1 Series E87 118d (M47T2) 5-door
On vehicles with automatic transmission, the whole drive has a greater, mechanical power loss. The engine
therefore operates under a higher load than in vehicles with manual transmission. The higher load has a
negative effect, however, on the carbon buildup in the engine. In comparison to the diesel particulate filter, it is a
simple separating system without sensor system. The particulate catalytic converter is necessary to ensure that
the EURO 4 exhaust emission regulations are satisfied in all operating ranges.
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Diesel particulate filter (E90, E87)
The diesel particulate filter can be ordered as an option in the E90 (E87 from 03/2005).
The diesel particulate filter is located in a housing together with the oxidation catalytic converter. The housing is
located close to the engine. The lower loss of temperature leads to:
•
lower volume of fuel required for post injection during cyclical regeneration of the diesel particulate filter
•
greater engine efficiency
•
continuous regeneration begins sooner
Additional electrical components if diesel particulate filter fitted:
•
1 Exhaust backpressure sensor
•
1 Exhaust temperature sensor (upstream of diesel particulate filter)
•
Electric throttle-valve actuator
The M47TU2 only needs one exhaust temperature sensor (2 on the M57TU).
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System functions
The diesel particulate filter is known from the M57TU 6-cylinder diesel engine in the E60 and E61.
Regeneration of the diesel particulate filter
The level of charge of the diesel particulate filter is calculated by the DDE using the operating statuses of the
engine. The diesel particulate filter can be regenerated continuously and/or cyclically.
•
Continuous regeneration:
In operating ranges in which the exhaust temperature is higher than the ignition temperature of the soot (>
350
°
C), the soot particulates are immediately converted. This involves the slow oxidation of the soot
particulates to carbon monoxide (CO) and carbon dioxide (CO
2
).
The nitrogen dioxide present in the exhaust (NO
2
) acts as the oxidizing agent. The nitrogen dioxide is
formed from nitrogen monoxide (NO) in the oxidation catalytic converter.
If the exhaust-gas temperature is insufficient for the catalytically-supported carbon conversion:
The soot particulates are initially collected and stored in the diesel particulate filter and then burned off the
next time the exhaust temperature is increased.
The location of the diesel particulate filter close to the engine favours this effect.
•
Cyclic regeneration:
If the driving pattern does not permit continuous regeneration of the diesel particulate filter (e.g. long
periods of low engine load in urban traffic conditions with low exhaust temperatures), selective regeneration
is initiated.
Regeneration on a cyclical basis occurs much more seldom
This process is controlled by the signals from the exhaust backpressure sensor and the exhaust
temperature. Like continuous regeneration, cyclic regeneration takes place without any noticeable effects
on vehicle behaviour.
Regeneration is carried out dependent on the engine load. The intake air is thereby throttled specifically
SBT M47TU2 diesel engine E83, E87, E90
BMW AG - TIS
18.01.2013 18:21
Issue status (12/2007) Valid only until next DVD is issued
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