Investigation of the Thermal Tension of the Bearings of the Crankshaft of an Internal Combustion Engine

Author Name(s): Ilnur R. Akhmetzyanov, Vyacheslav N. Nikishin, Elena P. Barylnikova, Oleg A. Kulakov
Author Email: 692401@mail.ru

Abstract

Plain bearings limit the performance of the crankshaft of an internal combustion engine (ICE) to major repairs. Their reliability is determined by heat resistance, wear-resistance and endurance limits of the materials of which the bearing is made. Dynamic loads reduce bearing life. Plain bearings, heavy-loaded and operating at a high rotational speed of the crankshaft, require a constant supply of oil under pressure to maintain the hydrodynamic friction mode and to remove heat generated during friction. In the hydrodynamic regime of friction, heat generation is determined by the viscosity of the oil, the thickness of the lubricating layer, and sliding speed. In operation for plain bearings, it is necessary to provide liquid lubrication at all established operating modes of the internal combustion engine. The oil in the gaps between the neck of the crankshaft and the liner should come under the action of the necessary overpressure, thereby ensuring: complete separation of the working surfaces of the contacting parts of the bearings of the crankshaft during operation; lack of direct friction between the metal surfaces of the shaft and bearing; insignificant value of the coefficient of friction; low friction and heat loss. The paper presents the results of studies on the impact of operational changes in lubrication conditions on the thermal tension of the connecting rod bearings of the crankshaft.

Introduction

The crankshaft is one of the main parts of an internal combustion engine that determine its resource. In operation, the most characteristic defect of the crankshaft is a malfunction of mating tribes (the neck of the crankshaft bearings). Analysis of domestic engines received for overhaul shows that the most common cause of engine failure is the scoring of connecting rod bearings [1, 2, 3, 4]. Crankshaft bearings only work reliably under fluid friction conditions. The main hydraulic parameters of the engine lubrication system that determine the reliability of the bearings are pressure and oil flow [4, 5]. These two parameters depend on each other, as well as on the viscosity of the oil and the gaps in the tribe-mating “neck-insert shaft”

Conclusion

The thermal condition of the crankshaft bearings is one of the reasons for changing and improving the conditions for supplying and consuming oil to the connecting rod bearings of the engine. The study made it possible to establish the maximum pressure in the engine lubrication system at which the bearing hydrodynamics are preserved and additional thermal stresses and shape changes do not occur in the liners. Avoiding the reduction of pressure in the lubrication system below 0.25 MPa allows you to save the hydrodynamics in the connecting rod bearings of the crankshaft, thereby eliminating their premature failure.

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