Advanced Direct Injection Combustion

i Advanced direct injection combustion engine technologies and development ii Related titles: The science and technology of materials in automotive engines (ISBN 978-1-85573-742-6) This authoritative book provides an introductory text on the science and technology of materials used in automotive engines It focuses on reciprocating engines, both four and two-stroke, with particular emphasis on their characteristics and the types of materials used in their construction The book considers the engine in terms of each specific part: the cylinder, piston, camshaft, valves, crankshaft, connecting rod and catalytic converter The materials used in automotive engines are required to fulfil a multitude of functions It is a subtle balance between material properties, essential design and high performance characteristics The intention here is to describe the metallurgy, surface modification, wear resistance, and chemical composition of these materials It also includes supplementary notes that support the core text HCCI and CAI engines for the automotive industry (ISBN 978-1-84569-128-8) HCCI/CAI has emerged as one of the most promising engine technologies with the potential to combine fuel efficiency and improved emissions performance Despite the considerable advantages, its operational range is rather limited and controlling the combustion (timing of ignition and rate of energy release) is still an area of on-going research However, commercial applications are close to reality This book reviews the key international research on optimising its use, including gasoline HCCI/CAI engines, diesel HCCI engines, HCCI/CAI engines with alternative fuels, and advanced modelling and experimental techniques Tribology and dynamics of engine and powertrain: Fundamentals, applications and future trends (ISBN 978-1-84569-361-9) Tribology is one element of many interacting within a vehicle engine and powertrain In adopting a detailed, theoretical, component approach to solving tribological problems, the minutiae can be overwhelmingly complex and practical solutions become elusive and uneconomic The system perspective generally adopted in industry, however, can lead to shortcuts and oversimplifications, industrial projects are subject to ad hoc trial and error, and subsequent ‘fire-fighting’ activity is required This book seeks to bridge this divide, using a multi-physics approach to provide sufficient fundamental grounding and understanding of both detailed and approximate analyses – thereby making ‘first time right’ design solutions possible Tribological issues and solutions in piston systems, valve train systems, engine bearings and drivetrain systems are addressed New developments in materials, micro-engineering, nano-technology and MEMS are also included Details of these and other Woodhead Publishing books can be obtained by: ∑ visiting our web site at www.woodheadpublishing.com ∑ contacting Customer Services (e-mail: sales@woodheadpublishing.com; fax: +44 (0) 1223 893694; tel.: +44 (0) 1223 891358 ext.130; address: Woodhead Publishing Limited, Abington Hall, Granta Park, Great Abington, Cambridge CB21 6AH, UK) If you would like to receive information on forthcoming titles, please send your address details to: Francis Dodds (address, tel and fax as above; e-mail: francis.dodds@woodhead publishing.com) Please confirm which subject areas you are interested in iii Advanced direct injection combustion engine technologies and development Volume 1: Gasoline and gas engines SUPERIOR DOWNSIZING Edited by OUR COMPETENCE FOR YOUR SUCCESS Hua Zhao Turbocharged engines, in conjunction with innovative technologies, provide the optimum solution for improved fuel economy and lower emissions Our downsizing engine with a displacement of 1.2 liters, which we developed as a technology demonstrator, offers the performance of a conventional engine twice the size More importantly, it reduces fuel consumption, and consequently CO2 emissions by up to 30 percent Our numerous high-performance projects and systems contribute to this achievement As a result of this extensive systems expertise, MAHLE is the leading development partner for the international automotive