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Diesel Injector Maintenance
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Diesel Injector Maintenance

Views:0     Author:Site Editor     Publish Time: 2018-08-27      Origin:Site

Heavy diesel than gasoline, the price is higher. But it has a high fuel thermal efficiency, low transportation costs, low air pollution, suitable for long operating at full capacity andother characteristics, in a variety of construction machinery has also been widely used.


When the end of the compression stroke diesel engine, in-cylinder pressure of 3~ 5 Mpa, a temperature of 500 ~ 700 C. For diesel fuel into the cylinder in this condition, theinjection pressure should be higher than 12.5 Mpa, the ejection speed is greater than 100 m/ s. Fuel pump and injector is used to accomplish this task, which is to make dieselfuel to generate high pressure fuel pump and injector timing quantitative lost. Diesel fuel injector will be atomized from the fuel injection pump, and uniformly distributed intothe combustion chamber ot each cylinder to obtain complete combustion.


Injector is a key component of the diesel engine, the material is good, fine manufacturing process. If normal fuel pump, fuel injector working poor, diesel can not properlycomplete combustion, resulting in increased fuel consumption diesel engines, power down, increasing the cylinder coke, mechanical wear and tear. Therefore, the use ofmaintenance of the injector must be highly valued.


An injector category


Diesel agency used on vehicles speed is greater than 1000 r / min high-speed diesel engines, which generally have pintle injector porous two. Pintle mainly for eddy current orpre-ignition combustion, reliable work. Since only one orifice, large aperture, and therefore carbon can not easily be clogged, but its low thermal efficiency, fuel consumptionrate. Porous type is mainly used for direct injection combustion chamber, which can spray several small cone angle, longer range jet column, thus the required injection


pressure which is much larger than the axis of the needle. This injector high thermal efficiency, fuel economy, but the grade of oil, there are strict requirements for quality andcleanliness, otherwise the diesel engine will not operate normally. For example, the 135 series diesel vehicles on the Yellow River, which has 4 injector spray holes withadiameter 0.35 mm.


Troubleshooting 2 injectors


The most sophisticated injector needle and needle vave body, with the gap only 0.002 ~ 0.004 mm. If diesel dirt impurities, will affect the sensitivity of the needle valve


opening and closing, and even its stuck. Due to the injector head in the combustion chamber in direct contact with high pressure gas, over time, the needle will swell, deformor carbon clogging the nozzle holes, thereby reducing fuel injection quality, affecting the normal operation of the diesel engine. Now common fault injector and exclusionmethods are described below.

2.1 Injector drip


When the injector work, sealing cone needle body will be subject to frequent needle strong impact, coupled with the high- pressure oil flow continuously ejected from the .premises, the cone will gradually appear nicks or spots, thus losing the seal, causing injector drip. When the engine temperature is low, white smoke exhaust pipe, it becomesblack smoke after the machine temperature rise, the exhaust pipe will be issued irregularly put guns. If the stop point to cylinder oil, exhaust and put the guns will disappear.Then detachable injector needle head dipped in a lit thin chromium oxide abrasive paste (careful not to stick in the needle holes) on the cone grinding, then diesel washedinto injector test. If you still fail, replace the needle Couples.


2.2 injector atomization bad


When the injection pressure is too low, there is carbon wear spray holes, springs or elastic face wear drops will cause injector early on, delay shut down, and the formation ofbad injector atomization. If the single-cylinder diesel engine will not work, multi-cylinder diesel engine is powered down, exhaust black smoke, the sound is not the normaloperation of the machine. Further, since the particle size is too large droplets can not be sufficiently diesel combustion, then flows into the volume of the oil pan along thecylinder wall, so that the oil surface of the oil increases, viscosity decreases, lubrication deterioration, but also may cause burn Valla cylinder accident. At this point should bedisassembled injector cleaning, maintenance, re-commissioning.


2.3 spray holes expand


Due to the high pressure oil jet stream constantly scour, needle spray holes will gradually wear, leading to fuel injection pressure drops, spray distance shortened, bad dieselfuel atomization, the cylinder of carbon increases. Hole injector needle shaft aperture is generally greater than 1 mm, can put a diameter of 4 ~ 5 mm steel ball in the hole side,gently tapping with a hammer, the spray holes localized plastic deformation and narrow aperture. Due to the porous injection injector number of holes, small aperture, onlywith high-speed steel polished like a hole punch gently tapping the end, if after debugging is still unsatisfactory, replace the needle Couples.

2.4 needle killed


Diesel fuel in the water or acidic substances cause corrosion and stuck the needle after needle sealing cone damage, combustible gas cylinder also fleeing the mating surfacesto form coke, needle valve killed injector injection will lose effect, causing the cylinder to stop working. Couples needle can be placed in the waste oil is heated to boiling untilsmoking, then remove with a soft cloth cushioned hand tail slowly needle clamp to live events, pull it out clean stained with oil, so that the needle in activities valve bodyrepeatedly grinding, until the needle even an upside-down from the needle valve body itself slowly exit. If the load injector test failed, replace the needle Couples.


2.5 needle valve body face wear


End face of the needle by needle frequent reciprocating impact over time will gradually formed pits, thereby increasing the needle lift and affect the normal operation of theinjector. Needle valve body can be clamped to this end face grinding repair the grinder, then with a fine abrasive grinding paste on the glass.


2.6 needle and needle hole guide surface wear


Needle in the needle bore frequently reciprocated, coupled diesel dirt intrusion of impurities, the needle hole of the guide surface will gradually wear, thus increasing the gapor notch strain occurs, resulting in increased leakage injector, pressure reduced, reducing the amount of fuel injection, injection time lag, causing diesel engine startingdifficulties. When the fuel injection time delay too much, can not even run the locomotive, you should replace the needle Couples.


2.7 injector head combined with channeling oil leak hole


When the injector mounted head, carefully remove the mounting hole of coke, copper washers must be flat, or other materials may not be used to replace asbestos board, toprevent bad or not achieve seal cooling. If homemade copper washers, you must be processed copper thickness required to ensure that the injector head Reach plane meetsthe technical requirements. For example this distance 135 series diesel engineis 1.5 ~ 2 mm, too big too small will. affect the cylinder compression ratio. In addition, the injectorplate concave downward should be installed, avoid unilateral tightening bias, should be required tightening torque evenly, otherwise the injector head will produce channelingoil leakage due to deformation deflection.

2.8 injector return pipe breakage


When the needle Couples badly worn or needle body and injector housing with tight enough, the fuel injector back on significantly increased, some up to0.1 ~ 0.3 kg/h. If thereturn pipe is damaged or missing equipment, oil return on draining away, resulting in waste. Therefore, the return pipe must be intact and install airtight, so the oil can


smoothly flow into the tank back. If the return pipe is connected to the fuel filter, and then the terminal should be located one -way valve to prevent reverse flow inside the fuelfilter in the fuel injector.


3 injector maintenance and repair


Working around 700 h injector adjustment should be checked once. If the opening pressure is below a predetermined value or above 1 Mpa severe needle coke head, theneedle should be discharged into the clean diesel using wood shaving coke, with a thin wire to clear the nozzle, installed after commissioning, require the same machine thecylinder fuel injection pressure difference must be less than 1 Mpa. Then do the oil seal test, namely injection pressure of 18 Mpa, let themselves down to 17 Mpa, its back tothe oil no less than 10 s in order to pass. Tests do not allow the diesel injector head shed or moist phenomenon from the cone. The discharge of oil mist beam must beaccompanied by crisp pops, each bore hole injector should be self- beam fog column. Each type injector using standard fog cone angle injector contrast examination.


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