Investigation of Potential Fuel Economy Improvements of a ... · IMOP 108.5°ATDCNF EMOP 110.5°BTDCNF Variable Cam Phasing Fixed Inlet / Fuel Fixed Inlet / MPI Part Load – Test

Investigation of Potential Fuel Economy Improvements of a SOHC Engine via Independent Inlet and Exhaust Cam Timing Controlg

2008 GT-SUITE Conference

Mike Bassett, Steve Simmonds, David Gurney,

Rob Lynn Hugh BlaxillRob Lynn, Hugh Blaxill

MAHLE Powertrain, UK

Falk Schneider

© MAHLE

MAHLE Valvetrain, Germany

ContentContent

IntroductionMAHLE CamInCam® System OverviewMAHLE CamInCam® System OverviewBaseline Engine Testing Engine Simulation– Baseline Model Correlation

– CamInCam® WOT Performance Optimisation

– CamInCam® Part Load Fuel Consumption Optimisation

Cam Timing Selection and Cam Phaser ConsiderationsCamInCam ® Engine Testing– Comparison with Engine Modelling ResultsComparison with Engine Modelling Results

Vehicle PerformanceConclusions

2MAHLE Powertrain Ltd., 14-October-2008 © MAHLE

IntroductionIntroduction

Fuel economy legislation for new vehicle fleets demands high engine efficiencyVariable Valve Timing (VVT) allows simultaneous improvementsVariable Valve Timing (VVT) allows simultaneous improvements– Wide Open Throttle (WOT)

– Part Load Fuel Economy and Emissions

Combustion stability– Combustion stabilityTraditionally VVT is achieved with camshaft phasers– Independent phasing of inlet and exhaust valves readily achieved for double overhead

camshaft (DOHC) enginescamshaft (DOHC) engines

– 2-valve per cylinder single overhead camshaft (SOHC) or overhead valve (OHV) engines

Advantages of cost and packaging

Single camshaft engine limited to dual equal phasing onlySingle camshaft engine limited to dual equal phasing onlyNew mechanical device – CamInCam®

– Allows inlet only, exhaust only or dual independent VVT on a single cam engine

Thi k d ib th li ti f th d i t E SOHC i


– This work describes the application of the device to a European SOHC engine

MAHLE CamInCam® SystemMAHLE CamInCam System

Exhaust Lobes permanently fixed to Exhaust Cam Lobes

Slots for Inlet Pinsp y

outer tube (1)Inlet lobes fixed to concentric inner shaft (2) with pins (3)

2

1Exhaust Cam Lobes

22

CamshaftBearing

Slotted T be3Inlet Cam Lobes

Slotted Tube

MoveableCam Lobe

Once assembled Inlet lobes have sliding fit over outer shaft

Fixed Cam Lobe


Manufacture similar to conventional assembled camshafts

Fixed Cam LobeInner Shaft Pin

Baseline TestingBaseline Testing

European production engineIndicating measurements Test Engine DetailsIndicating measurements – Water cooled cylinder pressure

sensors (Kistler 6041type)

– High speed inlet / exhaust pressures

Capacity / Layout 1.2L / 4 cyls InlineValvetrain 8v, SOHC, Direct actingCompression Ratio 9.8:1

224° (Top of Ramps)g p pWide Open Throttle (WOT) testing– manual AFR & ignition timing

optimisation

In / Exh Cam Profile 8mm peak lift

Valve TimingIMOP 108.5°ATDCNFEMOP 110.5°BTDCNF

Variable Cam Phasing FixedInlet / Fuel Fixed Inlet / MPI

Part Load– Test Points selected from vehicle drive

cycle

Inlet / Fuel Fixed Inlet, / MPIExhaust Manifold 4 into 2 into 1External EGR No

– Warm and Cold idle tested for stability Charge Dilution Tolerance– Inlet air sampled for CO2 dilution in the inlet runners


Part Load Test Point SelectionPart Load Test Point Selection

Part Load Test Points

Test Point Speed BMEP( ) (kP )

100

(rpm) (kPa)3rd hill 2500 150100km/h Cruise 3000 500WW Map point 1500 262

60

80

ure

[kP

a]

120km/h

p pWW Map point 2000 200

40

60

Man

ifold

Pre

ssu

3rd HillIdle

70km/h100km/h

0

20

M

1st Hill2nd Hill

Idle

50km/h


0 1000 2000 3000 4000

Engine Speed [rev/min]

Residual Gas Fraction Dilution ToleranceResidual Gas Fraction Dilution Tolerance

Tolerance to Residual Gas Fraction (RGF) has large influence on fuel consumptionFor engine simulation, combustion stability assumed proportional to RGFFor engine simulation, combustion stability assumed proportional to RGF– Ignores effects of charge motion and effective compression ratio

