LOAD TO PRESSURE CONVERSION FACTOR MED17.5

MED17.5 LOAD TO PRESSURE CONVERSION FACTOR

Calculation of gas exchange model BGLWM

In this function, the internal residual gas (pbrint) and the conversion factor intake manifold pressure into combustion chamber filling (fupsrl) are calculated.

Calculation of the conversion factor from intake manifold pressure to combustion chamber filling for the current operating point (fupsxs == actual values: fupsrl_w), for intake manifold pressure equal to pressure before throttle valve (fupsmxxs == fupsrlmx_w) and for intake manifold pressure equal to 95% of the pressure before throttle valve (“UGD”) (fupsugxs == fupsrlug_w). In addition, the combustion chamber pressure calculated when inlet valve closes (pbrsex == pbrse_w). This pressure is required as the final expansion pressure for the adiabic expansion of the residual gas.

Calculation of pulsation correction

Pulsation correction to calculate the combustion chamber pressure when the inlet valve closes depending on the speed, the inlet valve closing angle (wgvsxsmet == wgvsme_w) and the actuators in the intake manifold(LBK:flbxs == flb_w; SU(2): fsuxs(2) == fsu(2)_w; VS: fvxs == fvs_w). There are pulsation corrections for the throttled suction range (fpbrpsg == fpbrpsg_w), the suction area with the flap fully open (fpbrxmx) and the loading area (fpbrpslb == fpbrpslb_w).

Determination of which actuator in the intake manifold should be used as flap 1 (fkl1x == fkl1_w) or flap 2 (fkl2x == fkl2_w) (if available) is based on codeword CWPIRGKL1 and CWPIRGKL2

if CWPIRGKL1 is euqual to 1 flbxs is used as flk1x

if CWPIRGKL1 is euqual to 2 fsuxs is used as flk1x

if CWPIRGKL1 is euqual to 3 fvxs is used as flk1x

In our case flbx is used as fkl1x (CWPIRGKL1=1) ( we have only single actuator so fkl2x is not need to be considered)

Calculation of pulsation correction with single flap installed

Fbbrpsg = (KFFPBR+ ((KFFPBRKL1- KFFPBR)*fkl1x))

Here values of map KFFKUPRLMX and KFFKUPRLLB are same(unity)

So fpbrpsg_w = fpbrpswx_w = fpbrpslb_w (see above flow chart)

Interpolation

Calculation of the pulsation correction for:

Current operating point: fpbrx == fpbrps_w
Intake manifold pressure = 0.95 * Pressure before throttle valve: fpbrxug == fpbrpsug_w
Intake pipe pressure = pressure before throttle valve: fpbrxmx == fpbrpsmx_w

Where fiuewdk_w== fiuewdkX_w is the Interpolation factor in the DK(throttle valve) transition

wdkbaX_w can be any variable from the following

wdkba_w> Throttle valve angle related to the lower stop

wdkbam_w> Throttle valve angle related to the lower stop (average value ¨ and 1 segment)

wdkbab_w> wdkba_w limited (minimum selection between wdkba_w and wdkugd_w)

wdkbap_w >Throttle valve angle predicted for injection (Word)

wdkbapb_w>limitation Throttle valve angle predicted for injection (Word)

wdkbatn_w>DK angle for minimum mass flow over DK due to tolerances

wdkbatx_w>DK angle for maximum mass flow over DK due to tolerances

wdkugdX_w can be any variable from the following

wdkugd_w>Throttle valve angle at which 95% filling is achieved

wdkugoa_w>Throttle valve angle at which 95% filling is achieved without HFM adaptation

The associated throttle valve angle (wdkugd_w) is calculated from the unthrottled mass flow (msdkugd_w) using the inverse DK model

psrx >intake manifold pressure

pvdx>Pressure in front of the throttle valve (value range from 0…5120hPa

pu_w> atmospheric pressure

DFILBVPMNN is constant 0.449280

Calculation of fupsrlo

Calculation of the conversion factor from pressure to filling without pulsation correction (fupsrlro == fupsrlro_w).

The conversion factor can be calculated depending on the volume when the inlet valve closes (wgsxsmet == wgvsme_w) and the temperature of the fresh air in the combustion chamber (tahev_w).

Instead of the absolute volume, the volume is normalized to the displacement volume (FVBR = V(ES) / Vh) and the temperature is normalized to 273 K.

ftahev_w = 273K/(273K+tahev_w)

FVBR= Vzyl/Vhub

Vzyl = combustion chamber volume at wgvsmebv_w

VHub = displacement of a cylinder

* wgsxsmet == wgvsme_w is the average angle gas exchange valve closes of inlet valve

Fvbr

Calculation of fupsxs/fupsrl

Calculation of the conversion factor from pressure to filling including pulsation correction. During the calculation, the conversion factor is used without pulsation correction (fupsrlro == fupsrlro_w) multiplied by the corresponding pulsation correction (fpbrx == fpbrps_w; fpbrxug == fpbrpsug_w; fpbrxmx == fpbrpsmx_w) and the adjustment between modeled and measured intake manifold pressure (for systems with HFM and intake manifold pressure sensor). In addition, the combustion chamber pressure when the inlet valve closes is calculated (pbrsex == pbrse_w).

Conversion factor for:

Current operating point: fupsxs == fupsrl_w
Intake pipe pressure = 0.95 * Pressure before throttle valve: fupsugxs == fupsrlug_w
Intake pipe pressure = pressure before throttle valve: fupsmxxs == fupsrlmx_w

Calculation of FLB