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Railway Operation Technology Analysis of Dongfeng Criminal Diesel Locomotive Air Compressor Lubricating Oil Li Guilin. Wuchang South Locomotive Depot of Wuhan Railway Bureau, Wuhan 430062, Hubei, China, detailed analysis of the emulsification process of lubricating oil, and proposed preventive measures and recommendations based on the analysis results.
Beginning in March 2004, the Wuchang South Locomotive Depot was newly re-routed to the Dongfeng 4D diesel locomotive. The emulsification of the air compressor lubricating oil of this type of vehicle is very common. In severe cases, after the replacement of the lubricating oil, only the 2000, 1 air compressor lubricating oil is operated. It is emulsified. In the past, when the newly-built Dongfengke Dongfeng locomotive was used in the Wuchang South Locomotive Depot, the emulsification of the air compressor oil had occurred. However, after the automatic drain valve was installed at the air cooler of the air compressor. The situation has improved. The Dongfeng 4, type locomotive can only delay the emulsification cycle of the lubricating oil after installing the automatic drain valve of the air compressor, but it still cannot guarantee the operation of 20,000 km minor repair cycle.
1 Reasons The air compressor is circulated and does not come into contact with external substances except compressed air. Therefore, the moisture emulsified by the air compressor lubricating oil can only come from the compressed air of the air compressor.
There are two main ways in which compressed air is contacted with air compressor oil. Compressed air that enters the crankcase is in contact with the lubricating oil and its oil and gas. Under normal circumstances, as long as the air compressor starts to work, the temperature of the crankcase is higher than the outside air temperature, plus the lubricating oil, the part of the oil and gas produced by the mixing, a small amount of compressed air from the cylinder of the air compressor is thrown into the crankshaft. Because at this time, the pressure in the crankcase of the air compressor is higher than the pressure of the external environment, the source of air in the crankcase of the air compressor can only be the compressed air that is inserted into the cylinder. It is the substance that causes the emulsification of the lubricating oil in 1.1. The results of the emulsified air compressor oil test result show that the emulsification of the air compressor lubricating oil is caused by the excessive moisture in the air compressor lubricating oil.
1.2 Disintegration phenomenon The disintegration inspection of the air compressor replaced by lubricating oil emulsification found that compared with other good spare air compressors, the air compressor air valve is not tightly sealed, and the crankcase vent hole is smaller than the filter overlapping layer. The number is too large or the number of meshes is large.
1.3 Source of Moisture in Lubricating Oil The cooling method of the air compressor is air-cooled. Therefore, the moisture of the lubricating oil in the air compressor cannot be caused by the cooling material.
1.4 Lubricating oil emulsification reasons The air compressor for locomotive is a two-stage compressed piston air compressor. The combustion chamber is composed of a piston sleeve and a piston ring of a gas cylinder. When the prime mover drives the crankshaft of the air compressor to rotate, the piston of the air compressor drives the piston to reciprocate in the cylinder.
When the air compressor is working, the outside air enters the stage cylinder through the air compressor air filter, and is discharged through the air valve into the intercooler. The cooling stage exhaust temperature can be lowered by about 120 ft after cooling, and then enter the stage cylinder to compress and pass the gas. The valve duct enters the total air cylinder.
In order to prevent the total cylinder pressure from being returned to the cylinder when the air compressor stops working, a check valve is installed on the air duct between the total air cylinder and the air compressor, and the air valve also has a function of preventing backflow of the compressed air.
According to the nature of the air humidity, in the case of the absolute humidity of the air, the higher the temperature, the smaller the relative humidity; the greater the pressure, the greater the relative humidity of the air until the saturation pressure of the water reaches the temperature. From the structure and working principle of the air compressor, only the lubricating oil air and the air compressor itself are in the crankcase of the air compressor. The lubricating oil is in the analysis of the influence of the emulsification change of the air compressor lubricating oil on the relative humidity of the Dongfeng 40 diesel locomotive far greater than the pressure change. When the air compressor stops working, because the outer wall of the cylinder is a cast corrugated structure, the heat dissipation effect is better, the temperature and pressure of the cylinder decrease rapidly, the relative humidity of the air increases sharply, and the part of the piston remains on the top of the piston after the liquefaction of the water vapor. When the air compressor works When vaporized, it is discharged into the total air cylinder in the same manner as the compressed air, and partially mixed with the lubricating oil on the inner wall of the cylinder, and flows into the crankcase with the lubricating oil.
