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Design and Development of the Valve Train for a Racing Motorcycle Engine

Design and Development of the Valve Train for a Racing Motorcycle Engine

World SuperBike simulation and optimisation of gas dynamics

Ken Pendlebury – Ricardo UK

© Ricardo plc 2007 © Ricardo plc 2007 Contents q q q q q Conclusions breathing development Valvetrain development Introduction RD03/######## 2 © Ricardo plc 2007 Introduction q q q Areas offocusforthispresentation driveability Main enginedevelopmenttargetwastomaximisepowerwhilst main Wo – – – – – – – – Crankcase Crankshaft Valvetrain Ex Target of16000rpmwasidentified toachievetargetperformance • Baseline enginehadspeedlimitof14000rpm not behomologated Rule changesmeantthat900ccI3mustrace1000ccI4since anew Initial enginewasdesignedwhenrulesallowed900ccI3to compe rld Limited byvalvetraindynamics tensive useofanalyticaltechniques tominimisetesting Superbike championship tain good te with750ccI4 engine could RD03/######## 3 © Ricardo plc 2007 Valvetrain designobjectives q q q q By useofrigtechniquesdetermine limitsandmodeofvalvetrain Minimise valvetrainfrictionwithinconstraintsofthehomologat instantaneous failureofanyvalvetraincomponent Allow accidentalover 16000rpm Maintain vavletrain control andairflowatnewratedenginespeedof - speed to17000rpmwithoutpiston - valve contactor ed design failures RD03/######## 4 © Ricardo plc 2007 kinematic analysis Initial designanalysisfocusedoncamprofile using q q q Changes madetoenablehighspeedoperation Focused mainlyonintakevalvetrain Kinematics moduleofRicardoVALDYNused – – periodincreasedby2.8deg Peak intakeliftreducedby1mm ratio Closing sideacceleration ratio Opening sideacceleration closing flank(m/s Valve accelerationon nose (m/s Valve accelerationoncam opening flank(m/s Valve accelerationon Ramp velocity(m/s) Ramp hei Period Li L/D Inner seatdiameterD(mm) (mm) Peak kinematicvalveliftL Parameter ft areaintegral – top oframp(de ght (mm) 2 ) 2 ) 2 ) g) 14000 rpm 14000 rpm 14000 rpm 14000 rpm 36962 @ 11530 @ 29818 @ Baseline 0.432 @ 307.2 0.555 0.343 3.21 2.51 0.20 35.0 12.0 RD03/######## 16000 rpm 16000 rpm 16000 rpm 16000 rpm 41554 @ 13305 @ 33404 @ 0.500 @ 310.0 0.557 0.314 Final 3.12 2.51 0.20 35.0 11.0 5 © Ricardo plc 2007 This thenmovedtothecam/tappetinterface(kinematic analysis) q q q q q q edgeclearanceincreased Film thicknessattransitionimproved Film thicknessatnosereducedslightly Low speedcontactstressreduced High speedcontactstressincreased Kinematics moduleofRicardoVALDYNused clearance (mm) Mi speed le at whichoi consecutive crankdegrees Maxi number atpeaklift Deschl peak camlift( Lubricant filmthicknessat (N/mm stress atratedspeed Peak camtappetcontact stress atidle(N/mm Peak camtappetcontact Param ss than0.1 ni mum tappetedge mu eter 2 er andWittman ) m numberof l film µ µ m atrated m) thickness is

