Heavy Vehicle Systems OptimizationPeer Review

Parasitic Energy Loss Mechanisms Impacton Vehicle System EfficiencyProject 15171

Project Team: George Fenske, Robert Erck, Layo Ajayi, Ali Erdemir, and Osman Eryilmaz

Argonne National Laboratory

April 18-20, 2006

This presentation does not contain any proprietary or confidential

information

21CTP Technical Goal:

Program Structure Sub-Program Element R&D Phase DateProject ID/Agreement ID

Integration of materials, lubricants and surfaces into a low-friction system

Principal Investigator(s) -G. R. Fenske, R. A Erck, O.O Ajayi, and A Erdemir, Argonne National Laboratory, 630-252-5190, gfenske@anl.gov -L. Oberto, Ricardo Engineering - Z. Filipi, University of Michigan

Technology Development Manager Lee Slezak, DOE/OFCVT (202) 586-2335; Lee.Slezak@hq.doe.gov

Engine Systems: Develop technologies to achieve 55% efficiency by 2012

15171 Systems Optimization Parasitic Energy Losses Applied Research 4-06

Project Objectives -Increase fuel efficiency by reducing engine friction. -Develop mechanistic models of parasitic engine losses (and integrate with vehicle system analysis codes – e.g. PSAT) -Validate models and codes with experiments -Identify/assess advanced tribological concepts/systems to reduceengine friction (e.g. lubricants, additives, engineered surfaces) FY 2005/6 Focus -Model development, application of codes to predict fuel economysavings, and laboratory tests of advanced tribological concepts -Laboratory tests of low friction additives and coatings -Design of instrumented single-cylinder diesel engine Planned Duration October 2002 to September 2008 DOE Funding/Industry Cost ShareFY05:$125K FY06: $175K/$35K

Accomplishments Accomplishment 1: Mechanistic model predictions of .5 to 1.4% fuel savings with low friction surfaces Accomplishment 2: Mechanistic model predictions of 3-4% fuel savings with low friction surfaces and low-viscosity lubricants Accomplishment 3: Lab demonstrations of reduced friction surface treatments (up to 80 % reduction) Significant Future MilestonesMilestone 1: Instrumented single cylinder test rig – Dec 06 Milestone 2: Lab ring-on-liner tests of low-friction additives – Apr 07

SAE Viscosity Grade

-7% -6% -5% -4% -3% -2% -1% 0% 1% 2% 3% 4%

0 5 10 15 20 25 30 35 40 45 50 55Pred

icte

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Fue

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0% Reduction 30% Reduction 60% Reduction 90% Reduction

Parasitic Energy Loss Mechanisms: Impact on Vehicle System Efficiency

Relevance to 21CT Goals Technology Transfer

� Reducing friction in engines and drivetrains will increase the fuel efficiency of 21 CTtrucks

� Mechanistic models and low-friction engine/drivetrainsystems will provide a pathway to achieve engineand vehicle fuel efficiency improvements (50% thermalby 2010; 55% by 2012)

� Collaborations with researchers at: – Ricardo Engineering – Caterpillar – Eaton (CRADA) – University of Michigan – Suppliers

� Subcontractors: – Ricardo Engineering – University of Michigan

� Potential commercialization pathway

– Licensing of mechanistic models/codes (Ringpak, Valdyn, Pisdyn, Orbit)

– Integration of mechanistic models with vehicle system models/codes (e.g. PSAT)

– Materials & coatings, surface engineering, and additive development.

3

More Energy is Lost to Friction Than Delivered to the Wheel

� Energy Map- Passenger Vehicle EPA Cycle – Roughly 10% of energy input consumed by

friction – 1 million barrels/day lost to friction in

transportation

4

Energy In

100%

Indicated HP

35%

Brake HP

23%

Exhaust

35%

Engine Cooling

30%

Other Engine Friction

0.4%

Piston Assembly

2.8%

Valve Train

1.3%

Bearings

1.0%

Seals

0.5%

Air Pumping

6%

Others

1.6%

Transmission

2.0%

Braking

2.0%

Coast/Idle

4.0%

Axle

1.6%

Accessories

Oil Pump - 0.5%

Air Pump – 0.1%

Water Pump - 0.1%

Fuel Pump - 0.1%

Power Steering – 0.5%

Cooling Fan – 0.5%

Alternator – 0.5%

At Wheels

9.5% Viscous Loss – 1.35%

Friction Forces – 0.95%

Aero Drag

4.0%

Tires

5.5%

15% of IMEP (Indicated Mean

Effective Pressure – HP normalized to engine

displacement)

Blowby – 0.5%

Objective: Reduce Parasitic Engine Losses to 5-10% IMEP

� Integrate mechanistic models of friction losses for

Model low-friction surfaces and

lubricant viscosity

Lab-scale tribological testing

Instrumented, fired engine tests

Multi-cylinder engine tests

specific engine components � Apply codes to predict

FMEP at different engine loads and speeds

� Calculate the impact of friction and viscosity on fuel economy

� Benchtop tests to identify potential low-friction material/coating and lubricant systems

� Fired, single cylinder diesel engine studies to validate approach

� Multicylinder Engine tests

� PSAT, fleet tests, …..

