Mechanical engineering series  engine oils and automotive lubrication

In different chapters the follow ing topics are covered: — Film thickness in engine bearings - Base oils for automotive lubricants — Additives and mechanism o f effectiveness — Engine oi

ENGINE OILS

AND

AUTOMOTIVE LUBRICATION

MECHANICAL ENGINEERING

A Series of Textbooks and Reference Books

Editor

L L Faulkner

Columbus D ivision, Battelle Memorial Institute

and Department o f Mechanical Engineering

The Ohio State University Columbus, Ohio

1 Spring Designer’s Handbook, Harold Carlson

2 Computer-Aided Graphics and Design, Daniel L Ryan

3 Lubrication Fundamentals, J George Wills

4 Solar Engineering for Domestic Buildings, William A Himmelman

5 Applied Engineering Mechanics: Statics and Dynamics, G Booth-

royd and C Poli

6 Centrifugal Pump Clinic, Igor J Karassik

7 Computer-Aided Kinetics for Machine Design, Daniel L Ryan

8 Plastics Products Design Handbook, Part A : Materials and Compo­ nents; Part B: Processes and Design for Processes, edited by

Edward Miller

10 Vibrations o f Shells and Plates, Werner Soedel

11 Flat and Corrugated Diaphragm Design Handbook, Mario Di

Giovanni

12 Practical Stress Analysis in Engineering Design, Alexander Blake

13 An Introduction to the Design and Behavior of Bolted Joints, John

H Bickford

14 Optimal Engineering Design: Principles and Applications, James

N Siddall

15 Spring Manufacturing Handbook, Harold Carlson

16 Industrial Noise Control: Fundamentals and Applications, edited

20 Gear Drive Systems: Design and Application, Peter Lynwander

21 Controlling In-Plant Airborne Contaminants: Systems Design and Calculations, John D Constance

22 CAD/CAM Systems Planning and Implementation, Charles S Knox

23 Probabilistic Engineering Design: Principles and Applications,

James N Siddail

24 Traction Drives: Selection and Application, Frederick W Heilich

III and Eugene E Shube

25 Finite Element Methods: An Introduction, Ronald L Huston and

Chris E Passerello

26 Mechanical Fastening of Plastics: An Engineering Handbook, Bray-

ton Lincoln, Kenneth J Gomes, and James F Braden

27 Lubrication in Practice: Second Edition, edited by W S Robertson

28 Principles of Automated Drafting, Daniel L Ryan

29 Practical Seal Design, edited by Leonard J Martini

30 Engineering Documentation for CAD/CAM Applications, Charles S

34 Steam Plant Calculations Manual, V Ganapathy

35 Design Assurance for Engineers and Managers, John A Burgess

36 Heat Transfer Fluids and Systems for Process and Energy Applications, Jasbir Singh

37 Potential Flows: Computer Graphic Solutions, Robert H Kirchhoff

38 Computer-Aided Graphics and Design: Second Edition, Daniel L

42 Design of Mechanical Joints, Alexander Blake

43 CAD/CAM Dictionary, Edward J Preston, George W Crawford,

and Mark E Coticchia

44 Machinery Adhesives for Locking, Retaining, and Sealing, Girard

S Haviland

45 Couplings and Joints: Design Selection, and Application, Jon R

46 Shaft Alignment Handbook, John Piotrowski

47 BASIC Programs for Steam Plant Engineers: Boilers, Combustion, Fluid Flow, and Heat Transfer, V Ganapathy

48 Solving Mechanical Design Problems with Computer Graphics,

Jerome C Lange

49 Plastics Gearing: Selection and Application, Clifford E Adams

50 Clutches and Brakes: Design and Selection, William C Orthwein

51 Transducers in Mechanical and Electronic Design, Harry L Trietley

52 Metallurgical Applications o f Shock-Wave and High-Strain-Rate Phenomena, edited by Lawrence E Murr, Karl P Staudhammer,

and Marc A Meyers

53 Magnesium Products Design, Robert S Busk

54 How to Integrate CAD/CAM Systems: Management and Technol­ ogy, William D Engelke

55 Cam Design and Manufacture: Second Edition; with cam design software for the IBM PC and compatibles, disk included, Preben

W Jensen

56 Solid-State A C Motor Controls: Selection and Application, Sylves­

ter Campbell

57 Fundamentals of Robotics, David D Ardayfio

58 Belt Selection and Application for Engineers, edited by Wallace D

Erickson

59 Developing Three-Dimensional CAD Software with the IBM PC, C

Stan Wei

60 Organizing Data for CIM Applications, Charles S Knox, with

contributions by Thomas C Boos, Ross S Culverhouse, and Paul

F Muchnicki

61 Computer-Aided Simulation in Railway Dynamics, by Rao V

Dukkipati and Joseph R Amyot

62 Fiber-Reinforced Composites: Materials, Manufacturing, and De­ sign, P K Mallick

63 Photoelectric Sensors and Controls: Selection and Application,

Scott M Juds

64 Finite Element Analysis with Personal Computers, Edward R

Champion, Jr., and J Michael Ensminger

65 Ultrasonics: Fundamentals, Technology, Applications: Second Edition, Revised and Expanded, Dale Ensminger

66 Applied Finite Element Modeling: Practical Problem Solving for Engineers, Jeffrey M Steele

67 Measurement and Instrumentation in Engineering: Principles and Basic Laboratory Experiments, Francis S Tse and Ivan E Morse