and engine industry www.mahle-powertrain.com Unbenannt-2 13.05.2009 10:46:20 CRC Press Boca Raton Boston New York Washington, DC Woodhead publishing limited Oxford    Cambridge    New Delhi iv Published by Woodhead Publishing Limited, Abington Hall, Granta Park, Great Abington, Cambridge CB21 6AH, UK www.woodheadpublishing.com Woodhead Publishing India Private Limited, G-2, Vardaan House, 7/28 Ansari Road, Daryaganj, New Delhi – 110002, India www.woodheadpublishingindia.com Published in North America by CRC Press LLC, 6000 Broken Sound Parkway, NW, Suite 300, Boca Raton, FL 33487, USA First published 2010, Woodhead Publishing Limited and CRC Press LLC © 2010, Woodhead Publishing Limited; Ch © J.W.G Turner and R.J Pearson The authors have asserted their moral rights This book contains information obtained from authentic and highly regarded sources Reprinted material is quoted with permission, and sources are indicated Reasonable efforts have been made to publish reliable data and information, but the authors and the publishers cannot assume responsibility for the validity of all materials Neither the authors nor the publishers, nor anyone else associated with this publication, shall be liable for any loss, damage or liability directly or indirectly caused or alleged to be caused by this book Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming and recording, or by any information storage or retrieval system, without permission in writing from Woodhead Publishing Limited The consent of Woodhead Publishing Limited does not extend to copying for general distribution, for promotion, for creating new works, or for resale Specific permission must be obtained in writing from Woodhead Publishing Limited for such copying Trademark notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation, without intent to infringe British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging in Publication Data A catalog record for this book is available from the Library of Congress Woodhead Publishing ISBN 978-1-84569-389-3 (book) Woodhead Publishing ISBN 978-1-84569-732-7 (e-book) CRC Press ISBN 978-1-4398-0208-3 CRC Press order number: N10046 The publishers’ policy is to use permanent paper from mills that operate a sustainable forestry policy, and which has been manufactured from pulp which is processed using acid-free and elemental chlorine-free practices Furthermore, the publishers ensure that the text paper and cover board used have met acceptable environmental accreditation standards Typeset by Replika Press Pvt Ltd, India Printed by TJ International Limited, Padstow, Cornwall, UK v Contents Contributor contact details ix Preface xi Overview of gasoline direct injection engines H Zhao, Brunel University, UK 1.1 1.2 1.3 Introduction Overview of direct injection gasoline engines Potential and technologies for high-efficiency direct injection (DI) gasoline engine High-pressure fuel injection system Exhaust emissions and aftertreatment devices Summary References 1.4 1.5 1.6 1.7 2.1 2.2 2.3 Stratified-charge combustion in direct injection gasoline engines U Spicher and T Heidenreich, Universität Karlsruhe (TH), Germany 11 14 17 18 20 20 21 2.4 2.5 Introduction Thermodynamic and combustion process Production engines with stratified gasoline direct injection (GDI) Future trends References The turbocharged direct injection spark-ignition engine J W G Turner and R J Pearson, Lotus Engineering, UK 45 3.1 3.2 3.3 Introduction 45 Historical background: turbocharging for high specific output 46 Problems and challenges associated with turbocharging the spark-ignition (SI) engine 51 36 42 43 vi Contents 3.4 Advantages of combining direct injection and turbocharging in spark-ignition (SI) engines 65 Challenges of applying direct injection to a turbocharged spark-ignition (SI) engine 74 Future trends and possibilities 75 Summary 83 References 84 3.5 3.6 3.7 3.8 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 5.1 5.2 5.3 5.4 5.5 5.6 5.7 6.1 6.2 6.3 The lean boost combustion system for improved fuel economy T Lake, J Stokes, R Osborne, R Murphy and M Keenan, Ricardo UK Ltd, UK Pressures on the gasoline engine Downsizing strategies The lean-boost direct injection (LBDI) concept