Automotive Transmissions (eBook)

Harald Naunheimer studied at the Universität Stuttgart. He got his degree in mechanical engineering in 1988. Afterwards, he worked as a research assistant in the field of automotive transmissions at the Universität Stuttgart. He earned his doctorate in mechanical engineering in 1995. Harald Naunheimer is author of the English edition of “Automotive Transmissions”. From 1995-2001 he worked in the vehicle transmissions division of RENK AG in Augsburg, Germany. He joined ZF in 2001 as a senior manager for application engineering in the automatic transmissions business unit at ZF Getriebe GmbH in Saarbruecken, Germany. From 2006–2009 he was Director of Product Development, Automatic Transmissions for ZF Getriebe GmbH, in Friedrichshafen. Harald Naunheimer was named Vice President of Corporate Research and Development at ZF Friedrichshafen AG during July 2009, headquartered in Friedrichshafen, Germany. Professor Bernd Bertsche earned his degree and doctorate in mechanical engineering at the Universität Stuttgart. Afterwards, he worked for Mercedes-Benz AG in the passenger car development unit followed by a position as professor at the University of Applied Sciences in Albstadt-Sigmaringen. Later, he was appointed at the Universität Stuttgart. Since 2001, Professor Bertsche is the ordinary and director for the Institute of Machine Components at the Universität Stuttgart. Joachim Ryborz studied mechanical engineering and worked as research assistant of Professor Gisbert Lechner in the field of automotive transmissions at the Universität Stuttgart. He earned his doctorate in mechanical engineering in 2003. He is co-author of the 1st English edition of this book as well as coauthor of the 2nd German edition. Since 2002, he has been working in the transmission development for light commercial vehicle at ZF Friedrichshafen AG, amongst others as project manager for manual, automated and hybrid transmissions. Wolfgang Novak studied mechanical engineering at the Universität Stuttgart. From 2002–2003 he worked at McLaren Cars Limited as a development engineer for sports car transmissions. Afterwards, he worked as a research assistant of Professor Bernd Bertsche at the drive technology department and he is co-author of the 2nd German edition. He earned his doctorate in mechanical engineering in 2010. Since 2008, he has been working in the transmission development center at Daimler AG in Stuttgart, Germany.

Preface 7
Contents 9
Terms and Symbols 17
1 Introduction 25
1.1 Preface 25
1.2 History of Automotive Transmissions 31
1.2.1 Basic Innovations 31
1.2.2 Development of Vehicles and Drive Units 33
1.2.3 Stages in the Development of Automotive Transmissions 34
1.2.4 Development of Gear-Tooth Systems and other Transmission Components 44
1.2.5 Development of Torque Converters and Clutches 47
1.2.6 Investigation of Phenomena: Transmission Losses and Efficiency 48
1.2.7 Historical Overview 50
2 Overview of the Traffic – Vehicle – Transmission System 52
2.1 Fundamental Principles of Traffic and Vehicle Engineering 52
2.1.1 The Significance of Motor Vehicles in our Mobile World 54
2.1.2 Trends in Traffic Engineering 58
2.1.3 Passenger and Goods Transport Systems 60
2.1.4 Alternative Transport Concepts 64
2.2 The Market and Development Situation for Vehicles, Gearboxes and Components 65
2.2.1 Market Situation and Production Figures 65
2.2.2 Development Situation 70
2.3 Basic Elements of Vehicle and Transmission Engineering 70
2.3.1 Systematic Classification of Vehicles and Vehicle Use 71
2.3.2 Why do Vehicles Need Gearboxes? 73
2.3.3 Main and Auxiliary Functions of Vehicle Transmissions, Requirements Profile 75
2.3.4 Interrelations: Direction of Rotation, Transmission Ratio, Torque 76
2.3.5 Road Profiles, Load Profiles, Typical Vehicle Use and Driver Types 80
