Abstract. The article is devoted to the questions of technical operation of the internal combustion engines. Some questions of the technical diagnostics of the engine piston rings are considered. The authors propose a resonance method for the examination of the piston rings. The idea of the method is to cause oscillations in the ring at the frequency of its own mechanical resonance and at the multiple harmonics. The amplitude of the ring oscillations is measured in the gap by means of sensors according to two coordinates simultaneously. The frequency, phase and amplitude of the oscillations depend on the mechanical properties of the ring's material and its geometry. Micro-cracks, the areas with stresses, hardening defects, local overheating, loss of elasticity and other defects cause deviations of the frequency, phase and amplitude from the standard. One of the special features of the proposed method is registration of the frequency response of the piston ring oscillations simultaneously in two planes -radial (the plane of the ring) and in the direction of the axis. It allows to discover the defects (microcracks, thermal inhomogeneity, etc.) of the ring independently on their orientation along the assumed axes. This is a kind of non-destructive methods.Keywords: diagnostics, oscillations, frequency, amplitude, resonance. IntroductionThe piston rings are one of the important parts of the cylinder-piston group of internal combustion engines (ICE). A piston ring operates under very severe conditions -high temperatures, in the environment of aggressive chemical gases, with significant alternating mechanical stresses. The ring experiences continuous flexural-torsional vibrations in the grooves of the piston. The purpose of the piston ring is to segregate the combustion chamber and the crankcase space. The oil is supplied to the combustion chamber under the condition of increased gaps, the gases leak from the combustion chamber into the crankcase. This results in a significant deterioration of the technical and economic parameters of the engine and reduction of its service life.The paper suggests a method of present technical condition of the piston ring determination and analysing its frequency response plot (FRP) of its forced and self oscillations. The measurements are realized at the frequencies close to those of its own mechanical resonance and its harmonics. Thus, the piston ring plays a kind of tuning fork. Then the obtained FRP are compared with the reference plots.

This work is a further continuation of the investigations presented before at the previous conference. The basic attention is turned to improvement of the accuracy of the measurements of the oscillation changing, to development of a specified mathematical model of the oscillating process. The idea of the method is to cause oscillations in the ring at the frequency of its own mechanical resonance and at the multiple harmonics. The amplitude of the ring oscillations is measured in the gap by means of sensors according to two coordinates simultaneously. The frequency, phase and amplitude of the oscillations depend on the mechanical properties of the ring's material and its geometry. Micro-cracks, the areas with stresses, hardening defects, local overheating, loss of elasticity and other defects cause deviations of frequency, phase and amplitude from the standard. One of the special features of the proposed method is registration of the frequency response of the piston ring oscillations simultaneously in two planes-radial (the plane of the ring) and in the direction of axis. It allows to discover the defects (microcracks, thermal inhomogeneity, etc.) of the ring independently on their orientation along the assumed axes. This is a kind of non-destructive methods.

No abstract

When operating a hybrid vehicle (HEV), it is important to reduce maintenance and repair costs. The HEV electric drive (ED) consists of electronic, electrical and mechanical parts and is considered a complex diagnostic model. The availability of an electrical part greatly simplifies the process of monitoring and obtaining information about the state of the system. In order to create a hybrid diesel-electric propulsion system (HDEPS), the choice of structural and functional parameters as diagnostic ones is justified, the control points are chosen, and the necessary accuracy and unambiguity of measurements are determined. Qualitative evaluations of the electrical processes occurring in the power supply circuit of ED from a high-voltage accumulator battery for the selection of diagnostic parameters according to the criteria of sensitivity, informative character, stability and manufacturability of measurements are presented. It has been revealed that during HDEPS diagnostics both stable and transient modes of operation of electric machines should be considered; for analysis of ED technical state it is necessary to have information about current mode of HDEPS load; for measurement of instantaneous values of supply voltage and consumption current it is necessary to select the sensors with short response time and linear conversion function. In terms of sensitivity to structural changes in the circuit and parametric deviations, it is necessary to choose, as diagnostic parameters, the voltage or current, depending on the mode of operation of the ED and the point of measurement of the electrical value. The obtained results are the basis for creating a new system of diagnostics of electric power supply HDEPS in this direction.

No abstract