23
Introduction of the New Unimog Generation | Model Series 405
Exhaust aftertreatment
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Euro 6 technology and vehicle packaging
In order to meet the requirements of the Euro VI legislation
and customer demands for minimal fuel consumption, new
engines and a new exhaust aftertreatment system were
developed. The engines feature Common Rail injection and
exhaust gas recirculation and are designed for minimal con-
sumption. The new exhaust aftertreatment system removes
particulates and nitrogen oxides.
The exhaust aftertreatment system consists mainly of:
•
Oxidation catalytic converter (DOC)
•
Diesel particulate filter (DPF)
•
SCR catalytic converter
•
Slip catalytic converter
The system also includes the AdBlue® metering unit with va-
rious sensors, the ACM electronic unit (Aftertreatment Con-
trol Module) and the fuel (HC) metering system. Low-sulfur
fuel is required. The fuel may contain up to 7% biodiesel.
Function description:
•
The exhaust first flows through the oxidation catalytic
converter. This converts the hydrocarbons and carbon
monoxide present into carbon dioxide and water. Further-
more, part of the nitric oxide (NO) is oxidized to nitrogen
dioxide (NO2).
•
The particles are separated through adhesion and collec-
ted in the porous filter structure of the diesel particulate
filter (DPF). In the particulate filter, the NO2 reacts with
the stored soot to produce NO und CO2. The deposits
are broken down and the system regenerates itself: "pas-
sive regeneration". In order to achieve complete filter
regeneration, the "passive regeneration" is coupled with
"active regeneration". In the case of active regeneration,
a reaction takes place between O2 and soot at tempe-
ratures above the passive regeneration range. In order
to reach the temperatures required for this, the exhaust
temperatures are increased by injecting HC in the form of
diesel fuel. The HC reacts exothermically in the oxidation
catalytic converter and increases the temperature of the
exhaust.
•
SCR catalytic converter: The BlueTec diesel technology
reduces the proportion of nitrogen oxide in the exhaust
through the addition of AdBlue® (aqueous urea solution).
The aqueous AdBlue® solution is injected into the hot
exhaust via a metering valve.
– This printout will not be recorded by the update service. Status: 03 / 2013 –
