Hydrodynamic Lubrication Applied To Bearings With Oscillating Motion In Internal Combustion Engines

The purpose of this work is to develop a mathematical model for the hydrodynamic lubrication problem applied to bearings with oscillating motion. In contrast with common bearings, this type of bearing does not perform a complete rotation, belonging to a newly defined class: the bearings with oscillatory movement. For the analysis of the lubrication problem, we start from simple solutions for oscillating plates, parallel and inclined to each other, resulting in Couette and Poiseuille flows, respectively, which were solved by using the same approach as Stokes' 2 nd problem. The lubrication or friction reduction between the two surfaces in relative movement is caused by the induced movement of a viscous fluid inside the narrow and variable gap between them. The same basic assumptions of the classical Reynolds' lubrication theory were assumed. In the flat oscillating plates problem, the lower plate is assumed to have an oscillating movement and creates a Couette-Poiseuille combined flow inside the gap. After simplification, the momentum equation is solved to determine the velocity distributions. From integration of the mass conservation equation, we obtain a second order differential equation for the pressure distribution. It is shown that, at the limit of zero rotational velocity, this expression becomes the classical Reynolds' equation of hydrodynamic lubrication. As result we show graphcally the pressure distribution as function of angle θ and time t. We also solved the classical Reynolds' equation to compare with the results obtained from this model.