[Keywords] diesel engine; insufficient power; insufficient oil supply; fault; three major pieces; injection time
Many plants, mines and construction sites use medium or large diesel generator sets as active or standby power generation equipment. In the long-term use process, diesel engines are prone to power shortages, the main reasons are as follows:
1. Insufficient oil supply is one of the more common faults in the engine. There are two situations that may cause insufficient fuel supply to the engine: In the first case, the oil circuit is blocked, resulting in an increase in oil supply resistance, which makes the machine oil supply poor. When this happens, the machine performs normally at a small load, but when the power is supplied at a large load, the required oil supply increases due to poor oil supply, and the engine will have a significant failure phenomenon: the rotation speed drops and the sound becomes " Hard work." In this case, check the oil supply line and the diesel filter to remove the blockage or replace the filter. The second case is that the low-pressure oil circuit is not tightly sealed, resulting in air ingress and generating air resistance. This kind of fault phenomenon is also obvious: in addition to the lack of power of the machine, a clear "click" sound can be heard at the tubing joint, and the throttle is increased, and this sound is also increased. After finding the leak, retighten the joint screw or replace the seal as appropriate.
2. Failure of the intake and exhaust system When the intake system is clogged, the intake of the diesel engine is insufficient, the power is reduced, the sound is dull, and the exhaust is black smoke. The most common fault in the intake system is the blockage of the air filter. This kind of fault phenomenon is obvious and easy to judge, as long as the air filter is carefully cleaned. For turbocharged diesel engines, in addition to air filter blockage, air leakage in the intake and exhaust systems can also cause insufficient machine power. Because the supercharged diesel engine drives the turbine to rotate by the exhaust pressure, the compressed air is sent to the intake pipe to increase the engine power. Therefore, the intake and exhaust systems of the supercharged diesel engine must be completely sealed. If the exhaust system has air leakage, the exhaust pressure will decrease, the supercharger speed will decrease, and the intake pressure of the engine will also decrease, eventually reducing the power. , the performance is insufficient power. If there is air leakage in the intake system, the power of the machine will also drop due to insufficient intake air. Inspecting the air leakage of the intake and exhaust systems, you can use cotton wool, fine cloth strips, etc. close to the pipe joints. If there is obvious phenomenon of blowing or sucking into the joints, it means there is air leakage, and it needs to be installed at the pipe joints. Gasket or tighten the screws.
3. Supercharger failure The supercharger is an important part of the supercharged engine. It must be in good working condition, especially the axial and radial clearance of the rotor must be kept within the specified value range. If the supercharger fails, it will cause the speed to drop and the intake pressure to decrease, eventually leading to insufficient engine power. The main performance of the supercharger failure, one is "eat oil", and the other is scratching. The main cause of this phenomenon is the serious wear of the rotor shaft and the bearing and the damage of the seal ring, resulting in oil consumption and sound. When the rotor shaft and the bearing are seriously worn, affecting the normal operation of the machine, the parts must be replaced. The method to avoid accidental wear of the supercharger is to use the equipment strictly in accordance with the operating procedures. The most important thing is to pay attention to two points: First, after the engine is started, it must be idling for 3 to 5 minutes, and the standby oil has formed a circulation in the lubrication system. After the oil pressure rises to the normal value, the speed is increased and the load is increased. Second, the engine should be idling for about 3 minutes before stopping, and then stop after the engine and booster speed drops. It is forbidden to suddenly turn off the fuel after the throttle is lifted, because the operation will stop the oil pump and the supercharger will still rotate at high speed, which will cause the supercharger to form dry friction due to lack of oil, which will aggravate wear and strain, and even damage the turbine in severe cases. The rotor shaft is broken.
4. Piston Group Fault The failure of the piston group is mainly caused by wear and strain of the piston assembly. When the piston, piston ring and cylinder liner are worn, the cylinder will be poorly compressed and the engine will be insufficiently powered. The phenomenon is that the work is weak, the exhaust smokes blue smoke, and the oil is consumed. When the wear is severe, it is accompanied by crankcase helium and engine noise. The cause of serious wear and strain on the piston unit is that the engine is not fully warmed up after starting, and suddenly accelerates or loads in the cold state. Second, the engine temperature is too high, causing excessive expansion of the piston unit and the decrease in hardness and strength, causing severe wear or strain on the machine. After such a failure, the machine must be overhauled, the piston and the cylinder liner replaced, and it is strictly forbidden to continue to use the machine, otherwise it is prone to serious accidents. In order to avoid serious wear and strain on the engine, the machine should be operated in accordance with the regulations to ensure that the machine works in good condition. The most important thing is to pay attention to the following three points: First, after starting, fully warm up and then speed up to avoid cold strain on the machine; second, keep the oil pressure within the specified range, not too big or too small; third, idle before stopping After running for a few minutes, stop the machine temperature and then stop it. Do not stop suddenly during high-speed operation.
5. The three large wear parts of the plunger, the oil valve and the needle valve are the three major components of the diesel engine. They are the key components of the diesel engine. Any failure will affect the power output. When the plunger coupler wears, the high pressure is not established quickly, the oil pressure is too low, and the oil supply is insufficient. When the oil outlet valve is worn, the oil cut will not be crisp, and there will be secondary injection or oil drop. The machine speed is unstable, the vibration is intensified, and the exhaust smokes black smoke; when the needle valve is worn, the oil drop phenomenon will occur, causing the fuel injection nozzle to gel, which seriously affects the fuel injection quality, resulting in poor diesel atomization and exhaust Black smoke. The final result of the damage of the three major components is to affect the power output of the engine, so that the machine is underpowered. Even if the parts are damaged, they cannot be repaired and can only be replaced as a whole. The cause of the damage, in addition to the wear caused by normal use, is also closely related to the quality of the fuel and the method of operation of the user. Therefore, in addition to the use of quality qualified fuel, the equipment must be operated correctly according to the regulations. If you try to avoid rapid acceleration; when parking for a long time, check the condition of the machine carefully, especially check the flexibility of the plunger; regularly check the fuel injection pressure of the injector and remove carbon deposits.
6. Engine injection time is not allowed Different types of diesel engines have different requirements on injection time. For example, the injection time of 4135 diesel engine is 28° to 31° before top dead center. Improper injection time will cause a significant drop in engine power and damage to the machine. The fuel injection is too early, the engine is difficult to start, black smoke is generated, the vibration is increased during work, the sound becomes "violent", there is a knocking sound, the machine temperature rises, the exhaust color is thicker than normal; the fuel injection is too late, The engine is difficult to start and emits gray or white smoke. The sound is dull during work, the machine is unable to turn, the exhaust is gray and black smoke, and when the exhaust pipe is severe, the temperature of the exhaust pipe is significantly increased. The improper injection time is caused by the long-term vibration of the machine, which makes the coupling part of the drive shaft and the high-pressure oil pump camshaft loose, resulting in a certain angle difference. It is found that the injection time is not correct, as long as the specified data is re-adjusted to the specified value. And tighten the screws.
Sodium Sulphide
Sodium Sulfide,Sodium Sulphide Flake,Sodium Sulphide
Organic Acid Series Co., Ltd. , http://www.chorganic.com