2.4 Fundamental Performance Features of Vehicle Transmissions 82
2.4.1 Service Life and Reliability of Transmissions 82
2.4.2 Centre Distance Characteristic Value 84
2.4.3 Gearbox Mass Characteristic Value 86
2.4.4 Gearbox Cost Characteristic Value 88
2.4.5 Gearbox Noise 89
2.4.6 Gearbox Losses and Efficiency 90
2.5 Trends in Transmission Design 91
3 Mediating the Power Flow 97
3.1 Power Requirement 97
3.1.1 Wheel Resistance 97
3.1.2 Adhesion, Dynamic Wheel Radius and Slip 99
3.1.3 Air Resistance 101
3.1.4 Gradient Resistance 103
3.1.5 Acceleration Resistance 104
3.1.6 Total Driving Resistance 105
3.1.7 Efficiency Map 106
3.2 Diversity of Prime Movers 109
3.2.1 Overview 110
3.2.2 Electric Drive with Electric Energy Accumulator 111
3.2.3 Electric Drive with Fuel Cell 111
3.2.4 Hybrid Drive 113
3.3 Power Output, Combustion Engine Characteristic 117
3.3.1 Torque/Engine Speed Characteristic 119
3.3.2 Engine Spread, Throttle Map 121
3.3.3 Consumption Map 122
4 Power Conversion: Selecting the Ratios 124
4.1 Powertrain 125
4.2 Total Ratio and Overall Gear Ratio 126
4.2.1 Overall Gear Ratio 127
4.2.2 Selecting the Largest Powertrain Ratio 128
4.2.3 Selecting the Smallest Powertrain Ratio 129
4.2.4 Final Ratio 133
4.3 Selecting the Intermediate Gears 133
4.3.1 Velocity/Engine-Speed Diagram 134
4.3.2 Geometrical Gear Steps 135
4.3.3 Progressive Gear Steps 135
4.4 Ratio Variation in Continuously Variable Transmissions 137
5 Matching Engine and Transmission 139
5.1 Traction Diagram 141
5.1.1 Deriving a Traction Diagram (Example) 143
5.1.2 Engine Braking Force 144
5.1.3 Geared Transmission with Dry Clutch 147
5.1.4 Geared Transmission with Torque Converter 147
5.2 Vehicle Performance 150
5.2.1 Maximum Speed 150
5.2.2 Climbing Performance 151
5.2.3 Acceleration Performance 152
5.3 Fuel Consumption 152
5.3.1 Calculating Fuel Consumption (Example) 153
5.3.2 Determining Fuel Consumption by Measurement 155
5.3.3 Reducing Fuel Consumption 157
5.3.4 Continuously Variable Transmissions 158
5.4 Emissions 158
5.5 Dynamic Behaviour of the Powertrain, Comfort 162
6 Vehicle Transmission Systems: Basic Design Principles 164
6.1 Arrangement of the Transmission in the Vehicle 164
6.1.1 Passenger Cars 164
6.1.2 Commercial Vehicles 167
6.1.3 All-Wheel Drive Passenger Cars 170
6.1.4 Transverse and Longitudinal Dynamics with All-Wheel Drive 174
6.2 Transmission Formats and Designs 175
6.2.1 Transmission Format 176
6.2.2 Transmission Design 177
6.3 Basic Gearbox Concept 178
6.3.1 Shifting with Power Interruption 179
6.3.2 Shifting without Power Interruption 180
6.3.3 Continuously Variable Transmissions without Power Interruption 181
6.4 Gear Sets with Fixed Axles, Countershaft Transmissions and Epicyclic Gears 182
6.5 Solution Principles for Part Functions, Evaluation 184
6.5.1 Reverse Gear as Example 185
6.6 Passenger Car Transmissions 187
6.6.1 Manual Passenger Car Transmissions (MT) 188
6.6.2 Automated Manual Passenger Car Transmissions (AMT) 193
6.6.3 Dual Clutch Passenger Car Transmissions (DCT) 196
6.6.4 Automatic Passenger Car Transmissions (AT) 198
6.6.5 Passenger Car Hybrid Drives 206
6.6.6 Continuously Variable Passenger Car Transmissions (CVT) 210
6.7 Commercial Vehicle Transmissions 213
6.7.1 Manual Commercial Vehicle Transmissions (MT) 216
6.7.2 Automated Manual Commercial Vehicle Transmissions (AMT) 231
6.7.3 Commercial Vehicle Torque Converter Clutch Transmissions (TCCT) 237
6.7.4 Automatic Commercial Vehicle Transmissions (AT) 239
6.7.5 Commercial Vehicle Hybrid Drives 240
6.7.6 Continuously Variable Commercial Vehicle Transmissions (CVT) 243
6.8 Final Drives 246
6.8.1 Axle Drives for Passenger Cars 247
6.8.2 Axle Drives for Commercial Vehicles 249
6.8.3 Differential Gears and Locking Differentials 251
6.8.4 Hub Drives for Commercial Vehicles 256
6.8.5 Transfer Gearboxes 257
6.9 Power Take-Offs 258
7 Design of Gearwheel Transmissions for Vehicles 261