5

Technical Accomplishment Summary

� Integrated mechanistic models to predict impact of low-friction surfaces and low-viscosity lubricants on parasitic energy losses (FMEP) and fuel economy

� Developed/selected lab tests to evaluate and optimize advanced low-friction technologies for engine components – Comparison with baseline technologies

� Selected approach to validate models and low-friction technologies using a single-cylinder diesel engine – Ricardo/U Mich.

� Establishing protocols to translate 8-mode FMEP results into formats compatible with PSAT vehicle simulation toolkits.

6

7

Role of Boundary and Hydrodynamic Lubrication Regimes- Tribological System

� Different regimes of lubrication depending on the degree of contact between sliding surfaces

� Boundary lubrication characterized by solid-solid contact – asperities of mating surfaces in contact with one another

� Contrast boundary lubrication with full-film lubrication in which mating surfaces are separated by a film.

� In between, mixed lubrication occurs.

Boundary Lubrication

Mixed Lubrication

Full Film Lubrication

Viscosity * Speed/Load

Fric

tion

Coe

ffici

ent

ANL/Ricardo Phase I Studies – Identify/Model Frictional Losses in a Diesel Engine & Impact of Lowering Boundary Layer Friction on Fuel Economy

� FMEP calculated at 8 different modes and

Spee

d (rp

m)

1900

1700

1500

1300

1100

900

700

500

weighted to predict effect on fuel consumption •Rocker bushing * •Rocker tip to valve * for a HD driving cycle •Pushrod to rocker interface *

•Piston pin bearing * •Rings * •Piston Skirt *

•Cam - follower interface * •Cam bearings * •Follower - pushrod interface * •Timing drive

•Journal bearings •Crankshaft windage

•Crankshaft main bearings •Main seals *

1 (52%)

2 (3%)

3 (4%)

4 (15%) 5 (8%)

6 (6%) 7 (8%) 8 (5%)

Weighting factor

0 500 1000 1500 2000 •Oil PumpLoad/IMEP (kPa)

•Fuel injection system

FCSF = (Fuel Consumption Scaling Factor)

IMEP + ΔFMEP IMEP

* interface considered in current study

8

Boundary and Hydrodynamic Friction: Model Impact onFMEP and Wear Severity

� Total FMEP is the sum of the Asperity friction and the hydrodynamic friction – Boundary FMEP decreases with increasing lubricant viscosity – shifting from BL to ML regime – Hydrodynamic FMEP increases with increasing viscosity

Piston FMEP versus Viscosity Grade Normalized Piston - Liner Contact Severity

4.525

Asperity FMEP

20

No Treatment Total Est 30% Reduction Total Est 60% Reduction Total 90% Reduction Total Hydrodynamic Asperity / No Treatment Asperity / Est 30% Asperity / Est 60% Asperity / 90%

Viscous FMEP

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Rel

ativ

e W

ear L

oad

FMEP

(kPa

)

15

10

5

0.5

0 0.0 10 20 30 40 50 0 10 20 30 40 50

SAE Viscosity Grade SAE Viscosity Grade

9

Modeled Contact Severity/Loads – Impact of Low- Viscosity Lubricants on Engine Components

� As lubricant viscosity is reduced, contact between the piston skirt and cylinder liner increases in both magnitude and extent Normalized Piston - Liner Contact Severity

� Predicted total average contact severity per cycle, using 4.5

SAE 5 oil, is more than 4 times as high as that using 4.0SAE 40 oil � This model suggests that to allow the use of SAE 5 oil, a 3.5

surface treatment would have to provide approximately four times the wear resistance of the baseline system, if 3.0 the wear resistance remained constant over time

2.5

2.0

1.5

1.0

0.5

0.0 0 10 20 30 40 50

SAE Viscosity Grade

Rel

ativ

e W

ear L

oad

10

Argonne/Ricardo Phase II Studies – Impact of Reducing Lubricant Viscosity – 3 to 4 % Fuel Savings

