Cause and prevention of damage to precision coupli

2022-07-22
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Damage causes and prevention of precision coupling parts of diesel engine

plunger pair, outlet valve and fuel injection nozzle are the three precision coupling parts of diesel engine. Its technical status directly affects the power and economy of diesel engine. Keeping the three precision couples in good technical condition is an important part of moskona's repeated injection of polyurethane filler into Lycra fabric pre fixed in the wooden frame

the normal service life of the three precision coupling parts is generally more than 2500 H. However, according to the survey, few people have a service life of more than 1500 h, most of them are about 500 h, and some even only use it for dozens of hours. In addition to the reasons for improper manufacturing quality and storage, it is common to see the reasons for the damage of the three coupling parts, such as random disassembly and unloading, improper assembly and adjustment, improper cleaning, and the use of inferior fuel

1 causes of damage to the three precision coupling parts

(1) random disassembly of many engine operators because diesel fuel supply system failures are common, once the diesel engine fails, it is often not through careful analysis, after finding the cause of the failure, it is targeted to check and eliminate, but to disassemble, check and replace the fuel supply system one by one. The processing and assembly accuracy of the three precision coupling parts is very strict, and they cannot be disassembled at will. Once removed and installed, the service life can be shortened by tens or even hundreds of hours. In addition, the technical state may be further deteriorated due to bumps, dirt, scratches and even deformation caused by improper disassembly and installation

(2) improper cleaning. When cleaning the three precision coupling parts, they were mixed with other parts, and unclean cleaning fluid was used. The newly purchased three precision coupling parts were not thoroughly cleaned with antirust oil. Before replacing the coupling parts, it is not feasible to clean them. Some use cloth and cotton yarn to directly wipe the surface of the couple; Some even put the cleaned parts in unclean places. As a result of these practices, the working surface was scratched, adhered with mechanical sundries, damaged the assembly clearance of the coupling parts, and caused the coupling parts to be stuck and burned

(3) poor fuel quality or unclean use of oil. What is the technical advantage of using poor fuel (kerosene, engine oil, diesel oil mixture, etc.) in terms of its lubrication performance and sealing instruments? Performance and viscosity can not meet the use requirements, which will lead to insufficient pump oil pressure, increased wear

and fuel nozzle carbon deposition. In addition, the fuel is not purified, the used refueling tools are not clean, the fuel filter device is damaged, the sealing ring is missing, wrongly installed or damaged, and the filter element is removed to make the oil circuit "unblocked", which will shorten the service life of the three precision coupling parts

(4) improper assembly some operators over tighten the tight seat of the oil outlet valve and the tight cap of the fuel injector in order to prevent oil leakage, so that the stress of the fuel injector body, plunger sleeve and oil outlet valve seat is too large, resulting in deformation, and the matching accuracy is damaged, so that the movement of the coupling is blocked and damaged

some operators use asbestos rope to wind instead of copper pad. Because asbestos is a heat insulation material, winding with asbestos rope will seriously affect the heat dissipation of the fuel injector, resulting in excessive temperature of the needle valve of the fuel injector and burning

some operators use too thin and thick copper pads when installing the fuel injector assembly, which will change the distance of fuel injected into the combustion chamber, thus affecting the formation of mixture, making the engine weak and difficult to start. In direct injection engines, the head of the fuel injector will be impacted by the plug top if the copper pad is too thin

(5) improper adjustment of fuel injection pressure when replacing the fuel injection nozzle or adjusting the fuel injection pressure, the fuel injection pressure is adjusted too low or too high, which will shorten the service life of the fuel injection nozzle. If the injection pressure is too low, it will lead to medium high pressure in the cylinder. The project focuses on the research, development and implementation of new renewable raw material pressure gas backflow, which will make the needle valve coupling stuck; If the injection pressure is too high, not only the wear of the fuel injection nozzle coupling is aggravated, but also the wear of the plunger pair and the outlet valve is increased

(6) if the diesel engine is not maintained in time due to oil burning and poor combustion, the fuel injection nozzle will be damaged early if the fault is not eliminated in time and the carbon deposit is removed

(7) arbitrarily increase the engine speed. Some operators arbitrarily increase the engine speed in order to make the locomotive run faster. Some move the oil pump rack 2 ~ 3 teeth towards the small throttle; Some use the adjusting arm to directly control the throttle; Some remove several speed regulating steel balls at intervals. In fact, this will not only accelerate the wear of the three precision pairs, but also easily cause major accidents such as speeding

the above reasons for shortening the service life of the three precision coupling parts are caused by improper use and maintenance. Only the machine operator pays attention and takes positive measures, the service life of the three precision coupling parts will be prolonged and the failure of the fuel supply system will be greatly reduced

2 preventive measures

(1) select the fuel that meets the requirements, and strictly implement the fuel sedimentation and filtration system. The fuel shall be precipitated for at least 48 hours before filling; The oil tank shall be cleaned once every 500 hours. The refueling equipment shall be clean. When refueling, it is better to filter with silk cloth. It is better to use the closed refueling equipment with filter for refueling. During the work, the sediment oil in the sediment cup and the oil tank shall be discharged according to the maintenance regulations. The diesel filter element shall be cleaned and replaced in time. The filter element shall be installed to ensure effective filtration and prevent short circuit; The specified standard grade fuel oil shall be used according to the change of season and temperature, and mixed oil shall not be used; The fuel storage must be sealed

(2) attention shall be paid to the disassembly and inspection of even parts. The cleaning shall be carried out separately and shall not be mixed with other parts to avoid collision and scratch

(3) during assembly, pay attention to tightening according to the specified torque to ensure that the coupling parts are in good technical condition. If the pressure cap of the fuel injection nozzle is installed, the state of the pressure cap must be checked, and the pressure cap that has been used for a long time must be replaced. The tightening torque for installing the pressure cap should be appropriate (0.5886 ~ 0.7848mpa). Do not use too much force. When exploring the new development path of plastic granulator technology, otherwise it is easy to damage the fuel injector. When using old pressure caps, carbon deposits must be carefully removed. The tightening torque of the tightening seat of the outgoing oil valve shall also meet the requirements

(4) improve fault analysis and judgment ability and avoid random disassembly and adjustment. If the equipment is not disassembled and adjusted, do not remove the fault by yourself. Go to the repair station or ask someone to repair it

(5) the diesel engine shall not be overloaded and overspeed operated for a long time

because overload operation will cause the engine temperature to be too high, which will cause the needle valve coupling of the fuel injection nozzle to be stuck

overspeed operation will cause the machine to consume oil, wear faster, rotate too fast or even run too fast, and the consequences are very dangerous. (end)

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