Critical Component Wear in Heavy Duty Engines

The critical parts of a heavy duty engine are theoretically designed for infinite life without mechanical fatigue failure. Yet the life of an engine is in reality determined by wear of the critical parts. Even if an engine is designed and built to have normal wear life, abnormal wear takes place either due to special working conditions or increased loading.  Understanding abnormal and normal wear enables the engineer to control the external conditions leading to premature wear, or to design the critical parts that have longer wear life and hence lower costs. The literature on wear phenomenon related to engines is scattered in numerous periodicals and books. For the first time, Lakshminarayanan and Nayak bring the tribological aspects of different critical engine components together in one volume, covering key components like the liner, piston, rings, valve, valve train and bearings, with methods to identify and quantify wear.

• The first book to combine solutions to critical component wear in one volume
• Presents real world case studies with suitable mathematical models for earth movers, power generators, and sea going vessels
• Includes material from researchers at Schaeffer Manufacturing (USA), Tekniker (Spain), Fuchs (Germany), BAM (Germany), Kirloskar Oil Engines Ltd (India) and Tarabusi (Spain)
• Wear simulations and calculations included in the appendices
• Instructor presentations slides with book figures available from the companion site
  

Critical Component Wear in Heavy Duty Engines is aimed at postgraduates in automotive engineering, engine design, tribology, combustion and practitioners involved in engine R&D for applications such as commercial vehicles, cars, stationary engines (for generators, pumps, etc.), boats and ships. This book is also a key reference for senior undergraduates looking to move onto advanced study in the above topics, consultants and product mangers in industry, as well as engineers involved in design of furnaces, gas turbines, and rocket combustion.

