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CI Controller

Compression-ignition controller that includes air mass flow, torque, and EGR estimation

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  • Powertrain Blockset / Propulsion / Combustion Engine Controllers

  • CI Controller block

Description

The CI Controller block implements a compression-ignition (CI) controller with air mass flow, torque, exhaust gas recirculation (EGR) flow, exhaust back-pressure, and exhaust gas temperature estimation. You can use the CI Controller block in engine control design or performance, fuel economy, and emission tradeoff studies. The core engine block requires the commands that are output from the CI Controller block.

The block uses the commanded torque and measured engine speed to determine these open-loop actuator commands:

  • Injector pulse-width

  • Fuel injection timing

  • Variable geometry turbocharger (VGT) rack position

  • EGR valve area percent

The CI Controller block has two subsystems:

  • The Controller subsystem — Determines the commands based on tables that are functions of commanded torque and measured engine speed.

    Based OnDetermines Commands for

    Commanded torque

    Measured engine speed

    Injector pulse-width

    Fuel injection timing

    VGT rack position

    EGR valve area percent

  • The Estimator subsystem — Determines estimates based on these engine attributes.

    Based OnEstimates

    Measured engine speed

    Fuel injection timing

    Cycle average intake manifold pressure and temperature

    Fuel injector pulse-width

    Absolute ambient pressure

    EGR valve area percent

    VGT rack position

    VGT speed

    Air mass flow

    Torque

    Exhaust gas temperature

    Exhaust gas back-pressure

    EGR valve gas mass flow

The figure illustrates the signal flow.

The figure uses these variables.

N

Engine speed

MAP

Cycle average intake manifold absolute pressure

MAT

Cycle average intake manifold gas absolute temperature

EGRap, EGRcmd

EGR valve area percent and EGR valve area percent command, respectively

VGTpos

VGT rack position

Nvgt

Corrected turbocharger speed

RPcmd

VGT rack position command

Pwinj

Fuel injector pulse-width

MAINSOI

Start of injection timing for main fuel injection pulse

The Model-Based Calibration Toolbox™ was used to develop the tables that are available with the Powertrain Blockset™.

Controller

The controller governs the combustion process by commanding VGT rack position, EGR valve area percent, fuel injection timing, and injector pulse-width. Feedforward lookup tables, which are functions of measured engine speed and commanded torque, determine the control commands.

Air

The controller commands the EGR valve area percent and VGT rack position. Changing the VGT rack position modifies the turbine flow characteristics. At low-requested torques, the rack position can reduce the exhaust back pressure, resulting in a low turbocharger speed and boost pressure. When the commanded fuel requires additional air mass flow, the rack position is set to close the turbocharger vanes, increasing the turbocharger speed and intake manifold boost pressure.

The variable geometry turbocharger (VGT) rack position lookup table is a function of commanded torque and engine speed

RPcmd=fRPcmd(Trqcmd,N)

where:

  • RPcmd is VGT rack position command, in percent.

  • Trqcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

The commanded exhaust gas recirculation (EGR) valve area percent lookup table is a function of commanded torque and engine speed

EGRcmd=fEGRcmd(Trqcmd,N)

where:

  • EGRcmd is commanded EGR valve area percent, in percent.

  • Trqcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

Fuel

To initiate combustion, a CI engine injects fuel directly into the combustion chamber. After the injection, the fuel spontaneously ignites, increasing cylinder pressure. The total mass of the injected fuel and main injection timing determines the torque production.

Assuming constant fuel rail pressure, the CI controller commands the injector pulse-width based on the total requested fuel mass:

Pwinj=Fcmd, totSinj

The equation uses these variables.

Pwinj

Fuel injector pulse-width

Sinj

Fuel injector slope

Fcmd,tot

Commanded total fuel mass per injection

MAINSOI

Main start-of-injection timing

N

Engine speed

The commanded total fuel mass per injection table is a function of the torque command and engine speed

Fcmd,tot=fFcmd,tot(Trqcmd,N)

where:

  • Fcmd,tot = F is commanded total fuel mass per injection, in mg per cylinder.

  • Trqcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

The main start-of-injection (SOI) timing lookup table is a function of commanded fuel mass and engine speed

MAINSOI=f(Fcmd,tot,N)

where:

  • MAINSOI is the main start-of-injection timing, in degrees crank angle after top dead center (degATDC).

  • Fcmd,tot = F is commanded fuel mass, in mg per injection.

  • N is engine speed, in rpm.

Idle Speed

When the commanded torque is below a threshold value, the idle speed controller regulates the engine speed.

IfIdle Speed Controller
Trqcmd,input < Trqidlecmd,enableEnabled
Trqidlecmd,enableTrqcmd,inputNot enabled

The idle speed controller uses a discrete PI controller to regulate the target idle speed by commanding a torque.

The PI controller uses this transfer function:

Cidle(z)=Kp,idle+Ki,idletsz1

The idle speed commanded torque must be less than the maximum commanded torque:

0 ≤ TrqidlecomdTrqidlecmd,max

Idle speed control is active under these conditions. If the commanded input torque drops below the threshold for enabling the idle speed controller (Trqcmd,input < Trqidlecmd,enable), the commanded engine torque is given by:

Trqcmd = max(Trqcmd,input,Trqidlecmd).

The equations use these variables.

Trqcmd

Commanded engine torque

Trqcmd,input

Input commanded engine torque

Trqidlecmd,enable

Threshold for enabling idle speed controller

Trqidlecmd

Idle speed controller commanded torque

Trqidlecmd,max

Maximum commanded torque

Nidle

Base idle speed

Kp,idle

Idle speed controller proportional gain

Ki,idle

Idle speed controller integral gain

Speed Limiter

To prevent over revving the engine, the block implements an engine speed limit controller that limits the engine speed to the value specified by the Rev-limiter speed threshold parameter on the Controls > Idle Speed tab.

If the engine speed, N, exceeds the engine speed limit, Nlim, the block sets the commanded engine torque to 0.

To smoothly transition the torque command to 0 as the engine speed approaches the speed limit, the block implements a lookup table multiplier. The lookup table multiplies the torque command by a value that ranges from 0 (engine speed exceeds limit) to 1 (engine speed does not exceed the limit).

Estimator

Using the CI Core Engine block, the CI Controller block estimates the air mass flow rate, EGR valve mass flow, exhaust back-pressure, engine torque, AFR, and exhaust temperature from sensor feedback. The Info port provides the estimated values, but block does not use them to determine the open-loop engine actuator commands.

Air Mass Flow

To calculate the air mass flow, the compression-ignition (CI) engine uses the CI Engine Speed-Density Air Mass Flow Model. The speed-density model uses the speed-density equation to calculate the engine air mass flow, relating the engine intake port mass flow to the intake manifold pressure, intake manifold temperature, and engine speed.

EGR Valve Mass Flow

To calculate the estimated exhaust gas recirculation (EGR) valve mass flow, the block calculates the EGR flow that would occur at standard temperature and pressure conditions, and then corrects the flow to actual temperature and pressure conditions. The block EGR calculation uses estimated exhaust back-pressure, estimated exhaust temperature, standard temperature, and standard pressure.

m˙egr,est=m˙egr,stdPexh,estPstdTstdTexh,est

  • The standard exhaust gas recirculation (EGR) mass flow is a lookup table that is a function of the standard flow pressure ratio and EGR valve flow area

    m˙egr,std=f(MAPPexh,est,EGRap)

    where:

    • m˙egr,std is the standard EGR valve mass flow, in g/s.

    • Pexh,est is the estimated exhaust back-pressure, in Pa.

    • MAP is the cycle average intake manifold absolute pressure, in Pa.

    • EGRap is the measured EGR valve area, in percent.

The equations use these variables.

m˙egr,est

Estimated EGR valve mass flow

m˙egr,std

Standard EGR valve mass flow

Pstd

Standard pressure

Tstd

Standard temperature

Texh,est

Estimated exhaust manifold gas temperature

MAP Measured cycle average intake manifold absolute pressure

Pexh,est

Estimated exhaust back-pressure

PAmb

Absolute ambient pressure

EGRap

Measured EGR valve area percent

Exhaust Back-Pressure

To estimate the EGR valve mass flow, the block requires an estimate of the exhaust back-pressure. To estimate the exhaust back-pressure, the block uses the ambient pressure and the turbocharger pressure ratio.

