SsangYong Rodius (2013 year). Service manual — part 89

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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: 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.

Swirl valve

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 EGR

To reduce Nox, it is essential to increase EGR ratio. However, if EGR ratio is too high, the PM also

could be very higher. And, the exhaust gas should be evenly mixed with newly aspired air.

Otherwise, PM and CO are dramatically increased in highly concentrated exhaust gas range and

EGR ratio could not be increased beyond a certain limit. If the swirl valve operates in this moment,

the limit of EGR ratio will be higher.

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F. Relationship between swirl and fuel injection pressur

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.

15-28

Electric throttle

body

Accelerator

pedal

module

D20DTR

ECU

(9) 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.

To meet Euro-V regulation, the capacity and response rate of E-EGR valve in D20DTR 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 decresed.

B. Components

E-EGR cooler

Coolant

temperature

sensor

Oxygen sensor

HFM (intake

air

temperature)

Crankshaft

position

sensor

E-EGR valve

T-MAP

sensor

15-29

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C. Input/Output of E-EGR system

15-30

D. Bypass control for EGR cooler

Cooler temperature

▶

When the coolant temperature is below 70℃, the exhaust gas is bypassed the EGR cooler.

Exhaust gas temperature

▶

When the exhaust gas temperature is below 300℃, the exhaust gas is bypassed the EGR cooler

Otherwise, PM could be increased due to too low exhaust gas temperature.

E. Control elements for EGR system

Accelerator pedal (engine load) - Indicates the driver's intention and engine load. If the load goes

up, the EGR ratio is decreased.

T-MAP (boost pressure map stored in ECU) - Compensates the difference in boost pressure by

adjusting EGR ratio.

Engine rpm - Used as the signal for determining EGR operating range.

Coolant temperature - When the coolant temperature is low, NOx is decreased but PM could be

increased. So, to reduce PM, decrease EGR ratio when the coolant temperature is low.

Intake air mass and temperature - HFM sensor measures the intake air mass to calculate the

actual EGR volume. If the air mass is larger than programmed value in map, EGR ratio will be

higher.

EGR position sensor - Detects the actual opening angle of EGR valve and performs feedback

function according to PWM control by ECU.

Wide band oxygen sensor - Detects the oxygen volume in exhaust gas to check if the EGR ratio is

proper.

Electronic throttle body - Keeps EGR ratio to optimized level by controlling the throttle body in EGR

operating range (decreasing pressure in intake manifold).

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