Exhaust emissions control: drive-cycle emissions Exhaust emissions control: off-cycle emissions Selective catalytic reduction (SCR) NOx control as an alternative to lean NOx trap (LNT) Conclusions Future trends Exhaust gas recirculation boosted direct injection gasoline engines A Cairns, H Blaxill and N Fraser, MAHLE Powertrain Ltd, UK Introduction Fundamentals of wide-open-throttle exhaust gas recirculation (WOT- EGR) operation Exhaust gas recirculation (EGR) circuit design Exhaust gas recirculation (EGR) operating maps In-vehicle requirements Future trends References Direct injection gasoline engines with autoignition combustion H Zhao, Brunel University, UK 91 91 93 93 99 99 101 103 104 105 105 108 115 124 127 130 131 133 Introduction 133 Principle of autoignition combustion in the gasoline engine 135 Approaches to autoignition combustion operation in gasoline engines 137 Contents 6.4 6.5 6.6 6.7 7.1 7.2 7.3 vii Operation and control of direct injection gasoline engines with autoignition combustion 146 Development of practical gasoline engines with autoignition and spark-ignition (SI) combustion 158 Future trends 161 References 163 Design and optimization of gasoline direct injection engines using computational fluid dynamics 166 J Yi, Ford Research and Advanced Engineering, Research and Innovation Center, USA 166 169 7.6 7.7 Introduction Direct injection spark-ignition (DISI) injector technologies Homogeneous-charge direct injection (DI) system design and optimization Stratified-charge direct injection (DI) combustion system design and optimization Turbo-charged or super-charged direct injection (DI) combustion system design and optimization Future trends References and further reading Direct injection natural gas engines D Zhang, Westport Innovations Inc., Canada 199 8.1 8.2 8.3 8.4 8.5 8.6 8.7 Introduction Technologies Potential applications Strengths and weaknesses Future trends Sources of further information and advice References 199 200 221 222 225 227 228 Biofuels for spark-ignition engines 229 J D Pagliuso, University of São Paulo, Brazil and M E S Martins, Sygma Motors, Brazil 9.1 9.2 9.3 9.4 9.5 9.6 9.7 Introduction Types and sources of biofuels Performance Emissions Operation Conclusions References 7.4 7.5 173 189 192 194 196 229 231 237 246 253 255 256 viii Contents 10 260 Optical diagnostics for direct injection gasoline engine research and development V Sick, The University of Michigan, USA 10.1 10.2 10.3 10.4 10.5 Need for and merit of optical diagnostics Applications of optical diagnostics Future trends Conclusions References 260 262 278 279 279 Index 287 ix Contributor contact details (*= main contact) Chapter Chapter Professor Hua Zhao Brunel University West London Uxbridge UB8 3PH UK James W G Turner* and Dr Richard J Pearson Lotus Engineering Hethel Norwich Norfolk NR18 4EZ UK Email: hua.zhao@brunel.ac.uk Chapter Professor Dr Ulrich Spicher* and Thomas Heidenreich Institut für Kolbenmaschinen Universität Karlsruhe (TH) PO box 6980 76128 Karlsruhe Germany Email: ulrich.spicher@ifkm.unikarlsruhe.de; thomas.heidenreich@ ifkm.uni-karlsruhe.de E-mail: JTurner@lotuscars.co.uk; RPearson@lotuscars.co.uk Chapter Dr Tim Lake,* J Stokes, R Osborne, R Murphy and M Keenan Ricardo UK Ltd UK Email: Tim.lake@ricardo.com Chapter Dr Alasdair Cairns*, Hugh Blaxill and Neil Fraser MAHLE Powertrain Ltd Northampton UK E-mail: alasdair.cairns@gb.mahle.com 296 Index port fuel injection, 107 analysis of losses, 33 vs gasoline direct injection, comparison of combustion process, 34 potential reserves, 224 premixed combustion, 202 pressure atomisation, 13 pressure charging, 46 ProCo system, production engine stratified gasoline direct injection, 36–42 first-generation gasoline direct injection engines, 37–9 second-generation gasoline direct injection engines, 39–42 production ignition system, 96 propane-fueled square-piston engine, 276 proven reserves, 224 pulse-divided turbocharger, 62–3 concept in turbocharged engines, 63 pushback process, 188 pyrometry, Plate XII Rayleigh scattering, 270–1, 276 Reid vapour pressure, 247, 248, 252 Renault turbocharged V6 Formula engine, 50 reservoirs, 211–12 residual gas trapping method, 152 reverse-mode thermodynamic