In industrial production and daily life, diesel generator sets play an indispensable role. However, like all operating machinery, diesel generator sets are also subject to the inevitable phenomenon of component wear. Understanding the factors that lead to wear can not only help users to take targeted measures to reduce unnecessary wear but also effectively extend the service life of the generator set. This article will delve into the causes and types of wear in diesel generator sets, as well as how to reduce wear and ensure stable performance through proper operation and maintenance.
Wear of components in diesel generator sets during operation is an inevitable phenomenon. This wear not only affects the performance of the generator set but also shortens its service life. Therefore, understanding the causes of wear is crucial for taking effective preventive measures. The following are the main causes of wear in diesel generator sets.
The quality of diesel has a direct impact on the wear of the generator set. If diesel contains sulfur or other impurities, corrosive substances such as acids will be produced during combustion, which can accelerate the wear of the cylinder. In addition, when diesel contains too many heavy distillates, carbon deposits are likely to form after combustion. These deposits not only affect combustion efficiency but also cause abrasive wear between the piston rings and the cylinder. The viscosity of diesel is also important, as it affects the formation of the air-fuel mixture and the reliability of the fuel supply equipment. If the viscosity is either too high or too low, it will have an adverse effect on the performance of the generator set.
Lubricating oil is key to reducing mechanical wear. For diesel generator sets, the viscosity and antioxidant properties of the lubricating oil are the two most influential factors. Suitable lubricating oil can form a protective film on the friction surfaces, reducing direct metal-to-metal contact and thereby reducing wear. Therefore, users should select lubricating oil according to the operating conditions of the diesel engine and should not use it indiscriminately.
Tests have shown that the wear of diesel engines increases with the increase in speed and load. When the load increases, the unit pressure on the friction surface increases and the thermal condition deteriorates; when the speed increases, the number of friction cycles per unit time increases. In particular, at the same power level, the wear caused by increased speed is greater than that caused by increased load. However, too low a speed is also not good, as it cannot ensure good fluid lubrication conditions and will similarly increase wear. In addition, if a diesel engine frequently accelerates, decelerates, stops, and starts during operation, the frequent changes in speed and load will make the lubrication conditions and thermal state unstable, thereby increasing wear. Especially during startup, when the crankshaft speed is low and the oil pump cannot supply oil in time, combined with low oil temperature and high oil viscosity, it is difficult to establish fluid lubrication on the friction surfaces, resulting in severe wear.
Ambient temperature also has a significant impact on the wear of diesel generator sets. When the temperature is high, the engine is prone to overheating, the viscosity of the lubricating oil decreases, and the wear of the components increases. When the temperature is low, the viscosity of the lubricating oil increases, making it difficult to start the diesel engine. During operation, the cooling water cannot maintain a normal temperature, which also increases the wear and corrosion of the components. In particular, wear is more severe during startup at low temperatures.
The operating temperature of diesel generator sets is one of the important factors affecting wear. During use, due to the limitations of the cooling system structure, changes in working load and speed, and changes in ambient temperature, the operating temperature range of the diesel engine is quite large. Practice has shown that it is most favorable for the cooling water temperature to be controlled at 75-85°C and the lubricating oil temperature at 75-95°C.
Different types of wear have different manifestations and mechanisms of action. Understanding this knowledge helps us to better identify and deal with wear problems. The following are several common types of wear in diesel generator sets.
Adhesive wear is mainly caused by solid-state plastic deformation of the friction surfaces. When the actual contact areas of the friction surfaces are subjected to pressures exceeding the yield limit of the metal, plastic deformation occurs at the contact points. Under the action of intermolecular forces between the surfaces, as the friction surfaces move relative to each other, the weaker metal surface may be dug out by the stronger metal surface, or it may be scratched by the metal surface that has been strengthened by plastic deformation.
