6 Series E64 650i (N62TU) CONVER
> E65, E66
The fuel supply system on the BMW 7-Series is requirement-orientated and thus depends on consumption.
The DME calculates the amount of fuel required on the basis of various operating variables.
In turn, the engine's current fuel requirement is calculated from this value. The DME requests this value as a
volumetric flow with the unit "litres per hour".
The DME sends this request on the following path: DME (digital engine electronics -> PT-CAN -> SGM (safety
and gateway module) -> byteflight -> SBSR (B-pillar satellite, right) -> EKP (regulated fuel pump).
The B-pillar satellite, right converts the amount of fuel requested into a nominal speed for the fuel pump.
The pump speed is regulated via the cycle ratio of a pulse-width-modulated signal. This rectangular signal gives
the effective supply voltage for the fuel pump: The longer the pause between the edges of the rectangular
signal, the lower the supply voltage for the fuel pump. The fuel pump delivery volume is correspondingly lower.
The fuel pump speed is sent back to the B-pillar satellite, right as an input variable.
This method has the following benefits compared to the conventional way of actuating the fuel pump (fuel-pump
relay):
•
Lower current draw from fuel pump
•
Reduced heating up of fuel
•
Longer service life for fuel pump
•
No fuel-pump relay needed
The flow of fuel is interrupted in the event of a crash of sufficient impact. This prevents the fuel from escaping or
igniting (emergency fuel cutoff).
The fuel pump can be reactivated by switching the ignition off and on again.
If the request signal from the DME or the pulse-width-modulated signal from the SBSR is not received: The fuel
pump will operate a maximum delivery capacity. This guarantees sufficient fuel supply for all operating
conditions (emergency operation).
> E60, E61, E63, E64 and E70
The DME switches the fuel pump on using the fuel-pump relay.
Fuel injection
During fully sequential fuel injection, each injector is controlled by means of its own final stage.
Fully sequential fuel injection has the following advantages:
•
Improved fuel preparation for each individual cylinder
•
Adaptation of the fuel injection timing to suit the engine's operating condition (engine speed, load, engine
temperature)
•
Cylinder-selective correction of injected fuel quantity for varying load (during a cycle, the fuel injection timing
can be corrected by extending or shortening it)
•
Cylinder-selective cutoff (e.g. when an ignition coil is defective)
•
Diagnosis for each individual injector possible
The control of each injector by means of its own individual final stage achieves a fuel build-up which is the same
in all cylinders. This ensures a uniformly-effective fuel preparation throughout.
The fuel build-up time is variable and depends on the load, engine speed and engine temperature.
As it is only injected once per camshaft rotation, the spread of fuel due to tolerances in the components is
reduced.
In addition, the idle-running performance is improved as the response and dropout times at the injectors are
reduced.
Moreover, a marginal reduction in fuel consumption is also achieved.
SBT 8-cylinder spark-ignition engine N62TU E60, E61, E63, E64, E65, E66, E70
BMW AG - TIS
06.02.2013 10:27
Issue status (12/2007) Valid only until next DVD is issued
Copyright
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