Positive Crankcase Ventilation

Positive Crankcase Ventilation










Positive crankcase ventilation prevents hydrocarbon-enriched vapors (blow-by gases) from the crankcase from getting into the outer atmosphere. The positive crankcase ventilation system includes vent ducts in the cylinder block and cylinder head, the cyclone oil separator and positive crankcase ventilation heating.

The blow-by gases in the crankcase are drawn in by the intake manifold vacuum via:
- the vent ducts in the cylinder block,
- the vent ducts in the cylinder head,
- the cyclone oil separator and
- the positive crankcase ventilation heating system and are then introduced back into the intake manifold.

Cyclone Oil Separator







The cyclone oil separator is in the cylinder head cover. Its main function is to separate oil from the blow-by gases in the crankcase and return it to the oil circuit. A pressure regulating valve limits the intake manifold vacuum from approx. 700 mbar to approx. 40 mbar. This prevents the entire intake manifold vacuum and the internal crankcase pressure from affecting positive crankcase ventilation, thereby drawing in engine oil or damaging seals.







Function

The cyclone oil separator separates the oil from the oil vapor that is drawn in. It works according to the principle of centrifugal separation. The cyclone design of the oil separator means that the oil vapors are moved in a rotating movement. The centrifugal force that is created flings the oil onto the partition wall, where it combines to form larger drops. While the separated oil drips into the cylinder head, the gas particles are fed into the intake manifold through a flexible pipe.







Positive Crankcase Ventilation Heating







The heating element -1- is inserted in the flexible pipe connecting the cyclone oil separator to the intake manifold and prevents the incoming blow-by gases from freezing when the intake air is very cold.