Gang-specific torque limiting

Hello,

Many front-wheel-drive cars with powerful engines are unable to transfer the full engine torque to the road in first gear because the acceleration, even with optimal grip (a flat, dry surface), is limited to approximately 5 meters per second squared due to the reduced load on the front axle.
If the driver is in 1st... When the vehicle is driven aggressively (despite the system), the ESP typically intervenes and reduces the engine torque to the point where wheel slip no longer occurs.
For diesel engines, this can be achieved relatively elegantly by reducing the injection quantity, but gasoline engines would tend to sputter or overheat locally in the process. Therefore, the ignition timing is delayed or the throttle is partially closed because the "boost pressure" control parameter is too slow to allow for this type of control intervention.
This is about the most idiotic operating condition for a turbomotor: first, full boost pressure is applied, and then, in the next moment, the torque is reduced with control interventions that effectively destroy the efficiency of the system.

Therefore, I wonder why the OEM hasn't programmed a gear-selective torque limitation, even for gasoline engines.
"For example, my Polo has a factory-specified torque of 350 Nm on paper. Even when fully loaded (1670 kg), it's enough to achieve an acceleration of 5 m/s² in first gear." The engine produces 280 Nm of torque, but I believe that the last 70 Nm can never be translated into acceleration; instead, they must always be suppressed by the ESP system.
With a minimum weight of approximately 1270 kg (without luggage, with almost an empty tank, and a light driver), the 5 m/s² acceleration in first gear is already achieved with approximately 230 Nm of torque, and the ESP system even has to neutralize 120 Nm – even more so in wet conditions, when cornering, or on uneven terrain. However, the aforementioned ~70 Nm of torque must always be dissipated, and as mentioned, this torque can never be used for acceleration.

I know that the MED9.1 supports a gait-selective torque limitation, which could solve my "problem": It offers a maximum of 280 Nm in the first gear. "Under full load and with optimal grip, the ESP wouldn't need to intervene at all. Conversely, with minimal weight and optimal grip, only about 50 Nm would need to be dissipated instead of 120 Nm, etc."
Why isn't the OEM doing this? Is it simply a matter of convenience (since the ESP can handle the situation without anything breaking) or saved time in the software application, or are there specific technical reasons?

ulf wrote:

...time saved with the software application...

Correct, time is money, so why integrate anything that isn't truly necessary?!

ESP handles it, or alternatively: Simply get a better grip with your right foot.
Furthermore: Punishment must be served; those who order a lot of power with FWD are to blame themselves.

TDI-GTI-4-Motion wrote:

So, why integrate something that is not really necessary?

99% of modern cars are overflowing with "non-essential" electronics. But apparently, they are attractive to so many buyers that the development is worthwhile - unlike the reduced full-throttle experience in the lower gears .

I would have bet that you would be the first to interpret any selective limitation as a restriction of your free will, a form of disenfranchisement, or something similar. It seems I was wrong. But perhaps it's intentional, and the marketing team has discovered that the average buyers of overpowered subcompact cars are looking for exactly that.
Or simply another proof: When developing new vehicles, no one thinks about the human element anymore.

Just change the accelerator pedal mapping... doesn't that exist?

It has the advantage that you can better control the amount of gas delivered without being limited by the maximum torque.

Best regards, Rainer.

ulf wrote:

But apparently, they manage to attract so many buyers with those....

That's what it looks like.

matthiasTDI96 wrote:

I would have bet that you would be the first to interpret any selective limitation of something as a restriction of your free self-determination, disenfranchisement, or whatever. This is how one can be wrong.

Typical Ulf, sometimes it's okay, sometimes it's not.
If the limit were in place, the thread would now exist in a modified form, for every bet.

dieselschrauber wrote:

Why don't you just change the corresponding accelerator pedal characteristic curve... doesn't that exist? It has the advantage that you can better control the throttle without being limited by the maximum torque.

The MED9.1 has several pedal ranges, but without a fixed assignment to individual gears.

I understand how my issue could be resolved... here, the question is why the OEM doesn't do it proactively.

ulf wrote:

... For diesel engines, this can be achieved relatively elegantly by reducing the injection quantity, but gasoline engines would tend to sputter or overheat locally in the process. Therefore, the ignition timing is delayed or the throttle is partially closed because the "boost pressure" control parameter is too slow to allow for this type of control intervention. ...

Ulf, think again!

