Emitec System introduction - SEETECHNO · Doser continues to pump urea for 10 strokes, building...

Emitec System introduction

21/5/2013

Magic yang

Content

System layout and components

Control----Working flow

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System Layout

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Components

Dosing Pump Unit

ECM

Urea tank (level and temp sensor)

Air tank

Pipeline

(suction line, backflow line, mixture line, air flow line)

Urea injector nozzle

EGP

(Temp sensor, Nox sensor)

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Dosing Unit

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1. Urea in from tank

2. Air supply in (vehicle air tank/compressor)

3. Urea out to Injector nozzle (Urea & Air mix)

4. Urea return to tank (only used during prime)

5. 37 PIN ITT Can connector broadcasting on the J1939

6. Power supply to Solenoid 2 pin connector

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Function : deliver urea according to the message sent by engine

ECM.

Built-in heating device : allows the doser to operate with outside

temperatures < –11C, if the vehicle also has heated Urea lines and

tank.

It will also function in a working temp > 80C, but Urea > 50degC for

extended periods will damage the doser Unit.

Integrated self-diagnostic procedure, informing the Engine ECM

about its status by sending messages via the J1939 CAN link.

Accommodate both 12 VDC & 24 VDC supply voltages.

The desired flow rate repeatability :1%

Dosing Unit Specifications

Dosing Unit Components

A: Air Tank

B: Air filter

C: Doser unit

D: Engine ECM

E: Wema Sensor

F: Urea Tank

G: Nozzle

H: EGP Inlet Temp

I:EGP Outlet Temp

J: EGP

Dosing Unit Components

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Valves & lines

Motor

PCB

Dosing Pump controller

Pump heater

Temperature sensor

Temp sensor on the PCB

Connector

Valves & lines

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P

OBD

1 2

3

4 5

11 7

8

9

10

6

UREA TANK

1. Air valve (controlled by solenoid)

2. Air pressure regulator @ 4 bar

3. Orifice

4. Air Check Valve (ACV)

5. Back Pressure Valve (BPV)

6. Mixing chamber

7. Outlet check valve (spring loaded)

8. Actuated membrane

9. Inlet check valve (spring loaded)

10. Pressure switch

11. Air Actuated Valve (AAV)

AIR UNIT

MIXING VALVE

MEMBRANE PUMP

A UDS limits

C D

B

Dosing Unit

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Dosing Unit

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Dosing Unit

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Dosing Unit

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Pump motor

Stepper Motor

Stroke

One piston movement (back and force)

Origo

System which gives the membrane origin (Hall effect sensor)

Parking Position

Best position for parking:

In this position, the membrane can move easily during urea

expansion (freezing);

After the thawing of the pump head, the pump cycle will start

with the suction phase. So, this avoids increasing of pressure in

the pump head if the return line is frozen.

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Pump motor : Parking

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Connector

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Urea injector nozzle

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Urea injector nozzle location

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Urea injector nozzle location

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SCR

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Urea Decomposition and Hydrolysis in Exhaust:

NOx Reduction in SCR Catalyst:

NO + NO2 + 2NH3 → 2N2 + 3H2O Fast Reaction

4NO + 4NH3 + O2 → 4N2 + 6H2O Dominant Reaction

2NO2 + 4NH3 + O2 → 3N2 + 6H2O Slow

6NO2 + 8NH3 → 7N2 + 12H2O Slow

6NO + 4NH3 → 5N2 + 6H2O Slow

(NH2)2CO (s) NH3 (g) + HNCO (g)

HNCO (g) + H2O (g) NH3 (g) + CO2 (g)

Gas Flow

SCR

catalyst Urea Injector

Content

System layout and components

Control----Working flow

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Priming phase (1)

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P

1 2

3

4 5

11 7

8

9

10

6

UREA TANK

A

C D

B

Air valve closed (air solenoid valve off)

Pump motor working at max capacity (7.5l/h)

Urea back to tank, not build pressure

Pressure switch not activated

Prime phase (2) (continued)

After 30s the air solenoid valve open – air pressure closes the air

activated valve (AAV), the solenoid can be heard “clicking” on

Doser continues to pump urea for 10 strokes, building pressure in the

urea path

During the 10 strokes monitor pressure switch

If urea is present, and air bubbles have been purged out, then the

pressure switch will activate, indicating the presence of urea and a

successful prime, transition to dosing state

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Prime phase (3) (continued)

If no urea is present, the doser will be unable to build pressure; priming will be unsuccessful

The air solenoid valve will be deactivated, to allow urea to circulate back to the tank and the prime sequence will be repeated

After retrying 20 times, the doser will report UREA_DOSER_LOW_AIR_UREA_ERR

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Prime phase (4) (continued)

At the end of the Priming phase

Air solenoid valve open

Pump motor stop

Pressure switch activated

When priming is complete, the doser automatically enter the “Dosing”

state, but with a urea dosing rate of 0 ml/h.

Urea dosing phase

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P

OBD

1

2

3

4 5

11

7

8

9

10

6

UREA TANK

A

C D

B

Air valve open (air solenoid on)

Pump working at required capacity

Urea injected in nozzle line

Pressure switch activated

Purging phase

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P

OBD

1

2

3

4 5

11

7

8

9

10

6

UREA TANK

A

C D

B

Air valve open (air solenoid on)

Pump motor stopped (0l/h)

Only air injected in nozzle line

Pressure switch activated

Clear nozzle line

Purging phase

Air solenoid valve opens

Pump motor stop

Pressure switch activated

Air removes urea droplets that could crystallise and block the pump

valves, urea lines or the injection nozzle.

Lasts for 30 seconds then the system switches off, the solenoid can be

heard “clicking” off.

Stop phase

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P

1 2

3

4 5

11 7

8

9

10

6

UREA TANK

A

C D

B

Air closed (air solenoid off)

Pump stopped to parking position

No urea neither air flow

Pressure switch not activated

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THANKS!