1

Diesel SCR certification issues

V6 TDI Clean Diesel

LEV II / Bin 5 Program

NOx-Aftertreatment system • system overview• tank concept• heating strategy• refill concept• warning sequence• wrong medium

2

Diesel SCR certification issues

NOx-Aftertreatment system - system overview

SCR Cat

Oxi Cat

DPF

NOx-Sensor

Dosing unit

3

Diesel SCR certification issues

NOx-Aftertreatment system - tank concept

temperature sensor

2 tank concept

Dosingmodule

max.

min.

heatingfilter pump pressure

sensor

fillingdevice

functional tank

filling line

storage tank

1 tank concept

Dosingmodule

pressure sensor

heating

fillingdevice

filter pump

min.temperature

sensor

max.

4

Diesel SCR certification issues

NOx-Aftertreatment system - heating strategy

• Heating will be activated at temperatures below -11°C (12°F) after engine start• thawing of frozen Adblue (urea)

• avoid freezing of liquid AdBlue during vehicle operation

thawing

Dosingmodule

heated devices

• Both concepts ensure a continuous melting and dosing of 2 gallons of UREA

• During a long lasting freezing period (< -11°C) the unheated UREA volume couldremain frozen. Even in this case the operational range is approx. 4.000 miles afterwhich the tank can be refilled.

5

Diesel SCR certification issues

• If ambient temperature is constantly below <12°F (< -11°C) the urea tank will becompletely frozen after several days.

• These environmental conditions are unusual

-30

-25

-20

-15

-100 10 20 30 40 50 60

starting time [min]

Tank

Tem

p. [°

C]

4°F

-4°F

-22°F

• In this case, injection of UREA will start approx. 20 min. after engine start.

• This waiting time is needed to ensure continuous dosing - a certain amount of liquidurea has to remain in the tank to guaranty further thawing (avoiding thermalisolation).

NOx-Aftertreatment system - heating strategy

Adblueconsumption

Molten Adblueair

Frozen Urea

6

Diesel SCR certification issues

NOx-Aftertreatment system - refill concept

• Customer refilling through „Kruse bottle“ (0.5 gal.)

• Service refilling through nozzle with „Kruse adapter“

• leakproof concept - sufficient solution for customer and service staff

• Refilling of the wrong medium is avoided

• „Kruse“ system is recommended as a standard solution for all manufacturers

7

Diesel SCR certification issues

urea300 mi

10 mi

0 mi Reduced driveability

Insistent warning

Constant warning level

warning level

Safety margin-250 mi

1000 mi Refill indicated by a “Please refill AdBlue”

message and acoustic signal

Urgent refill indicated by a “Refill urea immediately”

message and acoustic signal

Last warning - “Reduced driveability in x mi” occurs

and insistent acoustic signal

Message - “Reduced driveability * ” occurs

and insistent acoustic signal

*) reduced driveability = max. speed 60 km/h

NOx-Aftertreatmentsystem - Warning Sequence

8

Diesel SCR certification issues

urea

300 mi

10 mi

0 mi Reduced driveability

Insistent warning

Constant warning level

warning level

Safety margin-250 mi

1000 mi Refill indicated by a “Please refill AdBlue”

message and acoustic signal

Urgent refill indicated by a “Refill urea immediately”

message and acoustic signal

Last warning - “Reduced driveability in x mi” occurs

and insistent acoustic signal

Message - “Reduced driveability * ” occurs

and insistent acoustic signal

*) reduced driveability = max. speed 60 km/h

NOx-Aftertreatmentsystem - Warning Sequence

9

Diesel SCR certification issues

urea

300 mi

10 mi

0 mi Reduced driveability

Insistent warning

Constant warning level

warning level

Safety margin-250 mi

1000 mi Refill indicated by a “Please refill AdBlue”

message and acoustic signal

Urgent refill indicated by a “Refill urea immediately”

message and acoustic signal

Last warning - “Reduced driveability in x mi” occurs

and insistent acoustic signal

Message - “Reduced driveability * ” occurs

and insistent acoustic signal

*) reduced driveability = max. speed 60 km/h

NOx-Aftertreatmentsystem - Warning Sequence

10

Diesel SCR certification issues

• „Reduced driveability“ is a limitation of the maximum speed (e.g. 35 mph)

• After this mode is activated there is still urea left (operational range: approx. 250 mi)

urea

300 mi

10 mi

0 mi Reduced driveability

Insistent warning

Constant warning level

warning level

Safety margin-250 mi

1000 mi Refill indicated by a “Please refill AdBlue”

message and acoustic signal

Urgent refill indicated by a “Refill urea immediately”

message and acoustic signal

Last warning - “Reduced driveability in x mi” occurs

and insistent acoustic signal

Message - “Reduced driveability * ” occurs

and insistent acoustic signal

NOx-Aftertreatmentsystem - Warning Sequence

11

Diesel SCR certification issues

NOx-Aftertreatmentsystem – OBD

Von VW !!!

OBD

Urea quality monitoring

System o.k.

Yes

No

maintenance

Refill ?

Below level switch ?

MIL on MIL on

Driver warning500 miles

Driverinducement

System monitoring

System not o.k.

Failure ?

Driver warning

Driverinducement

MIL on

YesYes