The timing chain is generally used for the camshaft drive for passenger vehicle engine because of high durability and compact package. However the chain elongation during the usage causes reduction in engine performance and rise in noise level. Therefore it is very important to design the chain specification by considering the chain load and engine oil lubrication condition.
This report introduces the environmental performance required for engine oil through the transition of ILSAC standards and the additive technology that enables it. Also, SAE J300 has gradually standardized low-viscosity oil grades that are expected to have fuel-economy characteristics, then GF-6B newly adopt 0W-16. Furthermore, JASO adopt 0W-8 as well as 0W-12. As viscosity decreasing, conflicting robust performance is also required, and further development of additive technology is expected.
Recent passenger car engine characteristics and their tribological issues are explained. Hybrid engine is characterized by its frequent stop and start and low temperature operating condition, and downsizing turbo engine is characterized by direct fuel injection and frequent boosted operating condition. Recent friction reduction technologies are also explained considering their trade-offs such as wear, noise and oil consumption, in terms of piston, piston rings, cylinder, crankshaft, bearings and oil.