DETERMINATION OF THE FREQUENCY OF NATURAL OSCILLATIONS OF THE ELEMENTSOF THE MECHANICAL SYSTEM OF THE MOTOR CARRIAGE ROLLING STOCK

Of particular importance is the problem of operational reliability and durability of locomotive power units (diesel engines), which equip a significant portion of freight and passenger rolling stock operating on non-electrified railway networks in Ukraine. This necessitates conducting computational and experimental studies of the stress-strain state of critical diesel engine parts and assemblies, among which the camshaft holds a special place. At the same time, such studies require, as one of the stages, measures aimed at developing an appropriate mathematical model that considers the peculiarities of formation of accumulating torque moments in the camshaft subsystem. Therefore, research aimed at developing a mathematical model that considers the design features of the mechanical system of a multi-cylinder locomotive diesel engine and allows obtaining simulation results of the camshaft stress state close to operational indicators should be considered relevant. The article highlights an approach to modeling torque accumulation in the diesel engine camshaft subsystem using a mathematical model developed by the authors, which takes into account the design features of the mechanical system of modern traction rolling stock. A structural-functional scheme of the locomotive power unit (LPU) mechanical system is presented, which was developed to study the interaction between its subsystems, the description of which is paramount among the series of stages in studying the loaded state of the LPU mechanical system elements. This scheme contains several subsystems, namely: the camshaft subsystem; cylinder modules; crankshaft; transmission mechanism; and auxiliary equipment. Its analysis allowed noting that loads in the camshaft subsystem are formed from the action of input torque and accumulation of series torque moments, which in turn include loads in the sections of valve gear cam mechanisms and high-pressure fuel pump drives. The presented results show the modeling of torque formation in the sections of intake and exhaust valves of the valve gear mechanism, fuel cams, and in the section of the camshaft drive gear. Generalized formulas are provided, which allowed obtaining arrays of torque moments in the sections of valve gear cam mechanisms and high-pressure fuel pump drives. It is noted that the formation of torque layering across cylinder modules occurs in accordance with the design features of the LPU mechanical system. Recommendations for further use of the obtained results are provided.