The following steps are taken to repair the diesel engine oil.
The return oil of the diesel engine back to the oil pipe is due to the gap between the nozzle needle valve and the needle valve of the injector, which is caused by the flow back to the oil pipe. Under normal conditions, the quantity should be very small. If a large amount of oil is found, the oil nozzle contact surface between the injector body and the nozzle needle valve body is not in contact with the oil, and the diesel will flow from this place to the fuel injection. Above the device, the back of the oil pipe is leaked out.
The reason for the failure of the light return oil of the diesel engine oil machine:
As the injector increases with working time, the gap between the needle valve and the valve body increases with the wear and tear, so the diesel oil leaks from the gap increases. Another reason is that the disassembly of the injector is not carried out according to the technical requirements, and the pressure spring is not removed first and the fuel injector fasten the screw cap. The upper end of the needle valve body is not strictly pressed with the lower end face of the injector body. In addition, the two surfaces in the assembly are not cleaned, or the fastener screw of the injector is unscrewed tightly. The sealing property of the two tight fitting ends is destroyed, and the high pressure diesel oil containing impurities is washed and leaking when working, that is, the amount of oil return can be increased.
Taking the S195 diesel engine as an example, in addition to the sudden increase in the return of the oil back to the oil pipe, the injector will only return oil only and the nozzle does not spray. At this time, if the pressure screw of the injector is loosely twisted, a little oil droplets will be sprayed out. The main reason is that the oil lateral oil channel and tappet from the high-pressure oil pipe are often on the injector body. The guiding part is perforated. The oil will not open the nozzle needle valve when the oil is downflowing, and enter the tappet guide position and then out of the oil back hole. As for the reason of the perforation, the transverse oil channel is drilled too deep in the manufacture, or is used for a long time, the high pressure diesel transversely penetrates the perforation, and connects with the tappet guide.
When testing the performance of the overhauled injector, the injector should usually be installed on the injector test bed. At this time, the injection pressure adjustment and the spray test are first carried out. The shape, direction, consistency and fine degree of oil spray in the injector are checked. At the same time, the injection nozzle should be observed or not. Accumulation of oil droplets or oil layers.
Then the pressure protection test should be carried out. Under the condition of the test diesel temperature of about 20, the pump oil handle of the pressure injector test rig. After the pressure meter reading value is 30MPa, the decline process of this value is observed. If the time of falling from 28MPa to 23MPa is less than 8s, and the end of the injector has no drop oil and oil layer accumulation, indicating the guide of the injection nozzle needle valve. If there is leakage to the part, the injection nozzle must be replaced. If the oil and oil layers are accumulated at the end of the injector, the nozzle couple is not sealed, and the new parts should be regrinded or replaced. It can be installed through the injector of the above test.
The injection quality of the injector can be judged by the following simple method when there is no special injector test bench: a pre adjusted standard injector and an inspected injector are installed on a "T" high pressure tubing. The lower end of the "T" shaped high pressure tubing is connected to the high pressure tubing joint on the upper part of the fuel injection valve. Then, try to press the fuel injection pump to make the fuel injection, and observe and compare the atomization degree.
For the 495 type diesel engine, the injector assembly and the high pressure oil pipe can be removed, and the high-pressure oil pipe can be transferred to the outside of the diesel engine body. After loading, the valve handle is moved to the maximum position and then the diesel engine is started. If the nozzle is observed at this time, a crisp noise will be issued and atomized. The fuel injector can be used normally without dropping any oil.