Companion website for the book: www.wiley.com/go/lakshmi

List of Contributors xv

Preface xvii

Acknowledgements xxi

PART I OVERTURE 1

1 Wear in the Heavy Duty Engine 3

1.1 Introduction 3

1.2 Engine Life 3

1.3 Wear in Engines 4

1.3.1 Natural Aging 4

1.4 General Wear Model 5

1.5 Wear of Engine Bearings 5

1.6 Wear of Piston Rings and Liners 6

1.7 Wear of Valves and Valve Guides 6

1.8 Reduction in Wear Life of Critical Parts Due to Contaminants in Oil 6

1.8.1 Oil Analysis 7

1.9 Oils for New Generation Engines with Longer Drain Intervals 8

1.9.1 Engine Oil Developments and Trends 8

1.9.2 Shift in Engine Oil Technology 9

1.10 Filters 9

1.10.1 Air Filter 9

1.10.2 Oil Filter 10

1.10.3 Water Filter 10

1.10.4 Fuel Filter 10

1.11 Types of Wear of Critical Parts in a Highly Loaded Diesel Engine 10

1.11.1 Adhesive Wear 10

1.11.2 Abrasive Wear 11

1.11.3 Fretting Wear 11

1.11.4 Corrosive Wear 11

References 11

2 Engine Size and Life 13

2.1 Introduction 13

2.2 Engine Life 13

2.3 Factors on Which Life is Dependent 14

2.4 Friction Force and Power 14

2.4.1 Mechanical Efficiency 14

2.4.2 Friction 15

2.5 Similarity Studies 15

2.5.1 Characteristic Size of an Engine 15

2.5.2 Velocity 16

2.5.3 Oil Film Thickness 17

2.5.4 Velocity Gradient 18

2.5.5 Friction Force or Power 18

2.5.6 Indicated Power and Efficiency 18

2.6 Archard’s Law of Wear 20

2.7 Wear Life of Engines 20

2.7.1 Wear Life 20

2.7.2 Nondimensional Wear Depth Achieved During Lifetime 21

2.8 Summary 23

Appendix 2.A Engine Parameters, Mechanical Efficiency and Life 25

Appendix 2.B Hardness and Fatigue Limits of Different Copper–Lead–Tin

(Cu–Pb–Sn) Bearings 26

Appendix 2.C Hardness and Fatigue Limits of Different Aluminium–Tin

(Al–Sn) Bearings 28

References 29

PART II VALVE TRAIN COMPONENTS 31

3 Inlet Valve Seat Wear in High bmep Diesel Engines 33

3.1 Introduction 33

3.2 Valve Seat Wear 34

3.2.1 Design Aspects to Reduce Valve Seat Wear Life 34

3.3 Shear Strain and Wear due to Relative Displacement 35

3.4 Wear Model 35

3.4.1 Wear Rate 36

3.5 Finite Element Analysis 37

3.6 Experiments, Results and Discussions 38

3.6.1 Valve and Seat Insert of Existing Design 39

3.6.2 Improved Valve and Seat Insert 39

3.7 Summary 45

3.8 Design Rule for Inlet Valve Seat Wear in High bmep Engines 45

References 45

4 Wear of the Cam Follower and Rocker Toe 47

4.1 Introduction 47

4.2 Wear of Cam Follower Surfaces 48

4.2.1 Wear Mechanism of the Cam Follower 48

4.3 Typical Modes of Wear 50

4.4 Experiments on Cam Follower Wear 51

4.4.1 Follower Measurement 51

4.5 Dynamics of the Valve Train System of the Pushrod Type 52

4.5.1 Elastohydrodynamic and Transition of Boundary Lubrication 52

4.5.2 Cam and Follower Dynamics 53

4.6 Wear Model 55

4.6.1 Wear Coefficient 55

4.6.2 Valve Train Dynamics and Stress on the Follower 55

4.6.3 Wear Depth 61

4.7 Parametric Study 64

4.7.1 Engine Speed 64

4.7.2 Oil Film Thickness 64

4.8 Wear of the Cast Iron Rocker Toe 64

4.9 Summary 66

References 66

PART III LINER, PISTON AND PISTON RINGS 69

5 Liner Wear: Wear of Roughness Peaks in Sparse Contact 71

5.1 Introduction 71

5.2 Surface Texture of Liners and Rings 72

5.2.1 Surface Finish 72

5.2.2 Honing of Liners 72

5.2.3 Surface Finish Parameters 72

5.2.4 Bearing Area Curve 74

5.2.5 Representation of Bearing Area Curve of Normally Honed Surface or Surfaces with Peaked Roughness 75

5.3 Wear of Liner Surfaces 76

5.3.1 Asperities 76

5.3.2 Radius of the Asperity in the Transverse Direction 76

5.3.3 Radius in the Longitudinal Direction 77

5.3.4 Sparse Contact 77

5.3.5 Contact Pressures 79

5.3.6 Friction 79

5.3.7 Approach 80

5.3.8 Detachment of Asperities 80

5.4 Wear Model 81

5.4.1 Normally Honed Liner with Peaked Roughness 81

5.4.2 Normal Surface Roughness 81

5.4.3 Fatigue Loading of Asperities 81

5.4.4 Wear Rate 82

5.4.5 Plateau Honed and Other Liners not Normally Honed 83

5.5 Liner Wear Model for Wear of Roughness Peaks in Sparse Contact 85

5.5.1 Parametric Studies 86

5.5.2 Comparison with Archard’s Model 88

5.6 Discussions on Wear of Liner Roughness Peaks due to Sparse Contact 89

