Crankcase Ventilation

C. B. Tracy and W. W. Prank, Fuels, Eubricants, andPositive Crankcase Ventilation System, SAE PT112, 451, Society of Automotive Engineers, Warrendale, Pa., 1963—1966. 

Crankcase emissions in the United States have been effectively controlled since 1963 by positive crankcase ventilation systems which take the gases from the crankcase, through a flow control valve, and into the intake... 

Figure 31-1 shows a cross sechon of a gasoline engine with the positive crankcase ventilation (PCV) system. 

Sparked in large part by this first research on fuel utilization, the petroleum and automotive industries set to work on the problem—the petroleum industry to provide separate summer and winter grade fuels having higher over-all volatility, the automotive industry to provide less critical engines by means of crankcase ventilating systems and better thermostatic control of engine temperatures. 

Blow-by losses have been virtually eliminated in recent model year cars by the compulsory fitting of positive crankcase ventilation (PCV) valves. To estimate blow-by rates from vehicles in a particular area, we must refer to the laws concerning PCV devices in that area. Estimates of blow-by rates from various vehicles are given in Reference 51. Evaporative emissions are diflBcult to measure and only gross estimates may be made (see, for example, Reference 52). 

Crankcase ventilation is even more important for hydrogen engines than for gasoline engines. 

In the second case, the "curing" or "clean up approach, various techniques have been evolved to reduce the emission closed crankcase ventilation systems, exhaust afterburning, catalytic converters, etc, whereby the control systems, and the technology, become more complex. 

Figure 4.7. PVC assembly for crankcase ventilation system preventing frost formation. [Adapted from Spix, T. A., US Patent 6,782,878, Aug. 31, 2004.1...

PVC assembly for crankcase ventilation system, pata from Spix, t a, us... 

The oil module controls and protects the oil system and ensures the correct function of the engine oil as a lubricant and heat dissipator. It combines different functions such as oil filtration, oil pressure control, cooling and crankcase ventilation. An indispensable technical requirement is that the module withstands high pressures and temperature fluctuations and is resistant to motor oil. In order to be economically justifiable, the module must be suitable for mass production. 

In the United States, measures to control the levels of automobile emissions and therefore of photochemical smog have become sophisticated since the first federal Clean Air Act of 1967. Modifications to the ICE have been extensive and included various redesigns of the combustion chamber, variations in the air-to-fuel ratio, reformulations of the composition of gasoline, the addition of the positive crankcase ventilation (PCV) valve to recirculate exhaust and underoxidized fuel gases through the combustion chambers, and the addition of carbon canisters that temporarily collect and then recirculate evaporated fuel from the gas tank and the fuel system. Some of these modifications have not always worked out as well as envisioned. For example, the 1990 modification to the Clean Air Act called for the addition of oxygenated... 

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