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Analysis on the use and maintenance technology of construction machinery turbocharger


1 Correct use of diesel engine

The first is the quality grade of diesel oil. For low-supercharged diesel engines, diesel oil of not lower than CC grade should be used; for medium-supercharged diesel engines, diesel oil of not lower than CD grade should be used. The second is the viscosity grade of diesel oil, and the appropriate viscosity grade should be selected according to the temperature conditions and the wear conditions of the parts. Again, it is the cleanliness of diesel oil, because the rotor shaft of the exhaust gas turbocharger and its bearing (sleeve) are closely matched. If the diesel oil is too dirty or deteriorated, impurities or abrasive particles will be brought into the supercharger, light Then the wear of the bearing will be accelerated, and the lubricating oil film will not be formed and the rotor shaft and the bearing will be seized. Therefore, it is necessary to keep the oil clean, clean the oil filter frequently, and replace the deteriorated oil in time.

2 The correct cold start method

After the vehicle is started, the diesel engine should be allowed to idle for a few minutes (depending on the engine temperature and the outside atmospheric temperature), the standby oil reaches a certain temperature and pressure, the flow performance is improved, and the supercharger bearing is fully lubricated, before increasing the speed and starting. This is especially important when the outside temperature is low. For vehicles that have been parked for a long time (such as more than a few days), the supercharger oil inlet pipe joint should be loosened before starting, and an appropriate amount of oil of the same brand as the oil pan should be added to the oil inlet to prevent poor lubrication during starting. Ablation of the rotor shaft. Some users have experienced similar situations on the Jiefang Engineering King dump truck and Komatsu grader in Japan, which should be avoided as much as possible.

3 The correct way to turn off the flame

If the diesel engine running at high speed suddenly stops, the oil in the exhaust gas turbocharger will stop circulating immediately because the oil pump stops, but the rotor shaft of the turbocharger is still rotating at high speed under the action of inertia, which is easy to cause. The oil is cut off and its bearings are burned to death. In addition, the temperature of the exhaust manifold of a diesel engine running under load is very high. If it suddenly stops, the heat will be transferred to the supercharger casing, and the oil that has stopped flowing will be boiled into carbon deposits. When the carbon deposits accumulate more and more, it will block the oil inlet and cause the bearing to lack oil. Even if the oil inlet is not blocked, the carbon deposits will accelerate the bearing wear. For this reason, it is necessary to gradually reduce the load of the diesel engine before turning off the engine, and then run the engine at idle speed for an appropriate time. After the speed of the rotor shaft of the supercharger is reduced and the temperature of the oil has dropped, the engine will be turned off and stopped. After the flame is turned off, the supercharger rotor shaft will continue to idle for a certain period of time, and sometimes a slight "humming" sound can be heard.

4 Correct operation in diesel engine operation

Maintain the normal operating temperature of the supercharger. When the supercharger is working, the normal temperature of the turbine casing is about 400 ℃, and the temperature of the compressor casing is not hot to the hand. Frequently banging the accelerator will cause the supercharger to overheat due to the high exhaust temperature and increase the wear and tear. If the oil seal at the turbine end fails, the oil in the supercharger escapes into the turbine casing, and is discharged together with the high-temperature exhaust gas discharged from the cylinder, resulting in excessive oil consumption and smoke from the exhaust pipe. If the oil seal at the compressor end fails, the oil in the supercharger will enter the compressor casing, and as the intake air is sucked into the cylinder for combustion, it will also cause excessive oil consumption, smoke from the exhaust, and increase carbon deposits in the cylinder.

Maintain normal lubrication system oil pressure. When the diesel engine is running, when the oil pressure of the lubrication system is lower than 015MPa, it should be stopped for inspection to prevent the rotor shaft and bearings from being ablated due to poor lubrication of the supercharger. The oil pressure should not be too high to prevent the oil from entering the turbine chamber or the compressor chamber. The time of the diesel engine idling at low speed should not be too long to prevent the supercharger from being poorly lubricated due to the low oil pressure.

Strengthen the maintenance of the air filter. To fully burn the diesel fuel injected into the cylinder, a large amount of clean air needs to be supplied. After the diesel engine is equipped with a supercharger, the fuel supply of the fuel injection pump is correspondingly increased. If the air filter is blocked and the intake air is insufficient, the power of the diesel engine will drop significantly. Therefore, it is necessary to strengthen the maintenance of the air filter to ensure its normal working condition. In addition, if the filter element is damaged or the sealing rubber ring fails due to aging, the supercharger will be unstable due to the intrusion of lime and sand, and the noise will be aggravated, and the bearing, oil seal and air seal components will be further worn. It should be noted that when maintaining the air filter, do not let hard objects fall into the intake pipe, so as not to crush the impeller or break the rotor shaft after inhaling the supercharger, which may also cause a cylinder pulling accident.

5 Correct maintenance of supercharger

In use, the bolts between the three housings of the supercharger should be checked and fastened frequently to eliminate oil leakage and air leakage. Every 500-1000 hours of operation of the diesel engine, the supercharger should be removed to check whether the rotor rotates flexibly, and whether there is carbon deposits at the inlet and return ports of the supercharger, and carefully remove it to ensure that the oil is unobstructed. Scrape off the tiny dust deposited on the throat of the compressor, clean the scale in the water interlayer of the intermediate shell, the air seal channel and the oil cavity, remove the carbon deposits in the turbine, nozzle ring and turbine shell, and clean the air seals and oil seals. Check for damage and replace if necessary. When disassembling and assembling the supercharger, since the turbine casing and the compressor casing are both thin-walled castings, avoid hitting and colliding. When assembling the rotor shaft assembly, it must be in place according to the original mark, so as not to affect its dynamic balance. Keep it clean during final assembly, and don't let sundries fall into the inner cavity of the shell or the pipes. The oil inlet and oil outlet on the intermediate shell should be installed vertically, and the oil outlet pipe should be gradually bent after being connected from the supercharger to the crankcase. Turbine or compressor room leaks.