Engine
SHOP MANUAL
Ch 1 page 29
Working principle
The working principle for exhaust gas aftertreatment is divided into three different operations:
Starting
Operation and reductant metering
Shutdown
Starting
The reductant pump starts when the following has taken place: The engine has started, the EEC3 control unit
has carried out a system check, the catalytic converters have started to heat up and have reached the correct
operating temperature (200–250°C) and any heating of the reductant is finished. The reductant pressure is built
up to 9–10 bar to then be injected into the hydrolysis catalytic converter by the reductant doser.
The EEC3 control unit monitors the values and functions of all sensors
The engine is started
The reductant pump (11) starts and builds up the reductant pressure to 9–10 bar.
When the temperature sensor (9) indicates that the temperature of the exhaust gases has reached 200–250°C,
the EEC3 control unit activates the reductant doser (12), which starts injecting reductant to the hydrolysis
catalytic converter (6). The dose is determined by the engine control unit EMS on the basis of the combustion
control in the engine which is currently being operated by the engine control unit.
The process in the SCR catalytic converter (8) starts.
Figure 42
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