analysis, 112 reverse tumble concept, 189 Reynolds decomposition, 263 Reynolds stresses, 263 rhodium, 103, 104 Rolls-Royce Crecy, RON gasoline, 83, 244 Royal Aircraft Establishment, 47 Saturn Aura, 161 SCR, see selective catalytic reduction selective catalytic reduction, 16, 101–3 SI combustion mode, 246 Siemens piezo injector, 173 Siemens swirl injector, 170 simple pressure-modulating solenoid valve, 160 single-cylinder testing, 188 slit injector, 173 Smart Idling Stop System, 10–11 solenoid actuators, 213 soot formation, 184 soot luminosity, 270 spark-assisted autoignition combustion, 157 spark-assisted compression-ignition, 261 spark ignition gasoline engines, xi spark-ignition (SI) engines biofuels, 229–55 emissions, 246–53 operation, 253–5 performance, 237–46 types and sources of biofuels, 231–7 combustion development of gasoline engines with autoignition and SI combustion, 158–61 successful CAI–SI and SI–CAI transitions, 162 valve lift profiles adopted by electromechanical camless system, 159 split injection, 73 spray-guided combustion systems, 27–32, 35–6, 189, 190, 192, 264, 265, 274 exhaust gas treatment, 35–6 fuel consumption, 32, 35 fuel economy in first- and secondgeneration DI vs port fuel injection, 36 nozzle types comparison, 29–31 spray profiles, 30 theoretical efficiency, 28 thermodynamic analysis, 31–2 spray-guided direct injection engine, 274 spray-guided spark-ignition direct injection engines, 264 spray nozzle, 29–31 stainless steel, 210 stillage, 234 stratified charge combustion direct injection gasoline engines, 20–43 future trends, 42–3 Index production engines with stratified gasoline direct injection, 36–42 thermodynamic and combustion process, 21–32, 35–6 stratified-charge DI combustion system, 189–92 cross-section through the spark gap at 25∞ bTDC for idle operation, 193 effect of spray cone angle for swirl injector, 191 Toyota stratified-charge combustion system, 190 sugar cane, 233–4 sugarcane bagasse, 232 sulfur dioxide, 269 supercharged DI combustion system, 192–4 supercharged engine, 206 swirl, 175, 188 control valve, 182, 184 injector, 191 ratio, 175 syngas, 230 approximate composition, 232 temperature control valve, 138 thermal energy, 59 thermal radiation, 271, 274 thermodynamics, 21–36 air-guided combustion systems, 26–7 comparison of wall-, air-, and spray-guided combustion, 25 constant-volume processes for port fuel injection and direct injection, 23 engine operation maps, 25 operating modes for gasoline direct injection engines, 24 principles, 108 spray-guided combustion systems, 27–32, 35–6 exhaust gas treatment, 35–6 fuel consumption, 32, 35 nozzle types comparison, 29–31 thermodynamic analysis, 31–2 thermal efficiency of the constantvolume process, 22 wall-guided combustion systems, 25–6 297 thermosyphon, 53 three-way catalyst, 112, 127, 130 titanium, 210 toluene, 266, 271, 274 Top Dead Centre (TDC), 142 Toyota’s 3GR-FSE engine, 182 tracer-LIF, 270 Tradescantia KU 20, 253 TSI 1.4 litre DI gasoline engine, tumble, 175, 188 tumble ratio, 175 turbo-charged DI combustion system, 192–4 engine design with less flow capacity for higher tumble ratio, 195 turbocharged engine, 206 turbocharged gasoline direct fuel injection engine, 106 turbocharger lag, 48, 54–7 BMW diesel configuration, 56 turbocharged engine transient and steady-state torque curves, 55 turbocharging direct injection spark-ignition engine, 45–84 advantages of combining with direct injection engines, 65–73 challenges in direct injection application, 74–5 future trends and possibilities, 75–83 historical background, 46–51 problems and challenges, 51–65 turboexpansion, 60–1 system in a turbocharged engine, 60 temperature-entropy, 61 turbulence intensity, 188 typical tumble port concept, 181 unburned hydrocarbon, 14–15, 64–5 urea, 101 US06 cycle driving, 102 US Tier Bin 5, 101 validated system simulation, 95 valve event timing, see variable cam timing vaporisation, 71–2 variable cam timing, 138, 186 devices, 159 298 Index variable compression ratio, 139 variable nozzle turbine, 94 variable valve actuation camless system, 143 variable valve train, 81 vinasse, 234 Viton, 254 Volkswagen Fox, 252 vortex induced stratified combustion concept, 190 VVA, see