University of Southern Queensland
Faculty of Engineering & Surveying
Spark Ignition Internal Combustion Engine Efficiency
Improvement - a Variable Compression Ratio Option
A thesis submitted by
Ray Malpress
in fulfilment of the requirements of
Doctor of Philosophy
Abstract
ii
Associated Publications
The following publications were produced during the period of candidature:
Malpress, R. and D.R. Buttsworth, ‘Air motor for improved engine brake efficiency: design and preliminary experiments’, in 3rd International Conference on Energy and Environment 2009: Advancement Towards Global Sustainability (ICEE 2009). 2009,
IEEE: Malacca, Malaysia.
Malpress, R. and D. Buttsworth. ‘A comparison of two-position variable compression ratio with continuously variable compression ratio using numerical simulation’ in Amer-ican Society of Mechanical Engineers, 2009 Internal Combustion Engine Division, Fall
Technical Conference. 2009. Lucerne, Switzerland: American Society of Mechanical Engineering.
Malpress, R. and D. Buttsworth. ‘Assessment of an eccentric link in the connecting rod of a spark ignition engine intended for variable compression ratio operation’ in6th Australasian Congress on Applied Mechanics, ACAM 6. 2010. Perth, Australia.
Malpress, R. and D. Buttsworth. ‘Internal combustion engines: a role to fill for trans-port in an energy conscious environment’ in 2010 Southern Region Engineering Con-ference (SREC 2010), 2010, Toowoomba, Australia
Certification of Dissertation
I certify that the ideas, designs and experimental work, results, analyses and conclusions set out in this dissertation are entirely my own effort, except where otherwise indicated and acknowledged.
I further certify that the work is original and has not been previously submitted for assessment in any other course or institution, except where specifically stated.
Ray Malpress 0038170152
Signature of Candidate
Date
ENDORSEMENT
Signature of Supervisor/s
Acknowledgments
I acknowledge the contribution of academic and technical staff of the University of Southern Queensland for their contributions to the work resulting in this dissertation.
I would like to especially thank my principle supervisor Professor David Buttsworth for his technical assistance and strategic advice over the duration of my PhD. My Associate supervisor, Dr Selvan Pather made a significant contribution via his grounding advice, especially early in the candidature.
Work colleagues Dr Alexander Kist, Dr Tony Ahfock and Dr Les Bowtell supplied timely technical advice that undoubtedly reduced the time I required to complete several tasks.
Mr Charlie Weeding ofDC Racing contributed technical advice and machining services for the manufacturer of some of the experimental engine components.
Lastly, I would like to thank my partner, Maree Luck, for her proof reading skills and advice for managing difficult situations during my candidature and of course for her encouragement and support.
Ray Malpress University of Southern Queensland
Contents
Abstract i
Associated Publications iii
Acknowledgments v
List of Figures xv
List of Tables xxiii
Acronyms & Abbreviations xxvi
Chapter 1 Introduction 1
1.1 Objectives . . . 2
1.2 Methods . . . 3
1.3 Dissertation Overview . . . 4
1.3.1 Chapter 2, Analysis of Efficiency Improvement Options . . . 5
CONTENTS vii
1.3.3 Chapter 4, VCR technology, Review, Modelling and New Directions 6
1.3.4 Chapter 5, Two-Position CR Compared with Continuously
Vari-able CR . . . 8
1.3.5 Chapter 6, Eccentric Bush for VCR . . . 9
1.3.6 Chapter 7, Transient Loading of Hydraulic Cylinder without Seals 10 1.3.7 Chapter 8, Hydraulic Connecting Rod . . . 10
1.3.8 Chapter 9, Conclusions and Further Work . . . 11
