3315483 - Introduction - DIESEL FUEL INJECTION
SPECIFCATIONS
FUNCTION
The EDC-16C8 Common Rail is a high pressure electronic injection system for direct injection fast diesel engines.The main features are:
- availability of high injection pressures (1400 bar);
- possibility of modulating these pressures between 150 bar and a maximum operating pressure of 1400 bar, irrespective of the engine rotation speed and load;
- capacity of operating at high engine speeds (up to 5000 rpm in full load conditions);
- precision injection (advance and duration of injection);
- reduction in consumption;
- reduction in emissions.
The main functions of the system are basically as follows:
- control of fuel temperature;
- control of engine coolant temperature;
- control of quantity of fuel injected;
- control of idle speed
- fuel cut off during deceleration;
- control of cylinder balance during idling
- control of irregular operation;
- control of exhaust fumes during acceleration
- control of exhaust gas recirculation (E.G.R.)
- control of maximum torque limiting
- control of maximum speed limiting
- control of heater plugs
- control of entry into operation of climate control system (where fitted)
- control of auxiliary fuel pump
- control of cylinder position
- control of main and pilot injection advance
- control of closed loop injection pressure
- control of electrical balance
- control of supercharging pressure
- self test
- connection with Body Computer for ALFA CODE.
OPERATION
OPERATING LOGICS
Introduction
The Common Rail systems makes it possible to carry out a pre-injection (pilot injection) before T.D.C. with the advantage of reducing the pressure in the combustion chamber more evenly, reducing the combustion noise, typical of direct injection engines.The engine management control unit controls the quantity of fuel injected, regulating the line pressure and injection times.The engine management control unit processes the following information to control the quantity of fuel to inject:
- rpm
- coolant temperature
- turbocharging pressure
- air temperature
- intake air quantity
- battery voltage
- diesel pressure
- accelerator pedal position.
With the temperature of the engine coolant greater than 105° C, the engine management control unit:
- reduces the quantity of fuel injected (reduces the engine power);
- operates the cooling fans through the fan control interface;
- lights up the coolant overheating warning light.
On the basis of the signals coming from the sensors and the values in the map, the engine management control unit:
- it operates the pressure regulator;
- varies the 'pilot' injection time up to 3000 rpm;
- varies the 'main' injection time.
The engine management control unit processes the signals coming from the various sensors and regulates the quantity of fuel injected:
- it operates the pressure regulator;
- it varies the injector injection time.
When the accelerator pedal is released the following logics are implemented by the engine management control unit:
- it cuts off the supply to the fuel injectors;
- it partially reactivates the supply to the injectors before the idle speed is reached;
- it operates the fuel pressure regulator.
On the basis of the signals received from the sensors, the engine management control unit controls the precision of the torque up to 3500 rpm.
- it varies the quantity of fuel injected in the individual injectors (injection time).
The engine management control unit processes the signals received from the various sensors and determines the quantity of fuel to be injected via:
- the pressure regulator;
- the opening time of the injectors.
When there is considerable acceleration, the engine management control unit determines the optimum quantity of fuel to be injected, on the basis of the signals received from the flow meter and engine rpm sensor:
- it operates the pressure regulator;
- it varies the injector injection time.
On the basis of the engine load and signal coming from the accelerator pedal potentiometer, the engine management control unit restricts the amount of air drawn in, implementing the partial intake of exhaust gases through:
- the adjustment of the E.G.R. solenoid valve opening
According to the number of revs, the engine management control unit calculates the following from predefined maps:
- the torque limit
- the permissible fumes (limit).
It compares these minimum values and corrects them with other parameters:
- coolant temperature
- engine rpm
- vehicle speed
- intake air temperature obtained from the built in air temperature/excess pressure sensor
According to the number of revs, the engine management control unit implements two intervention strategies:
- at 5000 rpm it cuts off the fuel, reducing the line pressure;
- above 5400 rpm it deactivates the auxiliary pump and the injectors.
In the following stages:
- starting,
- post-starting,
The engine management control unit operates the air conditioning compressor:
- switching it on/off when the relevant switch is pressed;
- switching it off momentarily (for around 6 s) if there is substantial acceleration or a request for maximum power.
Irrespective of the engine speed, the engine management control unit:
- supplies the auxiliary fuel pump with the ignition key in the ON position;
- excludes the auxiliary pump supply if the engine is not started up within a few seconds.
According to the battery voltage, the engine management control unit varies the idle speed:
- it increases the injector injection time;
- it regulates the line pressure.
At the various engine operating speeds, the engine management control unit processes the signal coming from the supercharging sensor and determines the quantity of fuel to be injected:
- it operates the pressure regulator;
- it varies the injection time;
- it regulates the geometry of the turbine in order to optimise performance under all operating conditions.
The engine management control unit, in accordance with the coolant temperature and pressure of the refrigerant in the air conditioning system, converses with the fan control interface to give the go ahead for:
- the switching on of the fans at the first or second speed.
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