Diagnostics in Automotive Engines and Vehicles
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F. BOZZA, A. GIMELLI Dept. of Mech. Eng. (DIME) Univ. of Naples “Federico II”, ITALY E. TORELLA PowerPoint PPT Presentation


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Diagnostics in Automotive Engines and Vehicles MECA ’02 Dept. of Mech. Eng. - University of Salerno October 4th 2002. F. BOZZA, A. GIMELLI Dept. of Mech. Eng. (DIME) Univ. of Naples “Federico II”, ITALY E. TORELLA ELASIS S.C.p.A, ITALY.

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F. BOZZA, A. GIMELLI Dept. of Mech. Eng. (DIME) Univ. of Naples “Federico II”, ITALY E. TORELLA

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F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Diagnostics in Automotive Engines and VehiclesMECA ’02

Dept. of Mech. Eng. - University of Salerno

October 4th 2002

F. BOZZA, A. GIMELLIDept. of Mech. Eng. (DIME) Univ. of Naples “Federico II”, ITALY

E. TORELLA

ELASIS S.C.p.A, ITALY

The Potential of 1D Simulation Models in Control Applications of VVT Engines


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Introduction

MECA’02 Workshop, Oct 2002

VVT

VVA

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.2

  • Intake (and exhaust) Variable Valve Timing (VVT) is nowadays commonly used in the standard SI Engine production (cam phasers):

  • Variable Valve Actuation (VVA) systems will be moreover adopted in the next SI engine generation (Electro-magnetic actuators):

  • Improvements on output performance at WOT and on BSFC and NOx emission at part-load have been assessed


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Motivation

MECA’02 Workshop, Oct 2002

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.3

  • With themost advanced VVA devices, an increased number of parameters must be controlled by the EMS:

    Spark Adv.,Throttle,A/F, IVO,IVC,EVO,EVC,IVL,EVL

    traditional ctrl’d parameters,valve-train arrangementparams

  • It is really difficult to characterize the engine behavior through a classical experimental analysis

  • The number of experimental tests to be conducted, is exponentially growing accordingly to the rising number of setting variables


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Motivation

MECA’02 Workshop, Oct 2002

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.4

  • Some difficulties also arise when a simple cam phaser system is employed (only one additional control parameter)

  • In this case, a different experimentally derived volumetric efficiency map must be employed within traditional speed-density procedure for predicting the port air mass flow

  • This depends on both the different development of the wave propagation phenomena in the external ducts, as well as on valve backflows, causing “internal EGR”


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Experimental data

MECA’02 Workshop, Oct 2002

Exh

Int

Miminum Load Line

 = 50 deg

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.5

Phased Intake & Exhaust VVT Engine

Volumetric Efficiency Contours

 = 0 deg

Engine: CBR 1400 16v


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Objective

MECA’02 Workshop, Oct 2002

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.6

  • Problem:

  • Variable Valve devices require additional experimental efforts to develop the Engine Management System, with a considerable penalty on costs and time-to-market of new engines

  • The employment of an accurate 1D simulation model to help the development of the EMS and reduce the demandof experimental data

  • Development of two examples aiming to show the “ Potential of the 1D Simulation Models in Control Applications ”

  • Proposed solution:

  • Test - cases:


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Summary

MECA’02 Workshop, Oct 2002

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.7

  • Brief description and validation of the 1D code

  • First example: Control-Laws of various VVA devices are derived through the matching of the 1D code with a numerical optimization procedure

  • Second Example: A Correlation of volumetric efficiency with some easily measurable parameters is derived, basing on “pseudo-experimental” data generated with the 1D code


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

MECA’02 Workshop, Oct 2002

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.8

Simulation Model

1Dime

  • 1D Flow model:

    • Finite Volume numerical scheme coupled to a flux correction TVD (Total Variation Diminishing) technique.

    • Eqs. for the scalar transport of chemical species (unburned fuel, xf, and burned products, xr, fractions) for a correct computation of in-cylinder composition (the presence of “internal EGR” is then accounted for)


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Simulation Code

MECA’02 Workshop, Oct 2002

Burned Gas

SL

u’

L

SL

Unburned Gas

SL

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.9

1Dime

  • Combustion, Turbulence and Emission Model

    • Fractal Approach: the turbulent flow field wrinkles the flame front, which assumes fractal characteristics:

  • Fractal dimension and wrinkling scales depend on turbulence intensity, computed with k-K model

  • Multi-zone approachfor NOx Emission computation, frozen equilibrium assumption for CO estimation, crevices and partial-burn mechanisms for HC production


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Experimental Analyses

MECA’02 Workshop, Oct 2002

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.10

Two Engines were tested at ELASIS:

  • A traditional fixed-valve engine (Fire 1242 16v)

  • A phased intake & Exhaust VVT Engine (CBR 1400 16v)

CBR 1400 16v

Sketch of the Port-Deactivation System employed to promote the burning speed at high EGR rate


