Analysis of the piston ring/liner oil film development during warm-up for an SI-engine

A one-dimensional ring-pack lubrication model developed at MIT is applied t o simulate the oil film behavior during the warm-up period of a Kohler spar k ignition engine. This is done by making assumptions for the evolution of the ail temperatures during warm-up and that the oil control ring during do wnstrokes is fully, flooded. The ring-pack lubrication model includes featu res such as three different lubrication regimes, i.e., pure hydro-dynamic l ubrication, boundary lubrication and pure asperity contact, nonsteady wetti ng of both inlet and outlet of the piston ring, capability to use all ring face profiles that can be approximated by piece-wise polynomials, and, fina lly, the ability to model the rheology of multigrade oils. Not surprisingly the simulations show that by Snr the most important parameter is the tempe rature dependence of the oil viscosity.