Investigation of the Influence of Lubricating Oil Viscosity on the Wear-Reducing Characteristics of Cylinder Liner Surface Texture

Abstract

Lubricating oil and cylinder liner surface textures can significantly reduce the friction coefficient between the piston ring and the cylinder liner, thereby improving engine performance. However, the friction-diminishing mechanisms between the lubricating oil and surface texture remain unclear. Properly combining lubricating oil and surface texture can achieve better friction reduction effects. This paper, based on a transient thermo-hydrodynamic model developed in MATLAB 2020a, conducted numerous simulation experiments to explore the matching characteristics of textured cylinder liners. The study provides theoretical support for the future selection of lubricating oils for textured cylinder liners. The results show that, within the range of the circular texture parameters used in this study, the texture radius is directly proportional to the reduction in friction mean effective pressure (FMEP), while the texture depth is inversely proportional to the FMEP reduction. At the same rotational speed, as the viscosity of the lubricating oil increases, the friction-reducing effect of the texture on the piston ring–cylinder liner pair decreases. When the texture depth is 2 μm, the engine speed is inversely proportional to the reduction in FMEP. As the texture depth increases from 2 μm to 6 μm, there is a significant change in the friction-reducing effect: for the 2 μm texture, the friction-reducing impact decreases with increasing lubricant viscosity, while for the 6 μm texture, the friction-reducing effect increases with increasing lubricant viscosity.

Keywords

• friction reduction mechanisms
• lubricant viscosity effects
• surface texture
• thermo-hydrodynamic modeling
• friction mean effective pressure