Cylinder head of internal combustion engine

摘要

A cylinder head (1) includes a water jacket (4) formed around an ignition plug mounting hole (5). Upper surfaces (12 to 14) of portions of the water jacket (4) between intake and exhaust ports (7, 8) and the ignition plug mounting hole (5) are formed lower than upper surfaces (15 to 17) of other portions of the water jacket (4) around the ignition plug mounting hole (5) so as to obtain increased rigidity. In this way, deformation of the cylinder head (1) due to cylinder internal pressure is prevented, and the concentration of stress around the ignition plug mounting hole (5) due to such deformation is reduced.