SsangYong: Engine Euro 4. Service manual - part 25

CHANGED BY

EFFECTIVE DATE

AFFECTED VIN

25

2411

EXHAUST SYSTEM

D27DTP/D27DT (EU4)  SM - 2006.08

D27DTP/D27DT (EU4)

ENGINE

FUEL

I

N

T

AKE

EXHAUST

PRE-HEA

TING

LUB

COOLING

SWITCHABLE

ECU

DIAGNOSIS

The vacuum modulator controls the throttle flap in the
throttle body.

Three vacuum modulators are installed in total, while only
two vacuum modulators are installed for D27DT engine
without CDPF. For the D27DTP (POWER UP) engine, only
one vacuum modulator for controlling VGT turbocharger is
installed since the vacuum modulator related to EGR is
deleted.

The vacuum modulator for controlling throttle body reduces
the amount of intake air by reducing the air passage when
the soot is burnt in low load range of engine.

Vacuum Modulator for Controlling Throttle Body

Modulator for

controlling

throttle body

Modulator for

controlling

EGR valve

Modulator for

controlling

turbocharger

wastegate

The turbocharger bearing has been changed from normal
pad type to oil pocket type since the exhaust pressure ex-
ceeds the limit (2.5 bar) when CDPF is installed.

For the turbocharger for CDPF, there is a name plate on
the turbocharger indicating “CDPF”.

Turbocharger

Conventional bearing

(normal pad type)

Bearing for CDPF

(oil pocket type)

The ECU operates the vacuum modulator for con-
trolling throttle body to control the amount of air
using the input values from the temperature sen-
sors and differential pressure sensor.

The throttle body is normally open. When the soot
is burnt in CDPF, the engine ECU performs the
post injection and the flap in the throttle body is
closed to decrease the amount of intake air to
the combustion chamber. Therefore, the tem-
perature of exhaust gas is increased and the
combustion temperature (approx. 600°C) is
reached in CDPF.

For more details, refer to the control logic on the
next page.

Throttle Body

CHANGED BY

EFFECTIVE DATE

AFFECTED VIN

26

2411

EXHAUST SYSTEM

D27DTP/D27DT (EU4)  SM - 2006.08

D27DTP/D27DT (EU4)

4. THE CONTROLS FOR SOOT COMBUSTION OF CDPF SYSTEM

Combustion Temperature and Procedures

As the soot is filtered in the CDPF, it is burnt and removed, and the CDPF is returned to the initial state to collect the
soot. Therefore, the burning procedures in the CDPF can be called as recycling.

The CDPF assembly is integrated with DOC (at front side) and DPF (at rear side). After the exhaust gas is passed
through the exhaust manifold, its temperature is approx. 250°C and the temperature is increased as the exhaust gas
is passed through the DOC. Normally, the soot is burnt at 600°C.  However, the temperature of the exhaust gas does
not reach 600°C even though temperature is increased as the gas passes through the DOC.

Sytem Composition for Soot Combustion

When the engine is running in low load range, the temperature of exhaust gas is decreased as the amount of fuel
supplied is decreased. To burnt the soot filtered in the CDPF, the control system should be installed to check the
operating range and increase the temperature of exhaust gas by controlling the amount of fuel supplied and and
intake air.

Two temperature sensors and one differential pressure sensor monitor the CDPF's operating range. According to
theses sensors' information, the throttle flap decreases the intake air entered to the throttle body. Also, the fuel
injection pattern is added to increase the temperature of exhaust gas for soot combustion.

There are two fuel injection patterns (pilot injection and main injection). As the CDPF is installed, the post injection
pattern is added.

Post Injection and Air Mass Control

When the differential pressure sensor detects the pressure difference between the front and the rear side of CDPF,
the sensor sends signal indicating the soot is acumulated and the post injection is performed to raise the tempera-
ture of exhaust gas. The amount of fuel injected is determined according to the temperature of exhaust gas detected
by the rear temperature sensor. If the temperature is below 600°C, the amount of fuel injected is increased to raise
the temperature. If the temperature is over 600°C, the amount of fuel injected is decreased or not controlled.

When the engine is running in low load range, the amount of post injection and the amount of intake air are controlled.
It is to raise the temperature by increasing the amount of fuel while decreasing the amount of intake air.