68 Centrifugal Pump Clinic: Second Edition, Revised and Expanded,

Igor J Karassik

69 Practical Stress Analysis in Enineering Design: Second Edition, Revised and Expanded, Alexander Blake

70 An Introduction to the Deisgn and Behavior o f Bolted Joints: Second Edition, Revised and Expanded, John H Bickford

71 High Vacuum Technology: A Practical Guide, Marsbed H Habla-

nian

72 Pressure Sensors: Selection and Application, Duane Tandeske

73 Zinc Handbook: Properties, Processing, and Use in Design, Frank

76 Handbook o f Electronic Package Design, edited by Michael Pecht

77 Shock-Wave and High-Strain-Rate Phenomena in Materials, edited

by Marc A Meyers, Lawrence E Murr, and Karl P Staudhammer

78 Industrial Refrigeration: Principles, Design and Applications, P C

Koelet

79 Applied Combustion, Eugene L Keating

80 Engine Oils and Automotive Lubrication, edited by Wilfried J Bartz

Additional Volumes in Preparation

Mechanical Engineering Software

Spring Design with an IBM PC, Al Dietrich

Mechanical Design Failure Analysis: With Failure Analysis System Software for the IBM PC, David G Ullman

ENGINE OILS

AND AUTOMOTIVE LUBRICATION

EDITED BX WILFRIED J BARTZ

Technische Akademie Esslingen

Ostfildern, Germany

CRC Press

T a y lo r & Francis G ro u p Boca Raton London New York CRC Press is an im p r in t o f th e

T h is b o o k c o n ta in s in fo r m a tio n o b ta in e d fro m a u th e n tic a n d h ig h ly re g a rd e d s o u rc e s R e a so n a b le e ffo rts h av e b e e n m a d e to

p u b lis h reliab le d a ta a n d in fo rm a tio n , b u t t h e a u th o r a n d p u b lis h e r c a n n o t a s s u m e r e s p o n s ib ility for th e v a lid ity o f a ll m a te ria ls

o r t h e c o n s e q u e n c e s o f th e i r u se T h e a u th o r s a n d p u b lis h e rs have a tte m p te d t o tra c e t h e c o p y rig h t h o ld e rs o f a ll m a te ria l r e p r o ­

d u c e d in t h is p u b lic a tio n a n d a p o lo g iz e to c o p y rig h t h o ld e rs if p e rm is s io n to p u b lis h in th is fo rm h a s n o t b e e n o b ta in e d I f an y

c o p y rig h t m a te ria l h a s n o t b e e n a c k n o w led g e d p lea se w rite a n d le t u s k n o w so w e m ay r e c tif y in a n y f u tu r e r e p rin t.

E x cep t a s p e r m itte d u n d e r U.S C o p y rig h t Law, n o p a r t o f th is b o o k m ay b e re p r in te d , re p ro d u c e d , tr a n s m itte d , o r u tiliz e d in an y

fo rm b y a n y e le c tro n ic , m e c h a n ic a l, o r o th e r m e a n s , n o w k n o w n o r h e re a f te r in v e n te d , in c lu d in g p h o to c o p y in g , m ic ro film in g ,

a n d re c o rd in g , o r in a n y in fo r m a tio n s to ra g e o r re trie v a l s y s te m , w ith o u t w r itte n p e rm is s io n fro m th e p u b lish e rs.

F o r p e rm is s io n t o p h o to c o p y o r u se m a te ria l e le c tro n ic a lly f ro m t h is w ork, p lea se a c ce ss w w w c o p y rig h t.c o m (h ttp ://w w w c o p y -

r ig h t.c o m /) o r c o n ta c t th e C o p y rig h t C le a ra n c e C e n te r, In c (C C C ), 2 2 2 R o sew o o d D rive, D a n v e rs, M A 01923, 9 7 8 -7 5 0 -8 4 0 0

C C C is a n o t-fo r-p ro fit o rg a n iz a tio n t h a t p ro v id e s lic e n ses a n d r e g is tr a tio n fo r a v a rie ty o f u s e rs F o r o rg a n iz a tio n s t h a t h av e b e e n

Lubricants and lubrication techniques are indispensable in the automobile industry Owing to the special operating conditions, characterized by high tem­peratures, loads and speeds, lubricants have to cover extreme requirements Therefore, the necessary properties of these lubricants require appropriate classification, production and form ulation, testing and application as well as expert disposal

