Combined lubricant–surface system approach for potential passenger car CO2 reduction on piston-ring-cylinder bore assembly

• Published in: Tribology international 2020-09, Vol.149, p.105514, Article 105514
• Main Authors: Tomanik, Eduardo, Profito, Francisco, Sheets, Brett, Souza, Roberto
• Format: Article
• Language: English
• Subjects: Boring; Carbon dioxide; Computer simulation; Cylinder bore; Cylinders; Finishes; Friction; Friction reduction; Impact strength; Lubricants; Oil additives; Piston rings; Reynolds equation; Stiffness; Superlubricity; Viscosity
• ISSN: 0301-679X; 1879-2464
• DOI: 10.1016/j.triboint.2018.12.014

The impact of reducing friction losses on the fuel consumption and CO2 emissions was investigated through computational simulation of piston ring dynamics. Experimentally determined cylinder bore surface finishes, low viscosity oil and ring coatings response to oil additives were used as simulation inputs. Oil viscosity grades from SAE10W-40 to SAE0W-4 were considered. 3D roughness measurements of regular and “mirror-like” cylinder bores were used to estimate the flow factors coefficients for the average Reynolds equation and asperity contact stiffness. The combination of smooth cylinder bores, low viscosity oils with appropriate additives promoted ring pack FMEP reductions of up to 66% at part load and WOT with consequent CO2 reductions of up to 10% at part load and 1.5% at WOT. •Regular grey cast iron and mirror like coated bores actual measurements were used to calculate asperity and hydrodynamic pressures.•Ring friction losses etc. were calculated for 2000 and 4000 rpm, 20 and 100% engine loads, using a computational model.•The smoother bore surfaces generated much lower oil film thickness without increase of the asperity pressures.•The use of smooth cylinder bores, low viscosity oils brought reductions of: Ring pack FMEP up to 66% at part load and WOT.•CO2 was reduced up to 10% at part load and 1.5% at WOT with the optimal combination.