VTG Adjustment: Control or Regulation?

Hello!

I am referring to the article by Rainer K.:
"VTG adjustment for VAG TDI engines." It describes, among other things,
what influence the adjustment of the linkage of the vacuum sensor has on...
VTG-loader installed.

Let's assume the rod is set to a length that is too long, but the adjustment range...
The remaining material in the container is sufficient to fully fill the bucket of the loader.
Adjusting the airflow (I assume this is possible).

According to the article, this results in "unusually weak acceleration at low engine speeds."

(1) Does this only apply to full load conditions, or also to partial load conditions?

(2) Why does a rod length that is not perfectly optimal have any influence at all?
"However, the resulting (too low) boost pressure from the control unit..."
the corresponding control of the solenoid valve is implemented (assuming that...
Is the duty cycle not yet at its maximum?

If the TDI is so sensitive to the length of the rods, then we have a problem here.
"Just" a control system, and no further regulation?

Greetings,

Klaus.

The conclusion in (2) is not entirely correct.

To prevent the regulation from becoming completely unstable when a few disturbances occur, it must always be dampened.

Within the expected performance range, the damping does not decrease further (correct rod length -> good acceleration).

However, if the originally fixed and specified dimensions (e.g., rod length) no longer fit, the system doesn't recognize the reason. Therefore, it doesn't know that it could potentially "fully compensate" without causing any harm.


So ended the first regulated FORWARD test run of my robot with a full-throttle REVERSE drive into the table (a classic overshoot during the deactivation process) .

m;

complementary:

The adjustment of the rod can be viewed from a control engineering perspective as a form of offset.

Therefore, adjusting the length shifts the operating point of the controller. This changes the dynamic behavior because the controller still assumes a correct setting and adjusts its output accordingly.
Due to the adjusted rod, only 60% of the can is engaged with the VTG (Vertical Transport Gripper), despite the rod being positioned to potentially engage 80% of the can.
Since a control system should generally operate conservatively, it will never be fully released from the start, especially in critical systems. Doing so would result in significant overshoots. (The most challenging scenarios involve control systems with dead time elements, which include things like turbocharger boost control as well as even a simple heating system.)
Okay, so first set it to 80%. Because the rod is twisted, only 60% of the pressure will reach the VTG (Variable Transmission Gear). There's a lack of pressure. Only when the pressure builds up, and it still doesn't reach the target value, will it be adjusted. -> This results in poor acceleration.

'If the rod is too short, it works in the opposite way. This can lead to over-oscillation, which can even build up to resonance. However, most of the time, the safety mechanism kicks in because the pressure builds up so quickly that it causes overpressure and triggers an emergency stop.'

CU Gremlin.

Okay, I understand. Thank you!

Rainer K. wrote:
Tip for AHF or similar engines: Adjust the length accordingly.
that when the engine is running at full throttle in 3rd, 4th, or 5th gear at 3900 RPM, the magnetic valve for controlling the boost pressure...
a duty cycle of approximately 85-90% is achieved.

(1) I have the AFN engine in my G3, which is probably a similar engine, right?
(2) Does the pressure chamber need to be removed to adjust the rod?

Thank you very much.
Klaus.

Klausel wrote:

(1) I have the AFN engine in my G3, which is probably a "similar" engine, or ? (2) Does the pressure chamber need to be removed to adjust the rod?

(1): yes.
(2): I always managed to do it without removing the dosing unit on my G3. To remove it, I would have had to unscrew the threaded rod anyway...