A turbocharger with variable turbine geometry and without a ”wastegate” is used for turbo pressure control.
On the exhaust side there are adjustable blades on the outside of the turbine on rotating bearings. Those blades vary the force applied to the turbine by the exhaust, thereby altering, as required, the charge pressure generated by the turbocharger.
An adjusting lever on the turbine housing activates the adjustable guide vanes.
The adjusting lever is operated by means of an electrical turbocharger pressure adjuster (electric motor with worm gear and control electronics) that is mounted directly on the turbocharger. The turbocharger pressure adjuster cannot be replaced separately.
The DDE provides the electrical turbocharger pressure adjuster with a pulse-modulated signal. The operating range of the signal lies between 10 % and 95 %, whereby 10 % means guide vane opened and 95 % means guide vane closed.
The electronics in the turbocharger pressure adjuster convert the PWM signal into a setting angle and activate the actuator motor.
Acknowledgement of the set position is only detected indirectly by the DDE via the turbo pressure sensor. The turbocharger pressure adjuster itself is self-diagnosable and reports faults to the DDE.
The adjusting lever must adjust between minimum and maximum activation by 35° to 45° angle of rotation. Adjustment must take place rapidly.
The charge-air-pressure control is monitored for the following faults:
Consequences of fault occurring in the turbo pressure control system:
Turbo pressure control is also deactivated when following faults occur: