The article describes the process of developing a model for improving the operational performance of vehicles. The development of the model is based on the interconnection and mutual influence of the basic elements of the vehicle. Since the internal combustion engine is the source of energy and the driving force, its performance directly affects the operation properties of the vehicle. In turn, they mainly depend on the nature of the working process and engine parameters. Therefore, a change in the technical and operational indicators of the engine will entail a change in the operational indicators of the vehicle on which it is installed. An information model of the influence of engine parameters on vehicle operational indicators allows establishing that, for a certain time of operation and fixed values of operating modes, improvement of vehicle performance is possible by changing the technical and operational parameters of the engine. At the same time, considering the functioning model of the internal combustion engine as a certain multidimensional and multilevel system, it was found that the working process taking place in the engine and the design parameters of its mechanisms have the greatest impact on changing engine parameters. The main working process takes place in the engine cylinder. Therefore, the details of the cylinder-piston group will have the greatest impact on the change in the engine output parameters. The use of mathematical modeling in solving this problem allows developing a concept for improving the performance of a vehicle, and optimizing the process of choosing ways to upgrade a vehicle and engine.

The work is devoted to the experimental studies of determining the magnitude of the electromotive force (EMF) that arises in the friction pairs of an internal combustion engine (ICE) and the possibility to assess its technical condition by the magnitude of the electromotive force. A research procedure was designed to carry out an experiment. The measurement of small value voltages was carried out using a control and measuring device, the principle of operation of which is based on operational amplifiers (OA). Based on the previously obtained theoretical values of the EMF, the designed millivoltmeter can make measurements in the range of the following values: from 50 μV to 1 mV and from 1 mV to 40 mV. To ensure the reliability of the readings of the measuring device, its calibration was carried out with the use of an AMPROBE 37XR-A digital multimeter. As a result of the measurements, the relationship between the EMF value and the crankshaft speed of the power plant was established. The analysis of the research results confirms the possibility of diagnostic assessment of the power machine condition by the values of the measured EMF using the proposed measuring complex.

The paper is devoted to theoretical studies of the feasibility to determine the clearance size in the friction units of an internal combustion engine by the magnitude of the electromotive force (EMF) that arises in them. The effect of the contact area of the friction pairs and the clearance between them on the electrical resistance in the contact, and, accordingly, on the magnitude of the emerging EMF was theoretically confirmed. As a result of the theoretical studies, the relationship of the influence of changing clearances on the magnitude of the EMF arising in them was established. To confirm the theoretical calculations, bench studies of the UMZ-417 engine were carried out to determine the magnitude of the EMF arising in its friction pairs depending on the change in the crankshaft rotation speed, followed by micrometry of the parts. The study was carried out using the designed current collector. The obtained theoretical and experimental results confirm the feasibility of determining the condition of friction units by the magnitude of the EMF generated in them and with sufficient accuracy to determine the dynamics of the clearance size between rubbing parts.

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