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The idea and method of removing common faults of diesel engine common rail injector

2018-05-09 06:24:23

Common rail injector is the precision of the diesel engine system, the working condition of the injector directly affects the power, economy and reliability of the diesel engine, it is not difficult to see from the working principle of the injector, the work of the injector needs to have a certain injection pressure, injection stroke, suitable injection cone Angle, in addition, the injector should be able to quickly cut off the fuel supply when it needs to stop the injection. No dripping occurs. In the working process of the injector, there will be a variety of faults and phenomena, so what are the ideas and methods for the elimination of common faults of the injector? Let's take a look at:

Tools/Materials
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Injector disassembly tool

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Dismounting rack

Methods/Steps
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1. Jet hole blockage Because the fuel is mixed with solid impurity particles, or because of poor combustion to produce carbon deposition, the working time is slightly longer will accumulate around the injector's jet hole, so that the jet hole becomes a semi-blocked state. Once the injection hole is blocked, the fuel supply pressure of the injection pump will rise and be accompanied by a tapping sound. Prevention method: On the one hand, the fuel entering the injector should be strictly filtered; On the other hand, by improving the combustion, it can prevent the blockage of the nozzle due to excessive carbon accumulation.

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2. Nozzle corrosion and end carbon deposit nozzle corrosion is caused by cold corrosion caused by sulfide in the exhaust gas, and the corroded nozzle is because the metal surface is too cold, so that it is subjected to chemical erosion. Any nozzles found to be corroded should be replaced. Carbon deposits at the end of the nozzle are easy to form when the diesel engine is running at idle speed or under low load. When the diesel engine load increases, the carbon residue collected on the nozzle will be burned off when the fuel is ejected. The end carbon deposit has a certain effect on the atomization of the fuel and the uniformity of the fuel distribution in the combustion, resulting in incomplete combustion, the power reduction of the diesel engine, and the generation of post-combustion phenomenon and various mechanical failures. Removal method: Remove the nozzle and remove the carbon deposit on the nozzle by mechanical or weak corrosion method. The removal of carbon deposits inside the jet hole is very important, but the sealing seat surface must be protected so that it is not damaged. In order to prevent the steel wire used for cleaning from breaking in the hole, the steel wire must be installed in the chuck, and the length of the steel wire exposed to the spray hole should not exceed 2 mm.

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Related content learned from experience

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4. Poor atomization of the injector When the injection pressure is too low, the spray hole wear has carbon deposit, the spring end face wear or the elasticity decline, it will cause the injector to open in advance, delay closing, and form poor atomization of the injection. Diesel engine power decreased, exhaust black smoke, machine running sound is not normal. In addition, because the diesel droplets with large particle size can not fully burn, they flow along the cylinder wall into the oil accumulation pan, so that the oil level increases, the viscosity decreases, the lubrication deteriorates, and may also cause the accident of burning the vara cylinder. At this time, the injector should be disassembled, cleaned, overhauled and re-debugged.

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5. Needle valve and needle valve hole guide surface wear Needle valve in the needle valve hole frequent reciprocating movement, coupled with the invasion of diesel impurities pollution, will make the needle valve hole guide surface gradually wear, so the gap increases or strain marks, resulting in increased leakage in the injector, the pressure is reduced, the injection amount is reduced, the injection time lag, resulting in diesel engine starting difficulties. When the injection time delay is too much, the diesel engine can not even run, and the needle valve coupling should be replaced.

Matters needing attention

Diesel vehicles have relatively high requirements for oil products, so several more diesel filters should be added and the nozzle should be washed frequently.

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