Pexh,est=PAmbPrturbo

For the turbocharger pressure ration calculation, the block uses two lookup tables. The first lookup table determines the approximate turbocharger pressure ratio as a function of turbocharger mass flow and corrected turbocharger speed. Using a second lookup table, the block corrects the approximate turbocharger pressure ratio for VGT rack position.

Prturbo=f(m˙airstd,Nvgtcorr)f(VGTpos)where:Nvgtcorr=NvgtTexh,est

The equations use these variables.

m˙egr,est

Estimated EGR valve mass flow

m˙egr,std

Standard EGR valve mass flow

m˙port,est

Estimated intake port mass flow rate

m˙airstdStandard air mass flow
EGRapMeasured EGR valve area
MAP

Measured cycle average intake manifold absolute pressure

MAT

Measured cycle average intake manifold gas absolute temperature

Pstd

Standard pressure

Tstd

Standard temperature

Texh,est

Estimated exhaust manifold gas temperature

Prvgtcorr

Turbocharger pressure ratio correction for VGT rack position

Prturbo

Turbocharger pressure ratio

Pexh,est

Estimated exhaust back-pressure

PAmb

Absolute ambient pressure

NvgtcorrCorrected turbocharger speed
VGTposMeasured VGT rack position

The exhaust-back pressure calculation uses these lookup tables:

  • The turbocharger pressure ratio, corrected for variable geometry turbocharger (VGT) speed, is a lookup table that is a function of the standard air mass flow and corrected turbocharger speed, Prturbo=f(m˙airstd,Nvgtcorr), where:

    • Prturbo is the turbocharger pressure ratio, corrected for VGT speed.

    • m˙airstd is the standard air mass flow, in g/s.

    • Nvgtcorr is the corrected turbocharger speed, in rpm/K^(1/2).

    To calculate the standard air mass flow through the turbocharger, the block uses conservation of mass, the estimated intake port, and EGR mass flows (from the last estimated calculation). The calculation assumes negligible exhaust manifold filling dynamics.

    m˙airstd=(m˙port,estm˙egr,est)PstdMAPMATTstd

  • The variable geometry turbocharger pressure ratio correction is a function of the rack position, Prvgtcorr= ƒ(VGTpos), where:

    • Prvgtcorr is the turbocharger pressure ratio correction.

    • VGTpos is the variable geometry turbocharger (VGT) rack position.

Engine Torque

To calculate the engine torque, you can configure the block to use either of these torque models.

Brake Torque ModelDescription
CI Engine Torque Structure Model

The CI core engine torque structure model determines the engine torque by reducing the maximum engine torque potential as these engine conditions vary from nominal:

  • Start of injection (SOI) timing

  • Exhaust back-pressure

  • Burned fuel mass

  • Intake manifold gas pressure, temperature, and oxygen percentage

  • Fuel rail pressure

To account for the effect of post-inject fuel on torque, the model uses a calibrated torque offset table.

CI Engine Simple Torque Model

For the simple engine torque calculation, the CI engine uses a torque lookup table map that is a function of engine speed and injected fuel mass.

Exhaust Temperature

The exhaust temperature calculation depends on the torque model. For both torque models, the block implements lookup tables.

Torque Model

Description

Equations

Simple Torque Lookup

Exhaust temperature lookup table is a function of the injected fuel mass and engine speed.

Texh=fTexh(F,N)

Torque Structure

The nominal exhaust temperature, Texhnom, is a product of these exhaust temperature efficiencies:

  • SOI timing

  • Intake manifold gas pressure

  • Intake manifold gas temperature

  • Intake manifold gas oxygen percentage

  • Fuel rail pressure

  • Optimal temperature

The exhaust temperature, Texhnom, is offset by a post temperature effect, ΔTpost, that accounts for post and late injections during the expansion and exhaust strokes.