– Significant savings possible by -2% combining low friction boundary friction technologies AND low- -3%

viscosity lubricants -4%

� Reducing the boundary layer 1%

friction enables the use of a 0%

lower-viscosity lubricant -1%

� Reducing only the asperity 4%

0% Reduction 30% Reduction 60% Reduction 90% Reduction

friction improves fuel economy by 0.4 to 1.3 % 3%

2%

Pred

icte

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hang

e in

Fue

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– Fuel savings dependent on driving schedule – using low-viscosity lubricants (and low friction surfaces) under driving cycles with high percentages of idling provide significant savings

-5%

-6%

-7% 0 10 20 30 40 50

SAE Viscosity Grade

11

Benchtop Validation of Friction – Can We Achieve 30 to 90% Reductions in Boundary Friction? And How?

� Measurement of friction using benchtop tribometers providing data on the potential of advanced engineered surfaces and lubricants to provide low-friction tribological systems

– Candidate low-friction technologies • Coatings (Amorphous carbon,

Superhard nanocomposites, Commercial Coatings – CrN, …)

• Lubricants (Additives – formation of low-friction boundary films)

• Textured surfaces – Benchtop test configurations

• Unidirectional Sliding – Pin-on-Disc

– Block-on-Ring

• Reciprocating Sliding – Ring-on-Liner

12

Argonne – Development of a Test Rig to Simulate Ring-Liner Conditions and Evaluate Potential Low-Friction Strategies

� Modified a Cameron-Plint Rig to operate with prototypic liner segments and ring segments

Liner Segment

Ring Segment

13

Computer Data Collection

� Measurement of friction, rpm, normal force, instantaneous position, contact resistance, temperature

� Samples Data @ 2 kHz � Data reduced with Sigmaplot software

14

Ring-on-Liner: Lubricant Additive (ROL 060228)

� 10W-30 Synthetic � Low-Friction Additive

15

Low-Friction Additive Consumed During 9-Day Benchtop Test

� During extended break-in tests with low- friction additive, the friction was initially low, continued to decrease, then increased as the additive was depleted

0.15 0.15 0.15 060319 10 rpm 150N silk first 3600 s 060319 10 rpm 150N silk 3600 s at 240,000s 060319 10 rpm 150N silk mid 3600 s

0.1 0.1 0.1

0.05 0.05 0.05

µ 0 µ 0

-0.05 -0.05 -0.05

-0.1 -0.1 -0.1

-0.15 -0.15-1.5 -1 -0.5 0 0.5 1 1.5 -0.15Position (cm) -1.5 -1 -0.5 0 0.5 1 1.5

Position (cm) -1.5 -1 -0.5 0 0.5 1 1.5 Position (cm)

16

µ 0

Pin-on-Disc: SuperHard Nanocomposite(More Details To Be Presented by Ali Erdemir)

� Room temperature pin-on-disc friction studies of steel ball sliding against steel disc or Superhard Nanocomposite, low-friction coatings – 50 % reduction in friction

17

Block-on-Ring: Scuffing Performance (More Details To Be Presented by Ajayi/Erdemir)

� Operation with low-viscosity fluids raises concerns with regard to scuffing.Steel/Steel Can we identify600 N

scuffing coating and/or

load additive systems that have improved scuffing resistance? – Block-on-ring

0.20 2000 configuration isFriction Coefficient

Load 1800 used to evaluate 1600 scuff resistance 0.15

1400

SHNC/SHNC >1700 N scuffing load

Fric

tion

Coe

ffici

ent

1200

Load

(N)

0.10 1000

800

600

0.05

400

200

0.00 0 0 480 960 1440 1920 2400 2880 3360 3840 4320

Time (s.)

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Textured Surfaces as a Method to Reduce Hydrodynamicand Mixed Lubrication Friction

� Argonne (in collaboration with Technion University – Prof. I. Etsion) is evaluating the potential of laser surface texturing to reduce friction on engineered surfaces

� Results suggest LST may provide significant energy savings regimes where

Mixed LubricationFull Film

Lubrication

Fric

tion

Coe

ffici

ent

With LST

BoundaryLubrication

Viscosity * Speed/Load

Fe conformal contact is present

mixed lubrication friction

act as oil reservoirs thereby Microdimples created by LST

minimizing boundary and

U

Textured ring

Liner Fr

ictio

n Fo

rce,

N

6.00 5.50 5.00 4.50 4.00 3.50 3.00 2.50 2.00 1.50 1.00

Untextured Full texturing Partial texturing

500 600 700 800 900 1000 1100 1200 Angular Velocity, RPM

19

Fired, Single-Cylinder Diesel Tests: Ricardo/U-Mich – Phase III – Validate Models and Low-Friction Technologies

