| 摘要 |
A cylinder head cooling passage structure comprises: a cylinder head H1; two intake valves 22; and an exhaust valve 32. The two intake valves 22 are provided in the cylinder head H1 such that the intake valves are substantially symmetric with respect to a plane that includes a center axis a1 of a cylinder of an OHC-type engine E and is orthogonal to a crank shaft Cr. The exhaust valve 32 is provided in the cylinder head H1 such that the exhaust valve is situated on an opposite side of the intake valves 22 with respect to a plane that includes the center axis a1 of the cylinder and is in a longitudinal direction of the crank shaft Cr. Intake ports 21 associated with the intake valves 22 and an exhaust port 31 associated with the exhaust valve 32 are formed in the cylinder head H1 such that the intake ports 21 extend in a direction substantially orthogonal to the crank shaft Cr and reach one end side of the cylinder head H1 and the exhaust port 31 extends in the direction substantially orthogonal to the crank shaft Cr and reaches the other end side of the cylinder head H1. A coolant passage 10 is formed in the cylinder head H1, for passing coolant therethrough. The coolant passage 10 has a coolant inflow opening 11 formed in a bottom face of the cylinder head H1 that is joined to a cylinder block of the engine E and a coolant discharge opening 12 formed in an outer face of the cylinder head H1. A water gallery 13 is formed in the coolant passage 10 such that the water gallery 13 communicates with the coolant discharge opening 12, the coolant which has finished heat exchange with the cylinder head H1 being gathered into the water gallery 13. The water gallery 13 is formed above the intake port 21 in the direction of the center axis a1 of the cylinder.
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