3D EHD lubrication and wear for piston ring-cylinder liner on diesel engines

The three-dimensional EHD lubrication and wear loss of piston ring-cylinder liner components for five rings in the firing diesel engine was studied by using VC++ programs. The gas blowby, variable density and viscosity of lubricant, the surface roughness, friction heat flux and the normal elastic deformation are all considered in the EHD lubrication analysis algorithm. Meanwhile, the wear loss of the cylinder liner was also calculated when the diesel was started under cold starting condition in which the wearing was more serious than that in warm starting condition. The simulated results were compared with the wear measurement of the cylinder liner, and they matched well. It was found that the hydrodynamic friction force was larger than the asperity friction force, and the wear distribution of the barrel piston ring was very different from that of the rectangular piston ring. The distribution trend of the nominal oil film thickness was similar to the normal elastic deformation, but opposite to the wear loss of the piston rings. The wear loss caused by the first piston ring was the biggest and played a dominant role in the wear loss of cylinder liner. The greatest wear loss of the cylinder liner occurs at the time near top dead centre.