Starved hydrodynamic lubrication of the piston ring cylinder liner contact: Preliminary study of the influence of surface texturing

Abstract

Some of the most important challenges concerning automotive engine research are related to the reduction offuel consumption, the increase of oil drainage intervals and the respect of the environment by a reduction of exhaust emissions. These improvements should not impair engine reliability. On the contrary, the operational life of the engine should increase. These demands are conflicting and a compromise has to be found. This compromise requires a thorough comprehension of the fundamentals of friction generation and oil consumption in an automotive engine and in particular of the piston ring — cylinder liner contact. The surface roughness of a cylinder liner influences these two parameters. nowadays, surface roughness is imposed by the machining process. But the surface topography can be improved by laser texturing. The current paper describes a transient analysis of a textured starved contact under pure rolling conditions. It shows the influence of the surface texture on oil thickness and pressure profile. Even if a piston ring contact operates under pure sliding conditions, these results allow the understanding of the possible interest of a textured surface. Steady state results for a smooth surface under pure sliding starved conditions are also presented in order to show a particular effect of sliding on the lubricant layer.