APSC

Bringing the Low NOx DieselUnder Control

John Pinson August 22, 2006

DEER Conference, Detroit

Dispersion management is the greatest challenge facing the low-NOx diesel

• Dispersion management is critical at the lowest standards

• Sub-bin 5 emissions may require active dispersion management -even with effective aftertreatment

Euro 3 (2000)

Euro 4 (2005)

Euro 5 (2008)

Tier 2, Bin 10 (2007-2010)

T2 Bin 5 10-14k HD Chassis

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

Part

icul

ate

Mat

ter (

g/m

i)

T2 Bin 8 / 8.5-10k HD Chassis

Emission Dispersion

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 NOx (g/mi)

Slide 2 Low-NOx Combustion Conventional

Roadmap to Low-NOx Combustion Premixed Charge Compression Ignition (PCCI)

Cyl

inde

r Pre

ssur

e

• Reduce charge temperature with cooled EGR and reduced compression ratio

• Enhance premixing through injection strategy

-40 -20 0 20 40 60 80 � Early PCCI for light loads

� Late PCCI for heavier loads

Issue • Minimum achievable NOx levels are

-40 -20 0 20 40 60 80 limited by the combustion quality and

Hea

t Rel

ease

Conventional Late PCCI

EarlyPCCI

robustness

Inje

ctio

n P

ulse

-40 -20 0 20 40 60 80

Crank AngleExtreme cases for illustration Slide 3

BM

EP (B

ar)

Combustion Mode Map over FTP for Chassis Certification HD Truck (8500 lb)

10

9

8

7

6 Late Conventional

5 PCCI Reduced fuel4 economy and3 instability prone 2

1 Early Noise and

0 PCCI instability proneat higher loads-1

-2 600 800 1000 1200 1400 1600 1800 2000 2200 2400

Engine Speed (rpm)

Slide 4

Combustion Feedback Control – The Promise

• Aggressive low-NOx calibration • Extended PCCI calibrations • Compensate for ageing and

variation • Early & accurate problem

detection

Combustion Feedback Control

Feedback

+++

+++

+++Sensors +++

SetPoints

++

−−

Engine Speed

Torq

ue

Conventional Diesel

PCCI

Expanded PCCI

Engine Speed

Torq

ue

ConventionalDiesel

PCCI

ExpandedPCCI

Extend PCCI Calibration

HC, CO, Soot

NOx

Extend Aggressive low-NOx Cals

partial burn

mis-fire

0 10 20 30 40 50

Load

Det

ectio

n

Engine Cycle Number

OBD

T2 Bin 8 / 8.5T2 Bin 8 / 8.5--10k HD Chassis10k HD ChassisT2T2

0

0.01

0.02

00 0.1 0.2 0.3 0.4

PM (g

/mi)

0

Euro 5Euro 5T2T2Bin 5Bin 5

NOx (g/mi)

Euro 5Euro 5

Bin 8 / 8.5Bin 8 / 8.5--10k HD Chassis10k HD Chassis

1010-14k14k HD ChassisHD Chassis

Dispersion Control

0.01

0.02

0.1 0.2 0.3 0.4

PM (g

/mi)

T2T2Bin 5Bin 5

NOx (g/mi)

Primary Detection • Comb Phasing FPRxxDetection

Slide 5

Major Sources of Dispersion

Major players: • Mass Air Flow Sensor (global) • Injector variability (timing and quantity – esp. pilot) • Compression ratio • EGR distribution • Fuel quality (cetane) • Environmental factors • Wear on everything

Tuning: • Global EGR level (slow) • Charge temperature control with sophisticated

EGR system (slow) • Individual injection quantity and phasing (fast)

Derived combustion quantities like the 50% burn rate provide good control parameters but require - a powerful engine ECU - robust sensors

Slide 6

Engine-Appropriate Sensor Considerations S

enso

r Tec

hnol

ogy

ResearchGrade

High Quality Production

Grade

Moderate Quality

ProductionGrade

Low Quality Production

Grade

Piezo

Ion-sense, Knock-sense, low-grade Piezo

Optical/Diaphragm

Piezo-Electric

Linearity: Excellent Calibrated: Yes

Linearity: Moderate/Good

Linearity: Poor

Calibrated: TBD

Linearity: Moderate/Good Calibrated: TBD

Calibrated: No

Piezo-Resistive

Linearity: Very Good Calibrated: TBD

SOC, Ignition delay, AcousticsSOC, Ignition delay, Acoustics((Sampling: Burst, 0.5 deg)) Combustion Metric