Texhnom=SOIexhteffMAPexhteffMATexhteffO2pexhteffFUELPexhteffTexhoptTexh=Texhnom+ΔTpostSOIexhteff=fSOIexhteff(ΔSOI,N)MAPexhteff=fMAPexhteff(MAPratio,λ)MATexhteff=fMATexhteff(ΔMAT,N)O2pexhteff=fO2pexhteff(ΔO2p,N)Texhopt=fTexh(F,N)

The equations use these variables.

F

Compression stroke injected fuel mass

N

Engine speed

Texh

Exhaust manifold gas temperature

Texhopt

Optimal exhaust manifold gas temperature

ΔTpostPost injection temperature effect
TexhnomNominal exhaust temperature

SOIexhteff

Main SOI exhaust temperature efficiency multiplier

ΔSOI

Main SOI timing relative to optimal timing

MAPexheff

Intake manifold gas pressure exhaust temperature efficiency multiplier

MAPratio

Intake manifold gas pressure ratio relative to optimal pressure ratio

λ

Intake manifold gas lambda

MATexheff

Intake manifold gas temperature exhaust temperature efficiency multiplier

ΔMAT

Intake manifold gas temperature relative to optimal temperature

O2Pexheff

Intake manifold gas oxygen exhaust temperature efficiency multiplier

ΔO2P

Intake gas oxygen percent relative to optimal

FUELPexheff

Fuel rail pressure exhaust temperature efficiency multiplier

ΔFUELP

Fuel rail pressure relative to optimal

Air-Fuel Ratio

The measured engine speed and fuel injector pulse-width determine the commanded fuel mass flow rate:

m˙fuel,cmd=NSinjPwinjNcylCps(60smin)(1000mgg)

The commanded total fuel mass flow and estimated port mass flow rates determine the estimated AFR:

AFRest=m˙port,estm˙fuel,cmd

The equations use these variables.

Pwinj

Fuel injector pulse-width

AFRest

Estimated air-fuel ratio

m˙fuel,cmd

Commanded fuel mass flow rate

Sinj

Fuel injector slope

N

Engine speed

Ncyl

Number of engine cylinders

Cps

Crankshaft revolutions per power stroke, rev/stroke

m˙port,est

Total estimated engine air mass flow at intake ports

Ports

Input

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Commanded engine torque, Trqcmd,input, in N·m.

Measured engine speed, N, in rpm.

Measured intake manifold absolute pressure, MAP, in Pa.

Measured intake manifold absolute temperature, MAT, in K.

Absolute ambient pressure, PAmb, in Pa.

Measured EGR valve area percent, EGRap, in %.

Measured VGT rack position, VGTpos.

Measured VGT speed, Nvgt, in rpm.

Engine cooling temperature, Tcoolant, in K.

Output

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Bus signal containing these block calculations.

SignalDescriptionVariableUnits

InjPw

Fuel injector pulse-width

Pwinj

ms

EgrVlvAreaPctCmd

EGR valve area percent command

EGRcmd%

TurbRackPosCmd

VGT rack position command

RPcmdN/A

TrqCmd

Engine torque

Trqcmd

N·m

FuelMassTotCmd

Commanded total fuel mass per injection

Fcmd,tot

mg

FuelMainSoi

Main start-of-injection timing

MAINSOI

degATDC

FuelMassFlwCmd

Commanded fuel mass flow rate

m˙fuel,cmd

kg/s

EstIntkPortMassFlw

Estimated port mass flow rate

m˙port,est

kg/s

EstEngTrq

Estimated engine torque

Trqest

N·m

EstExhManGasTemp

Estimated exhaust manifold gas temperature

Texh,est

K

EstExhPrs

Estimated exhaust back-pressure

Pex

Pa

EstEGRFlow

EstEGRFlow

EstEGRFlow

EstEGRFlow

EstAfr

Estimated air-fuel ratio

AFRest

N/A

EngRevLimAct

Flag that indicates if rev-limiter control is active

N/A

N/A

Fuel injector pulse-width, Pwinj, in ms.

