Regelgeschwindigtkeit des AGR Ventil

Hello everyone!

I am very interested in how quickly the AGR valve actually regulates.

Assuming I fully depress the gas pedal, how quickly does the AGR valve close?

And conversely?

If I take my foot off the accelerator while driving at full throttle, how quickly does the AGR (Exhaust Gas Recirculation) system react?
under 1 second ???


Please help me

Thank you in advance.

Hi

I can hardly measure it accurately, but due to the design of my EGR valve, it should close faster than it opens.

I estimate closing time = less than 0.5 sec, opening time = approximately 1 sec.

Then, the AGR also serves a bit of the function of a blow-off valve, just like gasoline engines that only have them.

If we switch from gasoline, a little of the remaining residual pressure (if there is any) will escape through the AGR (Exhaust Gas Recirculation) system into the exhaust. Is that a correct understanding, or am I completely wrong?

P.S.: I love this forum!! Super people!!! The best thing there is!!

Hi,

no, that's not correct. You can correct me, but as far as I know, a blowoff valve is used to reduce excess BOOST pressure. However, this doesn't exist in diesel engines because they don't have a throttle valve, so air can normally enter the cylinders and through this into the exhaust, without injection (since the gas was removed). There are no diesels and therefore no combustion. The boost pressure can therefore decrease very quickly.

Best regards,

Jan

I meant in the broadest sense!

I am already aware that the TDI does not have a throttle valve!

I just meant to ask if some of the pressure might also be released through the AGR system.

no, because there is no excessive charging pressure building up.

When the gas is turned off, the exhaust stream immediately stops, and the turbocharger doesn't operate against a throttle valve but can directly remove the air volume from the engine. It still sucks in with the full stroke volume... Furthermore, the AGR (Exhaust Gas Recirculation) is closed when the boost pressure is greater than the expected exhaust backpressure. Otherwise, the intake air would blow into the exhaust, which is not desired.
Therefore, newer diesel engines are also getting throttle valves again (not to be confused with the idle valve!). This allows the AGR to be maintained even in such conditions.

The AGR also slightly hinders the turbocharger, as when the valve is open (which is always the case in partial load), the exhaust volume is much lower with the AGR than without it. Therefore, when the AGR is 'defective,' the turbocharger's response is also much better...

If I directly control the valve, the response time is definitely less than 1 second. How long the control loop takes would need to be measured, but I find the effort too much.

See you, Gremlin

Hello,

That's interesting, what you guys are talking about here.

Exactly because I read that somewhere above, one should definitely...
to protect the intake system from excessive over-boosting by installing a manually adjustable "blow-off valve" in the intake system. I mean that this valve opens at a certain pressure and releases the excess pressure. This would be particularly beneficial for tuned engines and especially their intake systems? Or am I making a mistake right now?

The AGR valve on my AFN seems to be functioning rather sluggishly.
I've tried that before.

Greetings
Thomas

Thomas wrote:

Hello, should ..to protect the charger from excessive overpressure by installing a manually adjustable "blow-off valve" in the intake air circuit. Or am I making a mistake right now?

Unfortunately, I think so. The high pressure itself is not the danger, but rather the speeds at which it is generated. Adding a wastegate in addition to the VTG would be the most helpful.

Thomas wrote:

Because I read something like that somewhere above, one should be able to protect the charger from excessive overshoots by installing a manually adjustable "blow-off valve" in the intake air circuit. I mean that this valve opens at a certain pressure and releases the excess pressure. This should be particularly beneficial for tuned engines and especially their chargers? Am I making a mistake right now?

Hi Thomas

The regulation is primarily intended to protect the engine from excessive speeds. For this, she reduces its (exhaust gas) energy supply when the solar pressure is reached.

If you install a BlowOff valve that opens below the specified pressure, the turbocharger must also suck in as much air as possible, in addition to the engine, through the valve = spin faster, until the specified pressure is reached.
Once (if the loader is even capable of doing so, depending on the valve's opening cross-section ), the control system intervenes; until then, the loader operates with full power, wears out more quickly, increases exhaust gas resistance, and reduces engine efficiency -> higher fuel consumption.

Opening the BlowOff valve only above the oil pressure would, however, lead to faster dissipation of overpressure, but the EDC would only notice and counteract the overpressure = compressor speed, thereby "less energetically".
D.h. auch hier würde der Lader IMO höher drehen als ohne BlowOff.

Therefore, I would not pursue this idea further.

Furthermore: The purpose of the blow-off valve in gasoline engines is to prevent the turbocharger's speed from dropping too much when the throttle is briefly closed, so that full power is immediately available when the throttle is reopened. So, it's not about protecting the engine or the compressor.

christians wrote:

Also, der Zweck des Blow-Offs bei Benzinmotoren besteht darin, die Drehzahl des Laders nicht zu stark zu reduzieren, wenn man kurz Gas gibt, damit beim anschließenden Gasgeben sofort wieder Leistung verfügbar ist. So, it's not about protecting the engine or the compressor.

Hi Christian

that means the BlowOff valve is located before the throttle and only releases the "pressure buildup" = the over-boosted pressure before the just closed throttle?
(I've never seen anything like this up close or as a diagram )

that means the BlowOff valve is located before the throttle and only releases the 'pressure buildup' = the over-boosted pressure before the just closed throttle?
(I've never seen anything like this up close or as a diagram )


...that's why the name is exactly what it is.

As already mentioned, the compressor does not run against a wall, and therefore does not lose as much speed...

'Normally, a bypass is simply opened, effectively short-circuiting the charger 'internally'. However, the professionals need a valve that vents to the outside, because that creates a loud noise and makes it seem like the world is ending...'

see also: http://www.tyguy.net/gmc_popoff.htm


unnecessary when the engine has no throttle valve. It also pulls the turbo up even in push mode when the AGR is broken (which, incidentally, just sounds really cool )

See you, Gremlin