| 摘要 |
PURPOSE:To reduce fricitional resistance for a piston as a whole and improve the mechanical efficiency of the engine by a method wherein the roughness of the surface of the cylinder is made rough at the location near the upper dead point of the piston to realize a boundary lubricating condition while the same is made smooth near the lower dead point of the piston to realize a fluid lubricating condition. CONSTITUTION:The surface of the cylinder 2 is formed so as to have a part 2a, having a rough surface roughness and located near the upper dead point of the piston wherein a piston speed is small and the pressure of gas in a combustion chamber is high, and the other part 2b, having a smooth surface roughness and covering an area from the center of the cylinder to the vicinity of the lower dead point of the piston wherein the piston speed is increased and the pressure of the gas is reduced. Further, the intermediate part thereof is formed as another part 2c. According to this constitution, the lubricating condition is brought into the boundary lubricating condition near the upper dead point, a mixed lubricating condition at the intermediate part, and the fluid lubricating condition near the lower dead point, therefore, said conditions are adapted to respective lubricating conditions determined in accordance with the piston speed as well as the pressure of the gas and the frictional resistance may be reduced as a whole. |
