First, the structure of Delphi injectors

Second, Delphi injector assembly sequence:
Step 1, the needle insertion needle valve body, and installed glib spring

In Step 2, the orifice plate is installed as shown, on the body above the orifice

Step 3, as shown armature assembly into the valve body

Step 4, the valve spring pad and insert solenoid valve spring, and then the entire magnet assembly into the injector body

Step 5, the first three steps as shown Couples assembled components and assembled the fourth step injector body attached to a piece of

Step 6 Tighten the nipple tight cap, the entire injector assembly is completed

Third, Delphi injector works
Delphi Common Rail Injector China currently on the market can be divided according to the different ways of working hydraulic servo and piezoelectric crystals two. The vast majority of the injectors are all hydraulic servo type. Refers to the so-called hydraulic servo injector fuel injection or not controlled by the hydraulic properties of the fuel. The following figure shows a schematic diagram of Delphi DFI2 works.

1, the closure phase: the solenoid is not energized, the armature assembly in a tapered seal under the action of the spring force of the oil passage is sealed tightly. A pass into the control chamber due to fuel and pass into the tank B is filled with the same fuel pressure (common rail), and acting on the needle end face of hydraulic force area much larger than the tip of the needle and the guide portion by hydrodynamic force area, and therefore the effect of force on the part of the downward movement, the needle valve that is seated tightly sealed when the nozzle holes, no fuel injection.
2, the beginning of the power stages: when the solenoid is energized, an upward electromagnetic force, the electromagnetic force which attracts the armature assembly when the upward movement, when the high-pressure fuel within the control chamber A rapid upward return oil, A seat face of the cavity by hydraulic sharply. But the fuel oil tank filled cavity B remains similar pressure and rail pressure, so the role of force in the entire needle into upward.
3, the injection stages: a hydraulic needle valve is lifted, the high-pressure fuel injected into the combustion chamber through the nozzle holes, to achieve ejection. In the case of continuous energizing the solenoid valve, injector continuous injection.
4, the injection is stopped: if the electromagnet energization is stopped, the electromagnetic force generated by its immediate disappearance of the armature assembly under the action of the spring force of the downward movement of the oil to re-seal tightly channel. Then a rapid increase in oil until the oil pressure in the fuel rail close to the control chamber A. Force acting on the needle turned down, the needle is seated tightly sealed spray hole, stop fuel injection.

Since the hydraulic servo injector injection timing change completely rely on each hydraulic control chamber to achieve, so it is powered from the solenoid to the presence of certain hydraulic injection start delay. The condition of all moving parts to wear guide surface will affect the hydraulic delay long and short, usually wear more powerful injection delay greater. Delay schematically shown below:

Compared with similar Denso and Bosch hydraulic servo injector, Delphi injectors DFI2 hydraulic delay smaller. The reason DFI2 injector therefore no long stem hydraulic transmission time is relatively short. Popular terms, DFI2 corresponding rate than other similar injectors fast.

Fourth, Delphi injector common failure mode
1, the valve seat surface wear

2, the armature cone seal wear

3, orifice plates wear

4, carbon or spray nozzle holes blocked