The effect of SiO2 nanoparticles content in engine oil on tribological properties of valvetrain chain transmission components

Abstract

The drive from the crankshaft to the camshaft in an internal combustion engine is usually carried out by means of a cogged belt transmission or a chain transmission when high millage is required without service operations. The valvetrains in CI engines sometimes use the gear transmissions, and the historical rather bevel gear can be found in old cars of collectors or in some motorcycle engines. The chain gear used in SI engines has a two- or three-row chain with high strength, due the unevenness of loads that additionally induce chain pulling and valve timing deregulation. The chain transmission requires the use of pre-tensioners, usually self-acting and driven by springs or oil pressure. The vibrations and chain runout are limited using plastic guides placed on the outside of the long straight sections of the chain. The model of the chain transmission developed with the use of the Finite Elements Method, which operates under oil lubrication conditions, was analyzed. Such the model allowed obtaining weight and mass inertial moments of components. The aim of the study was to evaluate the effect of SiO2 nanoparticles content in engine oil on the friction between chain transmission components. The resulted values of the friction torque in the chain transmission operating in different conditions of lubrication have been presented in the paper.