DEVELOPMENT OF MEASURES TO INCREASE RELIABILITY TURBOCHARGER BEARING UNIT AUTOTRACTOR DIESEL ENGINE

To increase the reliability of small turbochargers, in particular the bearing unit, it is proposed to use in the automatic mode of local cooling of the bearing with compressed air. The design of the turbocharger with the central case which houses the bearing and to which engine oil from the engine lubrication system is brought under excess pressure is considered. This design is the most common among turbochargers of tractor engines. Forced engine modes can be critical for the bearing, accompanied by fluctuations in the exhaust gas temperature, for example, due to an uncontrolled increase in cyclic supply, a sharp increase in load. Such modes lead to an increase in temperature deformations of the turbine wheel, rotor, reduce the reliability of the turbocharger. Heat dissipation from the rotor through the bearing assembly into the lubrication system is insufficient, additional short-term local cooling is required. The study simulated heat transfer processes in the bearing assembly of a small turbocharger using the developed mathematical model based on the finite element method. To clarify the model, namely the boundary conditions of the thermal conductivity problem, a series of non-motorized experiments with a locally cooled bearing were performed. In the course of non-motorized experiments, the algorithm of the automatic control system operation was worked out, some of its structural elements were selected and tested in practice. Conducted non-motorized experiments and the results of mathematical modeling confirmed the effectiveness of using the system of automatic local cooling of the bearing assembly. These measures increase the reliability of small turbochargers.