� Validate model predictions and low-friction technologies

� Ricardo examined multiple approaches to validate fuel economy predictions – Direct fuel consumption, instrumented multi-cylinder engine, instrumented

single-cylinder diesel engine, motored engine, … � Selected Approach (Instrumented, Single-Cylinder Hydra Engine) :

– Modify an existing single-cylinder test engine for friction measurement, using the fixed-sleeve approach

– Run the engine with a variety of lubricants, with and without NFC coatings at each of the interfaces

– Measure instantaneous friction at these interfaces – Calculate the change in asperity friction coefficients due to the application

of the coatings – Use the experimentally-derived friction coefficient improvements to refine

the earlier estimates of fuel economy improvement over the FTP HD test

20

cycle

Ricardo/U-Mich – Modifications to Hydra Engine for in-situ

21

Friction Force Measurements

� Ricardo has been producing single cylinder engines for research and development since 1919

� A number of standard conversion kits exist to extend the range of operation of a Hydra engine, such as from gasoline to direct injection diesel operation

Friction Force

Strain Gauge

Sleeve

Liner

Support Wire

Coolant

Friction Force

Thermocouples

Proposed Test Matrix

� The following combinations of engine build, load condition, and lubricant will be tested:

Engine Configurations

Oil Viscosity Operating Conditions Data Collected

Baseline – Stock ring and Liner

SAE 40 Partial Load 1 Partial Load 2 Full Load

Cylinder Pressure Oil Sump Temperature Coolant Temperature Liner temperature Profile Friction Force Engine Blow-By Gas Flow

SAE 20

Low Friction Ring and/or Piston

SAE 40 Partial Load 1 Partial Load 2 Full LoadSAE 20

Lubricant Additive (s)) SAE 40 Partial Load 1 Partial Load 2 Full LoadSAE 20

Low-Friction Ring & Liner

SAE 40 Partial Load 1 Partial Load 2 Full LoadSAE 20

22

Summary/Conclusions

� A series of mechanistic models have been developed and integrated into a suite of codes capable of predicting parasitic energy losses in a heavy duty diesel engine

� The code predicts the impact of the tribological environment on the FMEP and fuel consumption by appropriate application of weighting factors applied to calculations at 8 engine load/speed modes

� Fuel consumption savings up to 3-4 % are predicted through a combination of low viscosity engine lubricants coupled with low-friction surfaces

� Benchtop friction tests are being employed to identify potential technologies/approaches to achieve levels of friction reductions required to improve fuel economy and to determine the conditions necessary to achieve reduced friction – Additives, coatings, and surface texturing

� Modifications to a fired, single-cylinder diesel engine are in progress to provide in-situ friction measurements of baseline and advanced low-friction components and to validate the mechanistic models

23

Future Activities:

� Single-Cylinder, Fired Diesel Tests with in-situ measurement of ring/piston – liner friction forces – Effect of viscosity, low friction coatings, and additives

� Multi-cylinder engine and/or fleet studies – Fuel efficiency and system durability

� PSAT integration – Development of PSAT modules to incorporate mechanistic models into

vehicle system efficiency studies � Auxiliaries

– Parasitic energy losses in auxiliary systems • Fluid pumps (fuel, oil, water) are often oversized to accommodate

degradation/wear over the system lifetime. • Compressors • Cooling fan, alternator, steering

24

� Transmissions and axles (Eaton/Caterpillar/ANL/NWU)

Closing Remarks ……

25

FCSF = (Fuel Consumption Scaling Factor)

IMEP + ΔFMEP IMEP

Application of Mechanistic Models to Vehicle System Optimization –Component Optimization & Vehicle Optimization (PSAT)

� Develop ‘look-up’ tables/regressions for use in PSAT Vehicle Simulation Software

0

10

20

30

0 500

1000 1500

2000 800

1200

1600

FMEP

(kPa

)

Speed(rpm

)

Piston Skirt FMEP Baseline BLL Friction

SAE 40

Load IMEP (kPa)

0

10

20

30

0 500

1000 1500

2000 800

1200

1600 FM

EP (k

Pa)

Speed(rpm

)

Piston Skirt FMEP 90% BLL Friction Reduction

SAE 40

26

Load - IMEP vs Speed - RPM vs FMEP Hydrodynamic Load - IMEP vs Speed - RPM vs FMEP Total

Load IMEP (kPa)

Load - IMEP vs Speed - RPM vs FMEP Hydrodynamic Load - IMEP vs Speed - RPM vs FMEP Total

– Do you treat only the skirt, only the rings, or both?? A low-friction treatment (e.g. coating) applied only to the rings is not much different from treating only the skirt. Treating both rings and skirt helps at low viscosities.

