Development of a Technique to Predict Oil Consumption with Consideration for Cylinder Deformation - Prediction of Ring Oil Film Thickness and Amount of Oil Passing Across Running Surface under Cylinder Deformation -

Abstract

Although various factors affecting oil consumption of an internal combustion engine can be considered, a technique to predict the amount of oil consumed within a cylinder that passes across a running surface of a ring wasdeveloped in this study. In order to predict the effect of cylinder deformation on oil consumption, a simple and easy technique to calculate the oil film thickness in deformed cylinder was proposed. For this technique, the piston ring was assumed to be a straight beam, and the beam bends with ring tension, gas pressure, and oil film pressure. From the calculated oil film thickness, amount of oil passing across the running surface of the TOP ring and into the combustion chamber was calculated. The calculated results were then compared to the oil film thickness of the ring and oil consumption measured during engine operation, and their validity was confirmed. As a result, the oil film thickness of the ring calculated by this technique was extremely close to the measured value, showing that it is possible to predict the oil film thickness in deformed cylinder using this simple and easy technique. In addition, the change in the amount of oil passing across the running surface of the TOP ring due to cylinder deformation calculated by this technique was confirmed to match qualitatively the effect of cylinder deformation on oil consumption.