Comparative study on the friction behaviour of piston/bore interface technologies

Engine crank case designs for passenger car applications are based today on two main material technologies: grey cast iron and an increasing share of aluminium-based concepts. Due to the low wear resistance of aluminium, the latter concepts require a wear protective layer for the cylinder bore surface. Iron-based thermal spray coats are widely used for this purpose. The coating improves the tribological behaviour significantly, as previous studies have shown. Additionally, aluminium-based concepts offer advantages regarding engine weight and thermal management. The aim of the presented work was the discussion of these technological concepts regarding the tribological and sealing properties of the piston/bore interface. The study was carried out based on the AVL FRISC Floating Liner Engine. While the basic engine remained unchanged, the cylinder bore surface was varied. In addition to the floating liner friction measurement, the blow-by and lube oil consumption were also measured. A state-of-the-art multi-body dynamic simulation model complements the experimental study, while both simulation and measurement lead to similar conclusions.