Abstract
In reciprocating internal combustion engines, the gas that leaks at the piston, rings and liner system is usually called blow-by. The blow-by is a complex mixture of air, burned and unburned gases and oil mist. In order to avoid external pollution, the blow-by is recycled in the air intake system (AIS). This is called Closed Crankcase Ventilation (CCV). The CCV is the cause of major issues such as air intake system fouling, oil consumption and participates in the exhaust catalyst poisoning phenomena. During recent decades a quite simple oil separation system based on baffles was acceptable. Emission regulations are now tougher and a more efficient blow-by separation system is required.
A suitable and efficient means to achieve a good separation is to use the coalescence principle through a specific media. Static coalescing separator is a good compromise between separation efficiency, pressure drop and cost.
To respect the majority of customer specifications, the most interesting technical solution is to use a rotating coalescing separator. Crankcase pressure is negative for all engine working conditions and efficiency is very high even for thin oil mist generated at max torque and max power. With this rotary blow-by coalescer, oil consumption is reduced and so exhaust catalyst poisoning is reduced. It permits us to make potential savings on vehicle fuel consumption and post-treatment systems value.
KEYWORDS: Blow-by, CCV, engine, coalescing separator, post-treatment.