A new approach for modeling and analysis of the lubricated piston skirt-cylinder system with multi-physics coupling

The lubrication of the piston skirt-cylinder interface involves multiple physical fields, and these physical fields are coupled. A new method is proposed in this study for modeling and analysis of the lubricated piston skirt-liner interface with multi-physics coupling. This method is implemented in COMSOL Multiphysics software by coupling the heat transfer of the cylinder and piston, multibody dynamics of the crank-connecting rod-piston-cylinder system, the hydrodynamics lubrication of the skirt-cylinder interface, the thermal and elastic deformation of the piston-cylinder system, as well as the rheological properties of lubricating oil. The proposed method is first validated with a previous method and then adopted to a four-stroke gasoline engine to predict its dynamics and tribological characteristics. Then, a case study of different skirt thicknesses is conducted to reveal the influence the stiffness of the piston skirt exerts on the tribo-dynamics performance of the piston-cylinder system. The results indicate that although a thinner skirt will affect the stability of piston motion and increase the slapping noise and wear, it will benefit hydrodynamic lubrication between skirt and cylinder and reduce friction power loss. •A new method is proposed for modeling of the lubricated piston skirt-liner interface with multi-physics coupling.•The thermal and elastic deformations of the piston skirt, as well as the rheological properties of lubricant, are considered.•The elastic deformation of the piston skirt can enhance the slapping noise, but reduce the friction power loss.•A thinner skirt will benefit hydrodynamic lubrication between skirt and cylinder and reduce friction power loss.