3 Series E36 320i (M50) COUPE
11 36 ...
Function description VANOS (variable camshaft control)
Control unit is activated by relevant engine control unit. The control unit operates a regulating element via a solenoid. In
this manner, engine-oil pressure is supplied to both sides of a hydraulic plunger.
Hydraulic plunger is held in one of both possible positions by way of mechanical stops and applied engine-oil pressure.
A rotating splined shaft gear is integrated in hydraulic plunger. This splined-shaft gear uses its helical-bevel splines to
convert plunger stroke into rotation of camshaft - relative to driven chain sprocket.
Hydraulic plungers with splined-shaft gear are located in a pressure cast aluminum housing on face end of cylinder
head, coaxial to intake shaft.
Nominal positions of intake camshaft (advanced or retarded) are different for M50 B20 and M50 B25 engines.
Adjustment of camshaft is activated by relevant engine control unit depending on engine load, engine speed and
coolant temperature.
The 4/2-way operating valve is designed in such a manner that when one pressure chamber is pressurized, the other is
without pressure (feedback) As soon as operating valve solenoid receives current, it moves control piston against
spring force into advanced position via an armature. A coil spring returns the unit to retard position. This means that, if
the armature is defective or the control unit fails, the camshaft will be retarded automatically.
In this manner it is still possible to start engine even when control unit fails. It would not be possible to start engine with
camshaft adjusted in advanced timing direction.
Control edges of valve are designed in such a manner that emergency operation properties of engine are guaranteed
even when control piston would seize in an undefined intermediate position.
RA Function description VANOS (variable camshaft control)
BMW AG - TIS
06.02.2013 22:22
Issue status (12/2007) Valid only until next DVD is issued
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