With an increase in the power/weight ratio of vehicles in cities and towns, the thermal loads of many functional units increase significantly. This requires the organization of the removal of excess heat into the environment, since the violation of the proper thermal regime in individual functional units prevents the realization of the potential operational properties of the entire vehicle up to failure. At the same time, the variety of operating conditions for vehicles, causing a change in a wide range of factors of the working environment, especially road and climatic ones, creates a difficult, both in practical and theoretical terms, problem of ensuring the required thermal regime for functional units. In this regard, the paper presents a consistent development of the theory of hydrothermodynamic properties of functional units based on the principles of constructing the operational properties of vehicles. The problems determining the further search and scientific substantiation of meters and indicators for assessing the efficiency of cooling systems, as well as the development of methods, tools and equipment for calculating and studying these systems are considered. At the same time, the work presents the improvement of the working process and designs of gas engines of tractors aimed at increasing reliability through the use of new production technologies. In conclusion, the definition of scientifically grounded methods and practical solutions for improving the performance of cooling systems is given, which has an important scientific and economic significance for increasing the operational properties of agricultural tractors, substantiating the current importance.
The problem of increasing the unit power of the engine without making changes to its design is solve by using a turbo supercharger. However, due to the intensity of the turbochargers operating mode, which are characterized by engine speed variability due to changing load indicators during operation (the number of rotor revolutions varies from 30000 min-1 to 120000 min-1, engine exhaust gases have a temperature of about 7500C), there is a need to improve the efficiency of the turbocharger bearing lubrication system. The purpose of the research is to ensure the operability and increase the reliability of turbochargers of diesel engines. To achieve this goal, a constructive solution for the lubrication system of the bearing assembly was propose, i.e., a membrane-type hydraulic accumulator was structurally provided in the lubrication system of the bearing assembly. Experimental studies were conduct to identify the operability and effectiveness of this constructive solution. The experiment was carried out on the KAMAZ-740 engine, the turbocharger shaft drive was carried out in normal mode, that is, from exhaust gases. L-02-40 fuel was use, SAE 10W–40 API was use as a lubricant. The turbocharger shaft speed varied from minimum to maximum by changing the engine speed and then stopping it. During the experiments, the following parameters of the turbocharger operation were measure: the duration of inertial rotation of the turbocharger rotor; the duration of pressure reduction in the turbocharger lubrication system. The dependences of the influence of the duration of the pressure drop in the turbocharger lubrication system and the duration of rotation of the turbocharger shaft by inertia with parallel inclusion of the accumulator in its lubrication system and in the normal mode of lubrication of the bearing are reveal. It is established that the installation of a device for feeding the turbocharger bearing during a sharp reduction in engine speed will increase the run-out of the turbocharger rotor from 30 to 65 s while maintaining the normal operating mode of the turbocharger lubrication system
The paper presents the main advantages and disadvantages of standard fuels in comparison with alternative fuels of methane series used in internal combustion engines. Particular attention in the article is given to the study of the heat transfer parameters of the calculated volume in the fuel tank filled with liquefied methane with thermal insulation, as well as methane outflow in special round tubes to transport gas in the liquid phase to the atomizer of the gas injector. Variants of numerical modeling of phase transitions of the heterogeneous system inside the tank are presented, as the calculated volume and flow of a two-phase flow of liquefied methane in tubes in the horizontal plane, taking into account the operating parameters of the elements of the fuel supply system.
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