Numerical Simulation Of Piston And Crankshaft Bearing Lubrication

Piston and crankshaft bearing system are critical movement components in internal-combustion engine (ICE). The performance of the system have directly effect on the reliability and durability of the engine. It has important significance when making research of hydrodynamic lubrication and elastohydrodynamic(EHD) lubrication analysis.In this paper, a mathematic model for piston skirt oil film lubrication is deduced, which based on the fluid dynamics lubrication theory and including the pressure flow factor,shear flow factor,contact factor. Influence of rms roughness in piston skirt surface and its profile are considered. Piston secondary motion that combining piston dynamics equation and oil film lubrication is also analyzed. A FORTRAN program code with finite element method for numerical solving the Reynolds equation is developed. The program is used for TBD620 engine as an example, and calculates oil film pressure,thickness,friction forces,profile of piston skirt etc. It also makes a comprehensive study of lubrication properties of the crankshaft bearing. Based on the common Reynolds Equation, it considers the cavitation,aligned journal,misaligned journal,elastic deformation influence synthetically. It adopts the JFO boundary condition and disperses governing equation with finite element method. It uses mass conserving algorithm,approximate factorization algorithm,frontal solution,Gear method. The FORTRAN and MATLAB program code are developed. They calculate oil film pressure,thickness,elastic deformation of bearing etc. Besides, the influences of some parameters on these properties are investigated systematically. Some conclusions are obtain, which will be very useful for the design and further study of piston and crankshaft in engines. The obtained results also have directive significance to the design of low noise ICE.