This book deals w ith the state o f the art in the field of automotive lubrication, particularly engine lubrication The different topics are covered by experts from the mineral oil, additive and automobile industries as well as from research institutes, thus providing high standard expert knowledge in any specific area of automotive and engine lubrication Experts from several countries contributed

to this book

In different chapters the follow ing topics are covered:

— Film thickness in engine bearings

- Base oils for automotive lubricants

— Additives and mechanism o f effectiveness

— Engine oils and their evaluation

- Sludge deposits in gasoline engines

- Special aspects of engine lubrication

- Two-Stroke-Engine Oils

- Tractor lubrication

— Gear lubrication

— Lubricant influence on ceramic and seal materials

This book is characterized by the fact that experts from all over the world gathered and summarized their knowledge, resulting in a general but nevertheless comprehensive presentation of all major aspects of automotive and engine lubrication

This book might be useful to all who are active in the field of automobile tribology and lubrication Experts from the mineral oil and additive industries can also find new points o f view to supplement their knowledge, as w ill junior scientists and engineers who are introducing themselves to this field of trib o ­logy and lubrication engineering In addition, w ith the aid of this book a great number of students of tribology may gain a great deal of useful information

Prof W.J Bartz

Table of Contents

1 Oil Film Thickness in Engine Bearings

1.1 Measurement of Oil Film Thickness in Big-End

Bearings and Its Relevance to Engine Oil

1.2 Does the Automotive Industry Need a

Standard Engine Test to Measure Journal

1.2.7 Is an Industry Engine Bearing Test o f any Sort Needed? 44

2.1 Structure of Oils According to Type and Group

Analysis of Oils by the Combination of Chroma­

P Daucik, T Jakubik, N Pronayova and B Zuzi

2.2 Dependency of Viscometric Properties on

Base-Stocks Chemical Structures in Multigrade

2.2.5.2 Change in Viscometric Properties w ith increasing

2.2.5.3 Dependency of Viscometric Properties on Single

2.2.5.4 Dependency of Viscometric Properties on Combined

1 02

102102103107107107110112112113114114115

116

117118123124

125

125125126130144145

Determination of Zinc and Calcium in Multigrade

Results and Discussion

Method precision limits

Effect o f VI Improvers on Measured Zinc and

Calcium Concentrations

Effect of Viscosity on Percent Reduction of

Measured Concentrations

Estimating Correction Factors

Via VI Improver Concentration

Via Blend Viscosity

Explanation of Results

Conclusions

References

The Characterisation of Synthetic Lubricant

Formulations by Field Desorption Mass

Tailor Making Polyalphaolefins

R.L Shubkin and M.E, Kerkemeyer

D.K Walters and J.V Bullen

Tailor Making PAO's

149150150150151153153154155157158158159159159160161162162163163163164167169169173