Throttle Body for Different Engines

The throttle body is not installed in the D27DT engine, but is installed in the following engines:

1) D27DT engine with CDPF

2) D27DTP (POWER UP) engine

Both engines are equipeed with the throttle body, but its appearance and the related control system are differ.

For the D27DT engine with CDPF, the throttle body is used to decrease the amount of air supplied when the engine
is running in low load range. For the D27DTP (POWER UP) engine, the throttle body is used to prevent the engine
from turning off with fluttering noise at the moment the air to intake manifold is blocked by closed flap when the
engine is switched off.

If the throttle body is installed in D27DTP (POWER UP) engine, its function can be added up to four functions by
changing the ECU software.

• Normally, when the vehicle is driven for 300 ~ 500 km, the enough amount of soot to be burnt is filtered and

accumulated in the CDPF. The ECU increase the amount of post injection to increase the tempeature of ex-
haust gas up to 600°C so that the soot is burnt. The soot is burnt for 15 ~ 20 minutes.

NOTICE

CHANGED BY

EFFECTIVE DATE

AFFECTED VIN

27

2411

EXHAUST SYSTEM

D27DTP/D27DT (EU4)  SM - 2006.08

D27DTP/D27DT (EU4)

ENGINE

FUEL

I

N

T

AKE

EXHAUST

PRE-HEA

TING

LUB

COOLING

SWITCHABLE

ECU

DIAGNOSIS

Ports for measuring

front/rear pressure

CDPF mounted in vehicle

CDPF rear

temperature sensor

Differential

pressure

sensor

To

differen-

tial

pressure

sensor

* DOC (Diesel Oxydation Catalyst)

DPF (Diesel Particulate Filter)

CDPF

5. CDPF (Catalyst & Diesel Particulate Filter) LAYOUT

Mounting location of

Differential Pressure Sensor

Connected to

exhaust manifold

Differential

pressure sensor

CDPF front

temperature sensor

DPF area

DOC area

CHANGED BY

EFFECTIVE DATE

AFFECTED VIN

28

2411

EXHAUST SYSTEM

D27DTP/D27DT (EU4)  SM - 2006.08

D27DTP/D27DT (EU4)

DOC area

DPF area

Front temperature sensor

(Measuring the temperature

of exhaust gass passed

through exhaust manifold)

Rear temperature sensor

(Measuring the temperature of

exhaust gass passed through DOC)

Differrential pressure sensor

(Front pressure port)

Differrential pressure sensor

(Rear pressure port)

6. SOOT FILTERING AND BURNING PROCEDURES

Operating Procedures of CDPF

The most efficient and practical technology for now is adopted to the diesel particulate filter (DPF).

This system collects the soot from the diesel engine to the filter and burns the soot so that over than 95% of soot
can be removed from the exhaust gas. However, the durability and the cost of additional system remain as problems.

Firstly, the exhaust gas is passed through the DOC and its temperature is increased as it is oxidized. The ECU
detects the temperature change with two temperature sensors. The CO, HC and partial particulate material are
removed from the exhaust gas (this procedures are the sames as the ones for the conventional DOC and no sensor
is required).

After the exhaust gas is passed through the DOC and oxidized, most of the harmful material is removed from the
exhaust gas. However, to meet the environmental regulations in the future, the soot is filtered and burnt again in DPF
to decrease the particulate material further.

• The filtered soot is burned whenever the vehicle is driven for 300 ~ 500 km. The driving distance can be

differed depending on the vehicle’s driving conditions. The soot is burnt for 15 ~ 20 minutes.

NOTICE

The exhaust gas enters into CDPF
assembly after passing through
the exhaust manifold.
(Normal pressure of exhaust gas:
approx. 250°C)

When the exhaust gas enters into
the CDPF assembly, its CO, HC
and particulate material are re-
duced as it is oxidized in DOC.
The remaining particulate mate-
rial is filtered and collected in DPF
and the temperature of exhaust
gas is increased to approx. 450 ~
500°C.

T h e   e n g i n e   E C U   d e t e c t s   t h e
amount of particulate material
coolected by the information from
temperature sensors and differ-
ential pressure snesor. When the
soot is accumulated, the pressure
difference between the front and
the rear side occurs. Then, the
engine ECU performs the post in-
jection to raise the exhaust gas
temperature and burn the col-
lected soot at approx. 600°C.