Influence of the balancing of the oil supply to the connecting bearings on their operations failures

Abstract

The relevance of the study is due to the need to study the laws of processes and phenomena leading to disruption of the normal functioning of the connecting rod bearings of automobile engines in operation and causing sudden costly failures. The goal is to ensure the reliability of automobile engines by minimizing in operation the influence of factors contributing to the occurrence of such a dangerous failure as cranking the connecting rod bearings. Methodical apparatus of the study – field observations and micrometry of the necks and liners of the crankshaft according to GOST 14846–81; experimental studies based on the author’s methodology using the created original test setup based on the KAMAZ–740 automobile engine and the AVL motor stand. The main results – factors and a mechanism for cranking the connecting rod bearings are described. According to the results of field observations and bench tests, it was established that during engine operation there is a shape change of the bearings as a result of a mismatch between the real operating modes of the connecting rod bearings and the design modes of hydrodynamic lubrication. The critical and necessary oil pressure for reliable lubrication of the connecting rod bearings in operation is determined; modes of operation of the KAMAZ engine were identified, at which oil starvation of its connecting rod bearings may occur, as well as modes of stable operation of the entire lubrication system. Scientific novelty: new knowledge has been obtained on the laws of the kinetics of oil supply to connecting rod bearings in operation, which are distinguished by the mutual influence of the self–regulating process of changing the geometry of the connecting rod bearing and the mechanism of pulsations of the oil flow in the oil supply channels, which make it possible to determine safe functioning parameters of the lubricating system. Practical significance: the results of the study are implemented in KAMAZ PJSC on KAMAZ engines by increasing the performance of the oil pump and the nominal pressure in the lubrication system, optimizing the passage sections of the channels and their location. Directions for further research and recommendations: theoretical interest and a mathematical description of the process of supplying oil to connecting rod bearings in the mode of repeated pulsations and draining from them, as well as assessing the survivability of connecting rod bearings.

Keywords

• car engine
• connecting rod bearings
• lubrication system
• oil consumption
• oil pressure
• turning of loose leaves