177

177179180181186192195197198199

Additives and Mechanism of Effectiveness

Engine Oils Additives: A General Overview

C Kajdas

Introduction

Engine Oil Properties

Properties o f Base Oils

Properties Imparted by Additives

Types and General Characteristics o f Additives for

Engine Oils

Description of the Engine Oil Additives

General Inform ation

Additives Responsible fo r Formation o f Deposits

Additives M odifying Oil Properties

Viscosity Index Improvers

Pour Point Depressants

Extreme Pressure Additives

Interactions o f Engine Oil Components

References

Effects of NOv on Liquid Phase Oxidation and

Inhibition at Elevated Temperatures

S Korcek and M.D Johnson

Blowby Composition

Experimental

Reactions o f NO and N 0 2

Effects o f Uninhibited Hexadecane Oxidation

Effects on Inhibited Hexadecane Oxidation

Effects on Inhibited Oxidation o f Preoxidized HexadecaneSummary

References

Appendix 1

Appendix 2

200200

202

202203206208209

210

210

212

212212213213216218219

220220220

221221222

222

223223225226227228230230230

Application of a New Concept to Detergency

J.M Georges, J.L Loubet, N Alberola and G Meille

H Bourgognon, P Hoornaert and G Chapelet

Gel Formation and its Consequences

Cracking and Overbased Detergent

Correlation between the ELF/EC L Coking Test and a

Renault 30 TD Engine Test

Other Bench Tests

Reciprocating Rig Wear Test

Engine Tests

Conclusion

Acknowledgement

References

3.5 Synthesis of Additives Based on Olefin-Maleic

3.5.6 Olefin-Maleic Anhydride Reaction Products as Raw Material

3.7 Resistance of Ashless Dispersant Additives to

Oxidation and Thermal Decomposition 253

L Bartha and J Hancsok, E Bobest

263263264264266267267269270272275275278278278280281281281283284285285286

287

287287288288288290290290290292293294

Anti-Wear Actions of Additives in Solid Dispersion

M.F Morizur and 0 Teysset

Results and Discussion

Additive decomposition mode in homogeneous phase

Behaviour o f additives in the presence of metallic surfaces

Adsorptions Isotherms

Surface Reactivity

Friction Tests

Rolling Tests

Type of Surface Film Formed in Slip

Chemical state of elements at the surface

Boundary Films Formed by Hyperbasic Detergents

Boundary Film Formed in the Presence o f Potassium

Triborate

Thickness o f Films Formed on Antagonistic Specimens

Results o f Mechanical Tests w ith Pure Slip

An Investigation of Effects of Some Motor Oil

Additives on the Friction and Wear Behaviour

of Oil-soluble Organomolybdenum Compounds

D Wei, H Song and R Wang

Abstract

Introduction

Experimental Methods

Friction and Wear Test

Base Oil and Additives

Analysis o f Surface Films

Experimental Results and Discussion

The Effect o f Additive Concentration

Detergent and Dispersant

Zinc Dialkyldithiophosphate

Rust Inhibitor

Influence o f Temperature

3.9.3.3 The Influence o f Oil Change - Running-in Process 2963.9.3.4 The Mechanisms o f the Synergistic Effects Between the

Molybdenum Compounds and the Calcium Sulfonate 299

3.10 The Study on the Antiwear Action Mechanism of

Alkoxy Aluminium in Lubricating Oil 308

J Dong, G Chen and F Luo

3.11 Functional Properties of EP-Additive Packages

Containing Zn-Dialkyldithiophosphate, Sulphurized EP-Additive and a Metal Deactivator 316

G.S Cholakov, K.G Stanulov and I.A Cheriisky,

3.11.3.4 Performance Related Tests and Ideas for Practical

3.12 Relationship between Chemical Structure and

Effectiveness of Some Metallic Dialkyl and

Diaryldithiophosphates in Different Lubricated

359

359359360360360361364365365375380381382

383

383383383385385385

Test Results and Discussion

Evaluation of the Antiwear Performance of Aged

Oils through Tribological and Physicochemical

Mathematic Model for the Thickening Power of

Viscosity Index Improvers Application in Engine Oil Formulations

H Bourgognon and C Rodes, C Neveu and F Huby

Summary

Introduction

Background

Objective o f the Study

Contribution o f Package Components to Viscosity

C ontribution of Package Components to Viscosity

Analysis o f Packages Used by a Blending Plant

Model Describing the Contribution o f Package to

Surface Morphology and Chemistry of Reaction

Layers Formed Under Wear Test Conditions as

Determined by Electron Spectroscopy and

Scanning Electron Microscopy

Y de Vita, I.C Grigorescu and G.J Lizardo

Abstract

Introduction

Experimental

Results and Discussion

Friction and Wear Behaviour

Wear Morphology vs Friction Coefficient Pattern

Comparison o f Worn Surface Morphology between

SRV Test Specimens and Valve Lifters

Conclusions

Acknowledgement

References

Engine Oils and Their Evaluation/

Engine Lubrication Aspects

Engine Oils and Their Evaluation

The Changing Requirements of the 1980s-

Automotive Oil Evaluation by Bench and

388

406

406406

407

409

409 413422424

425 425

429

429429431435

4.2 An Investigation into the Lubricating Engine

Oil's Mechanical and Chemical Behaviour 436

S.L A ly , M.O.A Mokhtar, Z.S Safar,

A.M Abdel-Magid, M.A Radwan and M.S Khader

Part I: Experimental Findings

4.3 Development of Superior Engine Oils for

J.R Nanda, G.K Sharma, R.B Koganti and P.K Mukhopadhyay R.M Sundaram

4.3.3 Development o f an Indigenous Formulation 4604.3.4 Development of Multigrade Fuel Efficient Railroad Oil 465

4.4 Very High Shear Rate, High Temperature Viscosity

Using the Automated Tapered Bearing Simulator-

T.W Selby, T.J Tolton

4.4.1.1 Background 4714.4.1.2 Importance o f the Tapered Coaxial Configuration -4 7 24.4.1.3 Thermoregulator and Heater Development Effects 4744.4.1.4 Continuous or Long-Duration Operation of the TBS 474

4.4.2.1 ASTM D4863-87 — Relative Rotor Position Method 475

4.4.3.2 Second Stage - Semi-Automatic Calibration 4794.4.4 Applications o f the TBS/Automated-TBS Viscometer 481

4.4.4.2 Singular Temperature — M ultiple Shear Rate Data 4814.4.4.3 M ultiple Temperature - M ultiple Shear Rate Data 4844.4.4.4 Correlation w ith the "Cross Equation" 4864.4.4.5 Correlation w ith Engine Oil-Film Thickness Studies 487

