| 摘要 |
PURPOSE:To improve the service life of a cylinderhead by casting-in the foamed metal having the thermal expansion coefficient smaller than that of the casted material, along the wall surface of the upper inner wall of a combustion chamber, in the cylinderhead of an internal-combustion engine. CONSTITUTION:In a cylinderhead, each upper inner wall 1 of a combustion chamber S is formed. A suction port 2, exhaust port 3, and an installation hole 4 for spark plug are opening-formed onto said upper inner wall 1. The fire contact surface 10 as the wall surface of the upper inner wall 1 and the inside part leading to a prescribed thickness are formed by a composite material A containing the foamed metal 11 casted. The thermal expansion coefficient of said composite material A is kept small. Since the composite material A suppresses the thermal expansion and contraction of the wall surface of the upper inner wall, the between-valve split can be suppressed, and the service life of the cylinderhead can be improved. |
