CDI high pressure circuit, function - GF07.16-P-3012IC

ENGINE 647.961 in MODEL 211 

ENGINE 648.960 in MODEL 220 

ENGINE 648.961 in MODEL 211 

Shown on engine 648 

The high-pressure circuit regulates and stores the fuel pressure required for injection.

The high pressure pump compresses the fuel up to an operating pressure of 1600 bar and pumps the controlled quantity of fuel it into the rail. The fuel flows along the high pressure lines to the individual fuel injectors.

Injected quantity control 

Injection quantity control is cylinder-selective and carried out by the CDI control unit (N3/9). For this purpose, either the actuation time for the fuel injectors or the rail pressure can be adapted via the pressure regulator valve or the quantity control valve.

High pressure control 

The CDI control unit uses its input signals to determine the actual operating status of the engine (load request) and regulates the rail pressure between around 300 and 1600 bar accordingly.

For rail pressure adaptation, a control current, dependent on performance mapping, is applied to the quantity control valve or the pressure regulator valve by the CDI control unit, until the target pressure is adjusted in the rail.

The rail pressure sensor measures the current rail pressure and sends the corresponding voltage signal to the CDI control unit.

Rail pressure regulation via pressure regulator valve 

The rail pressure is regulated via the pressure regulator valve up to 30 seconds following engine start and up to a fuel temperature of 20°C.

The fuel is heated by rail pressure regulation via the pressure regulator valve.

Rail pressure regulation via quantity control valve 

Rail pressure regulation via the quantity control valve takes place from 30 seconds following engine start and from a fuel temperature of 20°C.

Rail pressure regulation via the quantity control valve improves the efficiency of the high-pressure pump and lowers the fuel temperature in the fuel return.

	High-pressure pump, component description	19	GF07.02-P-3010IC
	Component description for the rail	21	GF07.03-P-6110IC
	Component description for the fuel injectors	Y76	GF07.03-P-6120IC
	Component description for the rail pressure sensor	B4/6	GF07.04-P-6210IC
	Component description for the quantity control valve	Y94	GF07.05-P-6010IC
	Component description for the pressure regulator valve	Y74	GF07.05-P-6020IC
	Component description for the fuel temperature sensor	B50	GF47.50-P-2010IC