– Good correlation reported by othersBaseline engine only available with fixed cam timingBaseline engine only available with fixed cam timing– Effect of RGF was replicated by addition of CO2 into inlet system

– Inlet air sampled in inlet runner for dilution measurementMaximum CO tolerance was defined for 0 15bar SDIMEPMaximum CO2 tolerance was defined for 0.15bar SDIMEP– Internal RGF calculated with engine simulation

– Gives an estimate for acceptable total RGF limit

Speed Load CalculatedRGF

Measuredmaximum CO2

Maximumtrapped residuals

(rev/min) (kPa) (%) (%) (%)3000 500 6.9 12.0 18.02500 150 12 3 7 0 18 4


2500 150 12.3 7.0 18.42000 200 11.7 8.5 19.21500 262 11.5 13.0 23.0

Baseline GT-Power Model Correlation at WOTBaseline GT Power Model Correlation at WOT( ) ( ) ( )

100

110

8

90

bar]

60

rque

[N

m]

80

90

100

effic

ienc

y [%

]

75

80

85

der p

ress

ure

[

45

50

55

Bra

ke to

60

70

MeasuredGT-Power model

Vol

umet

ric

65

70

axim

um c

ylin

d

35

40

Wiebe comb stion model sed ith meas red phasing (50% MFB) and d ration (10

50

Engine speed [rev/min]1000 2000 3000 4000 5000 6000

GT-Power model

60


M

30


Wiebe combustion model used with measured phasing (50% MFB) and duration (10-90% MFB) data – Maximum cylinder pressure indicates combustion is well modeledTorque correlation within 3%


Torque correlation within 3%Volumetric Efficiency within 4%

Baseline Model Correlation - WOTBaseline Model Correlation WOT

Pressure wave activity in the inlet runner well modeled

1.10Inlet Runner Pressure - 2500rpm

re [b

ar]

1.00

1.05

Pres

su

0.90

0.95

MeasuredGT P d l

0.85

Crank angle [°CA]0 90 180 270 360 450 540 630 720

GT-Power model

TDC firing


Part Load CorrelationPart Load Correlation

0.55

0.60

[bar

]

35

40

475

500 MeasuredGT-Power model

ic e

ffici

ency

0.40

0.45

0.50

der p

ress

ure

[

25

30

35

[g/k

Wh]

400

425

450 GT-Power model

Vol

umet

r

0.25

0.30

0.35M

axim

um c

ylin

d

15

20 BS

FC

300

325

350

375


0.20


M

10


275

300


4 part load test points investigated for fuel consumption optimisationBrake Specific Fuel Consumption (BSFC)


Test Point Speed BMEP(rpm) (kPa)

3rd hill 2500 150100km/h Cruise 3000 500


p p ( )correlation within 1%

100km/h Cruise 3000 500WW Map point 1500 262WW Map point 2000 200

Model WOT Performance OptimisationModel WOT Performance Optimisation

Torque contours for valve-timing variation using standard camshaft profiles

T [N ]1500 rev/min - standard cam profiles

-80

-70

-60

95956565105105

100105110

Torque [Nm]

[°C

A]

-100

-90

808080

8585

100100 7070 80859095

EM

OP

-130

-120

-110

7575

9090

65655560657075

Locust of standard cam phasing Standard timing Dual equal phasing optimum Dual indepedndent phasing optimum

-160

-150

-140 60605555

40455055



IMOP [°CA]50 60 70 80 90 100 110 120 130 140 150

1500 rev/min




-80

-70

-60

9595100105110

Torque [Nm]

[°C

A]

-100

-90

80

8080

9090

7070100100

80859095

EM

OP

-130

-120

-110

7575

85857070

5560657075

-160

-150

-140 65656060

40455055



2000 rev/min IMOP [°CA]50 60 70 80 90 100 110 120 130 140 150




-80

-70

-60

9090 7070100105110

Torque [Nm]

[°C

A]

-100

-90

80

7575

85859595

80859095

EM

OP

-130

-120

-110

9090

6565

100100

5560657075

-160

-150

-1408080

7070

6565

6060

40455055



2500 rev/min IMOP [°CA]50 60 70 80 90 100 110 120 130 140 150




-80

-70

-60

75758585 100

105110

Torque [Nm]

[°C

A]

-100

-90

808080

8585

9090 9595

80859095

EM

OP

-130

-120

-110

8585

9090

100100

5560657075

-160

-150

-140

656570707575

40455055



3000 rev/min IMOP [°CA]50 60 70 80 90 100 110 120 130 140 150




-80

-70

-60

6565 9090 100105110

Torque [Nm]

[°C

A]

-100

-90

80 7070

8080

85859090

80859095

EM

OP

-130

-120

-110

7070

75758585

9595

5560657075

-160

-150

-140

5050 55556060 6565

7575

40455055



4000 rev/min IMOP [°CA]50 60 70 80 90 100 110 120 130 140 150




-80

-70

-60

50505555

7575 100105110

Torque [Nm]