variable valve actuation camless system VW Lupo FSI, 38–9 wall-guided combustion system, 11, 13, 25–6, 189, 190, 270 wastegate, 48–9 Wave model, 205 wet ethanol, 246 wide open throttle EGR (WOT-EGR), 108–15, 127, 129 Wiebe function, 112 Woschni correlation, 112 WOT-EGR, see wide open throttle EGR Zamac, 254 CA = 460° (a) High flow port (b) High tumble port Plate I Comparison of near-valve flow structure between high flow port (left) and high tumble port (right) The high flow port has a more uniform velocity flow field around the valve seat area, while the high tumble port shows a more biased flow structure with flow separation on the short side of the port The operating condition is full load at 5000 rpm (Iyer and Yi, 2008) Air-fuel ratio 24.0 19.5 20° bTDC 60° bTDC 100° bTDC 15.0 10.5 6.0 Plate II Air–fuel ratio distribution at 6000 rpm full load in the initial combustion system design The start of injection is 10° After Top Dead Center (aTDC) in the intake stroke The injection duration is about 188° and the average air–fuel ratio is about 13:1 (Yi et al., 2002) Intake ports Air-fuel ratio 24.0 19.5 15.0 10.5 6.0 Injector mask (a) (b) (c) Plate III Fuel–air mixing homogeneity is greatly improved as compared with Plate II and Fig 7.16 by an injector mask that alleviates the interaction between intake flow and fuel spray: (a) the mask design to shield the fuel spray from the intake flow; (b) the resulting flow field at BDC with the mask design The fuel droplets penetrate further toward the exhaust side (left side) (c) The improved fuel–air mixing homogeneity at 20o bTDC The operating condition is the same as in Plate II (Yi et al., 2002) 2800 rpm, full-load SOI = 320° bTDC 284° bTDC Equivalence ratio Rich Conventional spray Developed spray (a) Top view of spark plug section Stoichiometry 284° bTDC Lean Conventional spray Developed spray (b) Side view of spark plug section Plate IV CFD modeling predicted more evenly distributed fuel spray dispersion and better mixing with the dual-fan-shape spray as compared with a conventional spray (Ikoma et al., 2006) Fuel +50 Modeling prediction –50 50 Optical engine –50 Plate V Correlation between modeling prediction and optical engine measurement of fuel–air mixing at 630° (90° bTDC compression) The modeling is with constant MAP of 62 kPa The experiment is at an operating condition of 1500 rpm, 2.62 bar BMEP The injector has a 60° spray cone angle and the EOI is 280° bTDC (Yi et al., 2004b) CA = 520° CA = 520° Velocity (cm/sec) 2000 1500 1000 500 CA = 520° CA = 520° Air-fuel ratio 24.0 19.5 15.0 10.5 6.0 Plate VI Effect of intake cam phasing on velocity and fuel–air mixture distribution Velocity (top) and air fuel ratio (bottom) for an operating condition of 1500 rpm, 2.62 bar BMEP In the case of MOP of 512° after TDC, the tumble flow structure moves the fuel cloud upward and to the exhaust port side The downward motion in the case of MOP = 472° is likely to be responsible for keeping the richer mixture from moving to the upper left, i.e., toward the exhaust side The injector has a 60° spray cone angle and the EOI is 280° bTDC (Yi et al., 2004b) Piston Oval-shaped Lean Bottom view Stoich Rich 1200 rpm, 12 mm3/st stratified charge combustion 6% Shell-shaped piston 20 THC (g/kWh) Shell-shaped 20 g/kWh Piston 1200 rpm, 12 mm3/st SFC (g/kWh) Side biew Oval-shaped piston 30% 10 Shell-shaped Oval-shaped piston piston 20°bTDC Plate VII CFD modeling predicted that mixture formation with an oval piston cavity is better located than in the case of a shell-shaped cavity (left), which agrees with the experimental results showing improvement in fuel economy and UHC emissions, (Abe et al., 2001) above 50.0 40.0 30.0 20.0 10.0 below 75° bTDC 65° bTDC 55° bTDC 45° bTDC 35° bTDC 25° bTDC Plate VIII CFD-predicted evolution of the fuel spray, air–fuel ratio distribution, and gas vector field in the central plane of the combustion chamber The simulated engine conditions are 1500 rpm, 10 mg injected fuel mass and 1.0 bar intake manifold pressure The nominal spray cone angle is 60°, the start of injection (SOI) is 70° bTDC, the injection duration is about 8.7 crank angle degrees, and the injection pressure is 100 bar (Han et al., 2002) Air-fuel