A NEW APPROACH TO DETERMINE LUBRICATION REGIMES OF PISTON-RING ASSEMBLIES

A nerv approach is developed to determine piston-ring assembly lubrica tion regimes from the instantaneous frictional torque measured for the whole engine. This is based on the variation of the friction coeffici ent with the duty parameter in the Stribeck diagram over the mired and hydrodynamic lubrication regimes, The derived equation determines til e lubrication regimes from the slope of the line in the Stribeck diagr am. A single cylinder spark ignition engine was instrumented to determ ine the total instantaneous frictional torque of the engine. Experimen ts were conducted under different loads al a constant speed. Results s how that the regime is mixed lubrication near the top dead center (TDC ) and shifts to the hydrodynamic lubrication regime as the piston move s away from TDC. The extent of the mixed lubrication regime depends on engine load and speed.