Sludge Deposits in Gasoline Cars

4.5 Literature Survey on Sludge Deposits Formation in

C.D Neveu, W Bottcher

4.5.3 Summarized Findings on Sludge Formation Mechanism 492

Appendix 3/2: Evaluation Possibilities 508

4.6 Development and Application of an "On the Road"

Test Method for the Evaluation of Black Sludge

Performance in Gasoline Passenger Cars 509

P.G Carress

4.6.3 Test Fuel 5094.6.4 Manufacturers Oil and Service Recommendations 510

Special Aspects of Engine Lubrication

4.7 Review of Oil Consumption Aspects of Engines 515

D.C Roberts

4.7.3 Influence o f Oil Viscosity and V o la tility in Gasoline Engines 524

4.8 The Contribution of the Lube Oil to Particulate

Emissions of Heavy Duty Diesel Engines 535

P T ritth a rt, F Ruhri and W Cartel I ieri

4.8.5.1 The Influence of Cooling Water Temperature 541

4.8.5.3 Effect o f Sulphur Content of Fuel on Lube Oil Particulates 5434.8 5.4 Influence o f Lube Oil Formulation on Particulate Emissions 5444.8.5.5 Effect o f Valve Stem Sealing on Particulate Emissions 5454.8.6 Oil Consumption and Lube Oil Particulates 5464.8.7 Strategy for Lube Oil Particulate Reduction 550

4.9 Gasoline Engine Camshaft Wear: The Culprit is

J.A McGeehan and E.S Yamaguchi

4.9.3 Blow-by Caused Engine Deposits in Gasoline-Engines 554

4.9.6 Search for the Wear-Causing Component in the Blow-by 560

4.9.10 Wear can be Controlled in the Presence o f N itric Acid 5654.9.11 Wear Film Analysed w ith and w itho ut Blow-by 568

4.11.5 Environmentally Relevant Engine Operating Conditions 605

616616616617619619622623624627628628

629

629630631631632633633633635635636

638641643644644

Two-Stroke Engine Oils

Development in Synthetic Lubrication for Air

Cooled Two Cycle Engine Oils: Effect of Esters

on Lubrication and Tribological Properties

D Moura and J.-P Legeron

Summary

Introduction

Two-Stroke Engines and their Conditions of Use

Lubricant Choice and Performance Considerations

Friction Test Procedure

PLINT Friction Machine

Classification o f Two-Stroke Lubricants

API TC and API TD/TE Test Conditions

API TC (ASTM D4859-89)

API TD/API TE

Synthetic Two-stroke Oils: Engine Test Results

Air-cooled Performance According to TSC-1/API TA

Air-cooled Performance According to TSC-3/API TC

Water-cooled Performance According to TSC-4/API TD

(NMMA TC-W) w ith Air-cooled Performance

According to API TC

Air-cooled Performance in Chainsaw Engines

Summary and Conclusions

References

Appendix

648649650650651651653653654654655658658659660

661

661662662663663664665665

666

668

671672672675678683684684685

Transmission and Gearbox

Rear Axle and Wet Brakes

IPTO

Hydraulics

Specification Requirements

Super Tractor Oil Universal

Universal Tractor Transmission Oils

Tractor Lubricants

Super Tractor Oil Universal

Universal Tractor Transmission Oil

Current and Future Developments

Use o f Low Speed FZG Test Methods to Evaluate Tractor Hydraulic Fluids

B.M O'Connor, H Winter

Introduction

Experimental

Full-Scale T ractor Test

Calculation fo r the Full-Scale Tractor Test

Calculation o f Contact Stress

Estimation o f Film Thickness

Establishing FZG Test Conditions

Test Stand

Test Gears

Operating Conditions

Test Lubricants

Test Results and Discussion

Comparison Between Tractor and FZG Test Methods

Evaluation o f Current Generation Fluids (Method B)

Influence o f Water as a Contaminant (Method C)

