From the perspective of dynamic seating characteristics, after the research, the dynamic motion equation of the needle valve lifting process was constructed, and compared with the static balance equation. Through a series of experimental research and theoretical analysis, the conclusions drawn are as follows: , compared with the static state, the dynamic opening pressure of the needle valve is significantly higher, but the dynamic closing pressure is relatively low, which is closely related to the engine operating conditions. Because the needle valve has the characteristics of dynamic seating, it also increases the diameter of the oil pull in the later stage of injection, thereby reducing the spray quality, and even shortening the life of the oil nozzle, posing a threat to the emission index. In the process of applying the needle valve coupling of the injector, due to the very harsh operating environment, the sealing cone surface is prone to wear and tear. The reason is due to the impurity generated in the fuel and the impact force caused when the needle valve is seated. After wear and tear, it will cause deformation of the sealing cone surface, increase the roughness of the surface, seriously reduce the sealing effect, and fail to produce a good spray effect. What's more, oil dripping will occur, and diesel oil cannot be fully burned. In the combustion chamber, injection holes and active cold parts, excessive carbon deposits are generated, resulting in blockage of the injection holes. In the end, the power of the diesel engine was severely reduced, resulting in more specific fuel consumption.
