2018 年 63 巻 6 号 p. 402-407
The friction regime between the piston ring and the cylinder liner in marine diesel engines changes from fluid film lubrication at mid-stroke to boundary lubrication near dead centers. As the lubrication conditions of large two-stroke engines become more severe with increasing the mean effective pressure and the piston speed, the prevention of severe wear and scuffing has become important issues. The temperature of the cylinder liner also tends to increase, keeping the sulfuric acid above its dew point to reduce corrosive wear. This manuscript describes the lubrication characteristics of the piston rings in marine diesel engines. The effect of the total base number (TBN) of the cylinder oil on the scuffing resistance is evaluated. The measures to prevent abnormal wear and scuffing are also described. The on-line monitoring to detect severe lubrication conditions is effective for enhancing durability and reliability of marine diesel engines.