| 摘要 |
PURPOSE:To improve the combustion efficiency by permitting the uniform and speedy temperature rise of a surface part by forming a high thermal conductivity layer onto at least a part of the surface part faced to a combustion chamber in the piston head part made of ceramics. CONSTITUTION:A piston is made of silicon nitride and equipped with a piston head part 10 having a combustion chamber at the center part, side surface part 20 which moves in sliding with the cylinder inner wall surface, and a hollow part 30 for holding a connecting rod. With such structure, each high thermal conductivity layer made of the pure copper in the uniform thickness of 2mm is formed onto all the surfaces of the side wall part 101 and bottom wall part 102 of a combustion chamber through plasma metallization. At this time, the high thermal conductivity layer is made of the material having the thermal conductivity higher than that of the ceramics which forms the piston. Therefore, the uniform and speedy temperature rise of the surface part is achieved. |
