Analysis of the Increase Level of Vibration in an Internal Combustion Engine due to the Degradation of the Lubricating Oil

摘要

When analyzing vibrations in internal combustion engines, it is noticed that the greatest sources of vibrations are generated by combustion and mechanical forces. These forces occur over a wide frequency range and are transmitted to the outer surface of the engine through several paths, such as through the piston mechanism, connecting rod, crankshaft and engine block. As a result of the action of these forces, the external surfaces of the engine are subjected to vibrations of various amplitudes. Vibration problems in internal combustion engines are common due to the wide variety of parts and components that make up such engines. The crankshaft undergoes transverse, longitudinal and torsional vibrations due to the dynamics of the stresses sustained mainly during the combustion phase of the engine. The effects of vibration produce premature wear on the internal components of the engine, which contributes both to reduce the lifespan of the engine itself as well as cause discomfort to the occupants of the vehicle. Thus, since it is impossible to totally eliminate vibrations from engines, it is important to understand the sources of vibration production and control them to acceptable levels. The objective of this work was to evaluate the vibration level of an internal combustion engine due to the degradation of the lubricating oil used in the engine. The level of vibration increases with the time of use of the lubricant, and that this increase is very significant from the moment the viscosity has reached the minimum limit stipulated by the lubricant manufacturer. The type of fuel and viscosity of the lubricant influence the level of vibration in the engine. The results show that engine running on ethanol with lubricant of lower viscosity have the highest rates of vibration.