Analysis On Piston Secondary Motion And Lubrication Of Piston Skirt Considering Lubricating Oil Transport And Deformation Of Piston

The piston is one of the important component of internal combustion engine,the piston skirt lead piston reciprocating in cylinder through interacting with cylinder wall when engine works,and the lateral thrust acts on piston skirt,the piston also has lateral motion in the cylinder.The lubrication of piston skirt-cylinder liner frictional pair has significant impact on the wear and friction of the piston and cylinder.When the engine running,the deformation of piston may affect the piton secondary motion and the performance of piston skirt lubrication.In current lubricating analysis on piston skirt-cylinder liner frictional pair in internal combustion engine,the lubricating status between piston skirt and cylinder liner was usually based on a hypothesis that the frictional pair is on a sufficient lubrication status or a poor lubrication status with certain quantity of lubricating oil,rather than defined by the formation of actual lubricating oil film,which will result in a difference between analysis result and actual situation.In this paper,a piston skirt-cylinder liner frictional pair in a internal combustion engine is employed to study the piston secondary motion and piston skirt lubrication considering deformation of piston and the lubricating oil transport in piston-cylinder liner frictional pair.The flexibility matrix used to calculate the elastic deformation of surface of piston skirt was acquired by using the three-dimensional finite element software,then the deformation of piston skirt surface was calculated by the flexibility matrix when the lubricating oil film pressure apply on piston.Meanwhile,the deformation of piston,when thermal load and combustion gas pressure apply on piston,are calculated.The law of piston secondary motion and the performance of piston skirt lubrication was study,considering deformation of piston and lubricating oil transport,through the model of piston secondary motion and the model of hydrodynamic lubrication.The results shows that,in the lubrication analysis of piston skirt,the minimal oil film thickness changes because the piston skirt profile is changed which caused by the deformation of piston;when considering the condition of deformation of piston,the friction loss of piston skirt will decreases;when considering the condition of lubricating oil transport,the deformation of piston has a little effect on the piston secondary motion and piston skirt lubrication;when considering the condition of both the deformation of piston and the lubricating oil transport,the law of piston secondary motion and the performance of piston skirt lubrication changed significantly.