Fuel injection SSANGYONG TURISMO 2013 User Guide

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3. INPUT/OUTPUT DEVICES
Front temperature sensor: This sensor is installed at the inlet of DOC and detects whether the
DOC can burn (oxidize) the post-injected fuel or not.
Rear temperature sensor: This sensor is installed at the inlet of DPF and monitors that the
temperature of the exhaust gas is kept at 600℃. 1.
2.
If the temperature exceeds 600℃, the life of CDPF can be reduced. So the amount of fuel
post-injection is decreased.
If the temperature drops under 600℃, the rate of regeneration can be decreased. So the
amount of fuel post-injection is increased. -
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Differential pressure sensor: This sensor checks the amount of PM collected by calculating the
pressure difference between before and after the CDPF.
Electric throttle valve: This valve reduces the intake air flow to raise the temperature of the exhaust
gas when the CDPF is operating during idling. 3.
4.

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4. POST-INJECTION AND AIR MASS CONTROL
A DPS (Differential Pressure Sensor) measures the pressure difference between before and after the
CDPF and detects whether the soot is collected in the CDPF or not. If PM is collected in the CDPF (In
this case the pressure difference between before and after the CDPF exceeds the specified value.
Normally, the system sends the signal when the driving distance becomes approx. 600 to 1,200 km), the
temperature of exhaust gas is increased and the post-injection is started for regeneration. The amount
of fuel post-injection is controlled by the exhaust gas temperature measured by the rear temperature
sensor. If the temperature is less than 600℃, the amount of post-injection is increased to
increase the regeneration temperature. Otherwise, the fuel injection amount is decreased or the fuel is
not injected.
When the engine is running with low load, the intake air amount is also controlled as well as fuel injection
amount. This function is used to increaser the combustion temperature by increasing the amount of fuel
post-injection with the lowest air amount within the specified control logic.

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Rear temperature sensor
Measure the outlet
temperature of DOC.
This sensor is located at the
rear side of DOC and
monitors the overheating of
CDPF and post injection
volume.
Differential pressure sensor
Measures the difference between
inlet and outlet pressures of CDPF.
If the difference is higher than the
specified value when collecting the
PM, this makes the post injection
for forced recycling of PM.
Front temperature sensor
Measures the temperature of
exhaust gas.
This sensor is located at the rear
side of exhaust manifold and
monitors the temperature of
combusted gas to prevent the
exhaust system from overheating.
When the temperature gets higher,
this sensor cuts off the fuel delivery
and controls the EGR to lower the
temperature.
Engine ECU (D20DTR)
T-MAP sensorIntake air
mass
Measures
the
excessive
amount of
PM.
Injector (C31)
Controls the post injection.
Electric throttle body
Controls the intake air mass.
HFM sensor
Wide band
oxygen
sensor
Boost
pressure/
temperature

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2) Collecting PM of DPF
There is a filter installed in the DPF and the PM filtered by this filter is burned (regeneration) when the
temperature of exhaust gas is increased due to post-injection. The filter has a honeycomb-like
structure to capture the particulate matter and the inlet and outlet of each channel are closed
alternatively. Once the exhaust gas enters to the inlet of a channel, it is released from the outlet of the
adjacent channel through the porous wall because of the closed outlet of the first channel, and the PM
is collected in the first channel.
[Collecting PM of CDPF]
Normally, when the driving distance becomes approx. 600 to 1,200 km, enough amount of soot to
be burned is filtered and accumulated in the CDPF. The ECU increases the amount of fuel post-
injection to increase the temperature of the exhaust gas up to 600°C, so that the soot is
burned. The soot is burned for 15 to 20 minutes (may differ by conditions).

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4) Fuel Injection During CDPF Regeneration
The injection method in D20DTR engine has three steps;
Pilot injection, Main injection, Post injection
Post injection ▶
The post injection is the injection process after main injection and consists of ‘After injection”,
“Post 1 injection” and “Post 2 injection”. All of post injections are to reduce the PM and
harmful exhaust gas. The post injection does not make the actual output. The post injection activates
the fuel by injecting the fuel to the incompletely combusted gas after primary combustion. Through the
process, the PM and smoke in the exhaust gas could be reduced. There are totally 7 injections as
shown in the figure. However, all of 7 injections are not performed during driving because it decreases
the fuel economy. Totally 5 injections can be performed in one cycle.