Chapter 2 Analysis of Passenger Vehicle Options Compelling Internal Combustion Engine Efficiency Improvement 12 2.1 Introduction . . . 12
2.2 Internal Combustion Engine Characteristics and Attributes . . . 13
2.3 Personal Transport Options - Consumers Have Extensive Choice . . . . 15
2.3.1 Introduction . . . 15
2.3.2 Role of Life Cycle Assessment . . . 16
2.4 Effect Of Propulsion Type On Vehicle Consumer Appeal . . . 17
2.4.1 Electric vehicle intrinsic drawbacks . . . 17
2.4.2 Alternative electrical storage systems . . . 18
2.4.3 Electric hybrids - a more usable concept . . . 19
2.4.4 Alternative energy storage technologies . . . 20
CONTENTS viii
2.4.6 Conclusion . . . 22
2.5 Direct Energy Conversion Efficiency At The Vehicle . . . 23
2.5.1 Introduction . . . 23
2.5.2 Spark Ignition ICE . . . 23
2.5.3 Compression Ignition ICE . . . 24
2.5.4 Electric hybrid . . . 25
2.5.5 Battery electric vehicles . . . 25
2.5.6 ICE efficiency for on board energy conversion . . . 27
2.5.7 Conclusion . . . 28
2.6 Life Cycle Assessment of ICE Powered Vehicles, HEVs And BEVs . . . 28
2.7 Variable Compression For Fuel Consumption Improvement . . . 29
2.8 Vehicle Energy Sources . . . 31
2.8.1 Introduction . . . 31
2.8.2 Electrical energy sources . . . 31
2.8.3 ICE powered vehicles can directly use renewable/alternative fuels 32 2.9 Conclusions . . . 33
Chapter 3 Induction Air Motor for Improved Engine Brake Efficiency 34 3.1 Introduction - Throttling Losses . . . 34
3.2 Background on Design of Motor . . . 35
CONTENTS ix
3.3 Prototype Design Based on Preliminary Modelling . . . 40
3.4 Simulation for IAM/Engine Combination . . . 47
3.5 IAM Prototype Design and Build . . . 48
3.5.1 Blow-by analysis . . . 49
3.5.2 Material Selection . . . 51
3.5.3 Prototype Refinement . . . 51
3.6 Model of IAM Performance . . . 54
3.7 Experiment and IAM Performance . . . 58
3.7.1 Experimental Results . . . 58
3.8 IAM Experiment and Model Correlation . . . 64
3.9 IAM Performance Explained . . . 72
3.10 Conclusion . . . 73
Chapter 4 VCR Technology: Review, Modelling and New Directions 75 4.1 Introduction . . . 75
4.2 Review of VCR . . . 76
4.3 Use of Engine Simulation Models in VCR Analyses . . . 80
4.4 The Engine Simulation Models . . . 81
4.5 Identifying Attributes for VCR Devices . . . 86
CONTENTS x Chapter 5 A Comparison of Two-Position CR with a Continuously
Vari-able CR Using Numerical Simulation 92
5.1 Introduction . . . 92
5.2 Validating the Model . . . 93
5.3 Selecting Model Parameters for the VCR Configuration . . . 95
5.4 Fuel Efficiency Assessed Using Vehicle Driving Cycle . . . 98
5.5 Selection of the LVCR . . . 101
5.6 Defining Load Paths for Use in the Model . . . 102
5.7 Vehicle Loads Determined from Coast-Down Test . . . 103
5.8 The Net Fuel Consumption Simulation . . . 105
5.9 Modelled Vehicle Fuel Consumption for NEDC . . . 106
5.10 Results: Comparison of Two-Position with Continuously VCR . . . 107
5.11 Conclusions . . . 108
Chapter 6 Eccentric Bush for VCR 111 6.1 Introduction . . . 111
6.2 Modelling . . . 112
6.2.1 Background . . . 112
6.2.2 Free Body Analysis . . . 112
6.2.3 Implementing the Model in Matlab . . . 116
CONTENTS xi
6.3 Prototype Experiment . . . 120
6.3.1 Prototype Physical Characteristics . . . 124
6.3.2 Measurement of Eccentric Motion using High Speed Video . . . . 129
6.4 Experimental Results and Comparison with Simulation . . . 131
6.4.1 Simulation Improved by Correlation with Experimental Results . 131 6.4.2 Enhanced Simulation . . . 139
6.5 Simulation for Predicting Prototype Motion . . . 146
6.6 Assessment of the Viability of the Eccentric VCR Device . . . 151
Chapter 7 Transient Energy Storage and Recovery Using Oil Under Impact Loading 154 7.1 Introduction . . . 154
