Low Friction Ring Pack for Gasoline Engines Available to Purchase

Lower emissions, reduced friction and low lubricant oil consumption are the main drivers for new gasoline engines. In terms of piston ring pack, the trend is to reduce ring tangential load and width. On the other hand, the main concern is to have proper ring conformability and lube oil control. This work presents the comparison of a baseline ring pack with a low friction pack in terms of friction, blow-by control and lube oil consumption. Besides ring width and tangential load reductions, evaluations of ring materials are also carried out. Narrow compression rings, 1.0 and 0.8 mm, were engine tested. PVD top ring was also tested and showed about 10% friction reduction compared to the usual Gas Nitrided one. 3-piece 1.5 mm oil rings were compared with the usual 2.0 mm ones. Being more flexible, the narrower oil rings can have same conformability with reduced tangential load. Friction was measured in the mono-cylinder SI Floating Liner engine at 5 operational conditions. Effect of cylinder roughness on friction is discussed by reciprocating bench tests. Compared with a typical 1.2/1.2/2.0 mm SI ring pack, the proposed 1.0/1.0/1.5 mm pack brought about 28% reduction in ring friction in the tested conditions, which would mean in about 1% of fuel savings in urban use.