– Alternatively can one identify an additive that effectively works on all surfaces – Can one tailor the surface chemistry of select components for enhanced

60

50

40

30

20

10

0

Which Components Have the Biggest Impact – What Should be Treated?

� Approach can be extended to consider treating a few select components with variable friction reductions

lubrication W

eigh

ted

(HD)

FM

EP

(kP

a)

Baseline 90% Skirt Only 90% Rings Only 90% Rings & Skirt

27

5 10 20 30 40 50

SAE Viscosity Grade

Benchtop Studies – What Is the Magnitude of Friction Savings That Can be Achieved, and What Level of Increased Protection

� Models assumed 30, 60, and 90% reductions in boundary friction – what are realistic friction coefficients, how do they compare to the baseline assumptions – are there technologies that can provide these levels of improvements

� Pin-on-Disc, Reciprocating, Block-on-Ring, and Ring-on- Liner Configurations

– Friction, Wear, Scuffing- Resistance of test coupons and prototypic rings and liner segments

28

� Coatings, Surface Texturing, and Additives

Ricardo Study – FMEP SAE 40 Energy In

100%

Indicated HP

IMEP (kPa)

Brake HP

BMEP (kPa)

At Wheels

??

Exhaust

??

Engine Cooling

??

Aero Drag

??

Tires

??

� FMEP is a significant fraction of the IMEP

Other Engine Friction

0.4%

Piston Assembly

2.8%

(8% IMEP)

Valve Train

1.3%

(3.7% IMEP)

Bearings

1.0%

(2.9% IMEP)

Seals

0.5%

Air Pumping

6%

Asperity (kPa)

Viscous (kPa)

Asperity (kPa)

Viscous (kPa)

Asperity (kPa)

Viscous (kPa)

19.4 kPA 3.1% <IMEP>

1.82

2.81

7.93

1.73

2.64

1.34

1.14

12.3

3.6 kPa 0.6% <IMEP>

0

0

0

0

0

0

0

0

48.4 kPa 7.8% <IMEP>

3.2

5.8

16.9

3.0

5.4

2.4

2.1

29.7

Weighted Average

8) 1800/1683

7) 1800/983

6) 1800/325

5) 1590/1683

4) 1590/983

3) 1170/1683

2) 960/1683

1) 750/104

Mode Rpm/kPa

1.0

0.1

0.4

1.3

0.2

1.8

1.9

5.2

Piston FMEP

0.010.1

0.00.2

0.00.6

0.010.1

0.010.2

0.020.2

0.020.2

10.15 4.6

Bearings FMEP Valvetrain FMEP

11.5% of IMEP

29

Ricardo Study – FMEP SAE 20 & 90 % Asperity Reduction Energy In

100%

Indicated HP

IMEP (kPa)

Brake HP

BMEP (kPa)

At Wheels

??

Exhaust

??

Engine Cooling

??

� FMEP is a significant fraction of the IMEP

Other Engine Friction

0.4%

Piston Assembly

2.8%

(8% IMEP)

Valve Train

1.3%

(3.7% IMEP)

Bearings

1.0%

(2.9% IMEP)

Seals

0.5%

Air Pumping

6%

Mode Piston FMEP Valvetrain FMEP Bearings FMEP Rpm/kPa

Viscous Asperity Viscous Asperity Viscous Asperity (kPa) (kPa) (kPa) (kPa) (kPa) (kPa)

1) 750/104 20.58 0.73 0 1.591 10.2 0.026

2) 960/1683 1.52 0.01 0 0.004 1.0 0.013

3) 1170/1683 1.75 0.012 0 0.004 1.2 0.004

4) 1590/983 3.81 0.009 0 0.023 2.3 0.002

5) 1590/1683 2.17 0.019 0 0.006 1.5 0.002

6) 1800/325 12.14 0.008 0 0.025 7.2 0.000

7) 1800/983 4.14 0.004 0 0.011 2.5 0.000

8) 1800/1683 2.32 0.009 0 0.004 1.6 0.001

Weighted 30.6 kPA 2.4 kPa 16.8 kPa Average 5% <IMEP> 0.4% <IMEP> 2.7% <IMEP>

Aero Drag

??

Tires

??

8.1% of IMEP

30

Ring-on-Liner: Lubricant Additive (ROL 060228)

� 10W-30 Synthetic � Low-Friction Additive

31