Application of Low Pressure Direct Injection and Semi...

Institute for Internal Combustion Engines & Thermodynamics

G r a z U n i v e r s i t y o f T e c h n o l o g y

Application of Low Pressure Direct Injection and Semi-Direct Injection to a

Small Capacity Two-Stroke Engine

Franz Winkler

Roland Oswald

Oliver Schögl

Roland Kirchberger

Andreas Ebner

2SAE 2008-32-0059

JSAE 20084759

Benchmark4

Engine & vehicle

development

3

Combustion system

development

2

Introduction1

Conclusion5

Structure

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Benchmark4

Engine & vehicle

development

3

Combustion system

development

2

Introduction1

Conclusion5

Introduction

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New European emission legislation EURO III < 50 cm³:

including cold start emission (weighting factor of 30% (50%))

catalyst durability (up to 10000km)

Introduction

Motivation

European emission cycle ECE R 47

0

10

20

30

40

50

60

0 112 224 336 448 560 672 784 896

time [sec]

veh

icle

sp

eed

[km

/h]

.

warm up phase hot phase

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Introduction

The Engine

Basic engine data

Capacity: 50 cm³ 2-stroke engine

Bore: 40 mm

Stroke: 39.2 mm

Compression ratio: 11.68

Power: 3.7 kW

Torque: 5 Nm

…

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Introduction

The Engine

Basic engine data

Port configuration

Loop scavenged

5 transfer ports

Reed valve

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Introduction

The strategyDirect injection mode

Fuel injection duringscavenge process

Homogenization in the cylinder

Figure 1

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Introduction

The strategyDirect injection mode

Fuel injection duringscavenge process

Homogenization in the cylinder

Stratified mode

Fuel injection trough the window of the piston

Figure 2Figure 2

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Introduction

The strategyDirect injection mode

Fuel injection duringscavenge process

Homogenization in the cylinder

Stratified mode

Fuel injection trough the window of the piston

Stratified scavenging troughthe boost port

Homogenization in the cylinder

Figure 2

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Introduction

The strategyDirect injection mode

low HCs

low BSFC

Stratified mode

low BSFC

max. Power @ high rpm

crankcase cooling

stability at idle and part load

lower HCs than carburettor

Figure 3

SPC SPO

EPC EPO

BDC

TDC

stratified

direct injection

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Introduction1

Benchmark4

Engine & vehicle

development

3

Combustion system

development

2

Conclusion5

Combustion system development

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Combustion System Development

Spray Quality and Fuel PressureTwo different spray types

400 kPA two holes 700 kPA three holes

Figure 4

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5000

10000

15000

20000

25000

3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000

engine speed [U/min]

HC

[p

pm

]

carburetted

700 kPa direct injection

400 kPa direct injection

Figure 5

Combustion System Development

Spray Quality and Fuel Pressure

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Combustion System Development

Spray Quality and Fuel Pressure400 kPA injector

visualization 6000 rpm WOT simulation

Figure 6

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Combustion System Development

Spray Quality and Fuel Pressure700 kPA injector

visualization 6000 rpm WOT simulation

Figure 6

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Thermodynamic analysis

Combustion System Development

Figure 7

24.7 26.1 26.0 26.8

2.5

2.6 2.0 3.0 2.1

4.0

4.5 4.8 4.5 4.4

0.9

1.0 0.81.8 2.1

19.1

15.6 14.814.1 14.1

20.8

0.0

10.0

20.0

30.0

40.0

50.0

ext. mix.

preparation

4 bar DI 7 bar DI 4 bar DI (piston

bowl)

7 bar DI (piston

bowl)

eff

icie

nc

y[%

]

losses due to real working gas

scavenge losses

losses due to heat release rate

wall heat losses

charge exchange losses

indicated efficiency

Figure 7

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Combustion System Development

5000

10000

15000

20000

25000

3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000

engine speed [U/min]

HC

[ppm

]

carburetted

direct injection

stratified

Figure 8

Injection strategies

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JSAE 20084759

Benchmark4

Engine & vehicle

development

3

Combustion system

development

2

Introduction1

Conclusion5

Engine & vehicle development

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Engine & vehicle development

