Top ring technology to low fuel consumption flex fueled engines 2009-36-0128
Several engine trends point out the increase on mechanical and thermal load on the top ring. Combining it with the use of alternative fuels, where lubrication is critical (mainly due to the low lubricity of such fuels), the increase of ring resistance to wear and toughness is demanded.
This work presents a new top ring to meet the targets defined by the new engine technology. It is based on CrN coating via PVD process, which provides improved wear resistance with enhanced toughness. This coating also presents reduced friction, that can represent up to 0.7% of reduction in fuel consumption, compared to gas nitrided steel on top ring which is the baseline technology used for spark ignited (SI) engines. It is presented bench and engine tests showing the improvements.
Bench test carried out in a floating liner rig to measure friction showed reduction up to 10% of the ring pack losses. Engine test also presented improvement on wear resistance for E100 fuel.