7.1 Gearwheel Performance Limits 261
7.1.1 Causes and Types of Damage 263
7.1.2 Calculating the Tooth Root Load Capacity 267
7.1.3 Calculating the Pitting Load Capacity 269
7.1.4 Calculating the Scuffing Load Capacity 270
7.2 Estimating Centre Distance 271
7.3 Estimating Face Widths 273
7.4 Operational Fatigue Strength and Service Life 274
7.4.1 The Wöhler Curve 276
7.4.2 Load Profile and Counting Procedure 278
7.4.3 Damage Accumulation Hypothesis 281
7.5 Developing Low-Noise Transmissions 288
7.5.1 Transmission Noise and Its Causes 289
7.5.2 How Noise Reaches the Ear 293
7.5.3 Assessment Criteria 294
7.5.4 Countermeasures 298
8 Specification and Design of Shafts 302
8.1 Typical Requirements in Vehicle Transmissions 302
8.1.1 Configuration of Shafts in Vehicle Transmissions 302
8.1.2 Designing for Stress and Strength 303
8.1.3 Deflection 304
8.1.4 Vibration Problems 304
8.2 General Design Guidelines 305
8.3 Transmission Drive Shaft Strength Design 307
8.3.1 Loading 307
8.3.2 Bearing Reactions 310
8.3.3 Spatial Beam Deflection 310
8.3.4 Shear Force and Bending Moment Diagrams 311
8.3.5 Critical Cross-Section 313
8.3.6 Stresses 314
8.3.7 Preliminary Specification of the Shaft Diameter 317
8.3.8 Designing for Endurance Strength 318
8.3.9 Designing for Operational Fatigue Strength 318
8.3.10 Common Shaft Materials 320
8.4 Calculating Deformation 320
8.5 Flow Chart for Designing Transmission Shafts 321
9 Gearshifting Mechanisms 324
9.1 Systematic Classification of Shifting Elements 326
9.1.1 Shifting Elements for Transmissions with Power Interruption 327
9.1.2 Shifting Elements for Transmissions without Power Interruption 330
9.1.3 Shift-by-Wire 333
9.2 Layout and Design of Synchronizers 334
9.2.1 Synchronizer Functional Requirements 334
9.2.2 The Synchronizing Process 340
9.2.3 Design of Synchronizers 345
9.2.4 The Tribological System of Synchronizers 358
9.2.5 Engineering Designs 360
9.2.6 Alternative Transmission Synchronizers 366
9.2.7 Detail Questions 367
9.3 Layout and Design of Multi-Plate Clutches 368
9.3.1 Multi-Plate Clutch Requirements 370
9.3.2 The Shifting Process 370
9.3.3 Design of Multi-Plate Clutches 374
9.3.4 Tribological System of Multi-Plate Clutches 379
9.3.5 Engineering Designs 382
9.3.6 Detail Questions 387
9.4 Parking Locks 389
9.4.1 Mechanically Activated Parking Locks 390
9.4.2 Electrically Activated Parking Locks 392
9.4.3 Detail questions 393
10 Moving-Off Elements 395
10.1 Dry Clutches 398
10.1.1 Structure of Dry Clutches 398
10.1.2 Design of Dry Clutches 409
10.1.3 Dry Multi-Plate Clutches 411
10.2 Wet Clutches 412
10.3 Dual Clutches 414
10.4 Hydrodynamic Clutches and Torque Converters 417
10.4.1 Principles 418
10.4.2 Hydrodynamic Clutches and their Characteristic Curves 421
10.4.3 Torque Converters and their Characteristic Curves 423
10.4.4 Engine and Torque Converter Working Together 425
10.4.5 Practical Design of Torque Converters 430
10.4.6 Engineering Designs 430
10.4.7 Design Principles for Increasing Efficiency 434
11 Design and Configuration of Further Design Elements 444
11.1 Bearings 444
11.1.1 Selecting Rolling Bearings 445
11.1.2 Rolling Bearing Design 447
11.1.3 Design of Rolling Bearings 450
11.1.4 Plain Bearings – Bearing Bushes and Thrust Washers 452
11.2 Lubrication of Gearboxes, Gearbox Lubricants 455
11.2.1 Bearing Lubrication 456
11.2.2 Principles of Lubricating Gearwheel Mechanisms 456
11.2.3 Selecting the Lubricant 459
11.2.4 Selecting Lubricant Characteristics 460
11.2.5 Lifetime Lubrication in Vehicle Gearboxes 464
11.2.6 Testing the Scuffing Resistance of Gearbox Lubricants 464
11.3 Oil Supply and Oil Pumps 466
11.3.1 Oil Supply 466
11.3.2 Oil Pumps 469
11.3.3 Detail Questions 475
11.4 Gearbox Housing 477
11.4.1 Gearbox Housing Design 477
11.4.2 Venting Gearboxes 480
11.5 Gearbox Sealing 484
11.5.1 Seals for Static Components 484
