SsangYong Korando III (2010 year). Service manual — part 369

15-21

0000-00

c. Types of swirl

Swirl: One cylinder has two intake air ports, one is set horizontally

and the other one is set vertically. Swirl is the horizontal air flows in

cylinder due to the horizontal intake air ports.

Tumble: Tumble is the vertical air flows in cylinder due to the vertical

intake air port

Squish: Squish is the air flows due to the piston head. Normally, this

is appears at the final process of compression. In CRDi engine, the

piston head creates the bowl type squish.

d. Swirl control

In DI type diesel engine, the liquefied fuel is injected into the cylinder directly. If the fuel is evenly

distributed in short period, the combustion efficiency could be improved. To get this, there should be

good air flow in cylinder. In general, there are two intake ports, swirl port and tangential port, in each

cylinder. The swirl port generates the horizontal flow and the tangential port generates the longitudinal

flow.

In low/mid load range, the tabgential port is closed to increase the horizontal flow. Fast flow decreases

the PM during combustion and increases the EGR ratio by better combustion efficiency.

15-22

Load

Engine speed

Swirl

valve

Amount of

swirl

Remarks

Low speed,

Low load

below 3,000 rpm

Closed

Heavy

Increased EGR ratio, better air-fuel
mixture (reduce exhaust gas)

High speed,

High load

over 3,000 rpm

Open

Light

Increase charge efficiency, higher
engine power

The variable swirl valve actuator operates when

turning the ignition switch ON/OFF position to

open/close the swirl valve. In this period, the soot

will be removed and the learning for swirl valve

position is performed.

Swirl valve

Swirl: This is the twisted (radial) air flow along the cylinder wall during the intake stroke. This stabilizes

the combustion even in lean air-fuel mixture condition.

e. Features

Swirl and air intake efficiency

To generate the swirl, the intake port should be serpentine design. This makes the resistance in air

flow. The resistance in air flow in engine high speed decreases the intake efficiency. Eventually, the

engine power is also decreased, Thus, the swirl operation is deactivated in high speed range to

increase the intake efficiency.

Relationship between swirl and fuel injection pressure

The injector for DI engine uses the multi hole design. For this vehicle, there are 8 holes in injector. If

the swirl is too strong, the injection angles might be overlapped and may cause the increased PM and

insufficient engine power. Also, if the injection pressure is too high during strong swirl, the injection

angles might be overlapped. Therefore, the system may decreases the fuel injection pressure when

the swirl is too strong.

-

-

15-23

0000-00

f. Relationship between swirl and fuel injection pressure

The injector for DI engine uses the multi hole design. For this vehicle, there are 8 holes in injector. If

the swirl is too strong, the injection angles might be overlapped and may cause the increased PM and

insufficient engine power. Also, if the injection pressure is too high during strong swirl, the injection

angles might be overlapped. Therefore, the system may decreases the fuel injection pressure when

the swirl is too strong.

-

Anti-knock methods:

Shorten the ignition timing by pilot injection, lessen the fuel injection volume during ignition delay

period.

Increase engine speed.

Maintain intake sir temperature with intercooler or glow plug device.

Increase intake air pressure with turbocharger.

Warm up engine to keep the normal operating temperature.

Increase compression ratio.

Use the fuel with high cetane.

*

-

-

-

-

-

-

-

15-24

T-MAP sensor

D20DTF ECU

Oxygen sensor

Electronic

throttle body

HFM sensor

(intake air temp.)

Coolant

temp.sensor

E-EGR valve

Crankshaft posi.

sensor

Accelerator

pedal

E-EGR cooler

(5) EGR control

a. Overview

The EGR (Electric-Exhaust Gas Recirculation) valve reduces the NOx emission level by recirculating

some of the exhaust gas to the intake system.

The major difference with the previous EURO 4 type, is that the DC motor with improved response rate

according to the EURO 5 regulation. The solenoid type actuator is used in the conventional model, but in

this new model, the DC motor type actuator with improved response rate is adopted. Also the hall sensor

which provides a more stabilized signal than the potentiometer, and the EGR bypass flap which

improves engine warming up efficiency are also used. The HFM sensor and the position sensor are

used to feedback the amount of EGR for both EURO 4 and EURO 5.

b. Components