Influence on friction from piston ring design, cylinder liner roughness and lubricant properties

•Halved friction for the oil control ring with kept sealing capability is found.•Effect on friction from piston ring design and cylinder liner roughness are studied.•The effect on friction from multi grade oil is compared to single grade oil.•Stribeck like curves are produced for investigation of DLC coated piston rings.•Good correlation between a numerical model and experimental results are showed.

The piston rings are responsible for a large portion of the fuel consumption in heavy duty diesel engines. In this work a high speed component test rig for evaluation of piston ring friction is used. A number of different piston rings and cylinder liners are evaluated based on their friction performance. Shear thinning of typical multi grade oil is investigated by comparing it to single grade oil. Experimental simulation of higher speeds by decreasing the viscosity is evaluated. A method for indication of effects on oil consumption, without combustion, for different oil control rings is presented. Finally, a numerical simulation model for the oil control ring is validated by comparing the friction predicted with the model to the experimental results.