7.2 Apparatus . . . 156
7.3 Experimental Approach . . . 159
7.4 Results of the Experiment . . . 162
7.4.1 Test Results . . . 162
7.4.2 Analysis of Cap Shape . . . 166
7.4.3 Analysis of the Effect of Reduced Oil Volume . . . 167
7.4.4 Energy Transfers During the Rebound Event Estimated from Consecutive Drops Test . . . 167
CONTENTS xii
7.5.1 Overview of Analysis . . . 168
7.5.2 Oil Temperature Rise . . . 169
7.5.3 Oil Leakage, Viscous Friction and Thermal Energy loss . . . 174
7.5.4 Shaft Motion Losses . . . 176
7.5.5 Plastic Deformation of the Steel Weight . . . 178
7.5.6 Summary of Distribution of Energy Transfers for the Rebound Event . . . 180
7.6 Discussion and Validation of Simulations . . . 182
7.6.1 Idealised Model . . . 182
7.6.2 Viscous Friction Between Shaft and End Cap . . . 182
7.6.3 Bulk modulus varies with pressure . . . 183
7.6.4 Viscous Drag on Immersed End of Shaft . . . 184
7.6.5 Validation of Model: Discussion . . . 185
7.6.6 Further Validation of Model Performance . . . 186
7.7 Conclusions . . . 188
Chapter 8 Hydraulic Variable Compression Ratio Connecting Rod 189 8.1 Introduction . . . 189
8.2 Hydraulic Connecting Rod Design . . . 190
8.2.1 Introduction . . . 190
CONTENTS xiii
8.2.3 Fixings Considerations . . . 193
8.2.4 Fabrication Considerations . . . 197
8.2.5 Material Selection . . . 197
8.2.6 Control of the Length of the Hydraulic Rod . . . 198
8.3 Hydraulic Rod Fabrication . . . 201
8.4 Hydraulic Rod Prototype Experiment and Analysis . . . 204
8.4.1 Bench Experiment . . . 204
8.4.2 Prototype Experiment Setup . . . 205
8.4.3 Initial Experiment . . . 210
8.4.4 Experiments without Engine Pressure . . . 212
8.4.5 Analysis of High Speed Camera Images . . . 215
8.4.6 Experiments for the Compressing Engine . . . 217
8.4.7 Reproducibility - Wear, Oil Temperature and Speed Effects . . . 225
8.5 Model to Simulate Rod Length Change . . . 232
8.5.1 Description of Model . . . 232
8.5.2 Model Tuning . . . 235
8.5.3 Oil Shear Stress Contributes to Journal Bearing Temperature . . 242
8.6 Simulation Results and Predicted Motion under Firing Pressure . . . 243
8.7 Discussion and Conclusions . . . 247
CONTENTS xiv
9.1 Piston-Rod-Crank Dominance . . . 249
9.2 ICE System Variations to Improve Efficiency . . . 251
9.3 Piston-Rod-Crank Variations to Improve Efficiency . . . 252
9.4 Further Work . . . 253
9.4.1 IAM . . . 253
9.4.2 VCR Hydraulic Rod . . . 253
References 255
Appendix A Definition of LVCR and Associated Factors 265
Appendix B Related VCR Literature 267
Appendix C Derivation of the Eccentric Angular Acceleration 274
Appendix D Derivation of the 2nd Derivative of the Length of the
Hy-draulic Connection Rod 285
List of Figures
2.1 Typical SI engine efficiency map (Adapted from Stone (1999)) . . . 24
2.2 Modelled operating efficiencies for a two position VCR engine . . . 30
3.1 Modelled engine brake power and throttling losses . . . 35
3.2 Solid model of an early design concept for an Induction Air Motor (IAM) 39 3.3 View of the solid model of an early design concept showing the complex-ity design . . . 40
3.4 Solid model of Induction Air Motor (IAM) prototype . . . 41
3.5 Idealised cycle analysis of the IAM. . . 42
3.6 IAM chamber volume diagram . . . 46
3.7 IAM chamber volume diagram for alternative port timing . . . 47
3.8 ESM output showing plots of engine efficiency versus engine BMEP for various parameter inputs . . . 48
3.9 Exploded view of IAM prototype vane assembly . . . 49
3.10 Hub stiffening plates in prototype modification . . . 53
LIST OF FIGURES xvi
3.12 Installed vane showing offset contact with drum. . . 60
3.13 Raw data from the pressure transducer for one revolution (six chambers) of the prototype IAM . . . 67
