diagram. An analysis obtained by numerically differentiating the first and second derivatives of the gas pressure diagrams in the working cylinder became possible after applying the Butterworth filter based on the discrete Fourier transform. A method has been developed for determining the delay of self-ignition of fuel in the working cylinder, using the phase of the onset of combustion in the cylinder and the phase of the leading edge of the nozzle vibrodiagram determined by the maximum of its first derivative. Heterogeneous diagrams were used – indicator and vibrodiagram. The needle lifting phase is determined by the maximum of the first derivative of the corresponding front of the vibrodiagram. The method gives a relative error in determining the ignition delay of not more than 3%. The method for calculating the speed of the crankshaft by determining the period of the working cycle between the midpoints of the intervals of the closing phase of the intake valves and the phase of the start of combustion is improved. The method allows with a relative error of less than 1% to determine the frequency of rotation on each engine cycle and to evaluate the cyclic unevenness of rotation of the crankshaft. The calculation of the average indicator pressure has been improved by determining the areas of elementary sections of the indicator diagram for calculating the average pressure on them. The indicator power calculation method is based on the use of modified calculations of the average indicator pressure and crankshaft speed. The total relative error in determining the indicator power does not exceed 2.5%, which makes it possible to further analyze the fuel consumption of a diesel engine as a means of transport, and increases the reliability and quality of diagnostic conclusions. The developed methods are implemented in the software for the monitoring of marine diesel engines DEPAS D4.0H, which is widely used in the practice of operating marine vessels of various types, in the «Ukrzaliznytsia» and in stationary diesel power plants. The solution of this scientific and practical problem improves the quality of operation and the efficiency of repair of transport diesel engines.