5.7 Summary 92

Appendix 5.A Sample Calculation of the Wear of a Rough

Plateau Honed Liner 93

References 93

6 Generalized Boundary Conditions for Designing Diesel Pistons 95

6.1 Introduction 95

6.2 Temperature Distribution and Form of the Piston 96

6.2.1 Top Land 96

6.2.2 Skirt 96

6.3 Experimental Mapping of Temperature Field in the Piston 97

6.4 Heat Transfer in Pistons 98

6.4.1 Metal Slab 98

6.5 Calculation of Piston Shape 98

6.5.1 Popular Methods Used Before Finite Element Analysis 99

6.5.2 Calculation by Finite Element Method 101

6.5.3 Experimental Validation 103

6.6 Summary 108

References 109

7 Bore Polishing Wear in Diesel Engine Cylinders 111

7.1 Introduction 111

7.2 Wear Phenomenon for Liner Surfaces 112

7.2.1 Bore Polishing 112

7.3 Bore Polishing Mechanism 113

7.3.1 Carbon Deposit Build Up on the Piston Top Land 113

7.3.2 Quality of Fuel and Oil 113

7.3.3 Piston Growth by Finite Element Method 113

7.3.4 Piston Secondary Movement 114

7.3.5 Simulation Program 115

7.4 Wear Model 115

7.4.1 Contact Pressures 115

7.4.2 Wear Rate 116

7.5 Calculation Methodology and Study of Bore Polishing Wear 116

7.5.1 Finite Element Analysis 116

7.5.2 Simulation 117

7.6 Case Study on Bore Polishing Wear in Diesel Engine Cylinders 118

7.6.1 Visual Observations 118

7.6.2 Liner Measurements 119

7.6.3 Results of Finite Element Analysis 119

7.6.4 Piston Motion 121

7.6.5 Wear Profile 123

7.6.6 Engine Oil Consumption 125

7.6.7 Methods Used to Reduce Liner Wear 125

7.7 Summary 127

References 127

8 Abrasive Wear of Piston Grooves in Highly Loaded Diesel Engines 129

8.1 Introduction 129

8.2 Wear Phenomenon in Piston Grooves 130

8.2.1 Abrasive Wear 130

8.2.2 Wear Mechanism 130

8.3 Wear Model 132

8.3.1 Real Contact Pressure 132

8.3.2 Approach 132

8.3.3 Wear Rate 132

8.4 Experimental Validation 134

8.4.1 Validation of the Model 134

8.4.2 Wear Measurement 135

8.5 Estimation of Wear Using Sarkar’s Model 137

8.5.1 Parametric Study 138

8.6 Summary 139

References 140

9 Abrasive Wear of Liners and Piston Rings 141

9.1 Introduction 141

9.2 Wear of Liner and Ring Surfaces 141

9.3 Design Parameters 143

9.3.1 Piston and Rings Assembly 143

9.3.2 Abrasive Wear 143

9.3.3 Sources of Abrasives 144

9.4 Study of Abrasive Wear on Off-highway Engines 144

9.4.1 Abrasive Wear of Rings 144

9.4.2 Abrasive Wear of Piston Pin and Liners 144

9.4.3 Accelerated Abrasive Wear Test on an Engine to Simulate Operation in the Field 146

9.5 Winnowing Effect 149

9.6 Scanning Electron Microscopy of Abrasive Wear 150

9.7 Critical Dosage of Sand and Life of Piston–Ring–Liner Assembly 150

9.7.1 Simulation of Engine Life 151

9.8 Summary 152

References 153

10 Corrosive Wear 155

10.1 Introduction 155

10.2 Operating Parameters 155

10.2.1 Corrosive Wear 155

10.3 Corrosive Wear Study on Off-road Application Engines 156

10.3.1 Accelerated Corrosive Wear Test 156

10.4 Wear Related to Coolants in an Engine 161

10.4.1 Under-cooling of Liners by Design 161

10.4.2 Coolant Related Wear 161

10.5 Summary 165

References 165

11 Tribological Tests to Simulate Wear on Piston Rings 167

11.1 Introduction 167

11.2 Friction and Wear Tests 168

11.2.1 Testing Friction and Wear of the Tribo-System Piston Ring and Cylinder Liner Outside of Engines 168

11.3 Test Procedures Assigned to the High Frequency, Linear Oscillating Test Machine 170

11.4 Load, Friction and Wear Tests 172

11.4.1 EP Test 172

11.4.2 Scuffing Test 172

11.4.3 Reagents and Materials 172

11.5 Test Results 175

11.5.1 Selection of Coatings for Piston Rings 175

11.5.2 Scuffing Tribological Test 178

11.5.3 Hot Endurance Test 179

11.6 Selection of Lubricants 184

11.7 High Performance Bio-lubricants and Tribo-reactive Materials for Clean Automotive Applications 185

11.7.1 Synthetic Esters 185

11.7.2 Polyalkyleneglycols 185

11.8 Tribo-Active Materials 190

11.8.1 Thematic ‘Piston Rings’ 190

11.9 EP Tribological Tests 192

11.9.1 Piston Ring Cylinder Liner Simulation 192

Acknowledgements 194

References 194

PART IV ENGINE BEARINGS 197

12 Friction and Wear in Engine Bearings 199