Engine development

Design

Cylinder

Cylinder head

Intake system

Exhaust system

…

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Engine & vehicle development

Engine development

Design

Prototyping

Cylinder

Cylinder head

Intake system

Exhaust system

…

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Engine & vehicle development

Engine development

Design

Prototyping

Engine test bench

Performance

Emissions

Durability

…

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Test bench results – Engine test bench

0

1

2

3

4

5

3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000

engine speed [U/min]

po

we

r [k

W],

to

rqu

e [

Nm

]

0

100

200

300

400

500

BS

FC

[g

/kW

h]

Power

Torque

BSFC

Figure 9

Torque, Power and BSFC

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Figure 210

25

50

75

100

3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000

engine speed [rpm]

BS

HC

[g

/kW

h] HC untreated

CO untreated

Figure 10

Untreated HC- & CO-Emissions

Test bench results – Engine test bench

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Test bench results – Engine test bench

Figure 19

Exhaust gas purification

0.00

0.25

0.50

0.75

1.00

1.25

1.50

3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000

engine speed [U/min]

eq

uiv

ale

nce r

atios [

- ]

Equivalence ratio

Equivalence ratio (unburned exhaust gas)

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0

10

20

30

40

50

60

70

80

90

100

3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500

engine speed [U/min]

co

nve

rsio

n r

atio

[%

]

Conversion ratio HC

Conversion ratio CO

Conversion ratio of HC and CO

Test bench results – Engine test bench

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0

25

50

75

100

3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000

engine speed [rpm]

BS

HC

[g/k

Wh] HC untreated

CO untreated

Figure 10

Test bench results – Engine test bench

Figure 190

25

50

75

100

3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000

engine speed [rpm]

BS

HC

[g/k

Wh]

HC untreated

HC after catalyst

CO untreated

CO after catalyst

Figure 10

HC- & CO-Emissions after catalyst

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Engine & vehicle development

Vehicle development

Design

Fuel system

Oil system

Cooling system

…

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Engine & vehicle development

Vehicle development

Design

Prototyping

4 prototype vehicles

2 different speed versions

45 km/h ECE R47 (<50 cm³)

+60 km/h ECE 40 (<150 cm³)

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Engine & vehicle development

Vehicle development

Design

Prototyping

Chassis dyno & on road development

Performance (CVT setting)

Cold start

Warm up strategy (emissions)

Transient calibration

Cold chamber & altitude

…

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Test bench results – Chassis test bench

0

10

20

30

40

50

60

0 112 224 336 448 560 672 784 896

time [sec]

ve

hic

le s

pe

ed

[k

m/h

] .

warm up phase hot phase

Test cycle ECE R47

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0

10

20

30

40

50

60

0 112 224 336 448 560 672 784 896

time [sec]

ve

hic

le s

pe

ed

[k

m/h

], H

C [

pp

m]

x1

0

0

1

2

3

4

5

6

ac

cu

mu

late

d H

C [

g]

target speed transient emissions accumulated emissions

warm up phase hot phase

Figure 12

Test bench results – Chassis test bench

HC-Emissions

Catalyst light-off for HC < 60sec

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0

10

20

30

40

50

60

0 112 224 336 448 560 672 784 896

time [sec]

ve

hic

le s

pe

ed

[k

m/h

], C

O [

pp

m]

x1

0

0

1

2

3

4

5

6

ac

cu

mu

late

d C

O [

g]

warm up phase hot phase

Figure 12

CO-Emissions

Test bench results – Chassis test bench

Catalyst light-off for CO < 30sec

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Test bench results – Chassis test bench

0

10

20

30

40

50

60

0 112 224 336 448 560 672 784 896

time [sec]

veh

icle

sp

eed

[km

/h],

NO

x [

pp

m]

0

0,5

1

1,5

2

2,5

3

accu

mu

late

d N

Ox [

g]

warm up phase hot phase

Figure 12

NOx-Emissions

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1

1.2

CO [g/km] 0.90

HC + NOx [g/km] 1.14

CO 0.44 43.8 CO 0.57 57.0

HC + NOx 0.50 41.3 HC + NOx 0.68 56.7

CO [g/km] 0.24

HC + Nox [g/km] 0.22x

Emission results ECE R 47 (mileage ~1000 km) limits:CO [g/km]:

