Blow-by gas inlet structure of oil separator for internal combustion engine

1. An internal combustion engine comprising a blow-by gas inlet structure of an oil separator and a cam chamber, the blow-by gas inlet structure placed above the cam chamber, the blow-by gas inlet structure comprising:

a plate that forms a bottom wall of the oil separator;

a blow-by gas inlet opening that is formed in the plate;

an oil blocking structure that is provided below the blow-by gas inlet opening in a manner to divide the blow-by gas inlet opening into front and rear inlet openings through which the blow-by gas is led into the oil separator, the front and rear inlet openings being arranged in a first direction; and

a transverse rib that is provided on the oil blocking structure and extends in a second direction that is perpendicular to the first direction,

the oil blocking structure comprising:

a first inclined flat wall that faces the front inlet opening while being inclined relative to the front inlet opening;

a second inclined flat wall that faces the rear inlet opening while being inclined relative to the rear inlet opening; and

a first side wall that extends between one ends of the first and second inclined flat walls; and

a second side wall that extends between the other ends of the first and second inclined flat walls.

2. An internal combustion engine as claimed in claim 1 , in which the oil blocking structure is arranged to extend in the second direction and covers a longitudinally central portion of the blow-by gas inlet opening.

3. An internal combustion engine as claimed in claim 2 , in which the transverse rib transversely crosses a center portion of the blow-by gas inlet opening while being spaced from both the front and rear inlet openings ( 16 , 16 ) by the same distance.

4. An internal combustion engine as claimed in claim 2 , further comprising another longitudinal rib that is provided on the oil blocking structure and extends across the blow-by gas inlet opening in the first direction.

5. An internal combustion engine as claimed in claim 4 , further comprising a longitudinal rib that is provided on the oil blocking structure and extends across the blow-by gas inlet opening in the first direction.

6. An internal combustion engine as claimed in claim 1 , in which the transverse rib is integrally provided with an elongate horizontal rib that extends on and along an upper end of the transverse rib, the width of the elongate horizontal rib being larger than the thickness of the transverse rib.

7. An internal combustion engine comprising a blow-by gas inlet structure of an oil separator and a cam chamber, the blow-by gas inlet structure placed above the cam chamber, the blow-by gas inlet structure comprising:

a plate that forms a bottom wall of the oil separator;

a blow-by gas inlet opening that is formed in the plate;

an oil blocking structure that is provided below the blow-by gas inlet opening in a manner to divide the blow-by gas inlet opening into front and rear inlet openings through which the blow-by gas is led into the oil separator, the front and rear inlet openings being arranged in a first direction;

a transverse rib that is provided on the oil blocking structure and extends in a second direction that is perpendicular to the first direction; and

first and second longitudinal ribs that are provided on the oil blocking structure and extend across the blow-by gas inlet opening in the first direction,

the oil blocking structure comprising:

a first inclined flat wall that faces the front inlet opening while being inclined relative to the front inlet opening;

a second inclined flat wall that faces the rear inlet opening while being inclined relative to the rear inlet opening; and

a first side wall that extends between one ends of the first and second inclined flat walls; and

a second side wall that extends between the other ends of the first and second inclined flat walls.