The function of the Hitachi excavator oil injector is to spray the diesel fuel supplied by the injection pump into the combustion chamber at a certain pressure. When it is found that the engine is not uniform, the sound of knocking or the exhaust is seriously black smoke, the injector should be checked.
The wear of the injector of Hitachi excavator is mainly due to the wear of fuel injector coupling.
The wear of Hitachi excavator injector mainly includes the following aspects:
The wear of 1 seal cones
The main forms of wear are fatigue peeling and abrasive wear. In the work, in the work of the widening couple, because of the action of high pressure fuel and the spring of the injector, the frequent vibration of the needle valve and the carving of the hard abrasive in the oil make the sealing cone form extrusion plastic deformation, the cone wear and the collapse of the seat, and increase the sealing ring which was only 0.2 to 0.25 millimeter wide. To 0.5 ~ 1 millimeter. After wear, the surface of the seal face has trench, pitting and contact belt depression, which causes the seal not to be strict, the oil is not brittle, the oil is dripped at the hole, and the cylindrical part of the cylinder near the hole or the shaft needle is accumulated, and the needle valve is stuck seriously. The failure phenomenon on the engine is the knock, intermittent exhaust smoke and unstable operation.
Wear and tear of 2 axis needle and spray hole
In the work, the fuel and the impurities are ejected from the annular gap at high speed, causing the wear of the needle valve and the spray hole (scour and micromachining) and the comb scratch. After wear, the cylindrical parts of the shaft needle form a cone, the lower end wear is large, the wear of the upper end is small; the hole is worn large, the roundness error increases, the axial trench marks appear. The shaft needle and the spray The hole gap increases and the flow rate of fuel increases, resulting in the drop of injection pressure, the decrease of velocity, the deterioration of the spray quality, and the larger particles in the oil beam. The sound is not brittle at the time of injection, resulting in unsafe combustion, exhaust smoke, fuel injection nozzle, combustion chamber and piston top coke.
The wear of 3 inverted cones
The effect of the reverse cone is that when the oil is injected, the fuel flow is impacted by the cone to form atomization and to change its direction. The abrasive particles in the central zone of the fuel also scour and scrape the surface of the cone, and the central part of the cone is worn seriously, so that the inverted cone appears in the middle of the bar. After the cone is worn, the spray cone angle increases, making the oil beam not very good. With the combustor, the combustion condition deteriorated. When severe, some fuel was injected into the combustion chamber wall, causing incomplete combustion.
Wear of 4 needle valve guide face and needle valve body
When working, the abrasive in the fuel oil also enters, when the needle valve is vibrated, the abrasive wear cylindrical guide surface is worn out, the lower end wear is large, the upper end wear is small and the cone is formed. After wear, the gap increases, the sealing cones are neutral to the neutral, the amount of oil return is increased, the amount of fuel injection is reduced, the injection time is lags, engine power is insufficient, It's difficult to start.
In the work, the atomization quality of the injector is deteriorated, the drop oil, the spring pressure is too low or the spring is broken, or the abrasive is stuck into the guide surface, which makes the needle min high temperature carbon and dies. When the needle valve is stuck in the opening position, the engine has a strong percussion sound, black smoke, and the gas comes out when the high-pressure pipe is loosened; for example, the needle valve card dies in close position. At the time, the cylinder can't work.
Wear of 5 fuel injector body
Because the vibration frequency of the needle valve is very high, the upper part of the injector body contacts the middle pier of the plane into a concave pit, and the wear of the seal face increases the lift of the injector needle valve. The vibration frequency of the needle valve in the lift is reduced at each injection, and the fluctuation amplitude of the injection pressure in the vibration process is increased; and the needle valve is changed at the same time. The relative position of the opening with the spray hole of the needle valve makes the atomization quality worse.
