Engine designers today are faced with two paramount obstacles viz. rising demand for fuel efficient vehicles and stricter emission control norms. In this regard, the piston liner interface is a very important part of the engine, as it is the source of almost half of the frictional loss of an engine and defines the blowby, lubrication oil consumption and to some extent influences the hydrocarbon emission.
A single cylinder 4-stroke 110cc gasoline engine is taken up for study. A commercially available numerical code is used to simulate the piston and ring dynamics of the engine. The analytical FMEP results are correlated with the experimental FMEP found out by conducting a tear down motoring test on the engine. The blowby of the simulation model is validated with experimentally measured value of the fired engine. The effect of bore clearance and design of the piston rings on friction, oil consumption and blowby is studied. Further, ring dynamics phenomenon such as ring fluttering, blowback etc. and how it contributes to emission and oil consumption is discussed.
This paper is designed to give a brief understanding on the most significant aspects on piston design concentrating primarily on piston rings as it contribution to the system friction, emission and oil consumption is very significant. Methodologies are proposed to reduce friction contributed by the top ring and oil ring. Also suitable methods by which reverse blowby can be eliminated are discussed.