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Boundary Conditions

MECA’02 Workshop, Oct 2002

Dp

Exhaust mass flow rate

Slider

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.11

CBR 1400 16v

  • Only Input Data:

    • Throttle Opening

    • Rotational Speed

    • Air/Fuel Ratio

    • Spark Advance

    • VVT Position

    • Ambient Conditions

1D Geometrical representation:


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Validation

MECA’02 Workshop, Oct 2002

CO Emission

NO Emission

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.12

Traditional fixed-valve engine (Fire 1242 16v)

IMEP

Air-Flow


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Validation

MECA’02 Workshop, Oct 2002

 = 50 deg

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.13

Phased intake & Exhaust VVT Engine (CBR 1400 16v)

 = 0 deg

 = 28 deg


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Validation

MECA’02 Workshop, Oct 2002

EXP

NUM

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.14

CBR 1400 16v

 = 0 deg


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Validation

MECA’02 Workshop, Oct 2002

EXP

NUM

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.15

CBR 1400 16v

 = 50 deg


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Validation

MECA’02 Workshop, Oct 2002

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.16

  • A limited validation of the 1D whole engine models is frequently found in current literature (only at WOT for example)

  • The 1Dime model is indeed able to well describe whole engine operation, including low load, idle or high EGR conditions

  • Model derived engine operating maps can be employed in a number of control applications (static look-up tables)

  • A great potential there exist for a significant reduction of the experimental efforts required for the EMS


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

First Example

MECA’02 Workshop, Oct 2002

  • Intake only VVT

    ( = spark advance)

    ( = phase position)

  • Phased Intake & Exhaust VVT

  • Unphased Intake & Exhaust VVT

  • Early Intake Valve Closure (EIVC)

    ( = scale factor)

Exh

Int

Exh

Int

I

E

Exh

Int

s

Exh

Int

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.17

  • An optimization procedure, coupled to the 1D model, can identify the values of the independent variables (vector X) which minimize the BSFC, for 4 different VVT / VVA devices:


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

First Example

MECA’02 Workshop, Oct 2002

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.18

  • At each fixed engine operating condition (in terms of throttle opening *, speed n*, A/F ratio, external conditions)the following mathematical problem can be formulated:

  • “Optimal Control Laws” of the VVT devices were derived through repeated solutions of the above problem at different load levels (at a constant speed of 2250 rpm)

  • The objective function can also include inequality constraints (ALF formulation) on emission, or it can be evaluated on few representative points of the test cycles (NEDC, FTP, etc.)


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Optimization Results

MECA’02 Workshop, Oct 2002

Exh

Int

Exh

I

E

Exh

Int

Int

s

Exh

Int

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.19

2250 rpm

BSFC percent Variation


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Control Laws

MECA’02 Workshop, Oct 2002

I

E

Exh

Int

s

Exh

Int

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.20

Unphased Int.&Exh.

EIVC


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Second Example

MECA’02 Workshop, Oct 2002

EXP

NUM

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.21

Phased Intake & Exhaust VVT Engine

Vol. Eff. Iso-Contours

  • A different volumetric efficiency map arises at each VVT position

  • Can these maps be synthesized in a single correlation?

  • Model based Vol.Eff. mapswere built at =[0,15,30,35,40,45,50]

  • Each map consisting of 64 points, 448 “pseudo-experimental” data were generated at standard ambient conditions


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Vol. Eff. Correlation

MECA’02 Workshop, Oct 2002

Vol.Eff0 from Correlation

Vol.Eff0 from 1D Model

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.22

  • Numerical data were correlated as a function of Engine speed (rpm), manifold pressure (MAP) and phase delay (VVT)

  • A non linear regression technique provided the values of the 10 constants of the 2nd order polynomial model function


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Vol. Eff. Correlation

MECA’02 Workshop, Oct 2002

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.23

  • To take into account the effects of ambient conditions, additional simulations were carried out in a single operating condition (2000 rpm, 2 bar BMEP)

  • A slightly correction was required with respect to the expected linear dependence on (T/p) term, to take into account sound speed variations and heat losses


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Vol. Eff. Correlation

MECA’02 Workshop, Oct 2002

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.24

  • The comparison on TRUE experimental data at various phase positions furnished good results:

Vol.Eff from corrected correlation

Experimental Vol.Eff.


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

Conclusion

MECA’02 Workshop, Oct 2002

Black-Box

White-Box

Grey-Box

F&E Models

1D Models

Exp. Data

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.25

  • The two examples presented have shown the great potential offered by the 1D models in different control applications

  • The methodology is applicable to various VVA concepts and can certainly help a more rapid development of the EMS

  • Computing power of modern PC can allow to directly follow the unsteady behavior of the engine during a complete drive cycle

  • A “brighter” future seems near to come in control applications…


F bozza a gimelli dept of mech eng dime univ of naples federico ii italy e torella

MECA’02 Workshop, Oct 2002

Bozza, et al., DIME, Napoli, The Potential of 1D Simulation Models ... Pag.26

Optimization Results


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