Some common operators use the incorrect method to start the diesel engine. If they ask them why they are doing this, some shook their heads and said they learned from others; others replied eloquently, according to the book. Of course, there are no mistakes in the book, but most of them are an emergency measure under special conditions. It is a way to “get lighter than the two evils.†Therefore, if you start with an incorrect method for a long time, it is bound to Inflict adverse effects on the diesel engine and even cause major failures. The common incorrect startup method is as follows: (1) Put the throttle at the maximum position when starting. When some of the pilots started the diesel engine, the throttle was placed at the maximum position, which was thought to be beneficial for starting. This is not the case. For a diesel engine equipped with a full-scale governor, when the throttle is increased to a certain position at startup, the fuel supply of the fuel injection pump has already reached its maximum. If you continue to increase the throttle, the fuel supply of the fuel injection pump will no longer increase. At this time, the preload of the governor spring continues to increase, causing the speed of the diesel engine to increase sharply after it starts. However, the engine temperature of the newly started diesel engine is generally relatively low, and the lubrication conditions of each friction surface are relatively poor. Therefore, the diesel engine enters into high-speed operation as soon as it is started, which inevitably increases the wear of each pair of movements, and even causes serious problems such as the burning of the bearing shaft. malfunction. Therefore, when starting the diesel engine, the throttle should be placed at 2/3 of the positioning plate (this position is the maximum fuel supply of the fuel injection pump). It is not necessary to increase the throttle to the end so as to avoid excessively high speed after the diesel engine starts. If the technical condition of the diesel engine is poor, the throttle may be further enlarged, but it should not exceed 4/5 of the positioning plate. (2) Preheat the air with an open flame at startup. In winter, it is difficult to start the diesel engine. Some operators remove the air cleaner cover and ignite a group of tarpaulin at the intake nozzle to increase the air temperature entering the cylinder. Although this approach helps the start of diesel engines, but it also has some hazards: 1 preheat the air with an open flame, the air entering the cylinder is not filtered (dry centrifugal filtration) or not filtered at all (some operators In the cylinder head inlet ignited), air containing dust particles and other impurities directly into the cylinder, exacerbated the cylinder liner, piston, piston ring and valve, valve seat and other mechanical parts of the wear. In addition, the thick smoke from the open fire enters the cylinder and easily forms carbon deposits. 2 If the air filter is disassembled every time it is started, it may cause the air intake pipe to be closed tightly, resulting in air leakage, and some air will enter the cylinder without being filtered, which is extremely unfavorable to the operation of the engine. 3 The start of open fire is not conducive to safety, especially some old locomotives. The leakage of fuel oil is serious and can easily cause fire. Starting at low temperature, hot water may be added to the cooling system, and the oil pan may be baked with an understated fire to preheat the diesel engine. Preheating the air at the inlet of the diesel engine with an open flame is not desirable. (3) Slope starts diesel engine. Some of the pilots had problems with the starting devices (such as insufficient battery storage, malfunction of the starter or starting circuit, etc.). Instead of repairing them in time, they used an improvised method to park the car on the downhill before the engine stalled. When starting, the locomotive is allowed to slip down the ramp, and the engine is rotated with the drive wheel to start the diesel engine. The long-term adoption of a slippery slope has a lot of harm. The main ones are: 1 The diesel engine has no preheating process. If the engine is stopped for a long time, the lubricant on each friction surface is lost and the oil film is seriously damaged. The diesel engine suddenly runs at a high speed, but the lubricant cannot be sent to the friction surfaces in time, which exacerbates the mechanical wear. 2 When starting the sloping ramp, due to the excessive engagement of the clutch, it is easy to damage the transmission components such as the clutch and the transmission by excessive impact load. 3 After the diesel engine is started, it must be braked urgently, which will cause great wear on the brakes and components of the travelling mechanism, especially the tires. Moreover, after the start, the speed is higher and accidents are more likely to occur. (4) Start with a tractor. When the drag is started, the front vehicle is normally hung low and the rear vehicle is hung high (so that the starting speed of the diesel engine is lower). The diesel engine is started using the drive wheel and driving the diesel engine through the transmission mechanism. The harms of this starting method are as follows: 1 As the locomotive started by dragging hangs a high gear, once it is started, it is bound to rush forward, colliding with the vehicle in front and causing an accident. 2 Due to the thickened lubricating oil of the locomotive being started, the starting resistance is large. Especially in the cold season, the driving wheels tend to slip, causing the tires to wear rapidly. In this start-up process, the clutch has to be disengaged many times and combined, resulting in damage or severe wear of the clutch components. 3 If the engine is dragged for a long time, the engine cannot be started. This will cause a large amount of diesel to enter the cylinder, scour and damage the lubricating oil film on the cylinder wall, and aggravate the wear of the cylinder liner, piston ring and piston. At the same time, diesel oil infiltrating into the crankcase will dilute the lubricant and reduce the lubrication quality of the lubrication system. (5) Start the diesel engine without cooling water. This starting method is particularly harmful to the engine, because the engine in the outbreak of the moment, the cylinder temperature can be as high as 2000 °C or more, this temperature is not reflected on the water temperature meter, is to touch the cylinder with your hand can not be perceived. It can be inferred that after the engine starts to fire, the temperature of the wall of the combustion chamber will immediately rise (about 500 to 600 °C or more). Adding cold water to the engine at this time, the wall of the combustion chamber suddenly shrinks, it is very easy to damage the cylinder head (mostly in the crack between the two cylinders of the same cylinder) and the cylinder sleeve (breakage occurs under the sleeve shoulder). (6) Start the diesel engine with refueling. Before start-up, a small amount of oil is added from the intake pipe to improve the sealing performance of the cylinder components in order to facilitate the start of the diesel engine. This is mostly a starting method used by old and old diesel engines. Although it can work for a while, it has obvious side effects. If this method is often used to start, easy to make the piston ring cemented and stuck in the ring groove, the cylinder will be a large number of carbon deposition. The correct way to deal with this problem is to repair or replace the parts that are heavily worn in the cylinder in time to restore the good sealing performance of the cylinder. There is indeed a starting fuel with a lower autoignition point on the market. It consists of 70% ether, 27% 200# (or aviation kerosene), and 3% engine oil. Its auto-ignition temperature is 191°C. When starting, use a needle to suck about 10mL of starting fuel, and inject it into the intake pipe, then you can operate according to the normal start-up method, and the diesel engine can successfully catch fire. However, this startup method requires special attention to safety. Because the start-up fuel has a low self-ignition temperature and is prone to volatilization and evaporation, it can easily cause fires. Therefore, the start-up fuel should be stored in a closed container, stored at a low temperature, and kept away from the fire source. When using start-up fuel, the amount of each injection must not be excessive, and it is forbidden to add start-up fuel to the diesel tank to prevent air resistance or fire. Author: Heilongjiang Province Agricultural Machinery Maintenance Institute, Heilongjiang Province Qing'an Agricultural Machinery Station
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