Methodology for Dynamic Simulation of a Variable Valve...Methodology for Dynamic Simulation of a Variable Valve Actuation System in High Performance SI Engines V. Bevilacqua, A. Eichenberg,

07.10.2019- 1 -

Methodology for Dynamic Simulation of a Variable Valve Actuation System in High Performance SI EnginesV. Bevilacqua, A. Eichenberg, M. Porhansl, L. Olivieri

07.10.2019- 2 -


Methodology for Dynamic Simulation of a Variable Valve Actuation System in High Performance SI EnginesEuropean GT-SUITE User Conference 2019Frankfurt am Main, 7th October 2019V. Bevilacqua, A. Eichenberg, M. Porhansl, L. Olivieri

07.10.2019- 3 -


> Introduction

> Description of Cam Switching Mechanism

> Methodology, Simulation model

> Calibration

> Evaluation

> Conclusion

Agenda

07.10.2019- 4 -


0

2

4

6

8

10

12

-360 -180 0 180 360

Lift [

mm

]

CADeg TDCge

Variable Valve Actuation SystemsIntroduction

> In order to comply continuous tightening of regulations while keeping high performance, variable valve actuation systems can help engine development due to several advantages

Peak Power

Low-End Torque

Auxiliaries

FuelConsumption

PollutantEmissions

ExhaustIntakeStandard

07.10.2019- 5 -


0

2

4

6

8

10

12

-360 -180 0 180 360

Lift [

mm

]

CADeg TDCge


> In order to comply continuous tightening of regulations while keeping high performance, variable valve actuation systems can help engine development due to several advantages Performance targets

> Big cam profile for higher peak power Peak Power

Low-End Torque

Auxiliaries

FuelConsumption

PollutantEmissions

ExhaustIntakeStandardIntakeBig Cam

07.10.2019- 6 -


0

2

4

6

8

10

12

-360 -180 0 180 360

Lift [

mm

]

CADeg TDCge



> Big cam profile for higher peak power> Small cam profile for higher low-end torque

Peak Power

Low-End Torque

Auxiliaries

FuelConsumption

PollutantEmissions

ExhaustIntakeStandardIntakeBig CamIntakeSmall Cam

07.10.2019- 7 -


IntakeSmall Cam

0

2

4

6

8

10

12

-360 -180 0 180 360

Lift [

mm

]

CADeg TDCge




Efficiency Improvement> De-Throttling> Miller Cycle> Cylinder Deactivation

Peak Power

Low-End Torque

Auxiliaries

FuelConsumption

PollutantEmissions

Exhaust

IntakeBig Cam

07.10.2019- 8 -


IntakeEGR Cntrl

IntakeSmall Cam

0

2

4

6

8

10

12

-360 -180 0 180 360

Lift [

mm

]

CADeg TDCge





Pollutant Emission Reduction> EGR control

Peak Power

Low-End Torque

Auxiliaries

FuelConsumption

PollutantEmissions

Exhaust

07.10.2019- 9 -


IntakeSmall CamExhaustBraking

0

2

4

6

8

10

12

-360 -180 0 180 360

Lift [

mm

]

CADeg TDCge





Pollutant Emission Reduction> EGR control

Vehicle Management> Engine Braking Effect

Peak Power

Low-End Torque

Auxiliaries

FuelConsumption

PollutantEmissions

Exhaust

07.10.2019- 10 -


> Object of the presentation is a Dual Lift Shifting System No increased alternate masses Independent cam profiles Two actuating pins for each cylinder

> Main elements of this solution are: Slider with milled slot Actuating Pin Detent System Endstop

System OverviewCam Switching Mechanism

XZ

Y

07.10.2019- 11 -


> Nominal configuration: Small Cam profile for

Engine speed < 8500 RPM Big Cam profile for

Engine speed ≥ 8500 RPM

> At the threshold speed the actuating pin goes down making contact with the milled slot

> Slider forced to move in the axial direction


XZ

Y

07.10.2019- 12 -



XZ

Y> Nominal configuration: Small Cam profile for



> Detent System locks slider axial position after the shift

07.10.2019- 13 -



XZ

Y> Nominal configuration: Small Cam profile for



> Detent System locks slider axial position after the shift

> Endstop avoids out of range movements

07.10.2019- 14 -


Model OverviewMethodology

> The picture on the right shows how the system has been modelled in GT-SUITE

> In the following slides will be presented more detailed description of: Slider Actuation Pin Detent System Endstop

07.10.2019- 15 -


> The Slider performs the cam switch thanks to its 2 movements: Rotational movement together with

camshaft Translational motion due to contact

between pin and milled slot

Slider with Milled SlotMethodology

07.10.2019- 16 -


> The Slider performs the cam switch thanks to its 2 movements: Rotational movement together with

camshaft Translational motion due to contact

between pin and milled slot

> Inertia3D object is used to model the slider Rigid body No stiffness or damping properties

