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How to solve the poblem of diesel engine’s unstable speed?

How to solve the poblem of diesel engine’s unstable speed?

Normllay, we will meet the unstable engine speed when running diesel generator. “Traveling car” is a common name for unstable engine speed. When the engine is running, although the accelerator is fixed at a certain position, the engine speed still changes periodically in a large range, and it takes a long time to increase the speed during adding the loading. The power is insufficient, it takes a long period of time to reduce the speed after remove the loaded machines. That is, the acceleration or deceleration response is slow, the speed does not change in time, and the engine is weak.

What is reason of this problem?
The essence of the unstable engine speed is the deterioration of the speed regulation function. The main reason is that the resistance of the internal moving parts of the fuel injection pump and the governor is too large or the matching gap is too large, which reduces the sensitivity of the governor, and the change in circulating fuel supply lags behind the change in speed. The reasons are as follows:
The fuel injection pump oil volume adjustment lever, that is, the rack movement is not flexible.
The axial clearance of the camshaft of the fuel injection pump is too large.
The clearance between the fork fixed on the fuel injection pump adjustment rod and the adjustment arm is too large, and the clearance between the oil volume adjustment rack and the gear ring is too large.
The oil supply adjustment rod and fork, gear ring and plunger rotating sleeve are loose or deformed, which prevents timely adjustment of the circulating oil supply.
The oil inside the governor is too dirty, too little or too thick.
The moving parts in the governor are matched too tightly and the resistance is large.
The joints of the moving parts in the governor are worn out and loose.
The governor spring is deformed or broken.
The retracting and opening distance of the governor fly hammer is inconsistent.

How to check if this problem and how to solve this kind of problem?
First, check whether the oil in the governor is too little, too dirty or too sticky. If the amount of engine oil is insufficient, dirty, or sticky, check the cause of the fault and eliminate it.
If the quantity and quality of the engine oil meet the requirements, you can remove the inspection window cover of the fuel injection pump, and pinch the oil quantity adjustment rod or gear rod by hand. Move the rod or gear rod forward and backward to check its tightness. Yu-type pump. If the movement resistance of the oil adjustment lever is large, it means that the lever or the toothed rod is too tightly matched with the supporting hole or is bent or deformed or strained or rusted or blocked by foreign objects, and the movement is not flexible. The governor cover should be removed, the oil volume adjustment lever, that is, the gear rod and the governor should be disconnected, and then further confirm the oil volume adjustment lever movement resistance. If the resistance is still large, it means that the aforementioned inspection is correct and should be disassembled and eliminated. If it can move freely back and forth in a small range, it means that the tie rod, that is, the gear rod is bent and deformed, and the ring gear is deformed, should be replaced for repair or correction. If the lever moves freely after being disconnected from the governor, it means that the fault lies in the governor.
If you pinch the oil volume adjustment lever to move flexibly back and forth, it means that the clearance of the mating parts is too large or the fixing screws are loose. If you move the pull rod or gear rod back and forth, pinch the fork or gear ring with one hand and feel relative movement, indicating that the screw is loose and should be tightened. Too large tooth gap between the gear rod and the ring gear can also cause “traveling”.
If the above inspection results are normal, it means that the connection points of the governor are loose, such as the connection point of the fly hammer pin hole, the tie rod, or the gear rod, and the connection point of the speed control lever.
Check whether the governor spring is deformed, and whether the retracting distance of each fly hammer is consistent. Otherwise, it should be adjusted until the retracting distance of the corresponding flying hammer is equal.
Finally, check the camshaft axial clearance.

That is all the content about the diesel engine’s unstable speed.