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Why does the diesel generator set fail to pull the cylinder?

May 17, 2022
 Cylinder pulling of diesel generator sets is a common fault, which is manifested as scratch marks and groove-like strains on the surface of the cylinder wall. It usually occurs in the early stage of a new machine or after an overhaul. After the pull-off failure occurs, the lubricating oil will enter the combustion chamber, and blue-black smoke will be discharged from the exhaust pipe, resulting in a large amount of carbon deposits in the combustion chamber. At the same time, the combustible gas leaks into the crankcase, which will dilute the lubricating oil. In severe cases, it can be seen that there is a "gasp" phenomenon from the lubricating oil filling port, and oil smoke will spew out. There are many reasons for the failure of diesel generator sets to pull cylinders. This article JUNVOCH mainly analyzes the reasons for diesel generator sets to pull cylinders from the following aspects:
1. There is air resistance in the cooling system of the cold water diesel generator set
After the diesel generator is assembled on the vehicle, the auxiliary water tank is installed in the cooling system to communicate with the atmosphere, so there is a problem of air obstruction inside the cooling system. The cooling system is basically in a completely closed state before it is used, and the cooling water pump is forced to perform circulating cooling. In this state, if the air in the system is not discharged cleanly, the air will form in such a closed and forced system. Air resistance, the air resistance will move in the system with the forced action of the water pump (moving to a lower instantaneous pressure), and the air resistance will cause the partial cooling of the parts to be insufficient or even fail. In this case, it will cause the diesel generator set to overheat and cause the cylinder failure.
2. Reasons for the operation of diesel generator sets
 Diesel generator set pulling cylinder due to improper operation is mainly manifested in the following aspects:
       1. Drive with insufficient oil. When the diesel generator set is operated under the condition of insufficient oil supply (the oil level is too low), each lubricating part cannot achieve normal lubrication, and the surface of each machine part will cause friction and aggravate wear, causing failures such as cylinder pulling and tile burning.
       2. Run the diesel generator set when the oil pressure is too low. If the oil pressure is too low, the lubrication system cannot achieve normal oil circulation and pressure lubrication, and cannot reliably supply a sufficient amount of oil to the friction surface of each part so that each lubricated part is fully lubricated, resulting in wear, cylinder pulling, tile burning, etc. Fault.
       3. Overspeed load operation. Frequent overspeed and overload operation will cause the diesel generator set to operate under an overloaded working condition for a long time, resulting in rough combustion of the diesel generator set, resulting in overheating of the diesel engine, and increased thermal and mechanical loads on cylinder liners, pistons, etc. It is easy to cause damage to the parts and failure of pulling and holding the cylinder.
       4. During the running-in period, it runs at no-load for a long time or runs at high speed and high load for a long time. During long-term no-load operation during the running-in period, the cylinder may be pulled due to the dilution of the oil on the cylinder wall by the fuel. However, if the load operation is performed too quickly, the cylinder is more likely to be pulled. If the metal contact parts are not cooled in time, it will cause the phenomenon of cylinder pulling.
       5. In cold start, the load will be increased immediately without passing through the heater. Because the oil temperature is low, the viscosity is high and the fluidity is poor at the beginning, the oil cannot fully flow to all lubricating parts, and the oil supply of the oil pump is small. The lack of lubrication during operation results in rapid friction between the inner wall of the cylinder liner and the piston assembly, resulting in the failure of the cylinder.
       6. The amount of cold water is insufficient to drive. Insufficient cooling water (the water surface is too low) will affect the cooling effect, causing the diesel generator set to work too high, causing the cylinder liner, piston and other main heated parts to overheat, resulting in a decrease in its mechanical properties such as strength and toughness. The increase in the amount of deformation will destroy the normal technical cooperation state, thereby increasing the wear and tear, and in severe cases, the piston will be over-expanded and stuck in the cylinder. In addition, if the diesel generator set is overheated, the oil temperature will be high and the viscosity will decrease, and the lubricating oil film on the surface of each friction pair will not be easily formed and maintained, which will deteriorate the lubrication conditions of the cylinder liner, the piston assembly and other main friction surfaces, resulting in abnormal wear and pulling of the cylinder. , Burning tile, holding shaft failure.
3. Reasons for maintenance
This is mostly manifested in the lack of maintenance. Mainly include the following aspects:
       1. The oil filter is not cleaned in time, which will cause the oil filter to have too much resistance or even blockage, so that the oil does not pass through the filter element but pass through the bypass valve, and use unfiltered oil to lubricate the inner wall surface of the cylinder liner, then It is very easy to cause serious wear and strain of cylinder liner and piston assembly.
       2. It is not timely to check and adjust the fuel supply advance angle. This will cause the advance angle of the diesel engine to be too large, resulting in rough operation of the diesel engine, increased thermal and mechanical loads on the cylinder liner and piston, and easy to cause cylinder holding and cylinder pulling failures.
       3. Poor maintenance of the air filter. Dust, sediment, etc. in the air will be sucked into the cylinder with the air due to poor maintenance of the air filter or air leakage of the intake system, forming harmful abrasives, which adhere to the inner wall surface of the cylinder liner, making the cylinder liner and the piston The friction surfaces of the components are subject to intense particle wear and strain.
       4. If the oil is not added or replaced in time, and the oil is not added in time, the above-mentioned problem of insufficient oil will occur. During the continuous operation of the diesel generator set, the oil will be polluted by the dust inhaled from the air and the combustion products and wear products of the diesel generator set itself, and will gradually deteriorate under the influence of high temperature. If the usage requirements are not met, if not replaced in time, not only the mechanical impurities in the oil will aggravate the wear of the parts, but also make the lubrication worse and even cause the oil pipes and oil passages to be blocked, causing failures such as cylinder pulling and tile burning.
       5. If the oil of the specified quality and the specified label is not selected, and the oil for diesel engines that is not for diesel generator sets or whose performance does not meet the requirements is added to the diesel engine, the friction surface cannot establish a complete oil film with a certain thickness, which will change the lubricating performance. Poor, it is easy to cause cylinder pulling and tile burning failures. If the oil with too low viscosity is used, the oil film on each friction surface will be difficult to form and maintain when the temperature is high; if the oil with too high viscosity is used, the fluidity will be poor, and it will not be easily transported to the friction surface gap of each part, so it is impossible to realize the adjustment of each friction surface. Reliable lubrication of lubricating parts will also lead to cylinder pulling and tile burning failures.