Compared with gasoline vehicles, diesel vehicles have the advantages of strong power, good economy, high reliability, and low failure rate. However, there are also problems with high smoke emission and serious environmental pollution, which have been highly valued by the community.
To solve the above problems, most users adopt the method of adding additives to the fuel. Although the degree of smoke is reduced, there are still some problems. The most ideal method should start from improving the technical condition of the diesel engine so that it can work under the best conditions, thereby greatly reducing the exhaust fumes and achieving the goal of treating the symptoms.
1, exhaust management continuous smoke
This is caused by incomplete combustion of all or most of the cylinders of the engine. The reasons include the serious deterioration of the injection quality of the injector, the serious wear of the piston ring and the cylinder wall, the increase of gas leakage, the contamination of the air filter, the late start of the oil supply, and the severe wear of the valve drive mechanism, which opens the valve. The height is reduced and the time is delayed, resulting in reduced air intake and unclean exhaust.
In the inspection and determination of this failure, first observe whether the discharge of smoke in the exhaust pipe is accompanied by the phenomenon of oil discharge and fire discharge. If this is the case, the injector has poor injection quality and should be removed one by one at school. Check the fuel injection on the inspection table to eliminate the malfunction. If the black smoke emitted by the exhaust pipe is accompanied by blue smoke, the oil indicator light is bright, the crankcase ventilation device nozzle is seriously smoked, and the oil consumption increases. The piston ring and the cylinder wall are seriously worn, and the cylinder pressure gauge can be used for inspection. Cylinder tightness. The compression pressure of the cylinder should not be lower than 80% of the normal pressure, otherwise the piston ring or honing cylinder should be replaced and the cylinder liner replaced. After the above check, if it is in good condition, remove the air cleaner cover, remove the filter element, start the engine, and observe whether the exhaust pipe continues to emit black smoke. If there is black smoke, it indicates that the air filter is seriously dirty. Clean the filter or replace the filter element. Otherwise, check if the start of fuel supply is too late. If the start time of the fuel supply is normal, it means that the fault is caused by the height of valve opening. In addition, improper commissioning of the fuel injection pump results in excessive fuel supply, incomplete combustion, insufficient engine cooling, and high temperatures, which can also cause the diesel engine to emit black smoke.
2, the exhaust pipe intermittent black smoke
This is due to incomplete combustion of individual cylinders in the same engine.
The specific reasons include the poor injection quality of the injectors of the individual cylinders, the serious abrasion of the piston rings and the cylinder walls, or the leakage of the valves, resulting in a decrease in the intake air volume of the cylinder and a delay in the supply of oil to the individual cylinders. At this time, the oil cut method can be used to cut off the work of each cylinder one by one by cutting off the high-pressure oil line from the fuel injection pump to the injector, and observe the change of the exhaust gas condition, find the black smoke cylinder, and observe the change of the exhaust gas condition; Then change the cylinder to a standard fuel injector and observe whether black smoke is still emitted. If black smoke disappears, it indicates that the fault is caused by poor injection quality of the injector of the cylinder; otherwise, it is caused by poor sealing of the cylinder or late supply of oil. In order to prevent diesel vehicles from emitting black smoke, the following points should be maintained during maintenance:
(1) Clean the air cleaner. The air filter is heavily contaminated, resulting in a reduction in the amount of intake air, a richer mixture, and incomplete combustion of the diesel fuel, causing black smoke in the exhaust pipe.
The oil supply system should ensure that the fuel is supplied clean and sufficiently pressurized. The tank should be cleaned periodically to remove mechanical impurities, moisture, and gels from the tank. During the primary maintenance, the filter should be cleaned, and the filter element should be replaced if necessary; check the oil supply time is correct, check the fuel injector or replace the sprayer accessories as required to ensure the injection quality. Debug the fuel injection pump to ensure that the fuel injection pump can regularly supply diesel fuel with sufficient pressure to the injector, and the start and end of the fuel supply should be rapid so as to avoid drip leakage phenomenon.
(2) Check the cylinder tightness to ensure that the cylinder has sufficient compression pressure. If the piston ring and the cylinder are seriously worn, it will cause the cylinder to blow to the crankcase box, and the compression force of the cylinder will be reduced, which will affect the effect of the mixture compression combustion, the fuel can not be fully burned, and the oil in the crankcase can also enter the combustion chamber. Cause black smoke or blue smoke in the exhaust pipe, engine power drops. The valve clearance should be adjusted properly. If the valve clearance is too large, the cylinder intake valve will not close tightly, the air leakage from the cylinder, the compression pressure of the cylinder will decrease, and the mixed air pressure combustion will be affected, causing the exhaust pipe to emit black smoke.
(3) Keep the engine operating temperature normal. If the cooling is not good or the heat dissipation is not timely, the engine will overheat, causing the engine to produce the phenomenon of pre-ignition, and the intake air volume of the engine cylinder will decrease, and the air-fuel mixture will not burn normally, resulting in black smoke emission. For water-cooled diesel engines, add enough cooling water, clean the radiator and engine water jacket regularly, and remove the scale. For air-cooled diesel engines, the air fins and the cooling fins on the cylinder block should be cleaned, and the tightness of the fan belts should be adjusted properly to ensure that the engine has good heat dissipation.
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