SYSTEM
EC9-33
< SYSTEM DESCRIPTION >
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pressure in the rail. The measurement circuit consists of an pressure sensor on the rail and transmits the pres-
sure signal to ECM.
The high-pressure pump is self-supplied by an integrated gear pump. This supplies the rail, whose pressure is
controlled for loading by the fuel flow actuator. The flow regulation actuator allows the high-pressure fuel pump
to supply only the necessary quantity of diesel for maintaining pressure in the rail.
Pressure regulation can be done with one actuator in case of magnetic injectors because of their natural leak
during injector closing.
INJECTION CONTROL
The injection control parameters are the quantities to inject and their respective advances. The system per-
forms one to five injections.
The injectors are magnetic injectors. An electrical current (pulse) is sent to each injector holder based on the
previously computed data.
To control injector, ECM punctually drivers energy to obtain actuator deformation and the injector opening.
During the injection time, the length of electrical pulse is computed with the fuel flow demand and injectors cor-
rections. The system has three injector corrections:
• Injector adjustment value registration
• Zero fuel calibration
• Pressure wave correction
Injector Adjustment Value Registration
Injector adjustment value indicates manufacturing tolerance. The injector adjustment value which is correctly
stored in ECM is needed for precise fuel injection control. A performance of emission control and a driveability
may effect when there is a mismatch between the following two values.
• The injector adjustment value stored in ECM
• The injector adjustment value of the injector which is installed on the vehicle
Zero Fuel Calibration (ZFC)
During the lifetime of an injector, it is subject to thermal and mechanical constraints that modify the injection
characteristics. This wear-and-tear on the orifices (blocked or expanded holes) causes drift in the quantity of
injected fuel, which can lead to smoke generation or increased noise. To compensate for this drift, ECM imple-
ments a teach-in in the raised foot phase and under certain condition, which allows it to regulate the ZFC cor-
rector parameter.
Pressure Wave Correction:
The first injection causes a pressure wave in the pipe between rail and injector and the bores in the injector
itself. The quantity of the next injections is influenced by this pressure wave.
Main parameters of this influence are:
• Rail pressure
• Distance between the two injections
• Fuel temperature
• Injection quantities of both injections
The pressure wave correction minimizes the influence of the first injection on the next injections with simple
structure and parameters which can be measured.
TEMPERATURE BEFORE TURBINE CONTROL
Upstream turbine temperature control sequentially uses injection parameters:
• Main injection phasing
• Post injection fuel mass
• Total fuel mass quantity
• Maximum torque
In normal combustion mode (without regeneration), the regulation aims to protect the turbine. If the tempera-
ture exceeds the recommended limits, the regulation is able to limit total fuel mass quantity and torque
demand.
In regeneration mode, to increase the temperature in exhaust line, the regulation controls main injection phas-
ing and post injection.
The purpose is to obtain the highest temperature while respecting the recommended limits. In addition, the
regulation protects the turbine when the temperature is too hot.
WATER IN FUEL FUNCTION
The water in fuel detection sensor is an optional sensor integrated in the fuel filter. This function prevents seri-
ous damages on the common-rail system caused by water presence.
AFTER TREATMENT SYSTEM