Influence o f Surface Roughness

Summary

References

Appendix: Symbols and Units

688

689689690690691691691695696699701702

704

704704706706707707709713713713715715717718718

Axle Gear Tester

Test Hypoid Gears

Test Oils

Procedure

Results and Discussion

Gear Protection Performance Under High Temperature and High Speed Conditions

Load Carrying Properties Under High Speed and Shock

The Screening of E.P Oil Formulas by the Use

of a New Hypoid Gear Axle Test

G Venizelosand G Lassau

P Marchand

Summary

Introduction

Objectives and Test Equipment

Recalls on the Principle of the CRC L 42 Test

Severity Level of Test

Correlation w ith the CRC L 42 Test

Conclusions

References

719719719719720720720720721721722722722723725725725726728730731731

732

732734736739739741743746747748749

Automatic Transmission Fluids —

State of the Art

Future Chemistry Needs

Comparison in Key Properties

Comparison in DEXRON® II and MERCON®

Requirements

Comparison in Possible DEXRON® III Properties

Comparison in Industrial Requirements

Japanese ATF Formulations

Environmental Considerations vs Formulation

Conclusions

References

Prediction of Low Speed Clutch Shudder in

Automatic Transmissions Using the Low

Velocity Friction Apparatus

R.F Watts and R.K Nibert

Introduction

Background

Experimental Results

Effect of Mating Steel Surface

Effect of Friction Material

Effect o f Load

Effect of Temperature

Summary

References

Appendix 1 : Standard Test Procedure

Appendix 2: Test Results

752752753753755756758758758758759759760760762

765

765767767767767769770770772775777778778

Lubricant Influence on Ceramic and

Chemical Effects o f Water on Ceramic Tribology

Tribochemical Reaction of Ceramics w ith Water

Formation o f Lubricious Oxides

Chemically Induced Fracture in Oxide Ceramics

Interaction w ith Hydrocarbons

Boundary Lubrication by Paraffins

Effect of Hydrogenation Degree of HSN on

Various Lubricating Oil Additives Resistance

M Oyama, H Shimoda, H Sakakida and T Nakagawa

Introduction

Experimental

Test Samples and Physical Tests

Immersion Test fo r Commercial Lubricating Oils

Lubricating Oil Additive Resistance

The Determinations o f N, Mg, Ca, P, Cl and S Elements

in the Lubricating Oils Tested

Results and Discussions

Resistance o f Lubricating Oils

The Effects o f Unsaturation Degree o f HSN on the

Resistance to Oil Additives

Analysis o f Additives in Lubricating Oil

Conclusions

Acknowledgement

References

7.3 Electro-Chemical Investigation of Deposit

Formations on Mechanical Seal Surfaces for

H Hirabayashi, K K iryu, K Okada, A Yoshino and T Koga

1 Oil Film Thickness in Engine

Bearings

1.1 Measurement of Oil Film Thickness in Big-End Bearings and

Its Relevance to Engine Oil Viscosity Classifications

1.2 Does the Automotive Industry Need a Standard Engine Test

to Measure Journal Bearing Oil Film Thickness?

1.1 Measurement of Oil Film Thickness in Big-End Bearings and Its Relevance to Engine Oil Viscosity Classifications

T.W Bates, Shell Research Ltd., Chester, Great Britain

M.A Vickars, Esso Research Centre, Abingdon, Great Britain

Summary

Minimum oil film thickness (MOFT) measurements have been carried out in big-end bearings o f V -6 and in-line fo ur cylinder gasoline engines during engine operation MOFT decreases w ith increasing crankshaft speed above 2000 r/m in The most severe, practical, steady-state operation is high-speed cruising Maximum shear rates are in the region o f 107 s—1 at 4000 r/m in The dynamic viscosities at a shear rate o f 10® s-1 correlate significantly better w ith mono­grade MOFT data than w ith multigrade data; the correlation parameters for mono- and multigrade data are also significantly different Although the dynamic viscosity measurement correlates w ith multigrade data better than the low-shear-rate kinematic viscosity, the differences are not always significant

at the 95 % confidence level Some other rheological parameter or combination

of parameters may be better than either kinematic or dynamic viscosities

1.1.1 Introduction

Until recently, the most widely used method o f measuring journal bearing performance in operating gasoline or diesel engines was to measure bearing weight loss at the end o f a test which inevitably involved operating under severe conditions o f load and speed in order to obtain metal-to-metal contact ( 1.2) Such tests are the ultimate arbiter for assessing long-term durability perfor­mance They are less than ideal, however, fo r studying the effects o f oil rheology

on journal bearing performance because of: (a) poor test repeatability; and (b) complications arising from operating under boundary/mixed lubrication condi­tions where chemical effects o f the dispersant/inhibitor package complicate interpretation o f the results in terms of oil rheology (1,2) Poor repeatability also makes bearing weight loss experiments unsatisfactory fo r studying the effects o f bearing design on performance

A preferred assessment o f journal bearing performance is measurement o f the oil film thickness during engine operation The latter is critical since it ensures the bearing is subject to relevant dynamic loadings(as opposed to the use o f tactic­ally-loaded journal bearing rigs) Moreover, operation of the bearing under fu ll- film hydrodynamic loading ensures only oil rheology effects are involved Consi­derable progress has been made in the last ten years in instrumenting bearings of engines to allow measurement o f oil film thickness during operation Most o f the activity has centred around main bearings (3-9) Big-end bearings, however, are

of more interest because the combination o f smaller bearing area and severe dynamic loadings make them more prone to field failure than main bearings The problem of making electrical connections to the reciprocating big-end has been overcome by the use o f light-weight, mechanical scissor linkages to support the wires and prevent their premature breakage (10-14)

