Cylinder head

A cylinder head comprising:

• a cylinder head body fixed to an upper surface of a cylinder block;
• and
• a camshaft housing fixed to an upper surface of the cylinder head body, wherein
• a camshaft is accommodated in the camshaft housing,
• the camshaft housing includes
• two longitudinal frame bars, which extend in an axial direction of the camshaft, and
• a plurality of lateral frame bars, which extend between the longitudinal frame bars,
• a bearing portion is arranged in an upper surface of each of the lateral frame bars to rotationally support the camshaft,
• each of the bearing portions is a portion recessed from the upper surface of one of the lateral frame bars,
• a bolt hole is provided in each lateral frame bar to receive a bolt that is inserted through the bolt hole to fix the camshaft housing to the cylinder head body,
• each of the bolt holes extends through one of the lateral frame bars and is arranged on an outer side of the corresponding bearing portion in a longitudinal direction of the lateral frame bar,
• the longitudinal frame bars each have a plurality of joint points at which the longitudinal frame bar is joined to the corresponding lateral frame bar, and
• each longitudinal frame bar includes, between adjacent two of the joint points, a vibration reducing portion, wherein a cross-sectional area of a cross section of the vibration reducing portion that is perpendicular to a longitudinal direction of the longitudinal frame bar gradually changes in the longitudinal direction of the longitudinal frame bar.