1 Series E87 118i (N46) 5-door
combined effect of the front intake pipe and resonating pipe is similar to that of a long inlet pipe. The pulsating
air column inside it increases torque in the medium engine speed range considerably.
To increase performance in the higher engine speed range, the sliding sleeves are opened. This largely reduces
the dynamics in the front intake pipes. The short resonating pipes which are now effective can make high
performance figures in the upper engine speed range possible.
The DME control unit adjusts the sliding sleeves via the DISA actuator (12 volts) with integrated transmission.
The information as to whether a downwards or upwards gearshift was made is saved by the DME control unit.
When the value falls below 4400 rpm, the DME control unit closes the sliding sleeve with the assistance of the
DISA actuator. When the value of 4500 rpm is exceeded, the sliding sleeves are opened again. At changeover,
these engine speeds are displaced reciprocally (hysteresis) to prevent the sleeves opening and closing in rapid
succession.
In the event of system failure, the sliding sleeves remain in their respective positions. The driver will be aware of
system failure through a loss of power and reduction in the final speed. Once the engine has been switched off
(terminal 15 OFF), the sliding sleeves are run once to their limit position. This prevents deposits accumulating
and blockage of the sliding sleeve during longer journeys at low engine speeds.
Air mass computation (only N46B20 in the E87, E90, E91 and N45TU2/N46TU2)
The air mass drawn in is no longer measured directly by the air mass meter, but is rather calculated by the DME.
For this calculation, a charge calculation (charge model) is programmed in the DME.
The following signals are input into this calculation:
•
Inlet valve lift (load identification)
•
VANOS setting (load identification)
•
Throttle valve setting (choke action)
•
Intake-air temperature (air density correction)
•
Engine speed (cylinder fill levels)
•
Inlet pipe vacuum (correction for choke action)
•
Ambient pressure (air density due to altitude correction)
The air mass so calculated is compared to:
•
Signal from oxygen sensor (fuel-air ratio)
•
Injection time (fuel quantity)
The calculated air mass is corrected as necessary.
In the event of the oxygen sensor failing, a fault will be entered in the DME fault memory (air mass plausibility
check). In such cases, the calculated air mass is no longer compared.
"Valvetronic" variable valve gear
Valvetronic was developed to reduce fuel consumption.
The control device for Valvetronic is now integrated into the DME control unit.
The quantity of air supplied to the engine when Valvetronic is active is adjusted by the variable valve lift on the
inlet valve and not the throttle-valve actuator.
An electrically-adjustable eccentric shaft changes the action of the camshaft on the roller cam follower via an
intermediate lever. The result of this is variable valve lift.
With Valvetronic, the throttle-valve actuator is activated for the following functions:
•
Engine start (warm-up)
•
Idle speed control
SBT Engine control for N45, N46 E46, E60, E81, E83, E85, E87, E90, E91, E92, E93
BMW AG - TIS
20.01.2013 20:52
Issue status (12/2007) Valid only until next DVD is issued
Copyright
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