Load shedding at partial load

Hello!

Golf 3, AFN engine, 126,000 km.

I am interested in the specified charging current at partial load.

Measurement block 8 indicates:
Driver preference = fw
Torque limiting = db
Soot limit = rb

It can be observed that under low load conditions, the field "rb" in measurement block 8 remains significantly high.
shows higher values than the fw field.

A sudden burst of acceleration can certainly immediately reach its full extent.
will be released by the STG when the associated value of fw is equal to the current value.
not exceeding rb.

A higher value for 'fw' is initially capped at the current value of 'rb', and then...
Does the injection amount released by the engine control unit (ECU) keep pace with the increased fuel demand caused by a more aggressive turbocharger control?
gradually increasing value of rb.

The higher the value of rb at partial load, the more spontaneous the reaction would have to be.
Would a more aggressive turbo control strategy at partial load increase the value of 'rb'?
It might be possible to achieve a gentler turbocharger response at partial load by...
Acknowledging the reduction of the "rb" value to the level of "fw"), fuel savings are achieved because...
Exhaust back pressure decreasing?

Is the specification of the target charging pressure therefore a compromise for this trade-off?

How does the recently read quote "A diesel engine always runs with an excess of air" fit into this context?
come in?

Thank you for the tutoring.

Greetings, Klaus.

PS: It would be cool if you could "boost" the TDI shortly before overtaking (e.g., using the paddle shifters) by increasing the turbocharger boost pressure in partial load conditions.

Hello!

Is the specification of the target charging pressure therefore a compromise for this trade-off?


Yes. Furthermore, you can't arbitrarily increase the 'aggressiveness' of the charger because that would result in an unstable control loop.


How does the recently read quote 'A diesel engine always runs with an excess of air' fit into this context?
come in ?

A diesel engine always runs with an excess of air .

The only exception would be older turbo-diesel engines without a mass airflow sensor. In those cases, when there's a sudden increase in load, the engine might briefly use all the available air until the turbocharger kicks in, which can result in a puff of black smoke.
Otherwise, a diesel engine typically operates with an excess of air of approximately 20% even when running at full load.

It would be nice if you could 'boost' the TDI shortly before overtaking (e.g., using the paddle shifters) by increasing the turbocharger pressure in partial load conditions.

'There's only one problem: where are you going to get the power for that? Without more diesel fuel, there won't be enough exhaust gas produced to adequately drive the turbocharger for your pressure increase.'

CU Gremlin.

Hi,

Some manufacturers also market the function that allows the turbocharger to briefly allow a higher pressure when there is a sudden demand for power as an "overboost" function, where a potential exceeding the rated torque can be utilized for a short period.

In my personal opinion, this "behavior" is more likely due to a lack of control in the control loop (overshoot of the boost pressure) when there are such sudden changes in the target value... Because the "rb" value can only take effect once the system has reached a steady state, right?