BMW F97 - Front and Rear Axle Systems

F97/F98�Complete�Vehicle
4.�Powertrain
37
Index Explanation
1 M�Dynamic�Stability�Control�(M�DSC)
2 Body�Domain�Controller�(BDC)
3 Advanced�Crash�Safety�Module�(ACSM)
4 Components�of�the�regulated�M�rear�axle�differential�lock
5 Regulated�M�rear�axle�differential�lock�(M�GHAS)
6 Power�distribution�box,�rear
Interfaces
The�M�GHAS�control�unit�works�with�the�following�control�units�and�includes�the�following�information:
Control
unit
Bus�system Information
BDC FlexRay -�Terminal�status
-�Vehicle�identification�number�(for�encoding)
-�Vehicle�condition�(power�management�and�fault�memory�block,
e.g.�in�the�event�of�voltage�drop�by�engine�start)
DME FlexRay -�"Engine�running"�signal
M�DSC FlexRay -�Wheel�speed
-�Setpoint�axial�torque�distribution
-�Stabilization�status
-�Brake�value
-�Tolerance�adjustment�of�wheel�(adjustment�of�different
wheel�circumferences)
-�Driving�speed
ACSM FlexRay -�Lateral�acceleration
-�Yaw�rate
-�Road�longitudinal�tilt
-�Steering�angle
Electric�motor�location�determination
To�determine�the�position�of�the�electric�motor,�2�hall�effect�sensors�in�the�engine�are�evaluated.
To�calculate�the�characteristic�curve�for�lock-up�torque�over�motor�position,�recalibration�is�performed
at�regular�intervals�to�compensate�for�wear�in�the�clutch.
To�be�able�to�assign�a�certain�position�of�the�servomotor�a�certain�coupling�lock-up�torque�and�to�take
the�wear�influences�into�account�while�doing�so,�a�reference�run�is�performed�after�the�vehicle�engine
is�switched�off.�During�this�reference�run�the�engine�is�subjected�to�a�defined�current�level.�The�lock-
up�torque�of�0Nm�is�assigned�to�the�resulting�position.