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0000-00
Basic principle at low speed
At low speed, it utilizes the principle of venturi. For
example, when air flows through the venturi tube,
the flow speed is faster and the pressure is lower
at the point "A". In this case, if the inner diameter
of venturi is more narrowed, the flow speed is so
much faster (refer to the equation).
Control
rangeTurbocharger driving
mechanismControl method
EffectImproved
performance
At low
speedNarrows the flow
passage for the
exhaust gas by
folding the vanesThe flow rate is
increased as the
exhaust gas passes
the narrow passage
turbine & impeller
speed, Increased
compressive forceImproved
low speed torque
4. OPERATING PRINCIPLES
The E-VGT is designed to get more improved engine power in all ranges by controlling the turbine as
follows:
1) How it Works at Low Speed
Normal turbocharger cannot get the turbo effect because the amount of exhaust gas is not enough and
the flow speed is slow in a low speed zone, but VGT allows the flow passage of exhaust to narrow,
resulting in increasing the flow speed of exhaust gas and running the turbine quickly and powerfully.
Therefore, as VGT can intake more air than normal turbocharger, it can give the benefit of the increased
output even in a low speed zone.
Turbocharger lag
The turbocharger is at idle speed when there is no load or it is in the normal driving condition. During
this period, the amount of exhaust gas passing through the turbine is not enough to turn the
compressor wheel (impeller) fast. Therefore, the intake air is not compressed as needed.
Because of this, it takes time for turbocharger to supply the additional power after the accelerator
pedal is depressed. This is called "turbocharger lag".
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2) How it Works at High Speed
In a high speed zone, the amount of exhaust gas increases and it is accompanied with a great force.
Therefore, if the inner diameter of venturi is more widened, the turbine in the turbocharger by the
releasing force of abundant exhaust gas can deliver a more increased energy to the compressor. The
output will increase in submission to the increase of intake air volume.
Control
rangeTurbocharger driving
mechanismControl method
EffectImproved
performance
At high
speedExpands the flow
passage for the
exhaust gas by
unfolding the vanesThe flow rate is
increased due to the
Increased turbine &
impeller speed,
Increased
compressive forceImproved
maximum
power
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1413-00
1. OVERVIEW
The pre-heating system for D20DTF engine has the glow plug to the cylinder head (combustion
chamber), and improves the cold start performance and reduces the emission level.
The pre-heating resistor (air heater) is used to heat the intake air.
This enables the diesel fuel to be ignited in low temperature condition.
The ECU receives the information such as, engine rpm, coolant temperature, engine torque, etc.,
through CAN communication during pre-heating process; and the pre-heating control unit controls the
pre-heating, heating during cranking and post-heating by the PWM control.
Glow plugGlow plug control unit
(GCU)
Glow indicatorEngine ECU (D20DTF)
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1. SYSTEM DESCRIPTION
1) Overview
The EGR (Electric-Exhaust Gas Recirculation) valve reduces the NOx emission level by recirculating
some of the exhaust gas to the intake system.
To meet Euro-V regulation, the capacity and response rate of E-EGR valve in D20DTF engine have
been greatly improved. The EGR cooler with high capacity reduces the Nox, and the bypass valve
reduces the CO and HC due to EGR gas before warming up.
Also, the engine ECU adjusts the E-EGR opening by using the air mass signal through HFM sensor. If
the exhaust gas gets into the intake manifold when the EGR valve is open, the amount of fresh air
through HFM sensor should be decreased.
Benefits of E-EGR valve
Improved accuracy and response through electric control
Feedback function (Potentiometer)
Preventing chattering of EGR valve and improved durability
Self-cleaning function -
-
-
-
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1793-01
2) Location and Components
HFM sensor
Used as a main map value to control the EGR.
The coolant temperature, engine rpm, engine
load, intake air temperature (HFM: decreased at
(atmospheric pressure sensor: altitude
compensation) are used as auxiliary map values.
EGR pipe
Transports the exhaust gas from the EGR cooler
and EGR bypass valve to the intake duct.
E-EGR cooler and bypass valve
The cooler lowers the high temperature of the
exhaust gas and the bypass valve directly
supplies the exhaust gas to the intake duct
without passing through the EGR cooler to
reduce the emission of exhaust gas before
warming up the engine.
E-EGR valve
Receives the electric signal from the ECU to
control the valve.
EGR cooler
EGR bypass
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1793-01
2) Input/Output Devices
3) Control Logic
The EGR system controls the EGR amount based on the map values shown below:
Main map value: Intake air volume
Auxiliary map value:
Compensation by the coolant temperature
Compensation by the atmospheric pressure: Altitude compensation
Compensation by the boost pressure deviation (the difference between the requested value and the
measured value of boost pressure)
Compensation by the engine load: During sudden acceleration
Compensation by the intake air temperature -
-
-
-
-
The engine ECU calculates the EGR amount by adding main map value (intake air volume) and auxiliary
map value and directly drives the solenoid valve in the E-EGR to regulate the opening extent of the EGR
valve and sends the feedback to the potentiometer.
(1) Operating conditions
Atmospheric pressure: 0.92 bar or more
When there is no fault code related to EGR -
-
-
-
(2) Shut off conditions
Abrupt acceleration: with engine speed of 2600 rpm or more
When the engine is idling for more than 1 minute
Vehicle speed: 100 km/h or more
Engine torque: 380 Nm or more -
-
-
-
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1114-00
(3) Warning Lamp Related to CDPF
CDPF regeneration process (warning lamp NOT illuminated)
Overload of CDPF (warning lamp blinking)
The CDPF system enters the regeneration mode
when the driving distance becomes approx. 600
to 1,200 km (may differ by the driving condition
and driving style). Then, the engine ECU
performs the CDPF regeneration operation.
However, the driver is not informed with this
operation by any engine warning lamp or vehicle
signal, so he/she may not detect this operation.
The control logic at the post-injection dur-ing the
regeneration process is to increase the fuel
injection volume and control the intake air volume
(by the throttle body) in order to increase the
temperature of the exhaust gas. The driver may
not feel any particular difference from the vehicle.
If the CDPF cannot reach the regeneration
temperature due to low speed driving or other
reason during the regeneration process, the
soot is continuously accumulated in the
CDPF. When this condition continues and
the CDPF is overloaded with soot, the engine
warning lamp blinks to inform this situation to
the driver.
In order to solve this problem, drive the
vehicle at a speed of approx. 80 km/h for 15
to 20 minutes to perform the CDPF
regeneration process.
If the engine warning lamp on the instrument
cluster blinks, the CDPF is overloaded. In this
case, perform the step 2. 1.
2.
3.
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Engine ECU (D20DTF)
Post-injectionDifferential pressure sensor
Calculates the amount of PM
collected by reading the pressure
difference between before and
after the CDPF.Electric throttle body
Regulates the rate of air
intake.
CDPF
(DOC + DPF)Front temperature
sensor
Protects the
turbocharger.Rear temperature
sensor
Measures the
temperature of fuel
combustion.
2. COMPONENT
Oxygen
sensor