Generally, there isn't a significant difference between diesel and gasoline engines in this regard. When you close the throttle, the amount of air entering the engine decreases, which in turn reduces the amount of fuel injected. What's the difference compared to a diesel engine?
In diesel engines, the fuel injection quantity is directly controlled, while in gasoline engines, the control variable is the air mass flow rate, which indirectly influences the fuel injection quantity. The effect is the same as if the driver were taking their foot off the accelerator.
This is the most effective and lossless torque limiting system available, and it has been for over 100 years.

The ignition timing is retarded, just like when you let off the gas. I believe this was done for environmental reasons, but I'm not 100% sure.

ulf wrote:

. . . here, the issue was why the OEM wasn't doing it on their own

.

Because it involves unnecessary and pointless effort, which could potentially lead to even more errors.

Bertil wrote:

When you close the throttle, the air mass goes into the intake manifold, and consequently, the fuel injection amount also decreases. What is the difference compared to a diesel engine?

It's in the reaction speed (the diesel engine's electronic control unit can be changed almost instantaneously, while a direct injection intervention feels comparatively sluggish) and in the efficiency (too high boost pressure is "destroyed" by closing the direct injection system - yuck!).

ulf wrote:

In the reaction rate...

Wrong!
On the contrary. The DK is significantly faster.

Quote:

... (The Diesel EM can be changed almost immediately, while a DK intervention is comparatively slow.) ...

Wrong!
Unfortunately, EM is not everything (especially with gasoline engines) .

Quote:

... and in terms of efficiency (too high boost pressure is "destroyed" by closing the wastegate - yuck!).

Not entirely wrong (at least the part about the turbo boost is correct)!
You're only allowed to do that if you don't remove any gas!


Since your way of thinking limits the system to too few parameters, and you are therefore unable or unwilling to fully understand the system, it's pointless to explain to you where the problem lies.


For informational purposes only:
Sure, closing the throttle valve destroys boost pressure. However, this primarily has nothing to do with efficiency. It is well known that gasoline engines waste energy at the throttle valve (whether naturally aspirated or turbocharged). However, unfortunately, there is no simpler (more cost-effective) system for gasoline engines than the throttle valve.

So, Ulf... that means for you, starting today, only open DK (meaning full throttle!) ...

The problem with turbocharger boost can be solved using Anti-Lag Systems (ALS). However, manufacturers often avoid using them due to cost and emissions concerns. You are welcome to install one yourself; they are available for your car. Just don't be surprised by the popping, hissing, and sputtering that will then occur.

https://www.youtube.com/watch?v=TGVxnC-YxGE

Okay, I would like to disagree with Bertil and support Ulf on this. Reducing the torque of a diesel engine by retracting the electromagnetic valve is a quick and relatively straightforward process. However, it's a bit more complex with a gasoline engine, and Bertil is likely correct about that. Because simply removing electrolytes will lead to the problems mentioned.

A throttle valve doesn't destroy energy. That statement is factually incorrect because energy cannot be destroyed; rather, it's a matter of increased pressure occurring before the combustion chamber in a turbocharged gasoline engine.

The discussion about "WOT" (Wide Open Throttle) acceleration efficiency in first gear seems, in the described driving scenario, somewhat incomprehensible to me. Seriously, the technical efficiency of the internal combustion engine and the fuel consumption measured on a dynamometer (i.e., the advertised fuel consumption) don't correlate. There's no WOT on a dynamometer, not even remotely. Therefore, it's unlikely that regulating the excess performance in the lower ranks is a viable goal from that perspective.

"To my knowledge, an ALS (Anti-Lag System) is designed to keep the turbocharger spinning. This isn't just about releasing pressure before the throttle closes, but actively maintaining pressure by increasing the enthalpy of the air before it enters the turbine (I'm not sure if this actually exists in production turbochargers, but based on my understanding, the exhaust gas temperature would temporarily reach four digits...). Strictly speaking, this only helps to get through the gear shift pause so that you can start again with full boost pressure. Ulf, however, wants an electrical system that combats excessive power delivery at low RPM. He probably would benefit more if it were implemented directly in second gear." Torque of 350 Nm is needed to overcome the Polo's drive shafts and pull towards the horizon with regained traction... However, all the technical stuff... the electronics... are heavy and prone to failure .

Here's a simple question: In your preliminary calculation of potential pulling force and traction, did you use the original tires or your alternative tire options? Are all the data for the road, tires, etc. known?

My Audi, with its summer tires (large and wide), and also a good amount of torque (and of course, all-wheel drive), doesn't really accelerate quickly from a standstill. With the winter tires (which are relatively small and narrow), he sometimes finds himself in a situation on dry roads where the electronic stability control (ESC) is disengaged.

matthiasTDI96 wrote:

So, in this case, I would like to disagree with Bertil and support Ulf. Reducing the torque of a diesel engine by retracting the electromagnetic valve (EMV) is quick and relatively straightforward. With a gasoline engine, it is somewhat more complex, and Bertil is certainly correct about that. Simply removing the EMV leads to the problems mentioned.

