Lubrication adaptability to the variations of combustion modes by texturing cylinder liner in engines

Abstract

The application of different combustion modes in engines has placed greater demands on the lubrication of cylinder liners and piston rings. In this study, a mixed lubrication model was built to investigate the tribological properties of a liner textured with micro-dimples. The simulation results indicate that surface texturing can improve the lubrication and friction properties of the ring/liner pair and adapt to different combustion modes in an engine. Due to the significant differences in external loads around top dead center of the compression stroke under pre-mixed charge combustion ignition, conventional combustion and retarded injection modes, when the liner remains untextured, the lubrication performance of the friction pair appears to be unstable in a mixed lubrication region. For the textured liner, micro-dimples enhance the hydrodynamic effects between the ring and liner, increasing the oil film thickness and its bearing capacity. As a result, the mixed lubrication interval shrinks and the micro asperity contact is reduced, thus improving the tribological properties of the friction pair. The numerical fluctuation ranges of parameters, the maximum asperity pressure, the average friction force and the frictional loss, are narrowed by 21.6%, 27.8% and 24.5%, respectively, under the three different combustion modes around top dead center of the compression stroke.