Throttle Control via Full Throttle Switch/Boost Signal | Posts 32+

driklau wrote:

Where is the easiest place to access the tax signals from the full throttle switch and the boost pressure sensor?

Depending on the layout of the wiring harnesses...
The signals are best found directly at the accelerator pedal or the turbocharger pressure sensor (if it is not located in the engine control unit).

The full-throttle contact normally provides 5 volts and is shorted to ground when the throttle is fully open.

...
2. Evaluate the boost pressure signal using a threshold switch -> This prevents soot formation, but the tuning can become 'uncontrollable' even in partial load conditions.

3. Combine 1 + 2 using an AND operation -> In my opinion, this is the 'perfect' solution.

Hi Ulf,

Why use the boost pressure signal? Wouldn't the signal from the mass airflow sensor (MAF) be more suitable? My experience is that, especially during full-throttle driving and sudden 'throttle release,' the boost pressure remains for a longer time because the variable turbine geometry (VTG) probably re-engages, and additionally, the exhaust gas recirculation (EGR) valve opens.
Then the tuning would become active again, even with a small amount of intermediate gas.

Greetings.

Eike.

Hi,

I've been thinking about this again. Ulf's suggestion with the boost pressure signal is probably better than mine with the mass airflow sensor signal, because with constant boost pressure, the mass airflow signal continues to increase with increasing engine speed.

The best solution would be to make the tuning variable and dependent on the boost pressure.
Wouldn't it be possible to connect an optocoupler in series with the potentiometer, one that operates in its linear range? I've suggested something similar before for the 10-cent tuning, to make it dependent on boost pressure as well.
The effort should be kept to a minimum: 1 optocoupler, one dual operational amplifier, and 2 resistors. Use the first op-amp to decouple the LD signal, and the second to linearize the diode current in the optocoupler. Then, connect the transistor of the optocoupler in series with the potentiometer of the tuning module.
The question is how much the boost pressure regulation will fluctuate. Perhaps we could make the system a bit more sluggish by adding an electrolytic capacitor.

What do you think about it?

Greetings.

Eike.

Hi there,
A microcomputer needs to be installed there.
You can directly generate the holding current using PWM, and also program a proper speed-dependent characteristic curve.
With the analog input (AD) channels, you can directly measure things like boost pressure.
greetings

eike wrote:

The best solution would be if the tuning could be made variable, depending on the boost pressure. Wouldn't it be possible to connect an optocoupler in series with the potentiometer, which would operate in its linear range? I once suggested something similar for the 10-cent tuning, to make it dependent on boost pressure as well. The effort should be kept to a minimum: 1 optocoupler, one dual operational amplifier, and 2 resistors. Use the first op-amp to decouple the LD signal, and the second to linearize the diode current in the optocoupler. Then, connect the transistor of the optocoupler in series with the potentiometer of the tuning module. The question is, how much will the boost pressure regulation affect it? Perhaps it would be necessary to make the system a bit more sluggish with an additional capacitor...

With this concept, you are essentially at the level of the Authal VP box, which I consider to be quite good .

The turbocharger on my Golf 3 wasn't building up boost.
Only when the device was switched on under heavy load did the pressure increase by approximately 0.2 bar for about 1 second, after which it slowly decreased.
If the device remained active throughout, the pressure remained largely at its normal level.

Therefore, I believe that increasing the boost pressure in your PD proposal is rather unlikely.

ulf wrote:

If the PDE is open, the current is reduced to avoid unnecessary power loss.

Hi,

The current is not actually reduced primarily due to power loss, but rather to minimize the energy stored in the magnetic circuit (W = 1/2 * L * i^2). When the current through the coil is switched off, the coil attempts to maintain the current itself (using the energy stored within it) ==>
- a very high voltage would be generated at the coil, which would either have to be withstood by the switching transistor or...
- When using a flyback diode to protect the switching transistor, the current would continue to flow for a very long time, causing a significant delay in the closing of the valve ==> (that's why a flyback diode is actually not used).

To allow for faster switching of the valve, or to use a transistor with a lower voltage rating, and to avoid having to choose an unnecessarily high voltage rating for the coil/wiring, the coil current is regulated to a lower value after the initial activation ==> this reduces the amount of energy stored in the coil that would later need to be dissipated.

Best regards,
Munch.

Mampf wrote:

The current is not actually reduced due to power loss, but rather to keep the energy stored in the magnetic circuit (W = 1/2 * L * i^2) low. When the current through the coil is switched off, the coil tries to continue the current itself (using the energy stored in it) ==> - a very high voltage would be generated at the coil, which would either have to be withstood by the switching transistor or... - When using a flyback diode to protect the switching transistor, the current would continue to flow for a very long time, and the valve would close with a significant delay ==> (that's why a flyback diode is actually not usually used).

Hmm... if the PDE current is regulated with pulsed voltage, then a (smaller) inductive spike is created each time it is switched off, which puts a strain on the electronics .

ulf wrote:

Hmm... if the PDE current is regulated by a pulsed voltage, then a (smaller) inductive spike is created each time it is switched off, which puts a strain on the electronics

.

Hi,

If it is actually implemented like that, it shouldn't be a problem; otherwise, the whole thing wouldn't work (the power transistor has to be able to handle it) , unfortunately, I don't know what the final amplifier actually looks like.

Best regards,
Munch.

I suspect that the holding current for the proportional solenoid valves is primarily reduced to prevent the coils in the solenoid valves from overheating.
With a coil resistance of 0.3-0.4 ohms and a voltage of 12V, a significant amount of current would be drawn, potentially causing damage.

Bye driklau.

driklau wrote:

I suspect that the current limiting function in the PDE is primarily used to prevent the coils in the solenoid valves from overheating. With a coil resistance of 0.3-0.4 ohms and a voltage of 12V, a significant amount of current would be drawn, potentially leading to overheating or damage. Bye driklau

.

Hi,

The control system is similar for engines with electro-hydraulic injectors.

The coils are initially energized with a voltage higher than 12V (the calling phase), followed by 12V for the remainder of the calling phase, lasting approximately 150µS. Then, the voltage is switched off due to current limiting, and a power MOSFET with a diode is immediately configured as a freewheeling diode. Consequently, the armature remains energized for a short period, and the current decreases. Approximately 50µS later, 12V is applied again, and this process repeats. This maintains the current at a level of 5-10A.

Once the holding phase or injection phase is complete, the freewheeling circuit is activated, and the inductive voltage charges a capacitor. This rapidly dissipates the magnetic field. This capacitor is then used during the next injection phase to quickly re-magnetize the coil (calling phase).

In the CR Bosch Gen1 system, after the injection, the injector positioned opposite in the firing sequence is briefly activated to fully charge the 15µF capacitor (C) to its 80V rating. Due to self-induction after the injection, this capacitor only charges to approximately 45V.

The Bosch CR Gen2 system, on the other hand, generates the control voltage in the engine control unit. This 60V voltage activates the injector for 150µS, compared to only 80µS in the older system. Only then do 20A flow to lift the injector needle. Once the needle is lifted, the same process occurs for closing, and the holding current is reduced to below 10A.

OT/off