Patent ID: 8726876

Claim:
An oil separator for an internal combustion engine, disposed inside a cylinder head cover to separate oil mist from blowby gas to be discharged out of the cylinder head cover, the oil separator comprising: a section defining an elongate separator chamber and having first and second ends, the section including a blowby gas inlet located at a side of the first end, and a blowby gas outlet located at a side of the second end; a partition wall disposed to divide the separator chamber into an inlet chamber at a side of the blowby gas inlet and an outlet chamber at a side of the blowby gas outlet, the partition wall being formed with a plurality of passage holes each piercing the partition wall; a collision plate disposed inside the outlet chamber and located opposite to the plurality of passage holes of the partition wall, the collision plate having a lower section located at a lower part of the outlet chamber, the lower section of the collision plate defining a slit-like opening that is located at the lower part of the outlet chamber and extends throughout at least a part of a width of the collision plate; a drain section configured to discharge oil separated from blowby gas from the lower part of the outlet chamber into a valve operating chamber, wherein each of the plurality of passage holes of the partition wall is triangular in cross-section, wherein each of the passage holes is shaped as an isosceles triangle in cross-section, the cross-sectional isosceles triangle having a base parallel with a lower edge of the collision plate, wherein a plurality of passage holes are aligned along a direction in which the base extends, in which the respective cross-sectional triangles of two passage holes adjacent to each other are vertically reversed to each other.