As part o f an extended CEC programme (15-18) into the effects o f oil visco- metry on engine performance, the CEC Project Group PL-33 has initiated a study of the relationship between oil rheology and oil film thickness in the big-end bearings of tw o different engines This study was initiated partly in response to a request from CCMC for further information on the role o f high- temperature, high-shear viscosity (HTHSV) and other Theological properties on bearing performance, and partly to provide inform ation which could be used as input to the debate on HTHSV classifications and lim its in the SAE Viscosity Classification J300 There is considerable interest at the present time in a better characterization o f the high-temperature performance of lubricants than that provided by the present low-shear, kinematic-viscosity lim its in SAE J300 This interest stems from the trend towards lower viscosity oils fo r easier low-tempe- rature starting and improved fuel economy There is a concern that journal bearing durability problems may arise due to possible lim itations of the kine­matic viscosity as a guide to oil-rheological effects and its lack of relevance

in terms of temperature and shear rate to critical areas of the engine In journal bearings fo r instance shear rates in the region 10s s-1 to 107 s-1 occur

1.1.2 Experimental

1.1.2.1 Engines

The connecting-rod, big-end bearings o f tw o gasoline engines were instrumented One engine was an in-line, four-cylinder, 2.3 litre, fuel-injected unit (hereinafter referred to as the 2.3I L-4 engine) The ungrooved big-end bearings were o f lead/ bronze on a steel backing There was a squirt hole in the upper shell fo r lubri­cation o f the bore The bearing corresponding to cylinder number 1 (pulley-end) was instrumented The other engine was a 60 , V-6 , fuel-injected u n it o f 2.8 litre capacity (referred to as the 2.8I V -6 engine) The ungrooved bearing material was copper/lead on a steel backing w ith an overlay of lead/tin The cylinder of the instrumented bearing was in the middle of the bank Special big-end bearing shells w ith o u t the normal squirt hole in the upper shell were obtained from the engine manufacturer Values o f 40 pm and 25 pm were used fo r the radial

clearances of the instrumented big-end bearings of the 2.3 litre and 2.8 litre engines, respectively These are estimated values based on pre-build inform ation Since the bearings have not been dismantled their present radial clearances are not known precisely Table 1.1.1 gives further inform ation on the engines and the bearing dimensions.

The engines were installed in a test cell, speed and torque being controlled by

a dynamometer Oil temperature was controlled at the gallery by passing the oil through an external oil cooler and electric heater

Table 1.1.1: Test-engine data

★ Estimated fo r the instrumented big-end bearing

1.12 2 Oil Film Thickness Measurement

The oil film thickness in the big-end bearing during engine operation was calculated from measurement o f the total capacitance, C, o f the oil film in the bearing For a cylindrical bearing and shaft (i e no distortion) and in the absence o f cavitation (i e uniform dielectric constant o f the oil in the bearing),

it can be shown (3) that:

Here MOFT is the minimum oil film thickness at a given crankshaft position (see Fig 1.1.1), R is the radial clearance, k the p e rm ittivity o f free space, A the area o f the bearing and e the dielectric constant o f the oil at the temperature and pressure in the bearing

In order to measure capacitance of the oil film in the bearing, the bearing shell was electrically insulated from the connecting rod by replacing ca

200 j/m of metal in the bearing housing by an equal thickness o f alumina cera­mic applied by plasma spraying (see Fig 1.1.1) The journal was earthed by means o f copper braid held in tension over a pulley on the end o f the crank­shaft The bearing shells and the journal now act as a cylindrical capacitor w ith the oil film as dielectric

Figure 1.1.1: Electrical insulation o f the big-end bearing shell fo r the measure­

ment o f the minimum oil film thickness, MOFT, as a function

of crankangle

The oil film capacitance was measured continuously as a function of crank­shaft angle by a capacitive divider circuit (3) in the case o f the 2.31 L-4 engine and by a transformer ratio arm bridge circuit fo r the 2.81 V -6 engine (12)

A check was made (19) that both techniques gave the same capacitance by replacing the ratio-arm circuit by a capacitive divider circuit fo r the 2.8I V -6 engine The ac voltages applied to the bearing capacitor had frequencies of

100 kHz and 20 kHz fo r the 2.3 litre and 2.8 litre engines, respectively The

o utput voltage was used to calculate a capacitance by use of a voltage/capa­citance calibration relationship established by replacing the bearing by a series

of fixed capacitors Further details of the electrical circuits and the data acquisition systems are given elsewhere (3,4,12-14)

Electrical connections were made to the reciprocating big-end bearing by screened cables supported by a light-weight, aluminium-alloy, scissor linkage The linkages were custom b uilt fo r each engine by T&N Technology, Cawston, England and allowed operation at speeds up to 4000 r/m in fo r periods in excess

of 200 hours before wire breakage occured Connections of the wires to the bearing were arranged so that replacement of broken wires could be carried out w ith o u t removal o f the big-end bearing cap, thereby ensuring continuity

of results In the case o f the 2.8I V -6 engine, theoretical calculations (20) established that the linkage did not contribute significantly to loading in the bearing