Main start-of-injection timing, MAINSOI, in degrees crank angle after top dead center (degATDC).

VGT rack position command, RPcmd.

EGR valve area percent command, EGRcmd.

Parameters

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Controls

Air - EGR

The commanded exhaust gas recirculation (EGR) valve area percent lookup table is a function of commanded torque and engine speed

EGRcmd=fEGRcmd(Trqcmd,N)

where:

  • EGRcmd is commanded EGR valve area percent, in percent.

  • Trqcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

Commanded torque breakpoints, in N·m.

Speed breakpoints, in rpm.

Air - VGR

The variable geometry turbocharger (VGT) rack position lookup table is a function of commanded torque and engine speed

RPcmd=fRPcmd(Trqcmd,N)

where:

  • RPcmd is VGT rack position command, in percent.

  • Trqcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

Breakpoints, in N·m.

Breakpoints, in rpm.

Fuel

Fuel injector slope, Sinj, in mg/ms.

Stoichiometric air-fuel ratio, AFRstoich.

Fuel lower heating value, in J/kg.

The commanded total fuel mass per injection table is a function of the torque command and engine speed

Fcmd,tot=fFcmd,tot(Trqcmd,N)

where:

  • Fcmd,tot = F is commanded total fuel mass per injection, in mg per cylinder.

  • Trqcmd is commanded engine torque, in N·m.

  • N is engine speed, in rpm.

The main start-of-injection (SOI) timing lookup table is a function of commanded fuel mass and engine speed

MAINSOI=f(Fcmd,tot,N)

where:

  • MAINSOI is the main start-of-injection timing, in degrees crank angle after top dead center (degATDC).

  • Fcmd,tot = F is commanded fuel mass, in mg per injection.

  • N is engine speed, in rpm.

Fuel main injection timing fuel breakpoints, in mg per injection.

Fuel main injection timing speed breakpoints, in rpm.

Commanded torque breakpoints, in N·m.

Speed breakpoints, in rpm.

Idle Speed

Base idle speed, Nidle, in rpm.

Torque to enable the idle speed controller, Trqidlecmd,enable, in N·m.

Maximum idle controller commanded torque, Trqidlecmd,max, in N·m.

Proportional gain for idle speed control, Kp,idle, in N·m/rpm.

Integral gain for idle speed control, Ki,idle, in N·m/(rpm·s).

Engine speed limit, Nlim, in rpm.

If the engine speed, N, exceeds the engine speed limit, Nlim, the block sets the commanded engine torque to 0.

To smoothly transition the torque command to 0 as the engine speed approaches the speed limit, the block implements a lookup table multiplier. The lookup table multiplies the torque command by a value that ranges from 0 (engine speed exceeds limit) to 1 (engine speed does not exceed the limit).

Estimation

Air

Number of engine cylinders, Ncyl.

Crankshaft revolutions per power stroke, Cps, in rev/stroke.

Displaced volume, Vd, in m^3.

Ideal gas constant, Rair, in J/(kg·K).

Standard air pressure, Pstd, in Pa.

Standard air temperature, Tstd, in K.

The volumetric efficiency lookup table is a function of the intake manifold absolute pressure at intake valve closing (IVC) and engine speed

ηv=fηv(MAP,N)

where:

  • ηv is engine volumetric efficiency, dimensionless.

  • MAP is intake manifold absolute pressure, in KPa.

  • N is engine speed, in rpm.

Intake manifold pressure breakpoints for speed-density volumetric efficiency lookup table, in KPa.

Engine speed breakpoints for speed-density volumetric efficiency lookup table, in rpm.

The standard exhaust gas recirculation (EGR) mass flow is a lookup table that is a function of the standard flow pressure ratio and EGR valve flow area

m˙egr,std=f(MAPPexh,est,EGRap)

where:

  • m˙egr,std is the standard EGR valve mass flow, in g/s.

  • Pexh,est is the estimated exhaust back-pressure, in Pa.

  • MAP is the cycle average intake manifold absolute pressure, in Pa.

