Analysis of Causes of Fracture of Injector Nut of WD615 Diesel Engine

Maintenance Guide WD 615 diesel engine injector nut rupture analysis □ Hu Ziqing Xu Xianhai nozzle nut cracks will cause injectors not working, dripping, poor combustion, large amount of smoke and engine power shortages.

WD615 series diesel engine is a high-enhanced diesel engine. The working environment of the injector is relatively harsh. Because the injector is often in high temperature and high pressure gas, it can withstand the heat exchange load and the fuel pressure load, making the nozzle nut easier to break. . In order to overcome this problem, the WD615 series diesel engine has been designed with some measures, such as inserting the injector bushing on the cylinder head, directly cooling the injector by the coolant; and installing an insulation cover at the injector. The injector only extends 3.34mm into the bottom surface of the cylinder head to ensure that the injector nozzle absorbs less heat.

During the maintenance, we encountered several crackers in the injector nozzle nut, and checked that the insulation sleeve was good; the measuring injector only protruded into the bottom plane of the cylinder head by about 3.6mm, within the specified range; Disassemble and pull out the injector bushing. The water in the inner hole of the cylinder head is free of scale, which proves that the cooling water circulation is normal and the engine temperature is not high. But why is there a crack in the nozzle nut crack? After analysis, we think that the main reasons are as follows: the tightening force of the nozzle nut during maintenance is too large. The nozzle nut is connected to the injector and spray (on Continue to page 44. In the case where the requirements are not too high, you can use the instrument's special electrical check value instead of the standard sample gas for easy calibration.

The electrical check value is set at the factory to determine whether the HC value is the above set value. If not, perform the calibration as shown in the calibration procedure above.

In the case of the fastener of the oil body, in the case of disassembly of the injector during maintenance work, the injector nut must be removed first, and then the injector must be removed. The opposite is true for installation. The nozzle nut is a thin-walled hollow nut. If the strength of the nozzle nut is too large during the assembly process, the nozzle nut will be cracked, resulting in the injector not spraying, dripping, burning. Poor, engine power is reduced. Due to dripping oil, a large amount of unburned diesel fuel flows into the crankcase, which reduces the viscosity of the oil, deteriorates the oil, and seriously causes accidents such as burning of the engine.

Cylinder head inner hole injector seal damage injector In the installation, the lower part of the injector is equipped with a copper sealing gasket with a thickness of 1.0~1.5mra. This gasket is used when disassembling the injector during maintenance. Sometimes it will follow, sometimes it will stay in the inner hole of the cylinder head. After disassembly and cleaning, if the inspection is not fine, the sealing gasket is leaked. After the injector is installed, the injector will drop 1.01.5mm overall, so that the depth of the injector entering the bottom surface of the cylinder head exceeds the specified standard, which may easily lead to fuel injection. The mouth and the insulation cover are burnt and damaged, so that the engine is not working properly. Conversely, if there is a gasket in the inner hole of the cylinder head during installation, but with a gasket, it will cause the injector to rise as much as l.mm, because the injector is less than the bottom plane of the cylinder head. When the secondary filter is contaminated or the alarm buzzer sounds, replace the filter paper of the secondary filter and the filter element of the pre-filter.

A place where there is little change, no vibration, no oil.

After the device, it must be calibrated with standard gas before it can be used.

The electrical check value of the instrument has been set at the factory, and it takes 2 months to make a correction in actual application.

3mm, there is carbon deposit between the two seals, the seal is not good, the spray is affected by certain factors, and the engine will work poorly.

If the seal is forgotten during installation, the injector nut will be directly affected by the high temperature and high pressure gas, causing thermal deformation. In severe cases, the injector nut will crack.

Poor quality of fuel burned If the cetane number of diesel does not meet the requirements, it will cause the engine to run weakly, the amount of smoke is large, and the engine failure increases, especially the injector failure is high.

Poor diesel quality will accelerate the wear of the injector needle valve, and the diesel supply is not normal. At this time, the fuel is not injected into the combustion chamber as regularly, quantitatively and rapidly as in normal operation, but there is a phenomenon of dripping oil and oil. Due to poor atomization of diesel oil, it can not be quickly mixed with air and fully burned. Therefore, the burning speed is slow, so that the working time of the injector under high temperature and high pressure conditions is lengthened, and the absorbed heat is increased, resulting in the nozzle and the nozzle. The hot sleeve is burned and the nozzle nut is cracked due to overheating.

For the above reasons, paying attention to the correct maintenance method and checking more in the use and maintenance is an effective way to reduce the crack of the injector nozzle nut. □ (93327 troops Chai Xiu teaching and research section) When the standard gas is introduced into the instrument, the standard gas cylinder nozzle matched with the instrument should be aligned with the standard gas inlet, and the valve port will open when pressed slightly. At this point, the gas pump should be closed, otherwise the gas of the standard cylinder will be evacuated.

Because the instrument will drift, aging, etc. during use, the instrument will be calibrated after using it for a period of time (usually 3~6 months); the electrical characteristics should be checked once a week. Mouth (Hebei Xinji Transportation Bureau Transportation Management Station) 50 car maintenance 20U2 August issue