Study on Tribological Properties of Laser-Textured Plunger in Methanol Engine

Considering the eccentricity and deformation of the plunger, a lubrication model of laser-textured plunger pair was established to research friction-and-wear performance of typical surface texture on the plunger under diesel and methanol lubrication. The calculation results show that for the non-textured plunger, the oil film thickness and fluid friction under methanol lubrication are lower than diesel lubrication, and the asperity friction was greater than diesel lubrication, indicating that methanol may deteriorate the lubrication performance of the plunger surface. After texturing the plunger, the oil film thickness and fluid friction during methanol lubrication are greater than the non-textured scheme, and the asperity friction is lower than the non-textured scheme, which means that the surface texture has the potential to improve the lubrication performance of the plunger. The friction and wear tests results indicate that the average friction coefficient of the textured plunger is reduced by 3.4 ∼ 6.2 % compared with the non-textured plunger in methanol lubrication. The lubrication performance of the textured plunger during methanol lubrication reaches the level of the non-textured plunger in diesel lubrication. After the wear test, the surface wear depth of the textured plunger is reduced by 16.2 % compared with the non-textured plunger in methanol lubrication condition.