In diesel engines with purely electrically controlled individual pumps (PD, CR), the EMV can be changed from 100% to zero, or any desired intermediate value, within a single engine cycle (for example, at 3000 rpm, this takes about 40 milliseconds), and this can be done completely without inertia, without any delay times, overshoots, etc.
A throttle valve first needs to be set in motion and then slowed down when it reaches the target value, meaning it can only achieve delayed control responses and is therefore inferior to pure electromagnetic control.
If the "Diesel Emission Standard" regulation is proven to be circumvented through artificial runtime data or other artificial means within the application process, this does not change the fundamental inferiority of the heavier "Diesel Emission Standard" regulation.

Quote:

A throttle valve does not destroy energy. This is factually incorrect, as energy cannot be destroyed; rather, it results in increased pressure before the throttle valve in a turbocharged gasoline engine...

...and around the throttle valve, there are strong turbulence, which reduce the pressure where the boost pressure is supposed to be (namely, in front of the intake valves). This pressure was initially generated with difficulty, taking into account high exhaust backpressure and unnecessarily high thermal stress on the exhaust system.
Even though this state is usually traversed within a few seconds until the engine reaches its maximum RPM, it represents an unnecessary waste of energy from the perspective of overall efficiency (or, alternatively). Utilization energy destruction ).
"An application developer who would program such an operating state as a standard, fixed setting should, in my opinion, be in the first tier of expertise." Semester VKM (or whatever it is) banished.

Quote:

Just a naive question: In your preliminary calculation of the possible tractive force and traction, did you include the original tire specifications or your alternative tire specifications? Are all the data for the road, tires, etc., known?

Regarding the tires, I assume the standard rolling circumference of the mounted size or the measured rolling circumference plus the estimated moment of inertia for 4 wheels (e.g., 4 mkg² for wheels with 19 kg and a rolling circumference of 1.86 m), and as an influence on rolling resistance, a typical free rolling deceleration of 0.13 m/sec², and a slip factor of 0.05 (see...). Ernsts power performance diagram), and a total efficiency of 0.96, taking into account the power train losses.

As a limit for the possible acceleration, I'm taking 5 m/s², because I haven't been able to detect anything higher with my front-wheel-drive TDI cars (ASZ-Polo with 160 hp, BUK-Ibiza with 180 hp) in any ABS/ESP logs, on a dry, straight road, with the rear wheels spinning.
I haven't made any comparable measurements with the WRC Polo yet, so I can't rule out that it might achieve slightly more than 5 m/s². However, that doesn't change the fact that it's running at full throttle in first gear. The vehicle urgently needs an ESP intervention to maintain steering control.

Quote:

My Audi, with its summer tires (large and wide), doesn't really accelerate quickly from a standstill, even with its good torque (and of course, all-wheel drive). With the winter tires (relatively small and narrow), it sometimes reaches a point on dry roads where traction control kicks in...

I think you should also consider the weight of the wheels. If I remove the front axle load relief limit of 5 m/s² from my calculations for the WRC Polo and only increase the weight per wheel from 18 to 20 kg, the calculated maximum acceleration in 1st gear decreases. Acceleration from 7.25 to 7.0 m/s².

Quote:

A throttle valve first needs to be set in motion and then slowed down again when the target value is reached, meaning it can only achieve delayed control actions and is therefore inferior to pure electromagnetic control.

Switching to zero load in a gasoline engine can occur between any two strokes of the cycle. If no fuel is injected when the throttle is fully open, then no combustion occurs. If this only happens every other cycle... When the engine reaches a certain operating speed, a throttle valve motor can quickly reduce the power output by half, without needing to consider air flow effects.

ulf wrote:

"An application developer who would program such an operating state as a standard, fixed setting should, in my opinion, be in the first tier of expertise." Semester VKM (or whatever it is) banished.

This is a dynamic state within a minimal time unit. I wouldn't really care about that...

What exactly is your point? Are you concerned about the high fuel consumption when accelerating with spinning wheels, which is then compensated for by the electric motor? Or are you concerned about the loss of comfort that might result?

matthiasTDI96 wrote:

Exactly where is your point? Are you talking about excessive fuel consumption while accelerating with spinning wheels and being caught by the electric motor? Or are you concerned about the loss of performance that might occur?

More likely the former - and about the desire to replace a working, but otherwise sloppy, solution with a (theoretically) better approach.