2 ) 14000 rpm 3500 rpm Baseline 400 @ 831 @ 0.207 0.295 0. 8. 30 26 RD03/######## 16000 rpm 3500 rpm 436 @ 764 @ 0.272 0.278 Final 1. 7. 90 86 6 © Ricardo plc 2007 VA Following thisafullvalvetraindynamicsmodelwas builtusing LDYN bending contact andvalve head represent Combined stiffnessto of mass between tipandcentre Stiffness ofvalvestem (dependent oneccentricity) /tappet stiffness and supportstiffness bendingstiffness local massofcamshaft Node representingeffective - - - - Valve springmodels Node representingtappetmass with 2levelsfor eachrun uncertainty so modelled Spring interferencedamping Coil clashingmodel Connected bystiffness 8 massespercoil RD03/######## 7 © Ricardo plc 2007 Design Analysis q q q assumption Results notdependent onspringdamping Final design Baseline design – – – – – – – No failures Below 4m/sevenat17000rpm Loss ofcontrolfrom~16000rpm Failures ofvalvestemobserved Large valvebounceevidentat15000rpm rpm Sharp transitiontohighvelocityat~14800 Loss ofcontrolfrom~14000rpm – Valve seating RD03/######## 8 © Ricardo plc 2007 Design Analysis q q q Note: assumption interference damping Results sensitivetospring Final design Baseline design – – – separation at17000rpm Less than0.2mmpeak with highdamping separation from~16000rpm Progressive increasein rpm Sudden transitionat~14600 – Valve jump RD03/######## 9 © Ricardo plc 2007 Design Analysis q q q interference dampingassumption Results moderatelysensitive to spring Final design Baseline design – – – range Significant reductioninsurge across speed engines +/ High surgeamplitudeonbothsprings - 1mm normaltargetforpassengercar – Spring surge(1) RD03/######## 10 © Ricardo plc 2007 Design Analysis q valve closing between springandseatathighspeedjustafter On baselinedesignsurgeledtolossofcontact – – Some failuresofspringendtangsresulted • High forcewhencontactre Spring seathammering – Spring surge(2) - established RD03/######## 11 © Ricardo plc 2007 Design Analysis q q Final design Baseline design – – – level asbaselinedesign Dynamic stresseswerecontrolled tosimilar improved increased butthespringstrength wasalso Pseudo speed increases asvalvetrainlosescontrolathigh Stress atworstcaselocationinspring - static springstresslevelswere – Spring stress RD03/######## 12 © Ricardo plc 2007 Design Analysis q VALDYN modelwasextendedandusedtocalculate – – Dynamic loadsatgearsandfastenersforsubsequentanalysis Effect oftimingdriveoncompletevalvetrainmotion – Whole enginemodel RD03/######## 13 © Ricardo plc 2007 Example Valvetrainfailuremode,TappetBore q q q q q q Small changeinfilletradiusgave desiredimprovement FEARCE usedtocalculatesafetyfactors Reaction forcescalculatedandappliedtolocalFEmodel VALDYN analysisusedtocalculatemomentontappet Cracks incylinderheadatmachinedslotforcamclearance Several failuresofcylinderheadstructureattappetbore – Low safetyfactorsconfirmedandalternativedesignsaddressed RD03/######## 14 © Ricardo plc 2007 Valvetrain analysisconclusions q q q invaluable The contributionofworldclass componentsupplierstothesucce Success wasachievedby The finalintakevalvetrain – – – – – Combined withminimalrigtesting Making extensiveuseofdynamic simulation Wa Had exceptionaldurabilitywithrevlimitersetto16000rpm Had effectivemassreducedby15.3g(18%) s abletosurviveover - speed eventsatupto17000rpmwithoutfailure ss oftheprojectwas RD03/######## 15 © Ricardo plc 2007 Crankshaft designobjectives q q Crankshaft designoverview Main objectives – – – – – – – – – – – – – – Big end bearings supplied frommain bearings via drillings Full circumferential grooves inmainbearings Polished bearing journalsurfaces Gas Double vacuum re Integral drivegear Fully machinedcrank Maintain acceptableenginebalance Maintain adequatebearingdurability Maintain adequatecrankshaftstrength Reduce windage Reduce friction Reduce rotatinginertia Reduce crankshaftmass - nitrided to 800Hvdepth of0.3mm - melted steel31CrMoV9 RD03/######## 16 © Ricardo plc 2007 Summary ofcrankshaftdesigniterations q q q q discussed here) corresponding increaseinvibration (not Final designwasnotbalanced witha lightened duringtheproject andconnectingrodwere also through thebalancershaft web 5toavoidtransmittingpower The drivegearwasmovedfromweb3to crankshaft Pictures showthedesignevolutionof Final design Baseline design Intermediate design RD03/######## 17 © Ricardo plc 2007 Initial focuswasreducingmassandrotatinginertia q q q q q q q increase incrankshaft twistforfinaldesign ENGDYN 3Dcrankshaft dynamicsanalysisshows significant 35% inertiareduction 30% massreduction Use heavymetalinsertsincounterweights Drill throughthecrankpin Reduce themassof‘upper’portioncrankshaft longer fullybalanced(seelatersection) Smaller counterweightsusedforfinaldesignasenginewasno – – Final naturalfrequency of971Hz Baseline cranknatural frequencyof1317Hz 4.5 orderpeak RD03/######## 18 © Ricardo plc 2007 Stress analysis q q q crank pinfilletonwebNo.1 Baseline resultsindicatethatlowest safetyfactoroccurredat ENGDYN usedto Finite elementanalysiswasperformedonthebaselineandfinal – – – – – – Radius significantlyincreasedby use ofpistonguidedrod Calculate Goodmansafetyfactorsatfilletsandoilholes engine speed Calculate combinedstressesat5degreeintervalsforeach Solve equationsofmotion Combine FEmodels Calculate boundaryconditions RD03/######## 19 © Ricardo plc 2007 In parallel,analysisofthemainbearingswascarried out q ENGDYN bearinganalysisshows – – – 14000 rpm Slight increaseinhydrodynamic powerlossat at highspeed Slight reductioninminimumoilfilmthickness speed (peaktorque) Reduced peakspecificloadatworstcase RD03/######## 20 © Ricardo plc 2007 Crankshaft analysisconclusions q q q Riders preferredlowinertiaoffinal designandwerepreparedt The finalcrankshaftdesign whilst stillmaintainingacceptablelevelsofbalance,torsional Use ofadvancedanalysiswasabletosignificantlyreducethema – – Had partiallybalancedprimaryreciprocatingmoment • • increase intwistduetotorsionalvibration Had exceptionaldurabilityevenwhenrevlimiterwassetto1600 35% inertiareduction 30% massreduction vibration anddurability o tolerateincreasedvibration ss andinertiaofthecrankshaft 0 rpmdespiteconsiderable RD03/######## 21 © Ricardo plc 2007 Crankcase issuesandapproach q q q q from relatively simple 1D flow analysis Prediction of pumping losses canbe obtained began in2005 Conversion fromawettodrysump system Wi Pumping ofcrankcasegasincursapowerloss – – – – – – – ndage loss • • Analysis required to • • Targeted benefits crankcase fluid Interaction ofenginecomponentswith Losses canbesignificant • • Other minorlosses Gas exchangethroughexternalbreathers Gas exchangebetweenbays Limit amount oftesting Increase knowledge andunderstanding distribution Increased scopeforrevisedmass Reduction inCPMEP Heat transfertocrankcasewalls crankcase volumes Gas exchangebetweencylinderand

