A turbocharger with variable turbine geometry and without a ”wastegate” is used for charge-air 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-air 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 charge-air pressure controller (electric motor with worm gear and control electronics) that is mounted to the turbocharger directly. The charge-air pressure controller cannot be replaced separately.
The DDE provides the electrical charge-air pressure controller with a pulse-width 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 charge-air pressure controller convert the PWM signal into an adjusting angle and activate the actuator motor.
Acknowledgment of the set position is only detected indirectly by the DDE via the charge-air pressure sensor. The charge-air pressure controller 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 charge-air pressure control system:
Charge-air pressure control is also deactivated when following faults occur: