Most of the ablation of the piston top cover of diesel generators occurs in the upper end of the piston and the first and second piston ring grooves. The main forms of damage are: top surface molten hole, perforation, pit, upper end with keyway, collapse or upper end Complete ablation.
Reasons for failure: The main reasons for piston burning are as follows:
1. There is serious carbon deposit on the upper end of the piston. The carbon deposit on the piston crown causes the temperature of the upper part of the piston to be too high, resulting in high temperature weather. When part of the high temperature weather is higher than the melting point of the raw material, the upper end of the piston will melt to form a molten hole.
2. Piston ring glue will stick or crack. Bonding or cracking of the piston ring will prevent the piston ring from being in close contact with the cylinder wall, and the heat energy of the piston top will not be discharged in time. It will also cause high-temperature air to escape, leading to ablation of the piston top and ring groove.
3. Uneven oil supply. The fuel supply of each cylinder of the internal combustion engine is inconsistent with the fuel supply time. The combustion process of some cylinders deteriorates, forming carbon deposits and severe afterburning. The heat energy of diesel combustion cannot work. The temperature of the piston crown of some cylinders is too high, and the raw materials are exhausted and melted.
4. The nozzle does not work properly. When there is too much oil at the upper end of the piston, part of the temperature is too high, and the thermal stress increases. When there is too much oil at the upper end of the piston, part of the temperature is too high, the thermal stress increases, and burns.
5. The nozzle does not work normally. When the diesel generator is working, the piston crown should bear the periodic mechanical impact of the combustion explosive force, and the instantaneous impact force can reach more than 10.0 MPa. If the diesel generator runs poorly, its impact will increase. The thermal fatigue on the top of the piston and the normal combustion explosive force cause thermal fatigue and mechanical fatigue on the upper end of the piston, and finally melt and crack. However, the main reason for the rough working of diesel generators is the early fuel supply time, excessive carbon deposits in the cylinder, the compression ratio is too high, and the upper end of the piston forms a burner.
6. The oil cooling nozzle is blocked. Some diesel generators are equipped with oil cooling nozzles, which can spray oil into the piston cavity to help cool and dissipate heat. If the oil-cooled nozzle is blocked, the piston will become hot, which can easily cause the piston to burn out.
7. Diesel generators are overloaded and operated at overspeed for a long time, or diesel generators have poor heat dissipation. Long-term exposure to high thermal stress and mechanical stress can easily cause fatigue and ablation.
8. The piston is unqualified. Under high temperature and high pressure, if the piston has defects such as pores, shaking, micro cracks, and slag inclusion, some of the pores, shaking, and micro cracks will become fatigue sources and cause fatigue damage, the slag inclusion in the piston will melt first, causing the upper end of the piston to melt.
9. When the accelerator pedal is often stepped on, the diesel generator is running at high speed and heavy load, and the temperature is too high, which causes extremely hot ablation of the upper end of the piston.
10. When the air leakage in the on-board air compressor of the diesel generator and other factors cause excessive lower exhaust, a large amount of oil enters the intake pipe of the diesel generator through the exhaust pipe of the crankcase breather, and enters the combustion chamber to participate in combustion. The upper part of the piston burns.
Preventing failure: Analyzing the above-mentioned reasons for the ablation of the upper end of the piston, it can be known that the upper end of the piston is prevented from being ablated. The key points are:
1. Strengthen the maintenance of diesel generators, so that the diesel generators always maintain good technical conditions.
2. Avoid diesel generators overheating, carbon deposits and rough work.
3. Correct use to avoid long-term overloads of diesel generators.
4. In the process of diesel engine maintenance, strictly follow the technical requirements, pay special attention to the quality of fuel injectors, air compressors and other components to avoid piston ablation.
Repair method: After the upper end of the piston is melted, the fault diagnosis and treatment are similar to the pulling cylinder.
Jiangsu Starlight Electricity Equipments Co.,Ltd. is a diesel generator set manufacturer with more than 40 years of production experience. Its main brands include Yuchai generator sets, Cummins generator sets, Volvo generator sets, etc., and 64 sales and service departments nationwide. Users provide one-stop service of design, supply, debugging and maintenance. Welcome contact us by email sales@dieselgeneratortech.com
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