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EXHAUST AFTERTREATMENT
SYSTEM
The exhaust aftertreatment system consists of
two units, the filtration and regeneration unit and
the selective catalytic reduction SCR unit.
FILTRATION AND REGENERATION UNIT
The
main
purpose
regeneration unit is to capture and oxidize
(regenerate) the particulate matter (soot) in the
engine exhaust gas. The exhaust gas first enters
the Diesel Oxidation Catalyst (DOC) and then
flow through the Diesel Particulate Filter (DPF);
together they capture and regenerate the soot on
a regular or passive basis. Through constant
monitoring of the exhaust gas temperature and
the system back pressure, the engine control
module is able to manage regeneration.
PASSIVE REGENERATION
Passive regeneration is the process by which the
particulate matter is oxidized due to the heat
generated by the engine internal combustion
process. During normal highway operation,
exhaust temperatures alone are usually high
enough to oxidize accumulating soot. In low
ambient temperatures, however, or in some stop-
and- go applications, the system needs a little
help to regenerate, or clean itself. This process is
called "active" regeneration.
ACTIVE REGENERATION
Active regeneration is necessary when the
engine internal combustion process alone does
not generate enough heat. A dosing system
injects a mist of diesel fuel into the exhaust
system
to
increase
aftertreatment system temperature. Exhaust
temperature must be above 572°F (300°C) to
initiate the oxidation catalyst, which in turn
oxidizes the injected diesel fuel molecules to
achieve
up
to
1200°F
temperature at the particulate filter. This process
of active regeneration takes place during the
normal operation cycle of the vehicle without
charges in performance or control for the
operator. EPA2010 compliant and later Volvo
engines produce less soot, so less active or
stationary regeneration will be required.
DOB 1300-1556
of
the
filtration
and
and
maintain
the
(650°C)
exhaust
PA-1639 Operator's Manual 2020 X3-45 Commuter
STATIONARY (PARKED) REGENERATION
In a small number of specific engine duty cycles,
engine control module may not be capable of
completing an active regeneration. In these
situations, the operator will be notified that a
stationary or parked regeneration may be
required. A DPF telltale light will illuminate
indicating the need for user interaction. The lamp
gives the operator a grace period to allow this
process to take place at a time when most
convenient for the operator. This process
requires the vehicle to be parked while a driver or
maintenance technician initiates the regeneration
process using the DID menus. Once initiated, the
stationary regeneration process will be complete
in about 45 minutes.
The driver will be notified of the need for a
stationary regeneration (parked) by illumination
of the DPF Regeneration telltale light.
Other Features 5-3
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