Description
Book SynopsisAn Engineering Research Series title.
This excellent and long awaited book is based upon extensive research carried out by the Institute of Tribology at the University of Leeds in the UK and the Ford Motor Company Ltd. It is concerned with both the theoretical and experimental study of the tribological performance of an automobile valve train, having an offset taper cam and a domed follower, incorporated with an hydraulic lash adjuster, with particular reference to the ZETA engine valve train.
A sophisticated theoretical model has been developed that predicts the tribological performance of the valve train, and also provides a useful tool for the consideration of the tribological design of valve trains. Additionally the model can estimate the instantaneous and average rotational frequency of the follower, and the performance of the hydraulic lash adjuster.
In order to validate the theoretical model, the experimental measurements have been correlated with the theoretical predictions that simulate the test conditions of the valve train. The agreement between the measurements and the predictions show that the model is very reliable. This gives readers great confidence in using the model when dealing with novel and alternative designs of the valve train.
COMPLETE CONTENTS:
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Part One – Theoretical Formulation. Kinematics and dynamics of the cam and follower
- Hydraulic lash adjuster
- The maximum hertzian stresses
- Asperity interactions
- The oil film thickness
- Friction and power loss of the valve train
- The rotation of the follower
- The overall solution procedure and input/output data
- An example of the tribological analysis of a valve train.
- Part Two – Experimental Study. Test apparatus and the instrumentation
- Calibration of the instrumentation and commissioning tests
- Test procedure
- Data processing
- Experimental results and discussions
- Part Three – Correlation of theory and experiments. Experimental evidences
- Theoretical predictions
- Comparison of results and discussions
- Overall conclusions.
Table of ContentsSeries Editor's Foreword xi
Authors' Preface xiii
Notation 1
Chapter 1 Introduction 5
Part I Theoretical Formulation
Chapter 2 Kinematics and Dynamics of the Cam and Follower 11
2.1 Introduction 11
2.2 Kinematic analysis of a cam and domed flower pair 11
2.3 The load at the cam/follower interface 13
2.4 The solution procedure 15
2.5 References 15
Chapter 3 Hydraulic Lash Adjuster 17
3.1 Introduction 17
3.2 Check valve closed 17
3.2.1 The dynamics of the plunger 17
3.2.2 The governing equation of the displacement 19
3.2.3 Numerical analysis 20
3.3 Check valve open 21
3.3.1 The dynamics of the plunger 21
3.3.2 The governing equation of the displacement 23
3.3.3 Numerical analysis 24
3.4 The numerical solution procedure 24
Chapter 4 The Maximum Hertzian Stresses 25
4.1 Introduction 25
4.2 The contact geometry 25
4.3 The maximum Hertzian stress 27
4.4 The pressure distribution 27
4.5 The solution procedure 27
4.6 References 28
Chapter 5 Asperity Interactions 29
5.1 Introduction 29
5.2 The asperity contact force 29
5.3 The real area of contact 29
5.4 The asperity contact functions 30
5.5 The solution procedure 30
5.6 References 31
Chapter 6 The Oil Film Thickness 33
6.1 Introduction 33
6.2 The lubricant entraining velocity 33
6.3 The central and the minimum film thickness 35
6.4 The solution procedure 35
6.5 References 36
Chapter 7 Friction and Power Loss of the Valve Train 37
7.1 Introduction 37
7.2 The friction of the cam and follower interface 37
7.2.1 The friction due to shear of the lubricant 37
7.2.2 The friction due to asperity contact 38
7.3 The friction of the follower and bush interface 38
7.3.1 The tilting of the follower 39
7.3.2 The friction model 41
7.4 The friction of the valve and guide interface 42
