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REDUCTION OF PISTON SKIRT FRICTION USING THE MICRO-SCALE PATTERNED SURFACE
강종대,이종훈,김동립,박성욱 한국자동차공학회 2023 International journal of automotive technology Vol.24 No.1
The purpose of this study is to determine whether piston friction can be reduced by applying a micro-pattern to the skirt portion of the piston, which accounts for the largest proportion of engine parts. The roughness of the ready-made pistons was reduced before etching the micro-scale pattern onto the piston skirt. The micro-patterns were screen-printed on the piston skirt, and kept uniform through etching. The friction reduction effect of the piston was confirmed through an engine experiment using a 1.6 L four-cylinder gasoline engine to remove parts. A hexagonal shape that is representative of bionic textures was selected for the micro-pattern, and circular and cross-hatch patterns were additionally produced for comparison. The friction experiments with the patterning pistons confirmed that friction was reduced by up to 6.74 % by adjusting the spacing of the hexagonal pattern. It was also confirmed that friction was reduced in the cross-hatch pattern by up to 5.28 %. The friction reduction effect may vary depending on the parameters used for a specific pattern.
강종대,조진우,Sung Wook Park 한국자동차공학회 2023 International journal of automotive technology Vol.24 No.2
In this study, the floating liner method is utilized to measure the friction generated in the piston assembly of a single-cylinder gasoline engine. The piston assembly is subjected to combustion pressure, lubricating friction, and asperity friction during engine operation and reciprocates within the cylinder. Therefore, the main goal of this study is to investigate the effect of engine combustion and lubricant conditions on piston friction. First, we analyze how the combustion pressure, obtained by changing the combustion load and the ignition timing, affects piston friction. Second, by adjusting engine speed and coolant/oil temperature, we analyze how each condition affects piston friction. Through the experiments for each case, it was confirmed that the friction increased as the combustion pressure increased under the same lubrication conditions. It was also confirmed that the piston friction was significantly measured due to the increase in lubrication friction as the engine speed increased. Finally, it was confirmed that as the temperature decreased, the oil viscosity increased, resulting in a large friction loss.
가솔린 엔진에서 연료 분사량 및 오일 온도에 따른 피스톤 마찰손실 특성 연구
강종대,조진우,박성욱 한국분무공학회 2022 한국액체미립화학회지 Vol.27 No.3
To measure the change in friction loss due to the control of fuel mass and oil temperature in a gasoline engine, the floating liner method was used to measure the friction generated by the piston of a single-cylinder engine. First, to check the effect of combustion pressure on friction, the friction loss was measured by adjusting the fuel mass. It was confirmed that the friction loss increased as the fuel mass increased under the same lubrication conditions. In addition, it was confirmed that the mechanical efficiency decreased as the fuel mass increased. Next, to check the effect of lubrication conditions on friction, the friction loss was measured by controlling the oil temperature. It was confirmed that friction loss increased as the oil temperature decreased at the same fuel mass. As the oil temperature decreases, the viscosity increases, resulting in decreased mechanical efficiency and increased friction loss.