SSANGYONG KYRON 2010.01 Manual page 120

5. FUEL INJECTION CONTROL
1) Fuel Injection Control
Injection control is used in order to determine the characteristics of the pulse which is sent to
the injectors.
Injection control consists as below.
- Injection timing
- Injection volume
- Translating fuel injection timing and injection volume into values which can be
interpreted by the injector driver.
a reference tooth (CTP)
·
the delay between this tooth and the start of the pulse (Toff)
·
the pulse time (Ton)
·
▶ Main injection timing control
The pulse necessary for the main injection is determined as a function of the engine speed and
of the injected flow.
The elements are:
- A first correction is made according to the air and coolant temperatures.
This correction makes it possible to adapt the timing to the operating temperature of the
engine. When the engine is warm, the timing can be retarded to reduce the combustion
temperature and polluting emissions (NOx). When the engine is cold, the timing
advance must be sufficient to allow the combustion to begin correctly.
- A second correction is made according to the atmospheric pressure.
This correction is used to adapt the timing advance as a function of the atmospheric
pressure and therefore the altitude.
- A third correction is made according to the coolant temperature and the time which has
passed since starting.
This correction allows the injection timing advance to be increased while the engine is
warming up (initial 30 seconds). The purpose of this correction is to reduce the misfiring
and instabilities which are liable to occur after a cold start.
- A fourth correction is made according to the pressure error.
This correction is used to reduce the injection timing advance when the pressure in the
rail is higher than the pressure demand.
- A fifth correction is made according to the rate of EGR.
This correction is used to correct the injection timing advance as a function of the rate of
exhaust gas recirculation.
When the EGR rate increases, the injection timing advance must in fact be increased in
order to compensate for the fall in termperature in the cylinder.
During starting, the injection timing must be retarded in order to position the start of combustion
close to the TDC.
To do this, special mapping is used to determine the injection timing advance as a function of
the engine speed and of the water temperature. This requirement only concerns the starting
phase, since once the engine has started the system must re-use the mapping and the
corrections described previously.
09-9
1491-01
ENGINE CONTROL SYSTEM
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