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mp ing 22 © Ricardo plc 2007 An q q q q q q q aly Ex Scavenge points basesattachedtovariable under Program inputdata Automatically meshedinto1Dnetworkcomponents Complex geometriesconstructedusingW 1D time – – – – – – – – tical approachusingWA ternal breather Connected to ambient conditions Connected togear pumpwithimposedconstant velocity representing blow Connected tocylinderpressure viaaductandorifice Wa Scavenge flowrate Cylinder pressure ,,,rodlength,firingorder Engine internalcomponentvolumes ll temperatures - dependant fluiddynamics - by path VE - AVEBuild3D piston volume RD03/######## 23 © Ricardo plc 2007 Model validation q q Mean crankcasepressure Blow – – – – dimensions adjusted toachieveagoodfit Scavenge velocities andleakageorifice engine Variation inmeasureddataon drysump • • Blow • behavior ofpistonandrings Blow Copied todrysumpmodel data Adjusted toachieveareasonablefit showed considerablevariation Measurements onwetsumpengines - by flow - - by orificegeometry by affecteddrivingpressureand

PRES (bar) BLOW-BY (l/min) 10 20 30 40 50 60 70 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 6000 0 6000 wet_b1_1 Engine 519 Engine 511 Engine 513 8000 8000 10000 10000 ENGINE SPEED(rpm) ENGINE SPEED (rpm) 12000 12000 14000 14000 RD03/######## Measured Bay3 dry_b1: Bay3 dry_b1: Bay2 Measured Bay1 dry_b1: Bay1 16000 16000 18000 18000 24 © Ricardo plc 2007 FP1 Engine

POWER (kW) 0 1 2 3 4 5 6 7 Power lossat16000rpm 2. – 243 Results (1) 0. 152 0. 155 0. removed Leakage 076 path 4. 825 4. 837 5. 852 RD03/######## 25 © Ricardo plc 2007 FP1 Engine We t – Results (2)

CPMEP (bar) -0.50 -0.45 -0.40 -0.35 -0.30 -0.25 -0.20 -0.15 -0.10 -0.05 0.00 6000 8000 through balancershaft Single externalbreatherexit 10000 4 scavengepoints Inter - 12000 bay breathingholes ENGINE SPEED(rpm) removed 14000 16000 centre 0.38 18000 bar 20000 kW 4.7 22000 -5.0 -4.5 -4.0 -3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0

POWER (kW) Sump RD03/######## Dry 26 © Ricardo plc 2007 Crankcase analysisconclusions q q q Parametric studiesshoweddominant parameterseffectingCPMEP ~ 4 sump system Analysis showedapotential4.7kW – – - 5kW Breather size&dischargecoefficient total benefit realised in practice reduction incrankcasepumping – – Scavenge flowrate Crankcase compressionratio loss withadry RD03/######## 27 © Ricardo plc 2007 Conclusions q q q q q were prepared totolerate increasedvibration Riders preferred lowinertia offinaldesign and The finalcrankshaftdesign 2006 valvetrain failuresrecordedinraceconditions over Valvetrain reliabilityhasbeenimprovedwith cycles from around600,000cyclesto>1,000,000 Valvetrain lifehasbeenimprovedconsiderably programme 30ps overthetwoyearsofdevelopment im 14000rpm to16000rpmwhichalongwiththe Maximum enginespeedwasincreasedfrom – – proved parasiticlossesreleasedanadditional mo Had partiallybalanced primaryreciprocating • • torsional considerable increaseintwistdue to limiter wassetto16000rpmdespite Had exceptionaldurabilityevenwhen rev - speed capabilityto17000rpmandno 35% inertiareduction 30% massreduction ment vibration 6000 7000 2006 Performanc 2004 Bas 8000 line Performanc 9000 e 10000 Speed 11000 e 12000 13000 14000 RD03/######## 15000 16000 28

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