High Quality New Diesel Injector 28229873 33800-4A710 Common Rail Injector for Delphi Hyundai 2.5 CRDI Engine Spare Parts

Made of high-quality bearing steel, its sliding cylindrical clearance is only 0.001mm-0.0025mm, obtained by high-precision machining or grinding options, and different fuel injector couplings are not interchangeable. If the gap is too large, the injection pressure will drop and the spray quality will deteriorate; The gap is too small, and the needle valve is easy to jam. The annular cone (pressure-bearing cone) in the middle of the needle valve is located in the annular oil cavity of the needle valve body, and its function is to withstand the axial thrust generated by the oil pressure to make the needle valve rise. The cone at the lower end of the needle valve (sealing cone) matches the needle valve body to seal the inner cavity of the injector.

The upper part of the needle valve has a convex shoulder, when the needle valve is closed, the distance h between the shoulder and the lower end face of the injector body is the maximum lift of the needle valve, and its size determines the amount of fuel injection, generally H=0.4mm-0.5mm. There are 1-2 locating pins 8 at the junction of the needle valve body and the injector to prevent the needle valve body from rotating to avoid misalignment of the oil inlet hole.

When the injector is working, the high-pressure diesel from the injector pump, through the oil pipe joint into the oil inlet on the injector body, and then into the annular oil cavity in the middle of the needle valve body, acting on the pressure-bearing cone of the needle valve, forming an upward axial thrust on the needle valve, once this thrust is greater than the pre-pressure of the injector regulator spring, the needle valve immediately moves up, opens the injection hole, and the high-pressure diesel fuel is immediately injected into the combustion chamber. When the fuel injection pump stops supplying oil, the pressure in the high-pressure oil passage drops rapidly, and the needle valve returns to the position in time under the action of the pressure regulating spring, and the injection hole is closed to stop the fuel injection.

A small amount of diesel fuel entering the annular oil cavity of the needle valve body flows to the pressure regulating spring end through the gap between the mating surfaces of the injector couple, enters the oil return pipe, and flows back to the filter, which is used to lubricate the fuel injector couple.

The opening pressure (injection pressure) of the needle valve depends on the preload of the regulator spring. Different engines have different injection pressure requirements, which can be adjusted by the pressure regulating screw, the pressure increases when screwed in and decreases when screwed out.