| 摘要 |
PROBLEM TO BE SOLVED: To provide an internal combustion engine capable of forming a heat insulation film on a wall surface of a cylinder head near an opening portion of an intake port for a combustion chamber while improving a relation between a swirl ratio and a flow coefficient of the intake port.SOLUTION: An internal combustion engine comprises a tangential port 22 and a helical port 24 connected to a common combustion chamber 12 for forming a swirl flow. A wall surface around an opening portion 34 of the tangential port 22 includes a first cutter part 42 in a region downstream, in an intake flow direction, of a first valve seat section 36. A wall surface around an opening portion 38 of the helical port 24 includes a second cutter part 44 in a region downstream, in the intake flow direction, of a second valve seat section 40. Heat insulation films are formed on respective surfaces of the first cutter part 42 and the second cutter part 44. A surface roughness of the heat insulation film formed on the surface of the first cutter part 42 is lower than that of the heat insulation film formed on the surface of the second cutter part 44.SELECTED DRAWING: Figure 5 |