At the same time, part of the compressed air that has entered the crankcase is exhausted through the venting port of the crankcase, and part of the compressed air is mixed with the oil in the crankcase. The lower the temperature, the greater the pressure, the greater the relative humidity of the air with the water vapor content, and the greater the number of molecules of the water vapor liquefied into water. When the vent hole of the crankcase is unblocked, not only the compressed air that is intruded is discharged out of the crankcase in time, but also part of the water in the high-temperature lubricating oil is discharged to the crankcase with the compressed air, and the pressure of the mixed gas in the crankcase is only slightly greater than the ambient pressure. And the temperature is higher than the ambient temperature, the saturation of the water vapor in the mixed gas is higher than the saturated humidity of the ambient gas, and the water vapor in the mixed gas is liquefied into water in the case where the number of water molecules per unit volume is the same. The number of molecules is lower than the external environment.
When the ventilation of the vent hole is not smooth, the mixed gas pressure of the compressed air and the oil and gas in the crankcase will be greater than the ambient pressure. As the temperature decreases, part of the water vapor in the compressed air will be the same as that of the crankcase oil and gas due to the air compressor. The cylinder and crankcase are piston ring seals, and some of the high pressure gas always enters the crankcase through the piston ring. When the air valve is not tightly sealed, after the air compressor stops working, the structural limitation of the check valve from the check valve to the high pressure cylinder valve is impossible, and it is impossible to ensure that the compressed air 100 does not flow into the air compressor through the check valve. In this way, a large amount of compressed air will be drawn into the cylinder. After a period of time, the air compressor oil will be emulsified and deteriorated.
2Solutions 2.1 Improve the quality of valve inspection When the air compressor is overhauled, the inspection standard of the strict air valve, whether it is the inlet exhaust passage, is subjected to the diesel penetration test.
2.2 Improve the ventilation of the crankcase Increase the venting hole of the crankcase, replace the filter screen with a smaller mesh screen, and reduce the number of filter mesh layers. It is required to clean the crankcase filter every time.
Practice has proved that the air compressor has been operated by the above-mentioned measures to repair and replace the filter locomotive, the maximum has been run 140,000 km, there is no phenomenon of air compressor oil moisture exceeding the standard.
3 Recommendation 3.1 Strengthening overhaul The automatic drain valve overhaul is included in the scope of overhaul and repair. In addition, since the design life of the air compressor air valve of the locomotive is 1000, it is recommended to disassemble the air compressor during the minor repair and exchange the air valve.
The cleaning of the air compressor crankcase vent filter is included in the regular maintenance range of the locomotive to ensure the ventilation effect of the vent filter.
3.2 Increase the diameter of the venting hole The manufacturer of the air compressor should increase the diameter of the vent hole of the compressor crankcase and reduce the mesh number of the filter.
3.4 Using new technology The solenoid valve is used to discharge the residual compressed air in the high pressure cylinder when the air compressor is not working. At present, the anti-emulsification air compressor produced by Dalian Air Compressor Factory uses a solenoid valve to simultaneously discharge the air of the high-pressure cylinder and the water of the cooler, and the application effect is good.
The joint between the external wall and the concrete member is provided with a steel mesh of more than 20 and wide when being painted, and is fixed in the paint layer to prevent shrinkage cracks between the wall and the concrete. Separate the gaps and seal them to control the cracking of the plaster layer.
The outer wall of the awning balcony waist line window sleeve and other protruding parts, painting 2.4 other leakage caused by objective reasons such as design and natural environment, the designer should make a targeted design according to the actual situation of the project. The construction unit must strictly follow the design requirements and operating procedures, and control it as much as possible from the selection of materials. If there is any uncertainty in the design, it must be agreed with the designer before construction. For the leakage caused by the household decoration, it is necessary to start from the strengthening of the property management of the community and the quality awareness of the households.
When there is enough drainage slope, set the drip line to avoid water accumulation.
The paint finish wall should have strong impermeability and have a fixed bomb
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