CAT Medium Pressure Common Rail Injector HEUI

CAT Medium Pressure Common Rail Injector HEUI Meaning.

H: hydraulic

E:  electronic

U: unitI:  injector

CAT medium pressure common rail injector system features

(1) fuel metering based on time, and injection pressure is not affected by engine speed and load, injector timing is not limited.

(2) Fuel exists only in the necessary boost amplifier at high pressure.

(3) by changing the ratio of the cross-sectional area of the booster piston to the working plunger to obtain very high injection pressure
There are CAT C7, C9, C-9 injectors:

C7 injector nozzle: 6 holes

C9 injector nozzle: 5 holes

C-9 injector nozzle: 7 holes

Among them, C7 and C9 in addition to different injector nozzles, internal parts can be used interchangeably.

CAT medium pressure common rail injection principle:

The injector uses a change in the cross-sectional area of the booster piston and plunger to increase injection pressure. There are two oil channels inside the engine, one provides medium pressure (10-28MPa material for oil) used to push the booster piston, the other is a low-pressure oil circuit, used to inject fuel to the injector (material for diesel) other electrical control parts and high-pressure common rail system similar.

CAT medium pressure common rail injector working principle.

After the electromagnetic energized lift valve in overcoming the spring force to rise, the lower seat open at the same time, close the upper seat, the oil return hole cut off. At this time, the oil in the medium-pressure oil circuit into the top of the piston, under the action of pressure downward displacement, push the plunger compression fuel. As the fuel inlet and return channels are closed with a check valve, so the diesel oil pressure at this time will rapidly increase, pushing the nozzle needle valve to lift and start injection.

Solenoid valve power off in the role of spring tension lift valve down, the lower seat closed at the same time the upper seat open, the oil return hole open rapid pressure relief, booster piston in the role of spring force quickly lift, so that the pressure in the pressure chamber pressure drop, nozzle needle valve in the role of spring force quickly close the injection hole to stop spraying, while the fuel in the pump pressure through the one-way ball valve into the plunger below.

Solenoid valve energized time is the injection point, the length of time the solenoid valve is energized determines the size of the injection volume fuel pressure boosted injection pressure can reach 160Mpa, while the solenoid valve is controlled by the ECM

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