Controllable radial oil injection applied to main engine bearings-hybrid bearing configurations and control pressure rules

In order to reduce friction losses and vibrations in main engine bearings, fluid film lubrication is combined to controllable radial oil injection. This work evaluates different geometric hybrid bearing configurations and control pressure rules for applying radial oil injection in main engine bearings of internal combustion engines. The conventional hydrodynamic lubrication (CHL) is combined with hydrostatic lubrication which is actively modified by radially injecting oil at controllable pressures, through orifices circumferentially located around the bearing surface. The behaviour of a main bearing of a medium size combustion engine, operating with radial oil injection and with four different control strategies is analyzed, giving some insights into the minimum fluid film thickness (OFT) and reduction of viscous friction losses. The behaviour of such parameters is compared to the case when the bearing operates with conventional hydrodynamic lubrication.