Finite element modelling of piston-ring dynamics and blow-by estimation in a four-cylinder diesel engine

This paper presents the results of the simulation of piston-ring behaviour in a four-cylinder diesel internal combustion engine, using explicit finite element analysis. The finite element model consists of piston, piston rings, liners, connecting rods, and a crankshaft. The gas pressure and temperature are taken into account for the simulation. The mass flow is solved by using the explicit finite difference scheme. The ring geometry, its assembly load, and its mechanical and thermal properties are properly accounted for in the simulation. The ring dynamics are greatly influenced by the piston secondary motions that depend upon the piston geometry, piston pin offset, its centre-of-gravity location, and piston-liner clearance. The ring motions in the axial and radial directions are monitored; various gap areas are calculated to estimate the blow-by and compared with the experimental results. The mass flowrate obtained from the model agrees with the experimental values. The information obtained from the analysis serves as an input for piston and ring design and their development.