12.1 Introduction 199

12.2 Engine Bearing Materials 202

12.2.1 Babbitt or White Metal 202

12.2.2 Copper–Lead Alloys 203

12.2.3 Aluminium-based Materials 204

12.3 Functions of Engine Bearing Layers 205

12.4 Types of Overlays/Coatings in Engine Bearings 206

12.4.1 Lead-based Overlays 208

12.4.2 Tin-based Overlays 208

12.4.3 Sputter Bearing Overlays 208

12.4.4 Polymer-based Overlays 208

12.5 Coatings for Engine Bearings 209

12.6 Relevance of Lubrication Regimes in the Study of Bearing Wear 210

12.6.1 Boundary Lubrication 212

12.6.2 Mixed Film Lubrication 215

12.6.3 Fluid Film Lubrication 216

12.7 Theoretical Friction and Wear in Bearings 217

12.7.1 Friction 217

12.8 Wear 218

12.9 Mechanisms of Wear 219

12.9.1 Adhesive Wear 220

12.9.2 Abrasive Wear 223

12.9.3 Erosive Wear 230

12.10 Requirements of Engine Bearing Materials 234

12.11 Characterization Tests for Wear Behaviour of Engine Bearings 238

12.11.1 Fatigue Strength 239

12.11.2 Pin-on-disk Test 239

12.11.3 Scratch Test for Bond Strength 241

12.12 Summary 251

References 252

PART V LUBRICATING OILS FOR MODERN ENGINES 253

13 Heavy Duty Diesel Engine Oils, Emission Strategies and their Effect on Engine Oils 255

13.1 Introduction 255

13.2 What Drives the Changes in Diesel Engine Oil Specifications? 256

13.2.1 Role of the Government 256

13.2.2 OEMs’ Role 257

13.2.3 The Consumer’s Role 258

13.3 Engine Oil Requirements 258

13.3.1 Overview and What an Engine Oil Must Do 258

13.4 Components of Engine Oil Performance 265

13.4.1 Viscosity 265

13.4.2 Protection against Wear, Deposits and Oil Deterioration 268

13.5 How Engine Oil Performance Standards are Developed 268

13.5.1 Phase 1: Category Request and Evaluation (API, 2011a, pp. 36, 37) 269

13.5.2 Phase 2: Category Development (API, 2011a, pp. 41, 42) 271

13.5.3 Phase 3: Category Implementation (API, 2011a, p. 45) 273

13.5.4 API Licensing Process 275

13.6 API Service Classifications 276

13.7 ACEA Specifications 276

13.7.1 Current E Sequences 278

13.8 OEM Specifications 279

13.9 Why Some API Service Classifications Become Obsolete 279

13.10 Engine Oil Composition 280

13.10.1 Base Oils 280

13.10.2 Refining Processes Used to Produce Lubricating Oil Base Stocks 281

13.10.3 Synthetic Base Oils 285

13.10.4 Synthetic Blends 286

13.10.5 API Base Oil Categories 286

13.11 Specific Engine Oil Additive Chemistry 290

13.11.1 Detergent–Dispersant Additives 290

13.11.2 Anti-Wear Additives 294

13.11.3 Friction Modifiers 295

13.11.4 Rust and Corrosion Inhibitors 296

13.11.5 Oxidation Inhibitors (Antioxidants) 296

13.11.6 Viscosity Index Improvers 298

13.11.7 Pour Point Depressants 300

13.11.8 Foam Inhibitors 301

13.12 Maintaining and Changing Engine Oils 302

13.12.1 Oil Change Intervals 303

13.12.2 Used Engine Oil Analysis 303

13.13 Diesel Engine Oil Trends 306

13.14 Engine Design Technologies and Strategies Used to Control Emissions 306

13.14.1 High Pressure Common Rail (HPCR) Fuel System 309

13.14.2 Combustion Optimization 310

13.14.3 Advanced Turbocharging 312

13.14.4 Exhaust Gas Recirculation (EGR) 313

13.14.5 Advanced Combustion Emissions Reduction Technology 314

13.14.6 Crankcase Ventilation 315

13.14.7 Exhaust After-Treatment 315

13.14.8 On-Board Diagnostics (OBD) 324

13.15 Impact of Emission Strategies on Engine Oils 324

13.15.1 Impact of Cooled EGR on Engine Oil 325

13.15.2 Effects of Post-Injection on Engine Oils 327

13.16 How Have Engine Oils Changed to Cope with the Demands of Low Emissions? 328

13.17 Most Prevalent API Specifications Found In Use 329

13.17.1 API CH-4 329

13.17.2 API CI-4 330

13.17.3 API CI-4 Plus 331

13.17.4 API CJ-4 333

13.18 Paradigm Shift in Engine Oil Technology 336

13.18.1 Backward Compatibility and Engine Tests 337

13.18.2 New Engine Sequence Tests 338

13.18.3 Previous Engine Oil Sequence Tests 343

13.18.4 Differences Between CJ-4 and Previous Categories and Benefits of Using CJ-4 Engine Oils 347

13.19 Future Engine Oil Developments 348

13.20 Summary 352

References 353

PART VI FUEL INJECTION EQUIPMENT 355

