The Study of Residence Time and Flow Rate of Lubricating Oil Through the Top Ring Zone of a Gasoline Engine

With the ever increasing demand on lubricant manufacturers to improve fuel economy, fuel economy retention and increase the drain intervals of their lubricants there is an increasing need to understand which factors effect the degradation of the lubricant in the sump. The harsh conditions in the ring pack have been shown to be responsible for the majority of the lubricant degradation in the engine. Therefore in this investigation the flow rate of lubricant through, and residence time of lubricant in, the top ring zone of a gasoline engine with respect to load and speed has been experimentally measured. An initial effect of the lubricant viscosity on these parameters has also been investigated. The theory and experimental methods are described before the experimental results are presented and discussed. The work has shown that the overall effect of engine speed on sump lubricant degradation is nominal, and that the level of sump degradation increases with increasing engine load.