Piston Friction Phenomenon and Cylinder Corrosive Wear in Cooled EGR Condition

Abstract

If it is intended to apply cooled EGR to heavy-duty diesel engine for a more reduction of NO_x emission, it will also be necessary at the same time, to reduce corrosive wear induced by condensed water including the acids on piston rings and cylinder liner due to cooled EGR. This study aims at making clear the effects of condensed water supplied to the combustion chamber on the cylinder oil film formation when the temperature of EGR gas becomes lower. The piston friction has been measured under various temperatures of EGR gas for the verification of lubricating condition of piston and piston ring. As a result, it is found that the piston friction spiky increase just after TDC where the EGR gas temperature becomes lower and that the condensed water easily reaches the cylinder wall surface through the oil film.