Active lubrication applied to internal combustion engines - Evaluation of control strategies

The performance of fluid film bearings in a combustion engine affects key functions such as durability, noise and vibration. Therefore, this work evaluates different control strategies for applying active radial oil injection in the main bearings of internal combustion engines with the aim of reducing friction losses and vibrations between the crankshaft and the bearings. The conventional hydrodynamic lubrication 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, maximum fluid film pressure, friction losses and maximum vibration levels. The behaviour of such parameters is compared to the case when the bearing operates with conventional hydrodynamic lubrication.