China Made High Quality Common Rail Diesel /Fuel Injector NozzleDLLA144P191 FOR CUMMINS ENGINE

Analysis of why the injector nozzle stuck in the injectors. (part 1)

1 Confirmation of testing items

Through the analysis of the possible reasons for the sticking of the nozzle needle valve assembly, it was decided to conduct a series of inspection and analysis on the faulty nozzle assembly. The specific inspection items are as follows:

1) Check the matching clearance of the coupling and the fit of the needle valve seat surface;

2) Re-measure the roundness, cylindricity, roughness, and surface hardness of the needle valve after cleaning (removing surface rust, etc.);

3) Cleaning (removing surface rust, etc.)

4) Dissect the needle valve and nozzle, and perform coloring inspection on the mating surface of the needle valve and nozzle;

5) Submit the needle valve and nozzle for metallographic inspection, measure Impurity ratio.

2 test results
2.1 The measurement results of the outer diameter of the needle valve fitting surface and the inner diameter of the nozzle fitting surface are shown in Table 1. Among them, the even parts with stamp number HHM are not installed and running. From the measurement data, it can be seen that the fit gaps of the two sets of couplings are greater than the design value, the roundness of the inner hole of the needle valve and the nozzle with the stamp number HD all meet the design requirements, and the roundness of the inner hole of the needle valve and the nozzle with the stamp number HHM exceeds the design Require. The surface area of the needle valve with steel stamp number HD is relatively serious, and the fitting surface cannot be inspected. The specific situation is shown in Figure2.

The fitting surface of the needle valve with steel stamp number HHM is wider, with a bandwidth of about 2mm, as shown in Figure 3 (the mating surface will be darker after the pair is slightly ground, so you can check the fitting condition). In addition, the cone angle at the front end of the needle valve is measured, and the design requires a cone angle of 91°±5'. The needle angle of steel seal number starting HHM is 91°1′, and the needle valve angle of steel stamp number starting HD is 91°2′, both of which meet the requirements of the drawings.