11.5.2 Seals for Rotating Components 488
11.5.3 Seals for Reciprocating Round Components 490
11.5.4 Practical Examples 491
11.5.5 Final Inspection for Detecting Leakage 492
11.6 Vehicle Continuous Service Brakes 493
11.6.1 Definitions 494
11.6.2 Engine Braking Systems 495
11.6.3 Retarders 496
11.6.4 Actuation and Use 502
12 Typical Designs of Vehicle Transmissions 503
12.1 Passenger Car Transmissions 503
12.1.1 Manual Passenger Car Transmissions (MT) 505
12.1.2 Automated Manual Passenger Car Transmissions (AMT) 518
12.1.3 Dual Clutch Passenger Car Transmissions (DCT) 522
12.1.4 Automatic Passenger Car Transmissions (AT) 527
12.1.5 Passenger Car Hybrid Drives 535
12.1.6 Continuously Variable Passenger Car Transmissions (CVT) 538
12.2 Commercial Vehicle Transmissions 544
12.2.1 Manual Commercial Vehicle Transmissions (MT) 545
12.2.2 Automated Manual Commercial Vehicle Transmissions (AMT) 554
12.2.3 Commercial Vehicle Torque Converter Clutch Transmissions (TCCT) 562
12.2.4 Automatic Commercial Vehicle Transmissions (AT) 566
12.2.5 Commercial Vehicle Hybrid Drives 570
12.2.6 Continuously Variable Commercial Vehicle Transmissions (CVT) 571
12.3 Final Drives 572
12.3.1 Axle Drives for Passenger Cars 573
12.3.2 Axle and Hub Drives for Commercial Vehicles 575
12.3.3 Differential Gears and Locking Differentials 579
12.4 All-Wheel Drives, Transfer Gearboxes 584
13 Electronic Transmission Control 597
13.1 Networked Systems 597
13.2 Electronic Transmission Control Unit (TCU) 598
13.2.1 TCU Structure 599
13.2.2 Operating Conditions and Construction Technologies 600
13.3 Control Systems 601
13.3.1 Transmission Actuator 603
13.3.2 Clutch Actuator 603
13.3.3 Transmission Control Functions 604
13.3.4 Software 608
13.3.5 Further Examples of Transmission Control Systems 609
13.4 Transmission Calibration with Vehicle-Specific Software Data Input 611
14 Computer-Aided Transmission Development 613
14.1 Principles and Tools 614
14.2 Driving Simulation 618
14.2.1 Simulation of Vehicle Longitudinal Dynamics 619
14.2.2 Route Data Set, Route Data Acquisition 623
15 The Automotive Transmission Development Process 624
15.1 Product Life Cycle 625
15.2 Product Strategy, Product Planning 627
15.3 Release Stages in the Product Development Process 628
15.4 The Design Process and Systematic Design 630
16 Transmission Manufacturing Technology 639
16.1 Process Chains for Steel Part Processing 640
16.1.1 Soft Machining Methods 641
16.1.2 Heat Treatment Methods 641
16.1.3 Hard Machining Methods 641
16.2 Process Chains for Cast Part Processing 642
16.2.1 Casting Methods 643
16.2.2 Machining Cast Parts 644
16.3 Process Chains for Gear Machining 645
16.3.1 Soft Machining Methods 645
16.3.2 Hard Machining Methods 647
16.4 Process Chains for Sheet Metal Machining 647
16.4.1 Sheet Separation 648
16.4.2 Sheet Forming 649
16.5 Manufacturing and Factory Management 650
16.5.1 Work Preparation and Planning 650
16.5.2 Production Systems 650
16.5.3 Statistical Process Control in Manufacture 651
17 Reliability and Testing of Automotive Transmissions 655
17.1 Principles of Reliability Theory 656
17.1.1 Definition of Reliability 656
17.1.2 Statistical Description and Representation of the Failure Behaviour of Components 657
17.1.3 Mathematical Description of Failure Behaviour using the Weibull Distribution 660
17.1.4 Reliability with Systems 665
17.1.5 Availability of Systems 666
17.2 Reliability Analysis of Vehicle Transmissions 667
17.2.1 System Analysis 668
17.2.2 Qualitative Reliability Analysis 670
17.2.3 Quantitative Reliability Analysis 672
17.3 Testing to Ensure Reliability 675
17.3.1 Classifying Vehicle Transmission Test Programs 677
17.3.2 Test Benches for the Test Programs 680
17.3.3 Simulation during Bench Testing 682
References 685
Index of Companies/Transmissions 719
Index of Names 722
Subject Index 723
About the Authors 740