[°C

A]

-100

-90

80

858580859095

EM

OP

-130

-120

-1105555 6060

6565

7070

8080

5560657075

-160

-150

-1404040

45455050

40455055



5000 rev/min IMOP [°CA]50 60 70 80 90 100 110 120 130 140 150




-80

-70

-60

6060100105110

Torque [Nm]

[°C

A]

-100

-90

804040

5050

555580859095

EM

OP

-130

-120

-110

4545

5555 6565

5560657075

-160

-150

-140

40455055



6000 rev/min IMOP [°CA]50 60 70 80 90 100 110 120 130 140 150


Valve event durations and timings optimised for several VVT strategies– Increased inlet and exhaust durations selected– Increased inlet and exhaust durations selected

– ‘Dual equal’ – single camshaft with single phaser

– ‘Dual Independent’ - independent inlet and exhaust valve timing with CamInCam® device

N d ti f t t dNo reduction of torque at any speedValve timing range limited to allow part load optimisation with 60° phaser

m] 14

rove

men

t [N

68

1012 Dual independent

Dual independet - limited timing range Dual equal

Torq

ue im

pr

0246


0

Engine speed [rev/min]1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

Part Load Fuel Consumption OptimisationPart Load Fuel Consumption Optimisation

Carried out using GT PowerCamshaft profiles retained from WOT optimisationCamshaft profiles retained from WOT optimisationFixed Combustion assumed– Does not predict worsening of combustion due to RGF

– Fuel consumption likely to be slightly higher than predicted here

Combustion stability limit estimated from CO2 dilution resultsCam timing map generated at each operating point


Fuel Consumption Optimisation – 2000rpm 2bar

Fixed timing baseline Inlet only phasing

Exhaust only phasing

Fuel Consumption Optimisation 2000rpm 2bar

Cam timing map generated at each operating point

70345345

5050

Exhaust only phasing Dual equal phasing Dual independent phasing

Locus of dual equal cam phasing Dual independent timing window

BSFC [g/kWh]

p g pBSFC contoursRGF contours, with maximum limit

F]

50

60

345345

355355

365365

370370

360360350350

35353030

40404545

[g ] RGF [%] RGF limit

EVC

[°AT

DC

N

30

40

395395

385385 375375

390390

380380

20201919

16161414

2525

BSFCReductionin BSFC IVO EVC

(g/kWh) (%)Standard baseline 392 7 2 5

10

20

405405 385385

4004001212

1111

Standard baseline 392.7 - 2 5Inlet only 380.9 3 33 5Exhaust only 381.3 2.9 2 43Dual independent 362.2 7.8 33 43

0

IVO [°ATDCNF]-40 -30 -20 -10 0 10 20 30 40 50


Pumping MEP and Manifold PressurePumping MEP and Manifold Pressure

BSFC shows strong dependence on PMEP (area B)Inlet Manifold Pressure (MAP) does not explain PMEP minima at IVC of ~25 to 35°Inlet Manifold Pressure (MAP) does not explain PMEP minima at IVC of ~25 to 35°For retarded IVO timing, cylinder pressure much lower than MAP, increasing PMEP

2626 Fi d ti i b li70

345345

355355

365365

370370

360360350350

2222

24242626

26262828

3232

3636

3030

Fixed timing baseline Inlet only phasing Exhaust only phasing Dual equal phasing Dual independent phasing


BSFC [g/kWh] PMEP [kPa]

F]

50

60350350

360360

370370

365365

355355

3453457575

757570707070

6565

6060

5555

5050

BSFC [g/kWh] MAP [kPa]

395395

385385 375375

400400

390390

380380

34343838

4242

4040

EVC

[°AT

DC

N

20

30

40

380380

390390

400400

375375385385

395395

5050

4545

-40 -30 -20 -10 0 10 20 30 40 50

405405 385385

3636 38384040

0

10

20

-40 -30 -20 -10 0 10 20 30 40 50

385385405405 4040


IVO [°ATDCNF]40 30 20 10 0 10 20 30 40 50

IVO [°ATDCNF]40 30 20 10 0 10 20 30 40 50

BSFC Sensitivity to Combustion - 2000rpm 2barBSFC Sensitivity to Combustion 2000rpm 2bar

Presented BSFC cam timing maps have assumed constant combustionExpected that in reality the burn duration will increase with increasing RGFExpected that in reality the burn duration will increase with increasing RGFBSFC shown above against combustion duration and timing shown– Anticipated operating point degrades BSFC by around 1.3%

– Predicted BSFC improvement reduces to 6.5% at 2000rpm, 2 bar

nt

BSFC [g/kWh] Minimum BSFC with varying burn duation [%]