  • EGRap is the measured EGR valve area, in percent.

EGR valve standard flow pressure ratio breakpoints, dimensionless.

EGR valve standard flow area percent breakpoints, in percent.

The turbocharger pressure ratio, corrected for variable geometry turbocharger (VGT) speed, is a lookup table that is a function of the standard air mass flow and corrected turbocharger speed, Prturbo=f(m˙airstd,Nvgtcorr), where:

  • Prturbo is the turbocharger pressure ratio, corrected for VGT speed.

  • m˙airstd is the standard air mass flow, in g/s.

  • Nvgtcorr is the corrected turbocharger speed, in rpm/K^(1/2).

Turbocharger pressure ratio standard flow breakpoints, in g/s.

Turbocharger pressure ratio corrected speed breakpoints, in rpm/K^(1/2).

The variable geometry turbocharger pressure ratio correction is a function of the rack position, Prvgtcorr= ƒ(VGTpos), where:

  • Prvgtcorr is the turbocharger pressure ratio correction.

  • VGTpos is the variable geometry turbocharger (VGT) rack position.

Turbocharger pressure ratio VGT position correction breakpoints, dimensionless.

Torque - Simple Torque Lookup

For the simple torque lookup table model, the CI engine uses a lookup table is a function of engine speed and injected fuel mass, Tbrake=fTnf(F,N), where:

  • Tq = Tbrake is engine brake torque after accounting for engine mechanical and pumping friction effects, in N·m.

  • F is injected fuel mass, in mg per injection.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, for Torque model, select Simple Torque Lookup.

Torque table fuel mass per injection breakpoints, in mg per injection.

Dependencies

To enable this parameter, for Torque model, select Simple Torque Lookup.

Engine speed breakpoints, in rpm.

Dependencies

To enable this parameter, for Torque model, select Simple Torque Lookup.

Torque - Torque Structure

Fuel mass per injection breakpoints, in mg per injection.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

Engine speed breakpoints, in rpm.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

The optimal main start of injection (SOI) timing lookup table, ƒSOIc, is a function of the engine speed and injected fuel mass, SOIc = ƒSOIc(F,N), where:

  • SOIc is optimal SOI timing, in degATDC.

  • F is compression stroke injected fuel mass, in mg per injection.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

The optimal intake manifold gas pressure lookup table, ƒMAP, is a function of the engine speed and injected fuel mass, MAP = ƒMAP(F,N), where:

  • MAP is optimal intake manifold gas pressure, in Pa.

  • F is compression stroke injected fuel mass, in mg per injection.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

The optimal exhaust manifold gas pressure lookup table, ƒEMAP, is a function of the engine speed and injected fuel mass, EMAP = ƒEMAP(F,N), where:

  • EMAP is optimal exhaust manifold gas pressure, in Pa.

  • F is compression stroke injected fuel mass, in mg per injection.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

The optimal intake manifold gas temperature lookup table, ƒMAT, is a function of the engine speed and injected fuel mass, MAT = ƒMAT(F,N), where:

  • MAT is optimal intake manifold gas temperature, in K.

  • F is compression stroke injected fuel mass, in mg per injection.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

The optimal intake gas oxygen percent lookup table, ƒO2, is a function of the engine speed and injected fuel mass, O2PCT = ƒO2(F,N), where:

  • O2PCT is optimal intake gas oxygen, in percent.

  • F is compression stroke injected fuel mass, in mg per injection.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

The optimal fuel rail pressure lookup table, ƒfuelp, is a function of the engine speed and injected fuel mass, FUELP = ƒfuelp(F,N), where:

  • FUELP is optimal fuel rail pressure, in MPa.

  • F is compression stroke injected fuel mass, in mg per injection.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

The optimal gross indicated mean effective pressure lookup table, ƒimepg, is a function of the engine speed and injected fuel mass, IMEPG = ƒimepg(F,N), where:

  • IMEPG is optimal gross indicated mean effective pressure, in Pa.

