Evaluation of the lubrication conditions in the interaction between piston and cylinder

Lucas Tavares Selegatto¹; Gregory Bregion Daniel¹

¹ University of Campinas (UNICAMP)

doi:10.20906/CPS/COB-2015-0540

Resumo

The pursuit for more efficient vehicles has been a research field over the last few years in order to obtain a reduction in both fuel consumption and the release of pollutants to the environment. In this context, hydrodynamic lubrication has played an important role because it tends to reduce the friction that is a main cause of wear and power loss in internal combustion engines. Therefore, this work aims to evaluate the lubrication conditions in pistons, due to its importance and great influence in the performance of engines. For this, a mathematical model is developed taking into account two translational and two rotational motions to the piston within the cylinder. From these four degrees of freedom, the oil film thickness is determined and, consequently, the pressure distribution and the hydrodynamic forces acting on the piston can be evaluated. The results obtained in this work show the pressure distribution, the peak position of the maximum pressure and the hydrodynamic forces for different operational conditions. Due to the critical operational conditions, an estimation of the hydrodynamic forces is very important, since they act directly on the engine dynamic behavior. Finally, the model developed in this work can be successfully employed to estimate the hydrodynamic forces acting on the piston, being very important for the dynamic modeling of the slider-crank mechanism in internal combustion engines.

Palavras-chave: Hydrodynamic Lubrication; Piston Skirt; Hydrodynamic Forces; Slider-Crank Mechanism