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Abnormal wear and prevention of oil outlet valve of diesel engine (DIESELPARTSWORLD)       
2015-12-27   

Diesel engine fault causes more, but mostly concentrated in the fuel supply system, in which the fuel injection pump caused the fault is the most, and the oil valve wear, is one of the main causes of injection pump work is bad. Many machine hand because they did not understand the oil valve working principle and wear after the consequences, even rather than replace 10 times plunger vice, not changing a valve, the engine power and economic indicators declined.

1 out of the normal working principle of the oil valve
In the plunger pump oil stroke, high pressure fuel to overcome the oil valve spring pressure and fuel residual pressure in the fuel pipe, the oil valve to push upward to leave the seat, diesel oil will be from the oil valve slot medium pressure to high pressure tubing, when the plunger down, due to the pressure and the pressure of the oil chamber pressure relief valve, the oil valve from the oil position back to the closed position, the stem part of the oil into the valve seat. At this time, a decompression ring valve on the plunger and the high pressure oil pipe in oil and isolation. Because the decompression zone continue to fall into the valve seat, equivalent in the high-pressure oil pipe to expand the space, so that high pressure tubing pressure decreases rapidly, oil ends immediately and not cause injector drop of oil. On the other hand, valve to fall behind the seat, due to the valve seat surface of the seal, high pressure oil pipe residual fuel save some residual pressure (usually 15 to 20 kg / cm 2). Each time the fuel supply is terminated, the pressure value remains stable. In this way, the oil supply can be stabilized and the uniformity is good.
2 out of the normal wear of the consequences of the oil valve
The oil valve is precision parts, its role is to enable the injector rapid and accurate, and no oil dripping off the oil crisp. Therefore, requirements of valve sealing and vacuum ring must be matched with the valve seat is very precise. Wear is the main oil valve sealing cone and decompression ring wear, wear light guiding parts.

The closed cone wear, closed the line width, resorted to the oil seal valves. When the fuel injection nozzle does not fuel injection, the high pressure oil pipe is still oil to the plunger head. At this time, the pressure in the high-pressure oil pipe is reduced, which causes the reduction of fuel injection quantity, the lag of fuel injection time and the decrease of power.
Decompression valve seat ring and guide hole surface wear, increased clearance, decompression effect bad. So, at the end of the fuel pump oil, residual pressure in the high-pressure oil pipe is too high, up to 70 ~ 80 kg/ 2 cm. Injector off oil is not simply, and the fuel injection time in advance, a significant increase in the amount of fuel supply, engine work.
As the two parts of the oil valve wear and tear, the engine can not be quantified, timed to the role of oil, while the oil is not flat, resulting in the formation of late drops of oil.
So called post oil droplets, is refers to at the end of the fuel injection pump, due to the oil pressure relief valve ring wear serious, oil valve though, have been falling, but residual pressure in high pressure fuel pipe is still very high, resulting in slow decline of oil nozzle cavity of the oil pressure is still large, the nozzle needle valve, results at the end of the fuel injection pump, injector continues to drop of oil, so that when the next deflagration, due to the presence of oil droplets, resulting in poor atomization, poor combustion engine take black smoke, power down, combustion chamber deposits.
3 out of the oil valve is not normal wear prevention
A pair of valve clearance is only 0.009 ~ 0.016 mm is thinner than a human hair. A valve is not normal wear, mainly due to the fuel in the water and impurities in the oil valve guide cylinder surface and vacuum ring of the gap of oil valve core and valve seat produce rust and scratch caused by. Therefore, to extend the service life of the oil valve, it is necessary to ensure that the fuel clean, no water, no impurities. Before refueling, do a good job in precipitation filtration, try to use the seal gas method. All oil and gas containers and equipment must be kept clean.
If the oil valve wear lighter, can use gasoline to clean first, and then coated with oil, repairing and grinding; if serious wear and tear, the sealing cone appear too wide grooves, cracks or contact belt must be replaced and must be replaced in pairs.