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A crankcase ventilation system (CVS) removes unwanted gases from the crankcase of an internal combustion engine. The system usually consists of a tube, a one-way valve and a vacuum source (such as the inlet manifold). The unwanted gases, called "blow-by", are gases from the combustion chamber which have leaked past the piston rings. Early ...
Chevrolet went so far as to carry the positive crankcase ventilation system (PCV) over to the cross-ram induction system to retain emissions compliance mandated for U.S.-produced cars beginning in 1967, that also provided full-throttle crankcase pressure venting to the intake air to burn its vapors.
This is known as a positive crankcase ventilation system, in which the gases are burned with the fuel/air mixture. The intake manifold has historically been manufactured from aluminium or cast iron, but use of composite plastic materials is gaining popularity (e.g. most Chrysler 4-cylinders, Ford Zetec 2.0, Duratec 2.0 and 2.3, and GM's Ecotec ...
The first effort at controlling pollution from automobiles was the PCV (positive crankcase ventilation) system. This draws crankcase fumes heavy in unburned hydrocarbons – a precursor to photochemical smog – into the engine's intake tract so they are burned rather than released unburned from the crankcase into the atmosphere. Positive ...
If these gases accumulated within the crankcase, it would cause unwanted pressurisation of the crankcase, contamination of the oil and rust from condensation. [8] To prevent this, modern engines use a crankcase ventilation system to expel the combustion gases from the crankcase. In most cases, the gases are passed through to the intake manifold.
Manifold vacuum, or engine vacuum in a petrol engine is the difference in air pressure between the engine's intake manifold and Earth's atmosphere.. Manifold vacuum is an effect of a piston's movement on the induction stroke and the airflow through a throttle in the intervening carburetor or throttle body leading to the intake manifold.
Diagram of a crankcase scavenged valveless 2-stroke engine in operation. Some SI engines are crankcase scavenged and do not use poppet valves. Instead, the crankcase and the part of the cylinder below the piston is used as a pump. The intake port is connected to the crankcase through a reed valve or a rotary disk valve driven by the engine. For ...
EGR has nothing to do with oil vapor re-routing from a positive crankcase ventilation system (PCV) system, as the latter is only there to reduce oil vapor emissions, and can be present on engines with or without any EGR system. However, the tripartite mixture resulting from employing both EGR and PCV in an engine (i.e. exhaust gas, fresh air ...