1.1.2.3 Oils

A series of five mono- and sixteen multigrade oils were specially blended fo r this programme The oils are listed in Table 1.1.2 along w ith their viscosities and dielectric constants Viscosities were measured at 100°C, 130°Cand 150°C

at both low- and high-shear rates (see Table 1.1.2) The low-shear-rate viscosi­ties were measured in an Ubbelohde viscometer (ASTM Procedure D 445) which yields kinematic viscosities, V ^ IT ), at a temperature T The high-shear-rate viscosities were measured in a Ravenfield tapered plug viscometer by CEC procedure L-36-A-87 This procedure provides thedynam ic viscosity, V ^ IT , 10*),

at a temperature T and a fixed shear rate o f 106 s 1

The oils all contained the same (commercial) dispersant/inhibitor SF/CC performance package Conventional base oils from a single source were used, all fully-form ulated oils being blended from the same batches o f base oils The monograde oils covered the four SAE viscosity grades SAE 20, SAE 30, SAE 40 and SAE 50 The sixteen multigrade oils were formulated from four different, commercial, viscosity index (VI) improver types:

namely styrene-isoprene (S-l), styrene-butadiene (S-B), olefin copolymer (OCP) and polymethacrylate (PMA) The base oil and VI improver concentrations were determined by the respective supplier o f the VI improver Each VI improver type was formulated into the follow ing SAE grades: 10W30, 10W40, 15W40 and 20W50

The dielectric constants o f the fresh oils were measured by Southwest Research Institute, San A ntonio, Texas using a brass, cylindrical capacitor and an excitation signal of 100 kHz Results at 100°C are shown in Table 1.1.2 The mean dielectric constant is 2.13, there being little difference between the oils

A value of 2.1 was used throughout these studies, the effects o f temperature between 100°C and 150°C (13,14) and pressure between atmospheric and

100 MPa (21) being small (i e ca 1 %) Changes o f 1 % in dielectric constant alter MOFT as calculated by Equation (1) by about 1 %

1.1.3 Results

Voltage/crankangle curves were averaged over sixteen, 720°, engine cycles in order to minimise the effects o f cycle-to-cycle variations The repeatability is not very sensitive to the number o f cycles averaged, provided it is not less than about eight; sixteen is a somewhat arbitrary, convenient number

Measurements were taken after about one hour o f engine operation to allow temperature equilibrium around the engine to be established MOFT was determined as a function of crankangle fo r each o f the mono- and multigrade oils at the conditions shown in Table 1.1.3 One o f the SAE 40 oils, RL 153, was used fo r a study o f the effects o f engine speed and torque on MOFT; the engine conditions used are shown in Table 1.1.4

Table 1.1.3: Engine conditions used to measure MOFT o f mono- and m u lti­

grade oils

Condition

CrankshaftSpeedr/m in

The method, however, provides excellent precision in terms o f the magnitude

o f MOFT Thus MOFT values fo r repeat tests carried out sequentially are usually

w ithin 1 %: excellent repeatability is also obtained between measurements made on different days fo r the same oil at the same engine condition, e g such repeat tests have a standard deviation o f less than 3 % fo r the 2.8I V -6 engine MOFT values fo r in-house reference oils showed no d rift over the period

in which measurements were made

Table 1.1.4 shows the results o f the various speed/torque studies on the SAE 40

o il, RL 153 In this table, (MOFT)0 is the minimum value o f MOFT, as deter­mined from the MOFT/crankangle curve (see Fig 1.1.2), Gmax is the maximum shear rate (i e the shear rate o f M 0 F T )o — see later) and m is the crankangle locating (MOFT)0 (Note that 0° is top-dead-centre o f the firin g stroke o f the cylinder corresponding to that of the instrumented bearing.) A (MOFT)0 "re­

su lt" as reported in this paper is the mean of tw o sixteen cycle averages in the case o f the 2.3I L-4 engine and of five such averages fo r the 2.8I V -6 engine The individual averages were taken over a five to ten minute period

Table 1.1.4: Effect of torque and crankshaft speed on (MOFT)0 , Gj»,ax< ancl

hm SAE 40 oil RL 153 at a gallery temperature of 100°C

(MOFT)0

(im 106Gmax/s

mdegrees

40 % fo r the 2.3I L-4 big-end bearing than fo r that o f the 2.8I V -6 (i e 1.75 jum

vs 1.26 fxm) It is not possible to state whether this difference is real or is due to

uncertainties about the correct values o f the radial clearance to be used in Equation (1) - see previous section

Thus if a radial clearance o f 20 /xm, instead of 25 /xm, was assumed in Equation

( 1) fo r the 2.8I V -6 engine, the calculated value o f (MOFT)0 would be increased

to 1.59 (im This value would be obtained fo r the 2.31 L-4 engine by using a radial clearance o f 44 fxm instead o f 40 /xm Uncertainties of -t5 fxm are quite

possible fo r the radial clearances o f the big-end bearings since they have not been dismantled