  • F is compression stroke injected fuel mass, in mg per injection.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

The optimal friction mean effective pressure lookup table, ƒfmep, is a function of the engine speed and injected fuel mass, FMEP = ƒfmep(F,N), where:

  • FMEP is optimal friction mean effective pressure, in Pa.

  • F is compression stroke injected fuel mass, in mg per injection.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

The optimal pumping mean effective pressure lookup table, ƒpmep, is a function of the engine speed and injected fuel mass, PMEP = ƒpmep(F,N), where:

  • PMEP is optimal pumping mean effective pressure, in Pa.

  • F is compression stroke injected fuel mass, in mg per injection.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

Friction multiplier as a function of temperature, dimensionless.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

Friction multiplier temperature breakpoints, in K.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

The main start of injection (SOI) timing efficiency multiplier lookup table, ƒSOIeff, is a function of the engine speed and main SOI timing relative to optimal timing, SOIeff = ƒSOIeff(ΔSOI,N), where:

  • SOIeff is main SOI timing efficiency multiplier, dimensionless.

  • ΔSOI is main SOI timing relative to optimal timing, in degBTDC.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

Main start of injection timing relative to optimal timing breakpoints, in degBTDC.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

The intake manifold gas pressure efficiency multiplier lookup table, ƒMAPeff, is a function of the intake manifold gas pressure ratio relative to optimal pressure ratio and lambda, MAPeff = ƒMAPeff(MAPratio,λ), where:

  • MAPeff is intake manifold gas pressure efficiency multiplier, dimensionless.

  • MAPratio is intake manifold gas pressure ratio relative to optimal pressure ratio, dimensionless.

  • λ is intake manifold gas lambda, dimensionless.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

Intake manifold gas pressure ratio relative to optimal pressure ratio breakpoints, dimensionless.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

Intake manifold gas lambda breakpoints, dimensionless.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

The intake manifold gas temperature efficiency multiplier lookup table, ƒMATeff, is a function of the engine speed and intake manifold gas temperature relative to optimal temperature, MATeff = ƒMATeff(ΔMAT,N), where:

  • MATeff is intake manifold gas temperature efficiency multiplier, dimensionless.

  • ΔMAT is intake manifold gas temperature relative to optimal temperature, in K.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

Intake manifold gas temperature relative to optimal gas temperature breakpoints, in K.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

The intake manifold gas oxygen efficiency multiplier lookup table, ƒO2Peff, is a function of the engine speed and intake manifold gas oxygen percent relative to optimal, O2Peff = ƒO2Peff(ΔO2P,N), where:

  • O2Peff is intake manifold gas oxygen efficiency multiplier, dimensionless.

  • ΔO2P is intake gas oxygen percent relative to optimal, in percent.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

Intake gas oxygen percent relative to optimal breakpoints, in percent.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

The fuel rail pressure efficiency multiplier lookup table, ƒFUELPeff, is a function of the engine speed and fuel rail pressure relative to optimal breakpoints, FUELPeff = ƒFUELPeff(ΔFUELP,N), where:

  • FUELPeff is fuel rail pressure efficiency multiplier, dimensionless.

  • ΔFUELP is fuel rail pressure relative to optimal, in MPa.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

Fuel rail pressure relative to optimal breakpoints, in MPa.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

Fuel mass injection type identifier, dimensionless.

In the CI Core Engine and CI Controller blocks, you can represent multiple injections with the start of injection (SOI) and fuel mass inputs to the model. To specify the type of injection, use the Fuel mass injection type identifier parameter.

Type of InjectionParameter Value

Pilot

0

Main

1

Post

2

Passed

3

The model considers Passed fuel injections and fuel injected later than a threshold to be unburned fuel. Use the Maximum start of injection angle for burned fuel, f_tqs_f_burned_soi_limit parameter to specify the threshold.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

The indicated mean effective pressure post inject correction lookup table, ƒIMEPpost, is a function of the engine speed and fuel rail pressure relative to optimal breakpoints, ΔIMEPpost = ƒIMEPpost(ΔSOIpost,Fpost), where:

  • ΔIMEPpost is indicated mean effective pressure post inject correction, in Pa.

  • ΔSOIpost is indicated mean effective pressure post inject start of inject timing centroid, in degATDC.

