Basic knowledge of diesel generator set
2021-07-24
1. Maintenance of fuel injector
In the long-term work, due to the combined action of scouring of high-pressure oil, grinding of mechanical impurities and seating of pressure spring, the matching surface of needle valve and valve body will be worn, resulting in leakage before oil injection and oil dripping after oil cut-off, resulting in poor atomization, incomplete combustion, sharp increase of soot and serious carbon deposition. Therefore, the fuel injector must be maintained regularly.
(1) Remember the cylinder sequence of each fuel injector during disassembly
Remove the fuel injectors from the cylinder head for simple external cleaning, and then disassemble, inspect and assemble them one by one to prevent the same parts of different fuel injectors from mixing with each other during assembly. The specific steps are as follows: first clamp the nozzle hole of the fuel injector down on the bench vice, remove the protective cap of the pressure regulating screw, the pressure regulating screw and the spring, and clean them. After removing the fixing screw sleeve of the fuel injector on the bench clamp for necessary inspection, loosen the fixing screw sleeve of the fuel injector.
(2) The inspection is divided into visual inspection and sliding test
Visually check that the mating surface of needle valve and valve body shall be free of burning or corrosion; The needle shaft of the needle valve shall not be deformed or otherwise damaged. During the sliding test, the valve body must be tilted about 60 degrees, the needle valve shall be pulled out about 1 / 3 of the stroke and released, and the needle valve shall be able to slide smoothly by its own weight; Rotate the needle valve position and repeat the above operations. If the needle valve can not slide smoothly at any position, replace the needle valve coupling.
(3) Assemble
Clean the body and its oil passage, and assemble the pressure regulating spring and pressure regulating screw together. Note that the pressure regulating screw shall not be tightened too tightly, so as to facilitate exhaust and overall cleaning during later performance inspection. Put the available or replaced needle valve coupling parts in a plastic basin with clean diesel oil, and swim the needle valve back and forth for thorough cleaning. Fix the pressure regulating part of the fuel injector (should be at the bottom) on the bench vice, buckle the needle valve coupling on the joint surface according to the positioning requirements, then tighten the fastening screw sleeve of the coupling, and then conduct the following performance inspection.
2. Performance check of fuel injector
Check the fuel injection pressure and atomization condition of the fuel injector on the tester of the fuel injector. The tester is composed of manual oil pump, pressure gauge and oil storage tank. The diesel in the oil tank enters the manual oil pump, and the pressurized high-pressure diesel enters the fuel injector and sprays in a fog.
During inspection, loosen the pressure regulating screw on the fuel injector, install the fuel injector on the tester, and repeatedly press the handle on the tester up and down to make the fuel injector and high-pressure oil pipe fully filled with diesel. Then slowly press the handle and observe the reading of the oil pressure gauge at the same time. When the reading begins to drop, it is the opening pressure of the fuel injector, and its value shall meet the standard requirements.
In the long-term work, due to the combined action of scouring of high-pressure oil, grinding of mechanical impurities and seating of pressure spring, the matching surface of needle valve and valve body will be worn, resulting in leakage before oil injection and oil dripping after oil cut-off, resulting in poor atomization, incomplete combustion, sharp increase of soot and serious carbon deposition. Therefore, the fuel injector must be maintained regularly.
(1) Remember the cylinder sequence of each fuel injector during disassembly
Remove the fuel injectors from the cylinder head for simple external cleaning, and then disassemble, inspect and assemble them one by one to prevent the same parts of different fuel injectors from mixing with each other during assembly. The specific steps are as follows: first clamp the nozzle hole of the fuel injector down on the bench vice, remove the protective cap of the pressure regulating screw, the pressure regulating screw and the spring, and clean them. After removing the fixing screw sleeve of the fuel injector on the bench clamp for necessary inspection, loosen the fixing screw sleeve of the fuel injector.
(2) The inspection is divided into visual inspection and sliding test
Visually check that the mating surface of needle valve and valve body shall be free of burning or corrosion; The needle shaft of the needle valve shall not be deformed or otherwise damaged. During the sliding test, the valve body must be tilted about 60 degrees, the needle valve shall be pulled out about 1 / 3 of the stroke and released, and the needle valve shall be able to slide smoothly by its own weight; Rotate the needle valve position and repeat the above operations. If the needle valve can not slide smoothly at any position, replace the needle valve coupling.
(3) Assemble
Clean the body and its oil passage, and assemble the pressure regulating spring and pressure regulating screw together. Note that the pressure regulating screw shall not be tightened too tightly, so as to facilitate exhaust and overall cleaning during later performance inspection. Put the available or replaced needle valve coupling parts in a plastic basin with clean diesel oil, and swim the needle valve back and forth for thorough cleaning. Fix the pressure regulating part of the fuel injector (should be at the bottom) on the bench vice, buckle the needle valve coupling on the joint surface according to the positioning requirements, then tighten the fastening screw sleeve of the coupling, and then conduct the following performance inspection.
2. Performance check of fuel injector
Check the fuel injection pressure and atomization condition of the fuel injector on the tester of the fuel injector. The tester is composed of manual oil pump, pressure gauge and oil storage tank. The diesel in the oil tank enters the manual oil pump, and the pressurized high-pressure diesel enters the fuel injector and sprays in a fog.
During inspection, loosen the pressure regulating screw on the fuel injector, install the fuel injector on the tester, and repeatedly press the handle on the tester up and down to make the fuel injector and high-pressure oil pipe fully filled with diesel. Then slowly press the handle and observe the reading of the oil pressure gauge at the same time. When the reading begins to drop, it is the opening pressure of the fuel injector, and its value shall meet the standard requirements.