Piston dynamics, lubrication and tribological performance evaluation: A review

Mechanical power loss of lubricated and bearing surfaces serves as an attractive domain for study and research in the field of internal combustion engines. Friction reduction at lubricated and bearing surface is one of the most cost-effective ways to reduce gas emission and improve internal combustion engines' efficiency. This thus motivates automotive industries and researchers to investigate tribological performance of internal combustion engines. Piston secondary motion has prime importance in internal combustion engines and occurs due to unbalanced forces and moments in a plane normal to the wrist pin axis. Consequently, piston executes small translations and rotations within the defined clearance during the piston reciprocating motion. Mechanical friction power loss and lubrication at piston skirt/liner and radiated engine noise are dramatically affected by piston secondary dynamics. The lubrication mechanism, piston secondary motion and tribological performance are affected by piston design parameters (piston/liner clearance, wrist pin offset, skirt profile, etc.), lubricant rheology, oil transport mechanism and operating conditions. Therefore, this review is devoted to summarize the synthesis of main technical aspects, research efforts, conclusions and challenges that must be highlighted regarding piston skirt/liner lubrication and piston dynamics and slap.