New Injector Nozzle Dlla139p1497 0433171923 for Fuel Injector 0445110251

1. The working principle of the needle valve coupler:

The needle valve coupler is sealed by the sealing cone surface and the oil film in the top gap. The pressure at the high-pressure inlet port is the same as that of the common rail pipe, and the pressure at the low-pressure outlet port is lower. The low-pressure fuel flows back to the fuel tank from the low-pressure oil passage. When the needle valve is opened, under the action of high-pressure fuel, part of the fuel leaks to the low-pressure outlet port through the gap oil film. During the reciprocating motion of the pair, the oil film in the gap plays the role of sealing and lubricating at the same time, so as to take into account the sealing and lubricating effects at the same time.

2. Radial deformation of the needle valve couple:

As the pressure of the fuel supply system increases, the oil storage groove and the sliding surface clearance of the needle valve assembly are subject to a large load. It causes the elastic deformation of the needle valve coupling, changes the radial film thickness distribution of the oil film in the gap between the needle valve coupling, and thus affects the sealing characteristics of the needle valve coupling. When the gap between the needle valve assembly expands, the flow state of the fuel in the gap changes, the flow is unstable, and the needle valve may appear eccentric or tilted. On the one hand, the eccentricity of the needle valve increases the leakage of fuel in the gap, which reduces the sealing performance of the needle valve; on the other hand, on the side where the oil film is thin, the needle valve is prone to the risk of dry friction. Therefore, when analyzing the flow field of the oil film in the gap, it is necessary to consider the high-pressure deformation of the needle valve coupling. The radial additional total deformation of the needle valve coupling is positively related to the pressure of the gap oil film.