3.14 Raw data from the pressure transducer of six consecutive revolutions of the IAM prototype . . . 68
3.15 Filtered Data from the pressure transducer of six consecutive revolutions of the IAM prototype . . . 69
3.16 Filtered data from the pressure transducer of six consecutive revolutions of the IAM prototype showing only the last chamber . . . 70
3.17 Correlation between modelled pressure and experimentally measured pressure for the IAM prototype . . . 71
4.1 Surface map of the ignition timing used in the efficiency map model . . 83
4.2 Surface map of the equivalence ratio used in the efficiency map model . 84
4.3 Comparison of published and modelled effciency map . . . 84
4.4 Engine pressure output from Engine Simulation Model using original parameters . . . 85
4.5 Engine pressure output from Engine Simulation Model for late valve closing and atmospheric induction pressure . . . 85
4.6 Comparison of efficiency map for the reduced induction stroke volume, LVCR= 0.6 and the modelled full induction stroke . . . 86
4.7 Image of a typical VCR device (Source: United States Patent 6779495) 87
LIST OF FIGURES xvii
5.2 Typical SI engine efficiency map . . . 95
5.3 Comparison of efficiency map for LVCR of 0.6 and 0.7 . . . 97
5.4 Modelled comparison of efficiency map for LVCR of 0.7 using different ignition timing and burn rates . . . 98
5.5 Surface plot of CVT efficiency employed in the driving cycle modelling 99 5.6 Vehicle speeds used in the NEDC . . . 100
5.7 Alternative Load paths defined for transition through the reduced com-pression stroke maximum power limit . . . 104
5.8 Engine efficiency versus power for three load paths . . . 104
5.9 Cruise drive force and power derived from coast down test - Toyota Camry (1998) . . . 105
5.10 Optimum efficiency at engine power for continuously variable CR . . . . 107
5.11 Modelled engine power over the NEDC . . . 108
6.1 Schematic of crank-eccentric-rod-piston arrangement . . . 113
6.2 Free body diagram of eccentric link for dynamics analysis . . . 115
6.3 Stribeck Diagram . . . 117
6.4 Eccentric motion plot comparing the model implemented in Matlab with ProE and Ansys . . . 119
6.5 Eccentric motion plot comparing the model implemented in Matlab with ProE using friction . . . 120
6.6 The prototype eccentric bush experimental setup . . . 121
LIST OF FIGURES xviii
6.8 The prototype eccentric bush and rod assemble - ProE model exploded view . . . 123
6.9 Photograph of the prototype eccentric release actuation mechanism . . . 125
6.10 Photograph of the prototype eccentric actuation pin - disengaged . . . . 126
6.11 Photograph of the external solenoid activated release mechanism . . . . 126
6.12 Photograph of the prototype eccentric measuring scale . . . 129
6.13 Matlab ‘image’ of prototype eccentric showing measuring technique . . . 130
6.14 Montage of video frames of prototype eccentric showing relative motion of the eccentric . . . 131
6.15 Comparison of experimental results for 500, 1000 and 1500 rpm . . . 132
6.16 Eccentric motion at 500 rpm, experiment and simulation output . . . . 133
6.17 Eccentric motion at 500 rpm, experiment and simulation output, late release investigation . . . 135
6.18 Friction variables, eccentric to crankshaft surfaces at 500 rpm and 60oC 136
6.19 Friction variables, eccentric to connecting rod surfaces at 500 rpm and 60oC . . . 137
6.20 Eccentric motion at 1000 rpm, experiment and simulation basic model parameters . . . 138
6.21 Eccentric motion at 1000 rpm, experiment and simulation basic model parameters - sensitive to temperature . . . 139
6.22 Modified Stribeck diagram . . . 141
LIST OF FIGURES xix
6.24 Eccentric motion at 1000 rpm, Experiment and Simulation output with