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2) ECU Control
(1) Function
a. ECU Function
ECU receives and analyzes signals from various sensors and then modifies those signals into
permissible voltage levels and analyzes to control respective actuators.
ECU microprocessor calculates injection period and injection timing proper for engine piston speed
and crankshaft angle based on input data and stored specific map to control the engine power and
emission gas.
Output signal of the ECU microprocessor drives pressure control valve to control the rail pressure and
activates injector solenoid valve to control the fuel injection period and injection timing; so controls
various actuators in response to engine changes. Auxiliary function of ECU has adopted to reduce
emission gas, improve fuel economy and enhance safety, comforts and conveniences. For example,
there are EGR, booster pressure control, autocruise (export only) and immobilizer and adopted CAN
communication to exchange data among electrical systems (automatic T/M and brake system) in the
vehicle fluently. And Scanner can be used to diagnose vehicle status and defectives.
Operating temperature range of ECU is normally -40 to +85°C and protected from factors like
oil, water and electromagnetism and there should be no mechanical shocks.
To control the fuel volume precisely under repeated injections, high current should be applied instantly
so there is injector drive circuit in the ECU to generate necessary current during injector drive stages.
Current control circuit divides current applying time (injection time) into full-in-current-phase and hold-
current-phase and then the injectors should work very correctly under every working condition.
b. Control Function
Controls by operating stages
To make optimum combustion under every operating stage, ECU should calculate proper injection
volume in each stage by considering various factors.
Starting injection volume control
During initial starting, injecting fuel volume will be calculated by function of temperature and engine
cranking speed. Starting injection continues from when the ignition switch is turned to ignition
position to till the engine reaches to allowable minimum speed.
Driving mode control
If the vehicle runs normally, fuel injection volume will be calculated by accelerator pedal travel and
engine rpm and the drive map will be used to match the drivers inputs with optimum engine power. -
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(2) Fuel injection control
a. Multi injection
Fuel injection process consists of 3 steps: Main Injection, Pilot Injection, Post Injection
This is the injection before main injection. This consists of 1st and 2nd pilot injection, and Pre-injection.
The steps are normally used to control the NOx, noise, idle stability and engine vibration. Inject a small
amount of fuel before main injection prevents the instant high combustion temperature. It reduces the
NOx and decreases the engine noise and vibration. The main injection produces the actual output.
The vehicle output is based on the main injection. The post injection is the injection process after main
injection and consists of ‘After injection”, “Post 1 injection” and “Post 2 injection”. All of post
injections are to reduce the PM and harmful exhaust gas. The post injection does not make the actual
output. The post injection activates the fuel by injecting the fuel to the incompletely combusted gas
after primary combustion. Through the process, the PM and smoke in the exhaust gas could be
reduced. There are totally 7 injections as shown in the figure. However, all of 7 injections are not
performed during driving because it decreases the fuel economy. Totally 5 injections can be performed
in one cycle.
InjectionFunction
MainProduces engine power
Pilot 1Reduces PM by injecting before
main injection.AfterPM control
Pilot 2Reduces NOx and noise by
shortening main injection delay
due to flammability Post 1Reduces PM by enabling fuel
activation.
PreControls NOx emission level,
Combustion noise and
Stable idle Post 2
Activates CDPF by increasing
exhaust gas temperature and
supplying reduction material

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b. Pilot Injection
Injection before main injection. Consists of 1st and 2nd pilot injection, and Pre-injection
Inject a small amount of fuel before main injection to make the combustion smooth. Also, called as
preliminary injection or ignition injection. This helps to reduce Nox, engine noise and vibration, and to
stabilize the idling.
The injected fuel volume is changed and stopped according to the coolant temperature and intake air
volume.
Pilot injection is much earlier than main injection due to higher engine rpm
Too small injection volume (insufficient injection pressure, insufficient fuel injection volume in
main injection, engine braking)
System failure (fuel system, engine control system) -
-
-
Pilot injection
Main injection
Combustion pressure with pilot injection
Combustion pressure without pilot injection 1.
2.
1a.
2b. Stop conditions
Combustion pressure characteristic curve for pilot injection ▶

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c. Main Injection
The power of the vehicle is determined by the main fuel injection volume.
Main injection calculates the fuel volume based on pilot injection. The calculation uses the value for
accelerator pedal position, engine rpm, coolant temperature, intake air temperature, boost pressure,
boost temperature and atmospheric pressure etc.
d. Post Injection
Injection after main injection. Consists of After injection, Post 1, Post 2 injection.
Post injection reduces PM and smoke from exhaust gas. No actual output is generated during these
injections, instead, fuel is injected to the unburned gas after main injection to enable fuel activation.

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(3) Fuel Pressure Control
Fuel pressure is controlled by IMV opening according to the calculated value by ECU.
Pressure in the fuel rail is determined according to engine speed and load on the engine. ▶
When engine speed and load are high
The degree of turbulence is very great and the fuel can be injected at very high pressure in order to
optimize combustion.
When engine speed and load are low
The degree of turbulence is low. If injection pressure is too high, the nozzle's penetration will be
excessive and part of the fuel will be sprayed directly onto the sides of the cylinder, causing
incomplete combustion. So there occurs smoke and damages engine durability. -
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Fuel pressure is corrected according to air temperature, coolant temperature and atmospheric
pressure and to take account of the added ignition time caused by cold running or by high altitude
driving. A special pressure demand is necessary in order to obtain the additional flow required during
starts. This demand is determined according to injected fuel and coolant temperature.
Open loop determines the current which needs to be sent to the actuator in order to obtain
the flow demanded by the ECU. ▶
Closed loop will correct the current value depending on the difference between the pressure
demand and the pressure measured. ▶
If the pressure is lower than the demand, current is reduced so that the fuel sent to the high
pressure pump is increased.
If the pressure is higher than the demand, current is increased so that the fuel sent to the high
pressure pump is reduced. -
-Fuel Pressure ▶