1 Electrical turbocharger guide vane adjustment actuator
2 Actuating lever
3 Adjusting lever for guide vanes
Diesel engines with the Delphi common rail system, which are designed for emission standard IV, have a variable geometry turbocharger, which is actuated via an electrical turbocharger guide vane adjustment actuator.
Its exact positioning for each operating state is achieved by the electrical adjustment of the guide vanes. This has a positive effect on exhaust emissions and helps to achieve emission standard IV.
A Adjustment mechanism
B Control electronics
1 Servo motor
2 Servo motor contact block
3 Inductive sensor unit
4 Drive shaft
5 Worm gear
6 Drive pinion
7 Servo motor contacts
The electrical turbocharger guide vane adjustment actuator consists in total of the following two components:
โข Actuator unit
โข Control unit
Actuator
The servo motor in the actuator unit operates the drive shaft via a worm gear.
The drive shaft is connected to the guide vanes by the actuating lever. Adjustment of the guide vanes is achieved by moving the actuating lever.
There is an inductive sensor element at the end of the actuator unit drive shaft. When this drive shaft is turned, an induced pulse-width modulated signal is created here, by means of which the current angular position of the guide vanes is exactly determined.
Control unit
The control unit controls the servo motor. The control unit is connected to the PCM via the CAN data bus. The angular position for the electrical turbocharger guide vane adjustment actuator is calculated by the PCM and is transmitted to the electronic actuator unit via the CAN data bus.
The angular position of the guide vanes is recorded by the inductive sensor element in the form of pulse-width modulated signals and transmitted to the control unit.
There is a temperature sensor located in the control unit of the electrical turbocharger guide vane adjustment actuator, and if the maximum permitted temperature of 160 ยฑ 9 ยฐC is exceeded (e. g. through heating up in a traffic queue), the servo motor is moved into the safe position.
This means that the guide vanes are fully opened. This prevents, in extreme cases, maximum turbocharger pressure (almost closed guide vanes) being made available by a possible heat induced seizure of the mechanisms (caused by overheating).
Malfunctions in the electrical turbocharger guide vane adjustment actuator are detected by the PCM via the CAN data bus.
Effects of faults
In the case of a fault, the amount of fuel injected is limited to max. 20 mg per injection to protect the turbocharger and the engine from damage.
Diagnosis
Malfunctions are detected by the electrical turbocharger guide vane adjustment actuator itself and transmitted via CAN to the PCM.