Some faults with insufficient power are characterized by no smoke, but the speed is gradually reduced. This kind of fault mainly occurs when the fuel supply of diesel generator set is insufficient. The cause of insufficient fuel supply of the fuel system can be analyzed and investigated. For example, the low pressure pipeline is blocked, the diesel filter is blocked, the filter screen of the fuel inlet pipe of the fuel transfer pump is dirty and blocked, the fuel tank has vacuum, the fuel supply of the fuel transfer pump is insufficient, the fuel pipe is aged and damaged, and the joint is loose and unsealed. The main failure of the high-pressure oil circuit and speed regulation part is plunger wear. The governor failure causes errors in oil volume adjustment.
Faults in the high-pressure oil circuit must be repaired by professional personnel and calibrated on the professional oil pump test bench. Due to improper assembly, the resistance increases and power is consumed, mainly in the following aspects:
(1) Axial clearance: the clearance of crankshaft, camshaft and intermediate gear shaft is too small. Adjustments shall be made as required.
A. The axial clearance of the crankshaft is adjusted by the crankshaft backstop. When the axial clearance is too small, the backstop should be thinned and adjusted. The upper and lower backstop should be placed on the same plane at the same time. Grind with the "8" shape method. The abrasive cloth should be placed flat on the flat glass or polished marble.
B. The camshaft can adjust the axial clearance by replacing the thickness of the camshaft press plate, or by grinding.
C. The axial clearance of the intermediate gear is adjusted by replacing the intermediate shaft.
(2) Fit of hole and shaft: the parts in this respect include crankshaft and main bearing. Connecting rod bushing and crank pin, camshaft and bushing, connecting rod bushing and piston pin, cylinder liner and piston, intake valve and guide tube, timing gear meshing clearance, etc. The main bearing bush and connecting rod bush adjust the fit clearance of the hole and shaft by scraping, and the connecting rod copper bushing, guide tube and camshaft bushing use standard pressure to ream the pin hole to fit the clearance (see repair for the method). When assembling the engine, lubricating oil shall be applied to all moving mating surfaces to prevent damage to components due to temporary oil shortage during starting.
The failure of the fuel system will also cause the diesel engine to be unable to emit black smoke. The fuel injection quality has a great impact on the power. After the fuel injector is replaced and cleaned again, the fuel injection pressure test should be carried out. During the fuel injection test, the fuel injection speed should be controlled at 60 times per minute. The oil nozzle shall not drop oil or deflect, and the fog column shall not be too loose, nor shall it form a linear bundle. The spray from each orifice of the perforated nozzle should be uniform, and the return oil quantity should be observed at the same time. When the return oil quantity is too large, the cause should be found out, such as assembly technology, cleanliness, etc. If there are impurities on the sealing interface between the coupling and the fuel injector, it is easy to leak high-pressure oil, reduce the injection pressure and increase the return oil.
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