Introduction to Marine diesel engine parts: The working process of fuel injectors

The working process of the injector under the common rail injection fuel supply system is more exquisite. This system is composed of multiple key components such as high-pressure oil pumps, common oil supply pipes, and fuel injectors. The high-pressure oil pump is responsible for continuously delivering fuel to the common oil supply pipe, where the system can precisely control the oil pressure. When the fuel injector is in operation, as mentioned earlier, the electromagnetic coil generates a strong electromagnetic force at the moment of being energized. This electromagnetic force is sufficient to overcome the elastic force of the reset spring, thereby lifting the armature and the needle valve connected to it. At this time, the fuel injector's nozzle opens, and the fuel will be injected into the combustion chamber at a certain pressure, speed and direction. Once the electromagnetic coil is de-energized, the electromagnetic force disappears instantly. Under the action of the reset spring, the armature and needle valve fall back rapidly, closing the fuel injection hole and thus stopping the fuel injection.

After receiving the fuel injection pulse signal sent by the electronic control unit, the fuel injector can precisely adjust the fuel injection volume. The fuel comes from the high-pressure fuel line and it will flow to the fuel injector through a dedicated channel. During this process, the fuel will flow to the control room through the throttle hole simultaneously, and the opening and closing of the oil drain hole is controlled by the solenoid valve. When the oil drain hole is in the closed state, the hydraulic pressure on the needle valve control piston will exceed the force on the pressure-bearing surface of the needle valve, thereby keeping the needle valve closed. When the solenoid valve is triggered, the discharge hole opens, and the pressure in the control chamber drops accordingly. When the hydraulic pressure is lower than the force on the pressure-bearing surface of the needle valve, the needle valve will open for oil injection.