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Friction Reduction Technology for Low Viscosity Engine Oil Compatible with LSPI Prevention Performance
ISSN: 0148-7191, e-ISSN: 2688-3627
Published October 17, 2016 by SAE International in United States
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Increasing numbers of vehicles equipped with downsized, turbocharged engines have been introduced seeking for better fuel economy. LSPI (low speed pre-ignition), which can damage engine hardware, is a potential risk of the engines. We reported that engine oil formulation affects frequency of LSPI events, and formulating magnesium detergents into oil is a promising option to prevent LSPI events. From the viewpoint of achieving better fuel economy by engine oil, lowering viscosity is being required. However, it causes reduced oil film thickness and will expand boundary lubrication condition regions in some engine parts. Hence, a technology to reduce friction under boundary lubrication becomes important. To establish technology to reduce friction in low viscosity oils while ensuring good LSPI prevention performance, effective use of molybdenum dithio-carbamate (MoDTC) with magnesium detergents was investigated, since MoDTC is known as one of the most effective friction modifiers to reduce friction under boundary lubricating condition. Our friction study revealed that magnesium detergent deteriorates low friction performance of MoDTC. Throughout a series of XPS analyses, we clarified that magnesium detergent scraped poly-phosphate tribofilm derived from zinc dithio-phosphate (ZnDTP) on the sliding surface, which inhibited MoS2 tribofilm formation, causing high friction. Borated dispersant was formulated to oil to promote formation of harder poly-borophosphate tribofilm which prevents itself from being scraped by magnesium detergent, causing low friction. This formulation technology of engine oil is applicable for future ILSAC GF-6 engine oil and after, where LSPI prevention performance and low viscosity are required for excellent fuel economy.
CitationKaneko, T., Yamamori, K., Suzuki, H., Onodera, K. et al., "Friction Reduction Technology for Low Viscosity Engine Oil Compatible with LSPI Prevention Performance," SAE Technical Paper 2016-01-2276, 2016, https://doi.org/10.4271/2016-01-2276.
- Bandel, W., Fraidl, G., Kapus, P., Sikinger, H. et al., "The Turbocharged GDI Engine: Boosted Synergies for High Fuel Economy Plus Ultra-low Emission," SAE Technical Paper 2006-01-1266, 2006, doi:10.4271/2006-01-1266.
- Dahnz, C., Han, K., Spicher, U., Magar, M. et al., "Investigations on Pre-Ignition in Highly Supercharged SI Engines," SAE Int. J. Engines 3(1):214-224, 2010, doi:10.4271/2010-01-0355.
- Takeuchi, K., Fujimoto, K., Hirano, S, and Yamashita, M., “Investigation of Engine Oil Effect on Abnormal Combustion in Turbocharged Direct Injection - Spark Ignition Engines,” SAE Int.J.Fuels Lubr. 5(3):1017-1024, 2012, doi: 10.4271/2012-01-1615.
- Onodera, K., Kato, T., Ogano, S., Fujimoto, K. et al., "Engine Oil Formulation Technology to Prevent Pre-ignition in Turbocharged Direct Injection Spark Ignition Engines," SAE Technical Paper 2015-01-2027, 2015, doi:10.4271/2015-01-2027.
- SAE J300, Engine Oil Viscosity Classification, 2015
- ILSAC GF-6 recommendations for passenger car engine oils, Draft February 13, 2014
- De Barros’Bouchetm M.I., Martin, J.M., Le Mogne Th., and Vacher B, “Boundary Lubrication Mechanism of Carbon Coatings by MoDTC and ZDDP Additives”, Tribology International, 38 (2005) 257.
- Martin, J.M., Grosssiord C., Varlot K., Vacher B, Le Mogne Th., and Yamada Y., “Friction-induced two-dimensional solid films from lubricant additives”, Lubr. Sci., 15 (2): 119-132 (2003)
- Kusuhara, S. “Impact of Viscosity Properties of Engine Oils on Fuel Economy and Formulation Technologies in Low-viscosity Engine Oils”, International Tribology Conference, TOKYO 2015, 257-258 (2015)
- API1509, 17th edition, 2012
- Kobayashi, K. “Frictional properties of metallic detergents under the rolling-sliding condition”, Transactions of the JSME, No.984-1
- Fujimoto, K., Yamashita, M., Hirano, S., Kato, K. et al., "Engine Oil Development for Preventing Pre-Ignition in Turbocharged Gasoline Engine," SAE Int. J. Fuels Lubr. 7(3):869-874, 2014, doi:10.4271/2014-01-2785.
- Kubo, M. “TOF-SIMS analysis of boundary films derived from calcium sulfonates”, Tribology Letters, Vol.23, no.2, August 2006, DOI:10.1007/s11249-006-9093-9
- Shah, V. “Effect of B2O3 addition on microhardness and structural features of 40Na2O-10BaO-xB2O3(50-x)P2O5 glass system”, Bull. Mater. Sci., Vol.29, no.1, Feb. 2006, p43-48.