Diesel Injector Fuel Injector 0445120075 Bosch for Caseih Truck New Holland Truck Engine

How the injector works
The fuel injector is composed of a fuel injection pump body, an adjusting screw, a pressure regulating spring, a ejector rod, a fuel injector assembly and a cover cap, etc. Among them, the fuel injector assembly is the core component, and it is also one of the three major assemblies of the fuel system. Its condition determines the working performance of the fuel injector. Precision couples, ground in pairs, are not interchangeable. There are needle valve holes, annular oil passages, straight oil passages, pressure chambers and spray holes in the needle valve body. The needle valve head has two conical surfaces and an inverted cone-shaped pin. The large cone is in the pressure chamber, and the small cone is seated on the inner cone of the spray hole, which is also a pair of ground sealing surfaces. The inverted cone pin extends into the nozzle hole, and its function is to make the sprayed oil mist form an oil beam with a certain cone angle.
During the fuel supply stroke of the fuel injection pump, the diesel pressure acting on the large cone surface of the needle valve rises against the pretightening force of the pressure regulating spring. When the small cone surface leaves the inner cone surface of the nozzle hole, the nozzle hole is opened, and the high-pressure diesel oil is sprayed into the combustion chamber at a high speed in the form of a mist oil beam through the annular gap between the pin and the nozzle hole to form a certain cone angle. After the fuel injection pump stops supplying fuel, the diesel pressure in the pressure chamber drops rapidly, and the pressure regulating spring makes the needle valve quickly seat and close the nozzle hole, so that the fuel injection is stopped decisively. A small amount of diesel oil leaked through the matching gap between the needle valve and the needle valve body is sent back to the diesel oil filter through the spring cavity, the oil return screw and the oil return pipe. The pressure when the injector starts to inject fuel is called the fuel injection pressure, which is one of the important indicators of the diesel engine. It is adjusted by turning the pressure regulating screw to change the preload of the pressure regulating spring.