Department of diesel fuel in the three pairs of dual event, the fuel injector nozzle even pieces have a special detector to test its performance, fuel plunger pump through the rotating camshaft (high-pressure oil and fuel injector connected) On the basis of touch you can know that even pieces of good and bad, without the disintegration of testing, only a valve can not be detected in the pump test, when the school is generally only the pressure of the school to open it again, as its one-way sealing, vacuum sealing ring can not be tested by the this to the fuel system fault diagnosis and maintenance work has brought many difficulties.
In the revised school pumps often work with customers to tell their diesel crude, speed instability and low-speed Knocking sound serious, but the fuel injector atomization well, other parts of the diesel engine to normal, and therefore suspect that the problem of high-pressure oil pump repair. When checking the oil pump time, governor, fuel plunger seal, a valve opening pressure Dengjun normal positioning plunger set screw and plunger adjustment locking screw ring gear and a oil valve seat are is not loose, but is significantly higher than the individual cylinder fuel. If the high-cylinder fuel transferred to normal, often fail still. If the fuel oil before adjusting the high cylinder filling valve new ones, then the fault will be fully ruled out, why?
As we all know, the oil valve is a one-way valve, and its role is to ensure that when diesel fuel reaches a certain pressure into the high-pressure tubing, at the same time prevents the high-pressure diesel fuel injection pump flows down from the high-pressure tubing, and the end of each oil, its reduction pressure ring can quickly reduce high-pressure tubing to contain diesel oil pressure, prompting the oil injector to prevent post-drop off rapidly. If a decompression valve and valve seat ring with the gap is too large, then the decompression effects of variation, residual pressure within the high-pressure pipe higher than normal. Thus, when a total of plunger upward pressure oil on the one hand a valve to the increase in diesel fuel over the other hand, decompression valve seat ring and out of the oil is too large gap between the cone top opening direct access to high-pressure pipeline, which in fact starting point is equivalent to oil in advance. If we are debugging the corresponding pump cylinder when the only transfer a small amount of oil, although it solved the problem of uneven fuel each cylinder, but the original oil tank is still the high side compared to other oil tanks in advance, so diesel engine fault can not be completely resolved, thus see that right out of the oil valve testing room is necessary.
Because we in the diagnosis of fuel system failure, not only the sights on the governor and the oil plunger and the nozzle on the pump when the school had received, be sure to check out the valve should pay attention to the quality, otherwise the problem complicated, or even can not be solved. However, there is a lack of checking out the quality of the oil valve equipment, repair shop received a high-pressure multi-purpose pressure gauge tubing connector at the same time check the quality of the plunger valve check out the quality, but only testing out the valve cone seal, which can not be Measuring know-decompression valve seat ring and matching quality. To this end, we have a simple and practical trial out of the oil valve quality inspection tool, to bring a lot of easy maintenance work, are recommended as follows. Use, the first valve into a jig, and then the tube connector 1 with the fuel injector tester on the tubing connected, through the establishment of hydraulic injector tester can be. According to our experience in the use of maintenance, requirements:
Cone sealing performance: pressure from 21MPa down to not less than 1.5MPa time 50s, otherwise there should be sealed grinding cone.
Decompression ring sealing performance: first with the screw will come out jack up the oil valve from the valve seat 0.3mm, the pressure from 21MPa down 2MPa time not less than 3s, or scrapped.