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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 ...
The crankcase often forms the upper half of the main bearing journals (with the bearing caps forming the other half), although in some engines the crankcase completely surrounds the main bearing journals. An open-crank engine has no crankcase. This design was used in early engines and remains in use in some large marine diesel engines.
In a wet-sump engine, oil slosh against spinning parts causes substantial viscous drag which creates parasitic power loss. [5] [6] A dry-sump system removes oil from the crankcase, along with the possibility of such viscous drag. More complex dry-sump systems may scavenge oil from other areas where oil may pool, such as in the valvetrain.
Oil sludge or black sludge is a gel-like or semi-solid deposit inside an internal combustion engine, that can create a catastrophic buildup. It is often the result of contaminated engine oil and occurs when moisture and/or high heat is introduced to engine oil.
Crankcase dilution occurs when the fuel oil from the engine gets into the lube oil of the engine. This can be caused by the walls being wetted due to the fuel condensing in the cylinder. If the engine is cold, or there is an excess amount of cooling around the cylinder, [ 1 ] the fuel oil will condense and have a higher chance to end up in the ...
Crankshaft, pistons and connecting rods for a typical internal combustion engine Marine engine crankshafts from 1942. The crankshaft is located within the engine block and held in place via main bearings which allow the crankshaft to rotate within the block. [3] The up-down motion of each piston is transferred to the crankshaft via connecting ...
Day cycle engines are crankcase scavenged and port timed. The crankcase and the part of the cylinder below the exhaust port is used as a pump. The operation of the Day cycle engine begins when the crankshaft is turned so that the piston moves from BDC upward (toward the head) creating a vacuum in the crankcase/cylinder area.
Unlike a four-stroke engine, the crankcase of which is closed except for its ventilation system, a two-stroke engine uses the crankcase as part of the induction tract, so oil must be mixed with gasoline to be distributed throughout the engine for lubrication. [1] The resultant mix is referred to as premix or petroil. [2]