modified Stribeck friction . . . 143
6.25 Friction variable eccentric-to-rod bearing surfaces at 1000 rpm and 55oC 143 6.26 Friction variable crank-to-eccentric bearing surfaces, 1000 rpm and 56oC 144 6.27 Eccentric motion at 1500 rpm, experiment and simulation output with modified Stribeck friction . . . 145
6.28 Eccentric motion at 1500 rpm, experiment and simulation output with modified Stribeck friction . . . 146
6.29 Simulated motion for eccentric rod initially long, 1000 rpm . . . 148
6.30 Engine pressure for the VCR switch from high CR to low CR, 2000 rpm 149 6.31 Eccentric motion with and without engine pressure at 2000 rpm . . . 150
6.32 Eccentric motion without engine pressure at 1000 rpm with rod initially short . . . 151
7.1 CAD drawing of the drop guide . . . 157
7.2 Photo (frame from video) of the drop guide . . . 157
7.3 Solid model of hydraulic cylinder . . . 158
7.4 Solid models of hydraulic cylinder caps . . . 160
7.5 Solid model of slide for measuring shaft displacement . . . 161
7.6 Schematic of elements used in heat transfer analysis . . . 171
7.7 CAD drawing of the deformed portion of the weight . . . 179
LIST OF FIGURES xx
7.9 Simulated Shaft displacement over time . . . 186
7.10 Variation of maximum shaft displacement with weight drop height: com-parison of experimental data and simulation . . . 187
8.1 Solid model of the hydraulic rod design . . . 194
8.2 Exploded view of the floating bush . . . 195
8.3 Ansys simulation of pressure generated deflection in the rod body . . . . 196
8.4 One way valve detail in the floating bush . . . 199
8.5 Hydraulic rod control lever detail . . . 200
8.6 Photograph of the rod, control lever and control cam installed in the engine . . . 201
8.7 Photograph of control solenoids . . . 202
8.8 Photograph of camera periscope . . . 206
8.9 Image as seen by the periscope . . . 207
8.10 Photographs of lighting and viewing ports for the high speed camera . 208 8.11 Experimental set up for the prototype . . . 209
8.12 photograph of combustion chamber insert to increase engine compression pressure . . . 210
8.13 Photograph of engine decompression device . . . 211
8.14 Plot of oil temperature dependant motion for the hydraulic rod at two speeds . . . 217
LIST OF FIGURES xxi
8.16 Detail of the portion of the rod visible in the high speed video used to generate the images of the montage . . . 218
8.17 Plot of the number of revolutions required to complete the change in length of the hydraulic rod operating while the engine is compressing . . 221
8.18 Plot of the full pressure data range for test 55 of table 8.6 . . . 222
8.19 Plot of the selected pressure data range for test 35 of table 8.6 used to calculate the ensemble averaged pressure . . . 223
8.20 Ensemble averaged pressure for test 55 of table 8.6 . . . 224
8.21 Pressure trace during the rod length-change from test 55 of Table 8.6 . . 225
8.22 Pressure trace for test 66 of Table 8.6 . . . 226
8.23 Pressure trace for test 20 of Table 8.4 . . . 227
8.24 Pressure trace for stepped reduction in speed for flow through 6 mm intake orifice . . . 231
8.25 Diagram used for analysis of the the motion of the hydraulic rod . . . . 233
8.26 Simulation results using the initial estimates of parameter settings . . . 237
8.27 Simulation results after tuning of damping coefficient . . . 239
8.28 Effective oil temperature in the rod chambers . . . 243
8.29 Simulation results using revised oil temperatures for viscosity . . . 244
8.30 Simulation results for the prototype rod parameters when a motored engine pressure is applied . . . 245
LIST OF FIGURES xxii
8.32 Simulation results for the prototype rod parameters when a fired engine pressure is applied . . . 247