Scuffing wear is mainly caused by the melting and joining of molten metal on the friction surfaces. When the relative motion speed of the friction surfaces is high and the contact pressure is large, the temperature of the friction surfaces rises sharply due to plastic flow. In particular, under poor lubrication conditions, the surface metal may partially soften or melt. The less heat-resistant surface may adhere to the more heat-resistant metal surface. Adhesive and scuffing wear often occur on the friction surfaces of parts such as the crankshaft journals, camshaft cams, cylinders, and gears. This type of wear is especially likely to occur under conditions of high speed, high temperature, and poor lubrication in diesel engines, resulting in failures such as "seizing" and "locking."
Fatigue fracture refers to the phenomenon of fracture occurring after repeated cycles of stress or energy load. Approximately 60% to 80% of fractures that occur during the use of components are due to fatigue fracture. The characteristic of fatigue fracture is that the stress at the time of fracture is below the tensile strength or yield limit of the material. Whether it is a brittle or ductile material, fatigue fracture is a brittle fracture without significant plastic deformation on a macroscopic level. In diesel generator sets, the breakage of gear teeth and crankshaft fractures are mostly the result of fatigue fracture.
After understanding the causes and types of wear, let's look at how to reduce wear and extend the service life of diesel generator sets. Through proper operation and maintenance, the degree of wear can be effectively reduced to ensure stable performance of the generator set.
Choosing high-quality, standard-compliant diesel is the first step in reducing wear. Users should try to select low-sulfur, low-impurity diesel and pay attention to whether the viscosity of the diesel is suitable for their generator set. For lubricating oil, the appropriate viscosity and antioxidant properties should be chosen based on the operating conditions of the diesel engine. Regularly check the quality and level of the lubricating oil, and promptly replace any deteriorated oil to ensure the normal operation of the lubrication system.
When in operation, diesel generator sets should maintain an appropriate speed range. Avoid frequent acceleration, deceleration, stopping, and starting, and try to maintain a stable load and speed. During startup, ensure that the oil pump can supply oil in time to avoid wear caused by low oil temperature and high oil viscosity. In addition, regularly check key components such as the governor to ensure their normal operation and prevent dangerous situations such as "runaway" engines.
In high-temperature environments, pay attention to the cooling of the generator set to prevent engine overheating. In low-temperature environments, take appropriate preheating measures to ensure the fluidity of the lubricating oil and reduce wear during startup. At the same time, regularly check the cooling system to ensure that the cooling water temperature and lubricating oil temperature are within the appropriate range.
For new diesel generators or those that have undergone major repairs, during the initial stage of use, they should be operated at 50%-80% of full load for 60 hours of break-in, and then the engine oil and oil filter should be changed before full-load operation can commence. The break-in should be tailored to the specific use and load-carrying method of the diesel generator set. In principle, the speed and load of the diesel engine should be gradually increased in stages as the break-in time increases. During the entire break-in period, the load should be maintained at 50%-80% of the 12-hour rated power, and the speed should not exceed 80% of the rated speed. However, during the initial stage of break-in, the time spent running without load or with very low load should not be too long. Whenever the cylinder liner, piston, piston rings, connecting rod bearings, or crankshaft are replaced, a short-term break-in should also be carried out under the above break-in conditions.
For newly purchased diesel generator sets, after 60 hours of break-in, the engine oil, oil filter, and diesel filter should be changed before putting them into use. After maintenance, check the sealing condition of all pipe joints to avoid diesel leakage, which can cause air to enter the fuel line during shutdown, making it difficult to start the diesel engine. After the diesel generator set is put into normal use, regularly monitor the indications of all instruments and observe the dynamic operation of the entire machine. Regularly check the cooling system and the oil levels of all parts. If any non-compliance with specifications or leakage is found, immediately replenish or inspect and troubleshoot the problem.
Wear in diesel generator sets is a complex phenomenon involving a variety of factors. By understanding these factors, users can take corresponding measures to reduce wear and extend the service life of the generator set. Proper selection of fuel and lubricating oil, rational control of operating conditions, attention to ambient and operating temperature, emphasis on the break-in period, and regular maintenance and inspection are all effective methods to reduce wear. Only in this way can the stable performance of diesel generator sets be ensured, providing reliable power support for our production and daily life.