Default combustion data

% b

urne

d po

in

15

20

360 365

380

Default combustion data Anticipated operating point

atio

n of

50

%

0

5

10 360 365370

395390385380

375


Loca 0

10 to 90 % Mass fraction burned duration20 25 30 35 40 45 50

395

Cam Timing Selection and Phaser ConsiderationsCam Timing Selection and Phaser Considerations

Cam timing map shows optimum WOT and part load requirements

60q

Cam envelopes overlaid– Dual layer 60° phasers

– Front and Rear 60° phasers 30

40

50

TDC

NF)

Front and Rear 60 phasers

Over 100° phasing angle required for inlet cam between part load and low speed WOT– Phaser not yet available

10

20

EV

C (°

AT

WOTP/LPhaser not yet available

– Likely to be transient response issue for vehicle performance and feel

Default Timing

-10

0

-70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60IVO (°ATDCNF)

/Zero Overlap at TDCDual Layer Phaser LimtFront & Rear Phasers Limit

– Parked position when phaser control not possible or for phaser failure

– Must allow adequate combustion stability at idle


– 0° overlap can be achieved in this example using CamInCam end stop

CamInCam® Engine TestingCamInCam Engine Testing

Fitted with manually configured C I C

Peak torque increased by 7%Peak power increased by 16% Cam-In-CamPeak power increased by 16%Peak power speed increased by 1000rpm– Extends useful speed range of engine

– Can increase top gear ratio to give same top speed with better highway economy

Maximum Torque +7%

P 16%Power +16%

Average Torque (1500-6000rpm) +8%

Max Power Speed +1000rpm


CamInCam Part Load Test Results – 2000rpmCamInCam Part Load Test Results 2000rpm

Standard Deviation of NIMEP [Bar]

BSFC [g/kWh] Fixed timing baseline Inlet only phasing Exhaust only phasing

Dual equal phasing

DN

F]

40

45

502000rpm 2Bar

370400400

395395 390407 376

1500 2 62B

70345345

350350

5050

Dual equal phasing Dual independent phasing


BSFC [g/kWh] RGF [%]

(TO

R) [

°ATD

25

30

35

40

0.125

150

0.080

375

380

38038

538

5

379 375

367 364

CN

F]

40

50

60 355355

365365

370370

360360350350

3535

2525

3030

40404545

[ ] RGF limit

Valv

e C

lose

10

15

20

25

3

0.150

0.100

0.060

0.040

5

380 377

379 375LowestBSFC

EVC

[°AT

DC

20

30

40

395395

385385 375375

400400

390390

380380

20201919

16161414

1212

Exha

sut V

5

0

5

10 0.0400.0385

392

IncreasingOverlap

RetardingOverlap

0

10

20

405405 385385

12121111


-53000rpm 5BarIVO [°ATDCNF]

-40 -30 -20 -10 0 10 20 30 40 50

p ( ) [ ] p ( ) [ ]

Inlet Valve Open (TOR) [°ATDNF]-25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40

Vehicle SimulationVehicle Simulation

Data from the WOT and part load optimisations combined into a simple vehicle modelUse of variable valve timing over the fixed timing baseline gives:Use of variable valve timing over the fixed timing baseline gives:– 0-62 mph reduced by 1sec

– Vmax increased by 3mph

% f C– 4.7% fuel consumption reduction over the combine NEDC

D t 0 62 h 0 1000 V U b E t b C bi dData source 0-62 mph 0-1000m Vmax Urban Extra-urban Combined(s) (s) (mph) (mpg) (mpg) (mpg)

Published 14 36 96 39.8 58.9 50.4Baseline model 14.2 35.9 95.8 40.8 58.5 50.4Baseline model 14.2 35.9 95.8 40.8 58.5 50.4CamInCam model 13.3 34.9 99.2 43.2 60.9 52.9


ConclusionsConclusions

A correlated simulation model has been used to select cam profiles and estimate improvements to a SOHC engine made possible by VVT with a CamInCam® systemp g p y y– Peak power increase – up to 7%

– Part load fuel consumption reduction – up to 8%Engine tested with CamInCam® hardware fittedEngine tested with CamInCam hardware fitted– Peak power increase – 16%

– Peak power speed increased by 1000 rev/min

Part load fuel consumption reduction up to 8%– Part load fuel consumption reduction – up to 8%Good agreement between calculated and measured benefits of CamInCam® systemNEDC combined fuel consumption reduction estimated - up to 4.7% with improved acceleration and Vmax performanceacceleration and Vmax performance


Documents

Investigation of Potential Fuel Economy Improvements of a ... · IMOP 108.5°ATDCNF EMOP 110.5°BTDCNF Variable Cam Phasing Fixed Inlet / Fuel Fixed Inlet / MPI Part Load – Test