Diesel generator sets have the advantages of compact structure, large power reserve, stable operation, good speed regulation performance, low fuel consumption, low emissions, and low noise, and are widely used in military, civilian, marine and other fields. The fuel consumption rate and lubricating oil consumption rate are far superior to similar domestic products; However, some users have reported poor atomization of the fuel injectors in the unit. The following is an introduction to the problem of poor atomization of the fuel injectors and the corresponding solutions.
Fuel atomization is the process in which the fuel injection pump increases the pressure of the fuel and delivers it to the annular chamber of the fuel injector. When the volume of the annular oil gun is constant, due to the continuous increase of fuel, its density correspondingly increases, and the pressure continues to increase. When the fuel pressure is greater than the injection pressure of the fuel injector, it overcomes the pre tightening force of the spring and pushes the needle valve open, rapidly injecting fuel into the combustion chamber. The fuel injected into the combustion chamber expands and diffuses violently, forming a mist, which is called atomization. Poor atomization of fuel injectors refers to the quality of fuel atomization sprayed by the injectors not meeting the specified requirements. Poor atomization of the fuel injector can make it difficult to start the diesel engine, increase fuel consumption, and reduce power. The smoke color turns white during startup or low load, and black during medium and high load. If the atomization is extremely poor, even dripping oil, it can cause overheating and cylinder knocking of the diesel engine.
1. Fault phenomenon
The external manifestations of poor atomization of the fuel injector (fine injection lines or oil droplets) are: high temperature of the diesel engine, weak operation, and knocking sound from the upper part of the cylinder. The exhaust pipe emits black smoke, and some unburned diesel continues to burn, accompanied by a crackling sound.
2. Cause analysis
As can be seen from the above, poor atomization of the fuel injector is mostly caused by the fuel pressure entering the annular oil chamber of the fuel injector being lower than the starting fuel injection pressure and excessive fuel viscosity specified in the technical documents.
3. Maintenance methods
Use the comparison method to adjust the atomization quality of the fuel injector. In the absence of a fuel injector test bench, the comparison method can also be used to adjust the atomization quality of the fuel injector. On the two high-pressure oil pipes of the fuel injection pump, one is equipped with a new fuel injector (the new fuel injector generally has adjusted the injection pressure and good atomization quality) as the standard, and the other is equipped with a fuel injector to be inspected and adjusted. Do not install both fuel injectors inside the cylinder head to ensure that the injection directions of the two injectors are consistent for comparison.
If the fuel injection beam of the fuel injector being checked is too thin or does not spray, it indicates that the injection pressure is too high. If the fuel injection is weak and the fuel beam is scattered, it indicates that the fuel injection pressure is too low. At this point, it is necessary to adjust the fuel injection pressure to match the atomization situation of the new fuel injector. After adjusting the fuel injection pressure, if the atomization situation still does not improve, it can be repaired or scrapped according to the corresponding methods.
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