Engine | 608 |
with code U79 (BLUETEC (SCR) diesel exhaust treatment, generation 3) | |
Engine | 654 in model 118, 177, 247 |
with code U79 (BLUETEC (SCR) diesel exhaust treatment, generation 3) | |
Engine | 654 in model 167 |
with code U79 (BLUETEC (SCR) diesel exhaust treatment, generation 3) | |
Engine | 656 in model 167 |
with code U79 (BLUETEC (SCR) diesel exhaust treatment, generation 3) |
P49.20-2074-79
Example illustration of exhaust gas aftertreatment pump module |
1 | Pump module for exhaust gas aftertreatment |
Overview
This document contains information on:
General
Function
General
The exhaust gas aftertreatment pump module is primarily responsible for transporting the reduction agent from the exhaust gas aftertreatment tank.
It consists of the following components:
Pump
Heating element
Temperature sensor
Function
Pressure generation
The aftertreatment control module actuates the exhaust gas aftertreatment pump module with a pulse width modulated signal in a map-dependent manner. The actuation duration depends on the on-board electrical system voltage, the system pressure in the pressure line and the coil temperature.
Pressure measurement
The aftertreatment control module detects the system pressure generated by the exhaust gas aftertreatment pump module via the current curve of the pulse width modulated signal.
Flow reversal
In the case of ignition OFF (circuit 15), the run-on of the aftertreatment control module is started.
The aftertreatment control module actuates the exhaust gas aftertreatment pump module. During the control unit run-on, the remaining reduction agent is suctioned back from the pressure line and metering valve in the direction of the tank.
At the same time, the metering valve opens so that no vacuum occurs. The duration of the suctioning back process takes, depending on the vehicle application, between 8 to 10 s.
Antifreeze
The heating element ensures that liquid reduction agent is suctioned out of the tank even at cold temperatures.
Furthermore, the pressure line heating element heats the pressure line in a map-dependent manner.
The return of the remaining reduction agent prevents the pressure line and exhaust gas aftertreatment pump module from freezing at approx. -10 °C and being damaged.