Dec. 22, 2021
What causes bearing bushes of generator sets damage? Diesel generator manufacturer answers for you.
1. During the normal working of diesel engine, there is a gap between the crankshaft journal and the bearing bush and there is an oil film to form liquid lubrication. In this way, friction loss is small, and the heat generated by friction is also small. The heat is taken away by the oil, and the working temperature is at normal.
2. If the bearing bush of electric generator is in direct contact with the journal to form a partial dry friction state, the frictional power consumption will increase sharply, and a large amount of frictional heat will be generated and dissipated by the bearing bush. However, the heat taken away by the oil is not much, the heat accumulates in the bearing shell, and the temperature keeps rising. When the temperature of the alloy melting point on the bearing shell surface, the bearing shell surface will begin to melt until it burns, causing the diesel engine to fail to operate.
3. Oil temperature is too high or too low
A. When the oil temperature is too low, the viscosity of the lubricating oil is too high and the fluidity is poor. Especially in the cold start state, the amount of oil entering the crankshaft is small, which is easy to make the bearing bush and the crankshaft journal directly contact, and accelerate the wear and damage of the bearing.
B. When the oil temperature is too high, the viscosity of the lubricating oil will be too low, and the strength of the oil film will be weakened, resulting in the thinning of the oil film thickness, and it is also easy to cause early wear and damage of the bearing bush. In order to fully extend the service life of the bearing, the common temperature should be kept within the range of 95~105℃. Of course, this range maybe changed due different brand of diesel engine.
C. Lubricating oil quality is poor. The generator set used inferior lubricating oil or counterfeit lubricating oil during use. If the quality of the lubricating oil does not meet the requirements of the diesel engine manufacturer, it will also cause the diesel engine to produce bush burning failures.
4. Improper bearing assembly clearance
A. To improve the lubrication status of the main bearings of the existing diesel engine and prevent burn damage, the clearance between the bearing and the crankshaft journal should be strictly controlled in accordance with the requirements of the diesel engine operation manual.
B. When replacing the bearing bush, check the roundness and cylindricity of the crankshaft journal. If it exceeds the limit, it should be ground to avoid reducing the contact area of the journal and bearing bush and increasing the pressure per unit area.
C. In addition, the axial clearance of the crankshaft should be controlled, and if the wear is excessive, it should be repaired in time.
5. Lubricant deterioration
A. Generally speaking, during the use of lubricating oil, due to the wear of diesel engine cylinder liners and piston rings, as well as changes in piston ring opening gaps and opening positions, the high temperature and high pressure combustible mixture entering the crankcase continues to increase. This not only causes the temperature of the lubricating oil to rise, but also accelerates the oxidation and polymerization of the lubricating oil.
B. At the same time, coupled with the mixing of diesel engine combustion products, the mixing of external dust, metal wear debris, and the consumption of additives in the lubricating oil, the deterioration and deterioration of the lubricating oil are greatly accelerated. This not only increases the wear and corrosion of the friction pair in the lubricating part of the diesel engine, but also causes the main reason for the burning of the bearing.
6. Bearing quality problem
If inferior materials are used, the high temperature resistance and bearing capacity of the bearing bush are insufficient, even if the oil pressure is normal and the oil volume is sufficient, it will cause bush burning failure. Therefore, when you purchasing diesel generator, you should pay attention to the quality of diesel engine.
7. Too much vibration during diesel engine operation
A. Due to shock absorption damage or other reasons, the diesel engine vibrates too much during operation.
B. It is also possible that the damping element of the diesel engine crankshaft itself is damaged, causing the diesel engine crankshaft to vibrate too much; after a long period of operation, it may cause the bearing shell to loosen, resulting in bush burning or bush slipping failure.
In short, we can not only care product price, the product quality is also very important, then regular maintenance is also very important after using diesel generators.
May. 14, 2022
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