  • Fpost is indicated mean effective pressure post inject mass sum, in mg per injection.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

Indicated mean effective pressure post inject mass sum breakpoints, in mg per injection.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

Indicated mean effective pressure post inject start of inject timing centroid breakpoints, in degATDC.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

Maximum start of injection angle for burned fuel, in degATDC.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

Exhaust

Exhaust gas-specific heat, Cpexh, in J/(kg·K).

Exhaust Temperature - Simple Torque Lookup

The lookup table for the exhaust temperature is a function of injected fuel mass and engine speed

Texh=fTexh(F,N)

where:

  • Texh is exhaust temperature, in K.

  • F is injected fuel mass, in mg per injection.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, for Torque model, select Simple Torque Lookup.

Engine load breakpoints used for exhaust temperature lookup table, in mg per injection.

Dependencies

To enable this parameter, for Torque model, select Simple Torque Lookup.

Engine speed breakpoints used for exhaust temperature lookup table, in rpm.

Dependencies

To enable this parameter, for Torque model, select Simple Torque Lookup.

Exhaust Temperature - Torque Structure

The optimal exhaust manifold gas temperature lookup table, ƒTexh, is a function of the engine speed engine speed and injected fuel mass, Texhopt = ƒTexh(F,N), where:

  • Texhopt is optimal exhaust manifold gas temperature, in K.

  • F is compression stroke injected fuel mass, in mg per injection.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

The main start of injection (SOI) timing exhaust temperature efficiency multiplier lookup table, ƒSOIexhteff, is a function of the engine speed engine speed and injected fuel mass, SOIexhteff = ƒSOIexhteff(ΔSOI,N), where:

  • SOIexhteff is main SOI exhaust temperature efficiency multiplier, dimensionless.

  • ΔSOI is main SOI timing relative to optimal timing, in degBTDC.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

The intake manifold gas pressure exhaust temperature efficiency multiplier lookup table, ƒMAPexheff, is a function of the intake manifold gas pressure ratio relative to optimal pressure ratio and lambda, MAPexheff = ƒMAPexheff(MAPratio,λ), where:

  • MAPexheff is intake manifold gas pressure exhaust temperature efficiency multiplier, dimensionless.

  • MAPratio is intake manifold gas pressure ratio relative to optimal pressure ratio, dimensionless.

  • λ is intake manifold gas lambda, dimensionless.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

The intake manifold gas temperature exhaust temperature efficiency multiplier lookup table, ƒMATexheff, is a function of the engine speed and intake manifold gas temperature relative to optimal temperature, MATexheff = ƒMATexheff(ΔMAT,N), where:

  • MATexheff is intake manifold gas temperature exhaust temperature efficiency multiplier, dimensionless.

  • ΔMAT is intake manifold gas temperature relative to optimal temperature, in K.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

The intake manifold gas oxygen exhaust temperature efficiency multiplier lookup table, ƒO2Pexheff, is a function of the engine speed and intake manifold gas oxygen percent relative to optimal, O2Pexheff = ƒO2Pexheff(ΔO2P,N), where:

  • O2Pexheff is intake manifold gas oxygen exhaust temperature efficiency multiplier, dimensionless.

  • ΔO2P is intake gas oxygen percent relative to optimal, in percent.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

The fuel rail pressure efficiency exhaust temperature multiplier lookup table, ƒFUELPexheff, is a function of the engine speed and fuel rail pressure relative to optimal breakpoints, FUELPexheff = ƒFUELPexheff(ΔFUELP,N), where:

  • FUELPexheff is fuel rail pressure exhaust temperature efficiency multiplier, dimensionless.

  • ΔFUELP is fuel rail pressure relative to optimal, in MPa.

  • N is engine speed, in rpm.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

Post-injection cylinder wall heat loss transfer coefficient, in W/K.

Dependencies

To enable this parameter, for Torque model, select Torque Structure.

References

[1] Heywood, John B. Internal Combustion Engine Fundamentals. New York: McGraw-Hill, 1988.

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Introduced in R2017a