Mathematical modeling of dynamics of movement of the compound piston in the cylinder of the internal combustion engine

Abstract

Cylinder piston group is the main part of friction in the engine, where usually mechanical losses appear, that is why its work and design should be considered from the point of view of tribology. The task of designing a cylinder - piston group as a friction unit is to select the basic geometric dimensions, the profile of the guide part in the longitudinal and transverse planes, the diametric gap, the coordinates of the piston pin arrangement and the center of mass. The solution of these problems is directly dependent on the possibility of studying the complex plane-parallel motion of the piston within the piston-cylinder liner clearance in the lubricant layer. At present, compound pistons are gaining traction from forced diesel engines with increased loads on the cylinder-piston group. The study of the movement of the compound pis-ton must include the solution of interrelated tasks: the investigation of the motion of the piston crown with a set of piston rings and the study of the motion of the piston skirt, taking into account the effect of the rocking motion of the connecting rod on it. The derivation of the equations of motion of all components of the piston and connecting rod is given in the article. Their combined solution and the resulting equations allow us to investigate the transverse motion of the crown of the composite piston and to evaluate the operation of the piston rings, and also taking into account the hydrodynamic lubrication of the skirt, to carry out a comprehensive study of the state of the skirt of the compound piston and, first and foremost, to investigate the influence of its basic design parameters on the conditions of the hydrodynamic grease. The developed mathematical model will allow on the basis of complex research the influence of the above parameters to develop a composite piston design that provides high technical and economic parameters of the engine.