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Thread: Torque Demand, Timing, and GM's new engine run modeling

  1. #1
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    Torque Demand, Timing, and GM's new engine run modeling

    While looking for information on the new systems I have run into 2 key patents that tell us fairly clearly how to tune these engines. Just takes a keen eye and some thinking to put it into action.

    links:
    Link One
    Link Two

    Important Link One diagrams:






    Link Two Diagrams:







    The patents also provide Formulas:
    Link One:
    BTREQ =T ped +T IDLE =T ENG −T Access  

    BTREQ - Brake Torque Request
    Tped - Gas pedal torque request based on position
    TIdle - zero pedal torque. iow.. foot off pedal torque
    Teng - Engine torque
    T access - torque used by accessories

    T=f(APC,S,I,E,AF,OT,#)

    T- Torque
    APC - Air per Cylinder
    S - Timing
    I - Intake Phaser Position
    E - Exhaust Phaser Position
    AF - Air/Fuel Ratio
    OT - Oil Temp
    # - Number of Active Cylinders

    Trpm PR = T ZPE + T R + T Ppr + T Ipr
    Trpm IM = T AIRACT - T R + T Pim
    Trpm PR = T ZPE + T R + T Ppr + T Ipr + T Dpr
    Trpm IM = T ZPE + T I  im + T Pim + T Dim + T md
    T lim = F  ( T Ipr )
    T AIRACT = T PRCOMM + T ERR
    T ERR = T U - T PRACT
    T R = T U - T IM
    T R =  T PR - T IM 
    T Ppr = f  { Δ   N }
    T Ipr = ∑ x = 0 X   T Ipr · f  { Δ   N }
    T Dpr = Δ   RPM · K D

    Trpm PR - Predicted Torque Request
    Trpm IM - Immediate Torque Request
    T ZPE - Zero Pedal Torque Request
    T R - Torque Reserve
    T Ppr - Proportional Predicted Torque. At steady state it equals zero.
    T Ipr - Integral Predicted Torque. Equal to F(TIpr).
    T AIRACT - Actual Air Torque
    T Pim - Proportional Immediate Torque. At steady state it equals zero.
    T Dpr - Derivative Predicted Torque. At steady state it equals zero.
    T I - Integral Torque
    T Dim - Derivative Immediate Torque. At steady state it equals zero.
    T md - Torque Differential. At steady state it equals zero.
    T Iim - Integral Immediate Torque
    T PRComm - Commanded Predicted Torque
    T PrAct - Predicted Actual Torque
    T ERR - Torque Error
    T U - Unmanaged Torque
    T Dpr - Predicted Torque Derivative
    Kd - Derivative Constant. May be determined from a table based on the ΔN. ΔRPM is a rate of change in engine speed.

    Link Two:
    Sdes =T −1(Tdes, APC, I, E, AF, OT, #)  

    S des - Desired Spark
    T des - Desired Torque

    Seems to me that the key to tuning the torque tables are right here. What we need to do, I think, is log actual torque and whatever parameters will give us some sort of sensor base torque calculation and go from there. The correct data will allow the peak torque tables to be tuned for new mods. On top of that; tuning the VE looks to be the first thing required before the torque management section. We need to figure out which sensors and which torque readings give us meaningful data.

    Sorry for the giant google linked pictures.
    Last edited by Wnts2Go10O; 09-03-2014 at 01:44 AM.

  2. #2
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    Last picture as there are already 10 in the OP.


  3. #3
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    strangely... the driver demand maps a, b, and c are all in kW and not Nm...

  4. #4
    Senior Tuner Ben Charles's Avatar
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    Good info, a lot of that in a similar format has been posted by Hp tuners though.

    Of course its in KW, 1 kw is = to 1.34hp. You can map the DD tables by power of the vehicle, that's roughly how I dial in the table. I also take into account a linear ETC percent much like a DBC car.

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  5. #5
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    its odd because all the other models are strictly torque based.