Plunger pair, oil valve and nozzle coupling are the three precision coupling parts of diesel engine.The performance and economy of diesel engine are directly affected by its technical state.It is an important content to keep the three precision couplings in good technical condition.
The normal service life of the three precision couplings is generally more than 2,500 h.However, according to the survey, the service life of more than 1,500 hours of people are very few, generally in about 500 hours, some even only use a few hours.In addition to the manufacturing quality and storage of improper when the reason, to random disassembly, improper assembly adjustment, improper cleaning, the use of inferior fuel oil and other causes of damage to the three pairs of the cause is more common.
Three reasons for damage of precision couplings:
(1) Random demolition of machinery.
Diesel engine oil supply system fault is common, encountered problems should be carefully analyzed to find the cause of the fault.Then targeted inspection, exclusion, not optional replacement and disassembly.The machining and assembling precision of the three precision couplings are very strict, which can shorten the service life of dozens or even hundreds of hours by disassembling and installing once.In addition, due to disassembly, improper installation may cause bump, smudge, scratch and even deformation and further deterioration of its technical state.
(2) Improper cleaning.
Mix the three precision couple parts with other parts to clean or use unclean cleaning fluid or the newly purchased three precision couple parts without thoroughly cleaning the anti-rust oil.Before changing the coupling parts, although cleaning, but not law.Some use cloth, cotton yarn to wipe the surface of even parts directly;Some will wash clean even parts and put them in an unclean place.The result of these methods is that the working surface appears abrasion, adhesion of mechanical debris, damage the assembly clearance of even parts, resulting in even parts stuck, burned to death and other faults.
(3) Poor quality of fuel or unclean use of poor quality fuel (kerosene and engine oil, diesel mixture oil, etc.), its lubrication performance, sealing performance and viscosity can not meet the requirements of use, will cause insufficient oil pressure of the injection pump, wear and tear aggravate and nozzle carbon accumulation and other faults.In addition, the fuel oil without purification treatment, the use of the fuel tool is not clean, fuel filter device damage, sealing ring leakage, wrong or damage, remove the filter element, in order to make the oil road "smooth" and other wrong practices, will make the three precision couple service life shortened.
(4) Improper assembly.
Some operators in order to prevent oil leakage, the oil valve tight seat and injector tight cap screw too tight, so that the injector body, plunger sleeve and oil seat stress is too large.At last, deformation occurs and the accuracy of fit is destroyed, which causes the coupler movement to be blocked and damaged.Some operators also use asbestos rope winding instead of copper pad, because asbestos is a heat insulation material, with asbestos rope winding will seriously affect the heat dissipation of the injector, resulting in the injector needle valve temperature is too high and burned to death.Some operators in the injector assembly installation, with too thin, too thick copper pad, this will change the fuel injection into the combustion chamber distance, thus affecting the formation of the mixture, so that the engine is not strong, not easy to start.In direct injection engines, the copper pad is too thin and the piston head will hit the injector head.
(5) Improper adjustment of injection pressure when replacing the nozzle or adjusting the injection pressure, the injection pressure is set too low or too high, which will shorten the life of the nozzle coupling.If the injection pressure is too low, it will cause the high pressure gas in the cylinder to flow back, making the needle valve couple stuck;If the injection pressure is too high, not only the nozzle couple wear aggravate, but also increase the plunger pair and oil valve wear.
(6) If the engine oil is not maintained in time and the combustion is poor, if the fault cannot be removed in time and carbon accumulation is removed, the nozzle will be damaged at an early stage.
(7) Turn up the engine speed arbitrarily.Some operators turn up the engine speed at will in order to make the locomotive run fast.Some of the oil pump rack to the direction of small throttle to dial 2 ~ 3 teeth;Some use the adjusting arm to directly control the throttle;Some will speed - regulating steel ball interval removed a few.In fact, the result of doing so, not only will accelerate the wear and tear of the three precision couplers, but also easily cause serious accidents such as flying cars.