8.33 Simulation results for the prototype rod parameters when a fired engine pressure is applied, reduced clearance between rod and floating bush . . 248
List of Tables
3.1 Initial model analysis results for IAM thermodynamic cycle analysis . . 45
3.2 Original design material selection. . . 51
3.3 Manufacturing constrained material selection changes. . . 52
3.4 Data set 1: IAM experimental data for the late intake port opening configuration . . . 61
3.5 Data set 1: IAM experimental data for the late intake port opening configuration. . . 62
3.6 Data set 2: IAM experimental data for the late intake port opening configuration. . . 63
3.7 Data set 3: IAM experimental data for the early intake port opening configuration. . . 63
3.8 Early Inlet Port Configuration: model calculated indicated torque. . . . 65
3.9 Early Inlet Port Configuration: model calculated indicated torque. . . . 65
3.10 Early Inlet Port Configuration: model calculated indicated torque. . . . 69
LIST OF TABLES xxiv
5.1 Modified parameters for LVCR configurations . . . 97
6.1 Eccentric rod component materials . . . 128
6.2 Eccentric rod part’s mass properties . . . 128
7.1 Long plain cap results for drop heights of 2, 1.5 and 1 m . . . 163
7.2 Short plain cap results for drop heights of 2 m . . . 164
7.3 Long gland cap results for drop heights of 2 m . . . 164
7.4 Short gland cap results for drop heights of 2 m . . . 165
7.5 Short plain cap results for drop heights of 2 m with reduced cylinder oil volume . . . 165
7.6 Short plain cap results for 300 consecutive drop from a height of 2 m . . 166
7.7 Heat transfer model parameters which reproduced the experiment’s mea-sured temperatures . . . 174
7.8 Energy transfers for each impact event . . . 181
8.1 Measured sizes of hydraulic chamber slots and bosses . . . 203
8.2 Experimentally determined speeds to shift to HCR without engine pres-sure applying . . . 213
8.3 Experimentally determined speeds to shift to LCR without engine pres-sure applying . . . 214
LIST OF TABLES xxv
8.5 Experimentally determined number of revolutions required to shift to HCR without engine pressure for varying engine oil temperature at 2000 rpm . . . 216
8.6 Experimentally determined number of revolutions required to shift to HCR with engine pressure at 1600 and 2200 rpm . . . 220
8.7 Reproducibility tests with engine pressure at 1600 and 2200 rpm . . . . 226
8.8 Repeat of rod length-change experiments to identify changes over the duration of tests to the time . . . 228
8.9 Rod length-change at elevated oil temperature with engine pressure . . 229
Acronyms & Abbreviations
ATDC After Top Dead Centre BDC Bottom Dead centre
BEV Battery-powered Electric Vehicle
BICERI British Internal Combustion Engine Research Institute BMEP Brake Mean Effective Pressure
BTDC Before Top Dead Centre CI Compression Ignition CO2 Carbon Dioxide
CR Compression Ratio
CSHEV Charge-Sustaining Hybrid Electric vehicle CVT Continuously Variable Transmission ESM Engine Simulation Model
ESP Engine Simulation Program FEA Finite Element Analysis
GCR Geometric Compression Ratio (GCR) GDI Gasoline Direct Injection
HC Hydro-Carbons
HEV Hybrid Electric Vehicle
HV Heating Value
LIST OF TABLES xxvii
ICE Internal Combustion Engine LCA Life Cycle Assessment LIVC Late Intake Valve Closing
LVCR Late Valve Closing Ratio (defined in Appendix A) MEP Mean Effective Pressure
NEDC New European Driving Cycle NOx Nitrous Oxides
ODE Ordinary Differential Equation PHEV Plug-in Hybrid Electric Vehicles ProE ProEngineer
(Parametric Technology Corporation (PTC) solid modelling) RHC Rockwell Hardness, C
rpm revolutions per minute SI Spark Ignition
SIDI Spark Ignition Direct Injection TDC Top Dead Centre
