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14-112412-02
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
<009a008c0095009a00960099005500470070008d0047009b008f008c0047009b008c00940097008c00990088009b009c0099008c00470090009a00470093008c009a009a0047009b008f008800950047005d005700570b4500530047009b008f008c004700
8800940096009c0095009b00470096008d004700970096009a>t-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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14-12
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.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.
Engine ECU (D20DTR)
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.
T-MAP sensorIntake air
mass
Measures
the
excessive
amount of
PM.
Boos
t
pressure
/
temperature
Injector (C31)
Controls the post injection.
Electric throttle body
Controls the intake air mass.
HFM sensor
Wide band
oxygen senso
r
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14-14
1) Oxidation of DOC
The DOC oxidizes HC and CO of the exhaust gas in the two-way catalytic converter at 180℃ or
<009400960099008c0053004700880095008b00470097008c0099008d009600990094009a00470089008c009a009b00470088009b0047009b008f008c0047009b008c00940097008c00990088009b009c0099008c00470089008c009b009e008c008c009500
47005b00570057004700880095008b0047005c005700570b45>. The front EGT sensor
detects whether the DOC can burn (oxidize) the post-injected fuel or not, and sends the signal to the
<006c006a007c0047009b009600470094008800900095009b0088009000950047009b008f008c0047006b0076006a004700960097008c00990088009b00900095008e0047009b008c00940097008c00990088009b009c0099008c00470089008c009b009e00
8c008c00950047005a00570057004700880095008b0047005c>00℃. The DOC reduces CO
and HC of the exhaust gas by redox reaction and also reduces small amount of PM.
<0058005500470076009f00a0008e008c009500470088008b008f008c0099008c009a0047009b00960047009b008f008c0047008a0088009b0088009300a0009a009b004700940088009b008c0099009000880093009a006100470073008c009a009a004700
9b008f0088009500470058005f00570b45>
2. CO and HC are oxidized by the catalyst materials: More than 180℃
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14-152412-02
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-
<009000950091008c008a009b0090009600950047009b0096004700900095008a0099008c0088009a008c0047009b008f008c0047009b008c00940097008c00990088009b009c0099008c00470096008d0047009b008f008c0047008c009f008f0088009c00
9a009b0047008e0088009a0047009c00970047009b00960047>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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14-172412-02
4) Fuel Injection During CDPF Regeneration
Page 207 of 751
15-70000-00
Fuel rail pressure
sensorEGR valveFuel temperature
sensor
Electric throttle bodyKnock sensor
(2 ea)
Coolant temperature
sensor
T-MAP sensorD20DTR ECU
E-VGT actuator
Water sensorGCU (Preglow control
unit)
E-EGR bypass valve
Page 209 of 751
15-90000-00
Fuel rail pressure
sensor
(2) Components for ECU Input
CAN
- ABS & ESP
- GCU
- Instrument
cluster
- TCUSwirl valve
position sensor
Differential
pressure sensorE-EGR valve
position sensorCamshaft position
sensorCoolant
temperature
sensor
Exhaust gas
temperature
sensorHFM sensorOxygen sensorT-MAP sensor
Crankshaft
position sensorAccelerator pedal
sensorThrottle position
sensorKnock sensor
-Auto cruise switch
- Rear right wheel
speed (without ABS)
- Refrigerant pressure
sensor
- Clutch pedal signal
- Blower switch signal
- Brake pedal signal
Water sensor
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15-110000-00
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.
<00760097008c00990088009b00900095008e0047009b008c00940097008c00990088009b009c0099008c0047009900880095008e008c00470096008d0047006c006a007c00470090009a0047009500960099009400880093009300a000470054005b005700
47009b009600470052005f005c00b6006a004700880095008b> 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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