> Due to their complex shape, slot walls have been described with FEMesh3DSurface object

Slider with Milled SlotMethodology

07.10.2019- 17 -


> Contact with milled slot makes cam switch possible

> Pin is modelled with Inertia3D object Rigid body No stiffness or damping properties

> Contact port for pin is modelled as a simple cylindrical shape with ContactGeom3DCyl object

> Pin allowed movements: Vertical movement actuation Bending around Z-axis

Actuating PinMethodology

Rigid Body Contact Surface

07.10.2019- 18 -


> Pin and Slot Walls are modelled as rigid bodies

> Stiffness and Damping assigned to ContactDistributed3D object Constant Damping coefficient Stiffness Table depending on:

> Angular position> Deformation

Contact Pin-SlotMethodology

ContactDistributed3D

Stiff

ness

Forc

e [%]

Cam Angle [deg] Deformation [micron]

07.10.2019- 19 -


> Functionalities: To lock axial position after cam

switch To reduce vibrations

> Composed by: Detent Profile axial movement Sphere vertical movement Spring pushes the sphere

providing locking force

Detent SystemMethodology

07.10.2019- 20 -


> 2D elements have been used for modelling this mechanism: Profile ContactGeom2DArcs Sphere Inertia2D Spring Spring2D

> Spring2D chosen instead of HelicalSpring Simulation time decreased by

factor 3 Negligible impact on results

Detent SystemMethodology

07.10.2019- 21 -


> System requires high precision on axial position for cam-valve contact

> Endstop prevents out of range movements of the slider

> Ground3D element used to model Endstop

> ContactGeom3DPlane describes the contact geometry object of this element

EndstopMethodology

07.10.2019- 22 -


> In the following slides it is displayedhow the model works

> Small cam profile used for engine speed lower than 8500 RPM

> Big cam profile selected and held from 8500 RPM to10000 RPM

Complete model simulationMethodology

RPMx1000

RPMx1000

07.10.2019- 23 -






RPMx1000

RPMx1000

07.10.2019- 24 -






RPMx1000

RPMx1000

07.10.2019- 25 -






RPMx1000

RPMx1000

07.10.2019- 26 -






RPMx1000

RPMx1000

07.10.2019- 27 -






RPMx1000

RPMx1000

07.10.2019- 28 -






RPMx1000

RPMx1000

07.10.2019- 29 -






RPMx1000

RPMx1000

07.10.2019- 30 -






RPMx1000

RPMx1000

07.10.2019- 31 -


> Model validation has been performed comparing results at 8500 RPM

> Simulated axial movement corresponds to performed measurement

> The magnitude and position of the axial contact force peaks match the experimental data

Simulation vs Experimental ResultsCalibration Experimental Data

Simulation Results

Forc

e in A

xial D

irect

ion [N

]Di

splac

emen

t [m

m]

Cam Angle [deg]

07.10.2019- 32 -


> Model validation has been performed comparing results at 8500 RPM

> The bouncing effect on the milled slot tracks is shown below

Simulation vs Experimental ResultsCalibration Experimental Data

Simulation Results

Forc

e in A

xial D

irect

ion [N

]Di

splac

emen

t [m

m]

Cam Angle [deg]

07.10.2019- 33 -


> The track shape has been optimized for design shifting speed of 8500 RPM

> The effect of shifting at other engine speeds has been evaluated

> The most critical appears the speed of 7000 RPM

Important ResultsEvaluation

Force In Axial Direction Slider Axial Acceleration

0 100 %Fraction of Maximum Evaluated Value

07.10.2019- 34 -


> Production and Assembly tolerances have been taken into account

> The chain of tolerances influences the relative position of the pin and the track


0 micron +200 micron-200 micron

07.10.2019- 35 -


> Impact of different relative position between pin and track has been investigated

> Main Effects: First contact point Contact force distribution Contact force magnitude


Force In Axial Direction8500 RPM

Slider Axial Acceleration8500 RPM

0 100 %Fraction of Maximum Evaluated Value

07.10.2019- 36 -


> A New, Fast and Predictive Methodology for the Designand Evaluation of a Variable Valve Actuation System from clean sheet of paper has been developed

> The procedure has been validated against measurementdata of a high-reving engine

> The procedure is able to predict the effect of the main geometrical parameters and operating conditions on the slider behavior and in particular Contact Force Slider Dynamics

> Possibility of Load Optimization represents another benefit of the procedure

> The procedure has been already successfully applied in internal and external projects

Conclusions

07.10.2019- 37 -


Thanks for the attention!

Documents

Methodology for Dynamic Simulation of a Variable Valve...Methodology for Dynamic Simulation of a Variable Valve Actuation System in High Performance SI Engines V. Bevilacqua, A. Eichenberg,