LPP, SOC, Max Pressure, PressureLPP, SOC, Max Pressure, Pressure Rise Rate (Rise Rate (Sampling: Burst, 0.5 deg))

IMEP, Heat Release (CA50, 0IMEP, Heat Release (CA50, 0--90%)90%)((Sampling:Sampling: 1 deg1 deg))

Slide 7

Simple Phasing and Fuel Balance Control Using Pressure Feedback Control

Conventional mode Early-PCCI mode

Rel

ativ

e B

urn

Tim

ing

Rel

ativ

e B

urn

Tim

ing

Phasing Control

Fuel Balance Control Slide 8

Great! - But does it work?

Slide 9

NOx-HC Tradeoffs with Phasing and Fuel Control (Late-PCCI 1400 rpm, 400 kPa BMEP)

Open loop: Load Imbalance +/- 15% Closed loop Phasing in burn +/- 10% Open loop

5.5

Phasing Control 5.5

Fuel Balancing Control 5.5

Phasing and Fuel Control

5.0 5.0 5.0

4.5

HC

(g/k

g)

HC

(g/k

g)

4.5

HC

(g/k

g)

4.0 4.0

3.5 3.53.5

4. 0

4.5

3.0 3.03.0

2.5 2.52.5 0.6 0.8 1.0 1.2 1.4 0.6 0.8 1.0 1.2 1.4 0.6 0.8 1.0 1.2 1.4

NOx (g/kg) NOx (g/kg) NOx (g/kg)

• No NOx, HC or Smoke benefit observed due to linear emission response to the base engine cyl-to-cyl imbalance

Slide 10

MAF Correction with Phasing Control Late-PCCI 1400 rpm, 400 kPa BMEP

HC vs. NOx with MAF error and phasing controlProcedure 0% MAF Cntrl OFF

20• Ran open and closed 7% MAF Cntrl OFF

10 phasing advance

rich error lean error

Tradeoff -Cntrl OFF

-7% MAF Cntrl OFF

loop at each EGR 7% MAF Cntrl ON 15 10% MAF Cntrl OFF • For each EGR error,

swept phasing target under C/L control

• C/L phasing uses “no

HC

(mg/

sec)

10% MAF Cntrl ON

-7% MAF Cntrl ON 5 -10% MAF Cntrl OFF

EGR error” target as -10% MAF Cntrl ON

baseline 0 1.0 1.5 2.0 2.5 3.0 3.5

NOx (mg/sec)

• HC and NOx emissions resulting in rich/lean shift due to EGR can be partially recovered through phasing correction

• Requires individual cylinder pressure sensing

Slide 11

Global EGR Correction with Phasing Control Early-PCCI at 1400 RPM, 250 kPa BMEP

AVL noise, Ctl. OFF AVL noise, Ctl. ON • Simulate EGR error through MAF

AVL

noi

se (d

Ba)

89 66

Control On

EGR, Ctl. OFF EGR, Ctl. ON 90 68error (+/- 11%)

EGR

Wet

(%)

Closed-loop correction based on88 •6487 average combustion phasing

- Feedback to EGR valve62

8660855884 5683 • Effective in this case82 54

(but not in all cases)17 18 19 20 21 22 23 Air-Fuel Ratio

Smoke, Cntrl OFF Smoke, Cntrl ON HC, Cntrl OFF HC, Cntrl ON 0.8 8

HC

(mg/

sec)

NO

x (m

g/se

c)

Smok

e (F

SN)HC, Ctl. Off HC, Ctl. ON 0.7

Control On

8 1.5

HC

(mg/

sec)

NOx, Ctl. Off NOx, Ctl. ON

Control 1.26

70.60.5 6

0.9 0.44 On 0.30.6

0.22 0.3 0.10 0.0 0 17 18 19 20 21 22 23 0 0.5 1.0 1.5

Air-Fuel Ratio NOx (g/sec)Slide 12

3

4

5

Combustion Feedback Control Shows Promise for PCCI Operation

• Premixed combustion offers the potential to significantly reduce engine out emissions

• Comb feedback may be required due to production fleet variations and environmental factors

• Individual cylinder control combustion feedback shows potential for effective load balance and phasing control � Not all recoveries result in emission benefits � Works best in non-linear tradeoff regions

Slide 13

APSC

Thank you for your attention