Diesel Injector Fuel Injector 0445110845 Bosch for Qingling

(1) When the injector solenoid valve is not triggered, the valve ball seat presses the ball valve to the oil drain hole of the valve seat, the oil drain hole is closed, and the common rail high-pressure oil cannot enter the upper part of the valve seat. A common rail high pressure is formed in the nozzle cavity. The combined force of the common rail high pressure on the pressure of the end face of the control plunger and the nozzle spring is higher than the opening force of the high-pressure fuel acting on the cone of the needle valve, as a result, the needle valve is forced into the valve seat and the high-pressure channel is isolated from the combustion chamber, sealed, and the needle valve remains closed.

(2) When the solenoid valve is triggered, the armature piece and the valve ball seat move up, the ball valve opens, and the oil drain hole is opened, which causes the pressure of the control chamber to drop, as a result, the pressure on the piston also drops, once the pressure on the piston and the combined force of the nozzle spring is reduced to lower than the pressure acting on the pressure cone of the injector needle valve (here the oil pressure is still common rail high pressure), the needle valve will be opened, and the fuel is sprayed into the combustion chamber through the nozzle hole. This kind of non-direct control of the injector needle valve adopts a set of hydraulic pressure amplification system, because the force required to quickly open the needle valve cannot be directly generated by the solenoid valve, the so-called control effect required to open the needle valve is to open the oil drain hole through the solenoid valve to reduce the pressure of the control chamber, thereby opening the needle valve.

(3) Once the solenoid valve is not triggered by the power off, the spring force of the solenoid valve will make the armature core and the valve ball seat pressed down, and the ball valve will close the oil drain hole. After the oil drain hole is closed, the fuel enters the valve control cavity from the oil inlet hole to establish oil pressure, this pressure is the rail pressure, this pressure acts on the plunger end face to generate downward pressure, coupled with the resultant force of the nozzle spring is greater than the pressure of the high-pressure fuel acting on the needle valve cone in the nozzle cavity, so that the nozzle needle valve is closed.

(4) In addition, because of the high fuel pressure, leakage will occur at the needle valve and housing, and these leaked oils will flow into the oil return port of the injector through the oil return hole.