Reasons for the failure of exhaust circulating in crankcase of diesel generator set

- May 17, 2017 -

Diesel engine work, the crankcase ventilation, in the air intake stroke, will cause the combustion chamber negative pressure too much (far lower than the crankcase pressure), and make a large number of lubricating oil into the combustion chamber, generating a large amount of carbon accumulation in the combustion chamber and piston rings and other regions. At the same time, high temperature of the exhaust gas accumulation in the crankcase, but also causes the lubricating oil and crankcase to the piston ring range of the body temperature is too high, accelerating the oxidation deterioration of lubricating oil. The soluble solid oxide oxidized in lubricating oils, under the catalysis of high temperature hypoxia and metals, the complex oxide and unsaturated synthetic lacquer mixture surfaces adhere to the surface of the part, further and the carbonization of combustible mixture oxidation condensation into the paint film, attached to the crankshaft inside the surface and the connecting rod, piston skirt and piston pins and other parts of the surface. The higher the temperature of the body and lubricating oil, the more paint films are produced. Moreover, excessive oil temperature will cause the lubricating oil to dilute, evaporate, become granular oil mist, through the ventilation tube is inhaled into the combustion chamber;

When the body temperature is too low, channeling into the crankcase exhaust gas and unburned oil and gas, condensation after the formation of acidic material surface deposition in lubricating oil, further oxidation and deterioration of lubricants and corrosion wear. Moreover, some high-boiling components of exhaust gases and water vapor condensation with lubricating oils, also make lubricating oil and non-combustion oil and gas in the liquid-phase oxide further condensation, forming viscous substances. These viscous substances further with the crankcase solid matter, water vapor, carbon ash, abrasive and lubricants of the oxide bonded together to form sludge, deposited in the oil pan, lubricating oil and filter network, resulting in blockage of oil.

The data show that in recent years the high-hardening, high-compression ratio and the use of fuel Direct injection (DGI) and oil-bottom shell of small volume of diesel engines, if the crankcase ventilation is not smooth, but also will cause the viscosity increase, the increase in oxygen content and acid value increased, resulting in the lubricating oil smoke idle (a carbon-like sediment, generally colloidal suspended in lubricating oil) generation.

In addition, the exhaust gas in the crankcase is not circulating or circulating, but also can cause the diesel engine idling instability, exhaust gas abnormal, power drops, fuel consumption increase and hot start-up difficulty.

The main factors influencing the exhaust gas in the crankcase or the non-exhaust are: one-way flow control damage or open card lag; ventilation and sag blockage, gas oil (water) separator blockage, and connection hose aging caused bonding.

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