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 and other 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 ℃. For diesel fuel into the cylinder in this condition, the injection 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 diesel fuel 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 into the combustion chamber of 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 properly complete combustion, resulting in increased fuel consumption diesel engines, power down, increasing the cylinder coke, mechanical wear and tear. Therefore, the use of maintenance 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 or pre-ignition combustion, reliable work. Since only one orifice, large aperture, and therefore carbon can not easily be clogged, but its low thermal efficiency, fuel consumption rate. 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 and cleanliness, 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 with a diameter 0.35 mm.
Troubleshooting 2 injectors
The most sophisticated injector needle and needle valve 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, deform or carbon clogging the nozzle holes, thereby reducing fuel injection quality, affecting the normal operation of the diesel engine. Now common fault injector and exclusion methods 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 becomes black 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 little thin chromium oxide abrasive paste (careful not to stick in the needle holes) on the cone grinding, then diesel washed into 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 of bad 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 normal operation 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 the cylinder 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 be disassembled 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 diesel fuel 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, only with 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 surfaces to 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 until smoking, 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 body repeatedly 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 the injector. 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 gap or notch strain occurs, resulting in increased leakage injector, pressure reduced, reducing the amount of fuel injection, injection time lag, causing diesel engine starting difficulties. 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, to prevent 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 meets the technical requirements. For example this distance 135 series diesel engine is 1.5 ~ 2 mm, too big too small will affect the cylinder compression ratio. In addition, the injector plate concave downward should be installed, avoid unilateral tightening bias, should be required tightening torque evenly, otherwise the injector head will produce channeling oil 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 to 0.1 ~ 0.3 kg / h. If the return 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 fuel filter 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, the needle 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 the cylinder 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 to the 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 be accompanied by crisp pops, each bore hole injector should be self-beam fog column. Each type injector using standard fog cone angle injector contrast examination.
For the injector is injected into the cylinder for complete combustion of diesel fuel in a timely manner, time must be checked periodically pump oil. Oil too early, the vehicle will be difficult start and knock fault; oil too late, can cause black smoke exhaust, engine temperature is too high, increased fuel consumption.
With high precision dual injector needle pieces, and spray-hole diameter is small, so the choice must be strictly in accordance with the provisions of seasonal changes of clean diesel grades, otherwise injector will not work. When mixed with fuel to prevent rain or snow, avoid refueling in a dusty environment. To schedule maintenance diesel filter, regular discharge of oil filters and sedimentation tank, and to prevent the intrusion of gray sand impurities and increased wear needle even pieces.
When cleaning needle Couples must not collide with other hard objects, and do not make it fall to the ground, so as not to bruise bruises. When replacing the needle Couples, Couples should first new diesel fuel into the hot soak about 80 ℃ 10 s, let rust oil fully melted, then clean diesel in the needle back and forth in the valve body twitching, thoroughly wash net, so as to melt occurs because rust oil stuck needle injector failure to avoid work. Couples needle must be replaced in pairs, are not interchangeable mix.
If the high-pressure pipe joints loosen, see a lot of bubbles or oil foam sprang, then the needle is stuck in the open state, compressed gas cylinders thus generated during compression will be back to the high-pressure pipeline through the injector. At this point touch high pressure tubing, or if you feel less than pulsating pulsating relatively weak, then the needle has been dead card, should discharge needle Couples grinding, testing, debugging failed should be refitted after another for new products .
4 injector repair Problems
In need of repair due to the fuel injector on the head when the bond is difficult to remove, the diesel engine can be reduced, and crank crank, until the speed increases, immediately put down the decompression lever using cylinder pressure injector punch out, it should be noted not stand next to people, in order to avoid accidents.
You can also check the fuel injector in the car. Available tee will be checked with the standard injector injector in parallel to the fuel pump, while others remove each cylinder high-pressure pipe, crank crank or turn the engine with the starter, observe injection case. If both injectors simultaneously injection, then the injection pressure is normal; if checked injector first injection, then the injection pressure is too low, and vice versa too. Can be adjusted by screwing or twist the tail of the injector pressure regulator plug respectively.
Not long idling diesel engine, to prevent diesel fuel atomization bad injector worsen make work. Not long overloaded vehicles to prevent overheating of the body so that the injector needle stuck Couples. Long-term storage of the motorcycle, remove the injector it on a clean diesel after immersion cleaning machines, in order to prevent corrosion and can not use the needle.
In short, repair, replacement, maintenance and repair work to the strict implementation of technology standards, do adjust the injector in the daily check, a security operation, and maintenance. The only way to prolong the life of the injector.