| 摘要 |
PURPOSE:To make an engine compact, by integrally forming a cylinder with a cylinder head, and integrally forming a crank case, a water jacket and a skirt guiding cylindrical portion together, thus constructing a cylinder block from substantially two divided members. CONSTITUTION:The cylinder block has a two-divided structure consisting of an upper body 1 and a lower body 7. The upper body 1 comprises a cylinder head portion 3 and a main cylinder portion 2 continuously extending from a water jacket portion 4 of the cylinder head portion 3. The lower body 7 comprises a crank case 8, a water jacket outer wall 9 and a skirt guiding cylindrical portion 10 integrally formed together. In assembling the upper and lower bodies 1 and 7, the main cylinder portion 2 and the cylindrical portion 10 are aligned and registered in inner and outer diameters. A joint surface of the main cylinder portion 2 and the cylindrical portion 10 is set at a position such that when a piston 14 comes to a bottom dead center 14', a skirt guide portion 41 of the piston 14 is located beyond the joint surface. |
