Analysis And Research On Characteristics Of Internal Combustion Engine Piston Secondary Motion And Influencing Factors

Noise of an internal combustion engine can be divided according to the generation intocombustion noise, mechanical noise and aerodynamic noise. In the low frequency, mechanicalnoise occupies a major advantage. One of the main sources of mechanical noise is caused bypiston secondary motion, which leads to the impact between piston and cylinder. Therefore,from the characteristics of piston secondary motion and the generating principle of impactforce, carrying out related research and considering influence on piston secondary motion andimpact force due to different factors will be significantly worthy for analysis and suppressionof internal combustion engines.In working process of an engine, with the presence of the cylinder clearance, there arehorizontal movements, which are perpendicular to the centerline of cylinder and rotationalmovement around a piston pin while piston reciprocates in cylinder. The latter two forms ofmovement are called “piston secondary motion”. In this paper, with the basis of consideringmechanical loads and thermal boundary, with the result of piston secondary motion, thecontact load between piston and cylinder, the friction loss, the kinetic energy of the piston andthe impacting forces are listed. And deeply investigate the rules of different factors to pistonsecondary motion and impacting force.In this paper, the specific works are listed as follow:(1) Piston thermal analysis and thermal deformation are based on the third boundaryconditions. The piston thermal profile is superimposed with cold profile to get pistonworking profile. Calculate thermal deformation of cylinder liner in the installed state thenfit the thermal profile. The above results will be as the calculation boundary condition ofpiston motion characteristic and impacting force analysis. (2) Use related theory of kinematics and dynamics of crank mechanism and fluid lubricationto analysis piston secondary motion. Also, carrying out a series of results that secondarymotion characteristics of piston, contact load between piston and cylinder, friction lossand piston dynamic impacting force.(3) Search the influence factors of piston secondary motion. The main influence factorsconsidered includes piston pin offset, center of piston gravity, the clearance of cylinder,cylinder liner elastic deformation under the action of gas and so on. Summarize the relatedrules so that can provide corresponding reference for the design of internal combustionengine components.(4) Through the offset of piston pin and piston center, the piston radial move and titling movecannot be suppressed. The piston pin and piston center offset to the bearing surface canreduce the piston impacting force. Small clearance of cylinder can lead to reduce theimpacting force, but increase the friction loss as well. The result of piston radialdisplacement, titling angle and impacting force will be increased with the consideration ofcylinder deformation under the influence of gas.