14 Wear of Fuel Injection Equipment 357

14.1 Introduction 357

14.2 Wear due to Diesel Fuel Quality 357

14.2.1 Lubricity of Mineral Diesel Fuel 357

14.2.2 Oxygen Content of Biodiesel 361

14.3 Wear due to Abrasive Dust in Fuel 361

14.3.1 Wear of Injector Nozzle due to Heat and Dust 361

14.3.2 Fuel Filters 364

14.4 Wear due to Water in Fuel 365

14.4.1 Corrosive Wear due to Water Ingress 365

14.4.2 Use of Emulsified Water for Reducing Nitric Oxides in Large Engines 365

14.4.3 Microbiological Contamination of Fuel Systems 366

14.4.4 Water Separators 367

14.5 Summary 367

References 367

PART VII HEAVY FUEL ENGINES 369

15 Wear with Heavy Fuel Oil Operation 371

15.1 Introduction 371

15.2 Fuel Treatment: Filtration and Homogenization 373

15.3 Water and Chlorine 374

15.3.1 Fuel Injection Equipment 374

15.4 Viscosity, Carbon Residue and Dust 374

15.4.1 Fuel Injection Equipment 374

15.5 Deposit Build Up on Top Land and Anti-polishing Ring for Reducing the Wear of Liner, Rings and Piston 375

15.6 High Sulfur in Fuel 377

15.6.1 Formation of Sulfuric Acid 377

15.6.2 Mechanism of Corrosive Attack by Sulfuric Acid 377

15.6.3 Control of Corrosion by Basicity and Oil Consumption 378

15.6.4 Control of Sulfur Corrosion by Maintaining Cooling Water Temperature High 379

15.7 Low Sulfur in Fuel 380

15.7.1 Lubricity 380

15.7.2 Lack of Formation of Oil Pockets on the Liner Bore 381

15.7.3 Sudden Severe Wear of Liner and Rings 382

15.8 Catalyst Fines 383

15.9 High Temperature Corrosion 383

15.9.1 Turbocharger 385

15.9.2 Exhaust Valves 385

15.10 Wear Specific to Four-stroke HFO Engines 388

15.10.1 Wear of Bearings 388

15.10.2 Inlet Valve 391

15.10.3 Corrosive Wear of Valve Tips 391

15.11 New Engines Compliant to Maritime Emission Standards 391

15.11.1 Steps to Satisfy Emission Standards 391

15.12 Wear Life of an HFO Engine 393

15.13 Summary 393

References 394

PART VIII FILTERS 397

16 Air and Oil Filtration and Its Impact on Oil Life and Engine Wear Life 399

16.1 Introduction 399

16.2 Mechanisms of Filtration 400

16.3 Classification of Filtration 400

16.3.1 Classification by Filter Media 401

16.3.2 Classification by Direction of Flow 402

16.3.3 Classification by Filter Size 402

16.4 Filter Rating 403

16.4.1 Absolute Rating 403

16.4.2 Nominal Rating 403

16.4.3 Mean Filter Rating 403

16.4.4 b Ratio 403

16.4.5 Efficiency 404

16.5 Filter Selection 404

16.6 Introduction to Different Filters in the Engine 405

16.6.1 Air Filters 405

16.6.2 Cleaning Air Filters and Impact on Wear Life 409

16.7 Oil Filters and Impact on Oil and Engine Life 409

16.7.1 Oil Performance and Life 410

16.7.2 Oil Stress 411

16.7.3 Application of the Concept of Oil Stress 413

16.7.4 Advances in Oil Filter Technology 413

16.8 Engine Wear 413

16.8.1 Method to Predict Wear of Critical Engine Components 415

16.9 Full Flow Oil Filters 415

16.9.1 Bypass Filters 417

16.9.2 Centrifugal Filters 418

16.10 Summary 419

Appendix 16.A Filter Tests and Test Standards 419

References 419

Index 421

P.A. Lakshminarayanan is the Head of R&D at Ashok Leyland in India. He has been the team leader or lead designer of about 10 diesel and CNG engines for different applications. He has guided 2 PhDs at IIT Delhi and 4 M.Techs at IIT Madras, and has published 40 papers in ASME, SAE, IMechE, and AVL journals and conferences. Previous appointments include 20 years from Manger to Senior General Manger of R&D at Kirloskar Oil Engines Ltd, over 15 years as a Visiting Lecturer at IIT Madras, and 5 years as a Research Associate to J.C. Dent at Loughborough University of Technology. He is a Fellow of SAE-International. Lakshminarayanan holds a B.Tech, and M.S. and a PhD from IIT Madras.

Nagaaraj S. Nayak is a Professor of Mechanical Engineering based at Sahyadri College of Engg. & Management. Previously, he was a Senior Manager at the R&D department of Kirloskar Oil Engines Ltd for 9 years, and was a Postdoctoral Fellow at University of Wisconsin Madison for 2 years. He has been a team leader for emission upgrades on 3 engines platforms, and performance development of 2 new engine platforms.