Basic strategies for regulating boost;
Control pressure: The pressure that affects the wastegate actuator. (Either over, or under the membrane).
Over the membrane: The chamber in a WG that add boost with added pressure.
Under the membrane: The chamber in a WG that subtract boost with added pressure. (Normally the only chamber available on a built in wastegate).
Two way boost valve: Pneumatic valve with two ports, that open when energized.
Three way boost valve: Pneumatic valve with three ports, where one connects to one of the other two depending on if it is energized or not.
Restrictor: A small orifice that limits flow.
NO: Normally open.
NC: Normally closed.
EBP: Exhaust Back Pressure.
The strategies for a built in wastegate are:
Regulating under the membrane with a restrictor and a two way boost valve that bleed off control pressure to add bost.
Regulating under the membrane with a three way boost valve that proportionally mix between compressed air and atmospheric air to produce a control pressure that is lower than the actual boost pressure, to add boost.
To add to the above strategies, an external wastegate offers the following strategy:
Regulating over the membrane with a three way boost valve that proportionally mix between compressed air and atmospheric air to produce a control pressure to add boost pressure to the base pressure that is managed by direct connection from compressor housing to under the membrane. This "cussion/pillow"-pressure can be maintained through the standard boost control function, or with a PWM from a GPC.
The control pressure for boost regulating must be taken before the throttle. If the control pressure is taken from after the throttle, there will be excessive, uncontrolled backpressure at mid throttle affecting both power output and also the mapping accuracy.
Software Setup
Menu M1
O/P Setup
Enable O/P Boost to you output, normally PWM1 or PWM2, set the frequency to 10Hz or 20 Hz, use 20 Hz for a small wastgate.
Menu M5
Boost Setup
Boost Seetpoint 1-2
Value used for Automatic switching between Boost table 1 and 2, a speed sensor is needed (Vehicle speed). If not used set huigh value here, see help in software for calulation of value.
Boost Seetpoint 2-3
Value used for Automatic switching between Boost table 2 and 3, a speed sensor is needed (Vehicle speed). If not used set huigh value here, see help in software for calulation of value.
Over Boost Margin
Overboost margin has two effects.
If boost goes that amount over the boost setpoint for the time set in "Overboost time" one gets a boost cut. In fact, it is way more cleaver than that. But not going into a complex math explanation.
If boost is climbing over the set boost point, the boost controller will start getting more and more aggressive the nearer the "Boost setpoint"+"Overboost margin" that boost is currently getting. It also estimates how quick it is going into overboost and react more agressively on this too.
So, when getting near a boost cut, the boost controller will do something like lowering the "actual" boost control range. This will start treating the problem before it gets to be a problem. Great thanks to Autronic for designing it like this! Use 20-25 kpa as a start
Over Boost Time
The period of time boost can exceed the over boost margin before engine is shut down. Use 1-2,5 Sec as a good start value.
Boost setpoint 1 to 3
Set maximum boost in relation to engine RPM and a selected y axis "Setup under Table axis setup".
Tables 1, 2, 3 can be used so the engine runs different boost for every gear "Boost tune" sets this up or to switch between two boost levels (+1 or +2 leves setup under "M1, I/P Switches").
Boost Tune
Te help table describes a formula to calculate the value, but read the following to better understand the setting.
You will find that with a smaller value here, the boost valve will come in much later to start limiting the boost. And at the same time it will react much more aggressive to limit the boost pressure.
One can see it as a sort of gain. Setting it high will give smoother boost control, but it will start limiting lower down in boost, and will affect spoolup slightly, and it may also come short of the set boost point.
See it as where boost control will start limiting. If boost setpoint is 280, and ?boost control range’ is 150 - Then boost control will start juggling with the boost valve at about 280 - 150 = 130 kPa.
On cars with restrictors, one will find that the ?boost control range’ must be set very low. And that high values must be set in the "Boost Offset" table.
This is because compressed air is in a limited supply with a restrictor. Therefore the boost valve must be forced not to waste any air during spoolup.
Cars without restrictor, and with turbos that spools easy, will take a greater value in "boost control range", and sometimes does not need any other values than 0 in the "Boost Offset" table.
Boost Dynamic Comp
Boost control dynamic compensation.
Used to stop boost pressure hunting.
The bigger the value the more dampening effect.
Start with a low value as 5-10.After tuning everything else you can take up any eventual roughness or peaks in the boost curve by upping theese values. If needed.
Boost offset
The "Boost Offset" table can then correct the difference between wanted setpoint and actual boost pressure, by adding to the point in the "Boost Offset" table for each boost setpoint and rpm that you want it to up the boost a little.
One can just make a rpm sweep at full throttle in high gear to get a boost curve in the log. Then looking in the log at the difference between boost setpoint and actual boost. Normally one need to enter positive values here to up the boost. But some turbos need negative values here when the flow saturates the turbine at higher revs and one needs to force up the wastegate to avoid overboost. This is the equalizer!
If you wanted 280 at 5000 rpm, but got 255, then enter 25 in this table at boost setpoint 280 and 5000 rpm. As simple as that.
Boost Modifier
Used to reduce boost pressure in relation to other variables. X and Y axis can be setup inder Table axis setup
__________________
Robert Jansson
MRM-Racing
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MarkII 90 TourerV "Последний из Могикан"
MarkII 81 2jz-gte PsiXo
Supra 70 1g-gte GT
Autronic Team
SelfMade Works
Последний раз редактировалось №1, 22.01.2009 в 16:44
Over the membrane: The chamber in a WG that add boost with added pressure.
Under the membrane: The chamber in a WG that subtract boost with added pressure. (Normally the only chamber available on a built in wastegate).
В начале есть два определения, которые касаются вестгейта
Вестгейт состоит из двух камер над мембраной и под мембраной
1. над мембраной: Камера, которая добавляет буст с увеличением давления? Т.е. получается, что если дунуть в эту камеру, то она закроет клапан и давление турбины будет увеличиваться?
2. камера, которая уменьшает буст с увеличением давления. (дословный перевод) Соответственно, если дунуть в эту камеру, то клпан откроется и будет пропускать выхлопные газы, а соответственно давление турбины будет падать? Я так понимаю работу вестгейта!
__________________
MarkII 90 TourerV "Последний из Могикан"
MarkII 81 2jz-gte PsiXo
Supra 70 1g-gte GT
Autronic Team
SelfMade Works
управляется соленоидом, жесткость пружины определяет мин сработку (мин буст)
Спасибо, понял! А вот здесь идет речь про блоуофф?
Two way boost valve: Pneumatic valve with two ports, that open when energized.
Three way boost valve: Pneumatic valve with three ports, where one connects to one of the other two depending on if it is energized or not.
__________________
MarkII 90 TourerV "Последний из Могикан"
MarkII 81 2jz-gte PsiXo
Supra 70 1g-gte GT
Autronic Team
SelfMade Works
Спасибо, понял! А вот здесь идет речь про блоуофф?
Two way boost valve: Pneumatic valve with two ports, that open when energized.
Three way boost valve: Pneumatic valve with three ports, where one connects to one of the other two depending on if it is energized or not.
Pегулировка Буста в Аутроник
Линейный вид