7.5 The friction of the valve stem and valve seal interface 43
7.6 Power loss of the valve train 43
7.7 The solution procedure 44
7.8 References 44
Chapter 8 The Rotation of Follower 45
8.1 Introduction 45
8.2 The governing equation of the follower rotation 45
8.2.1 The Diving torque of the cam/follower interface 46
8.2.2 The resisting torque of the follower/bush interface 48
8.2.3 The resisting torque of the valve stem/plunger interface 49
8.3 The solution procedure 49
8.4 References 50
Chapter 9 The Overall Solution Procedure and Input and Output Data 51
9.1 Introduction 51
9.2 Input data 51
9.3 The kinematic analysis 51
9.4 The analysis of the hydraulic lash adjuster 51
9.5 Estimating the initial value of the follower rotational frequency 52
9.6 The tribological analysis of the valve train 54
9.7 The friction torque of the camshaft and average power loss 54
9.8 The output data 54
Chapter 10 An Example of the Tribological Analysis of a Valve Train 57
10.1 Introduction 57
10.2 Parameters of the intake valve train of the ZETEC engine 57
10.3 Results of the tribological analysis 59
10.4 A brief discussion of the results 59
10.5 References 60
Part II Experimental Study
Chapter 11 Introduction to Experimental Study 87
11.1 Preamble 87
11.2 The background of the current experimental study 88
11.3 The aim of the experimental study 88
11.4 References 89
Chapter 12 Test Apparatus and the Instrumentation 91
12.1 Introduction 91
12.2 The hydraulic lash adjuster 91
12.3 The data acquisition system 91
12.4 Monitoring the follower rotation 93
12.5 Locating the cam position 94
12.6 Sampling the torque of the camshaft 94
12.7 References 95
Chapter 13 Calibration of the Instrumentation and Commissioning Tests 97
13.1 Introduction 97
13.2 Calibration of the instrumentation 97
13.2.1 The Calibration to the torque measurement system 97
13.2.2 The parasitic friction of the test apparatus 99
13.2.3 The calibration for monitoring the follower rotation 99
13.3 Commissioning tests 100
13.3.1 Improving the signal for the follower rotation100
13.3.2 Tests at different camshaft rotational frequencies 101
13.4 References 101
Chapter 14 The Test Procedure 103
14.1 Introduction 103
14.2 The running-in of the valve train 103
14.3 The loop test 103
14.4 The duration test 104
14.5 Tests at different bulk temperatures References 105
14.6 References 106
Chapter 15 The Data Processing 107
15.1 Introduction 107
15.2 The torque on the camshaft 107
15.3 The rotational frequency of the follower 107
15.4 The camshaft trigger signal 108
15.5 References 109
Chapter 16 Experimental Results and Discussions 111
16.1 Introduction 111
16.2 Experimental variables and the test condition 111
16.3 Experimental results and discussions 112
16.3.1 The friction torque and power loss of the valve train 112
16.3.2 The rotational frequency of the follower 113
16.3.3 Inspection of the cam and the follower 121
16.4 Conclusions 122
16.5 References 124
Part III Correlation Of Theory And Experiments
Chapter 17 Introduction to Correlation of Theory and Experiments 127
Chapter 18 The Experimental Evidence 129
Chapter 19 The Theoretical Predictions 131
19.1 Introduction 131
19.2 Kinematics and dynamics 131
19.3 The cam/follower interface 131
19.4 The follower/bore interface 132
19.5 The hydraulic lash adjuster 133
19.6 The rotation of the follower 133
19.7 References 133
Chapter 20 The Comparison of Results and Discussions 135
20.1 Introduction 135
20.2 The input data of the model simulating the test conditions 135
20.3 The results of comparison and discussions 137
20.3.1 The average friction torque 137
20.3.2 The instantaneous torque on the camshaft 140
20.3.3 The instantaneous friction torque on the camshaft 140
20.3.4 The average follower rotational frequency 145
20.3.5 The instantaneous follower rotational frequency 146
20.4 Conclusions 149
20.5 References 149
Chapter 21 Overall Conclusions 151
Index 153