HC + NOx [g/km]:

0.5

Emissions warm up

Emissions hot

weighting

factor

% of limit % of limit0.5Emissions

[g/km]

+

weighting

factor

Emissions

[g/km]x

+

0.7

x

x

0.3

Test bench results – Chassis test bench

ECE R 47 emission results

Figure 13

Procedure

ECE R47 after 1000 km

Results< 50 % < 60 %

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Test bench results – Chassis test bench

Test cycle ECE 40 <150 cm³

0

10

20

30

40

50

60

0 195 390 585 780 975 1170

time [sec]

ve

hic

le s

pe

ed

[k

m/h

]

EURO II measurment phase EURO II warm up phase (2003)

EURO III measurment phase

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HC-Emissions

Test bench results – Chassis test bench

0

20

40

60

80

0 195 390 585 780 975 1170

time [sec]

veh

icle

sp

eed

[km

/h],

HC

[p

pm

x10]

0

1

2

3

4

acc.

HC

[g

]

acc. HC-Emissions

HC-Emissons

Figure 15

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Test bench results – Chassis test bench

CO-Emissions

0

10

20

30

40

50

60

0 195 390 585 780 975 1170

time [sec]

veh

icle

sp

eed

[km

/h],

CO

[p

pm

x10]

0

1

2

3

4

5

acc.

CO

[g

]

CO-Emissons

acc. CO-Emissions

Figure 15

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Test bench results – Chassis test bench

NOx-Emissions

0

10

20

30

40

50

60

0 195 390 585 780 975 1170

time [sec]

veh

icle

sp

eed

[km

/h],

NO

x [

pp

mx10]

0

1

2

3

4

5

acc.

NO

x [

g]

NOx-Emissons

acc. NOx-Emissions

Figure 15

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Test bench results – Chassis test bench

ECE 40 emission results

Procedure

ECE 40 after 1000 km

Results

CO [g/km]: 2

HC [g/km]: 0.8

NOx [g/km]: 0.15

CO

HC

NOx

limits:

Emission results ECE 40 urban cycle

(mileage ~ 1000 km)

Emissions

warm up + hot phase

% of the Limit

15.46

77.06

69.55

0.31

0.62

0.10

Emissions [g/km]

Figure 14

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Benchmark4

Engine & vehicle

development

3

Combustion system

development

2

Introduction1

Conclusion5

Benchmark

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JSAE 20084759

Benchmark

Figure 28

Benchmark

Procedure

Comparison of 3 different low emission concepts

ECE R47

Technologies

50 cm³ four-stroke, efi, 3-way-catalyst

50 cm³ two-stroke, air-assisted direct injection, oxidation catalyst

50 cm³ two-stroke, low-pressure direct injection, oxidation catalyst

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Benchmark

Figure 28

ASDI

LPDI

4T

=1

ASDI

LPDI

4T

=1

0,0

0,2

0,4

0,6

0,8

1,0

0,0 0,2 0,4 0,6 0,8 1,0 1,2

HC+ NOx [g/km]

CO

[g/k

m]

Euro II (since 2003) without coldstart

Euro III (from 20XX) including coldstart

Euro IV ?

Euro II - EURO III Benchmark

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Analysis of the 2-stroke

scavenge process

3

Assessment of mixture

preparation systems

2

Introduction1

CFD-Simulation of spray

and mixture preparation

4

Conclusion5

Conclusion

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Conclusion

It was demonstrated that with the introduced injection strategy the reduction of untreated HC emissions is ~ 40%

The reduction of scavenge losses lead to a ~ 25% lower fuel consumption

Very lean exhaust gas due to the stratification of the scavenge process increase the conversion ratio of HC and CO

The increased exhaust gas temperature shortens the cat light-off time leading to reduced cold start emissions

There is no need for specific technology development (standard two-stroke engine with standard injection components) therefore the development risk is comparatively low

Focusing costs and market acceptance, this strategy is a valuable alternative to existing DI-systems

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Thank you foryour attention