ratio above 30.0 25.0 20.0 15.0 10.0 below 24° bTDC = EOI 22° bTDC = EOI 16° bTDC (a) (b) Plate IX Computed air–fuel ratio distribution and superimposed spray and gas velocity vector fields in the central cutting plane with (a) initial injector position, and (b) injector position raised up mm along the injector axis The cross with the blue dot in the middle corresponds to the location of the spark plug Simulation conditions: 1500 rpm, 2.62 bar BMEP, EOI = 24° bTDC, SCV closed, MAP = 95 kPa, 80° cone piezo injector (Iyer et al., 2004) CA = 440° CA = 440° Velocity (cm/s) 5000 3750 2500 1250 (a) Medium tumble port (b) High tumble port Plate X CFD-predicted velocity field and spray distribution for medium tumble (left) and high tumble (right) intake port designs in a turbo-charged DISI engine equipped with a multi-hole injector mounted beneath the intake ports The operating conditions are 2000 rpm, 19 bar BMEP, split injection with 80/20 ratio between the first and second injection with start of injection of 400° and 500° aTDC, (Iyer and Yi, 2008) 6.0 5.5 5.0 Viewing area (shaded) 34° Ind 34° Avg 33° Ind 33° Avg 32° Ind 32° Avg 4.5 4.0 31° Avg 30° Ind 30° Avg 29° Ind 29° Avg 28° Ind 28° Avg 3.0 Equivalence ratio 3.5 31° Ind 2.5 2.0 27° Ind 27° Avg 26° Ind 26° Avg 25° Ind 25° Ind 24° Ind 24° Avg 1.5 1.0 0.5 23° Ind 23° Avg 22° Ind 22° Avg 21° Ind 21° Avg 20° Ind 20° Avg Plate XI The evolution of the fuel distribution near the spark plug in a spray-guided direct injection engine is not well represented by the average fuel distribution This is evident in the comparison of a sequence of fuel images that were captured with high-speed LIF in a single cycle and the average from hundreds of cycles Spatial gradients that critically determined ignitability get smeared out in the ensemble-average and thus imply favorable combustion conditions when in an individual cycle this might not be the case (J D Smith, PhD Dissertation, The University of Michigan, 2006) 50 1000 1000 (b) (e) Temperature [K] 1.0 0.5 10 (g) 50 KL Number 20° aTDC 20 2500 T (K) 30 2000 2000 (f) 40 1500 3000 Number (d) 3000 (a) 40 30 20 10 1.0 0.8 0.6 0.4 0.2 µm (c) 0.0 KL Fuel-film thickness Plate XII Two-color pyrometry data and analysis: (a) one frame from a spectrally resolved high-speed video shown in false color; (b) soot emission (650, 750 nm) components from (a) with the OH* contribution removed; (c) quantitative image of liquid fuel film on the piston recorded in a separate experiment under similar conditions (Drake et al., 2003); (d) line-of-sight-averaged temperature map evaluated from (b); (e) map of KL factor (relative line-of-sight integrated soot concentration); (f) and (g) histograms of soot temperature and KL factor from (d) and (e) Reproduced with permission of the Combustion Institute from Stojkovic, et al (2005), Fig 60 35° 30° 50 34° 29° 33° 28° 40 30 20 32° 27° 10 31° 26° Plate XIII Single cycle sequence of Mie scattering images that were acquired at 12 kHz in a spray-guided direct-injection engine The arc follows the original spray trajectory, showing the impact of the spray momentum of the development of the spark (Smith and Sick, 2006b) Homogeneous high swirl 363° 461° Stratified 353° 1.6e4 1.5e4 491° 6000 5500 1.4e4 1.3e4 1.2e4 1.1e4 5000 4500 4000 1e4 7000 3500 3000 ¥ No [ppm] 8000 ¥ No [ppm] 9000 2500 6000 5000 4000 3000 2000 1500 1000 2000 1000 500 Plate XIV The instantaneous concentration distribution of nitric oxide in a direct-injection engine shows the strong impact of mixture preparation on nitric oxide formation Measurements were performed with laser-induced fluorescence (Fissenewert et al., 2005) Reprinted with permission from SAE Paper 2005-01-2089, © 2005 SAE International ... gasoline direct injection engines H Zhao, Brunel University, UK 1.1 1.2 1.3 Introduction Overview of direct injection gasoline engines Potential and technologies for high-efficiency direct injection. .. design and optimization Stratified-charge direct injection (DI) combustion system design and optimization Turbo-charged or super-charged direct injection (DI) combustion system design and optimization... Research and Advanced Engineering, Research and Innovation Center, USA 166 169 7.6 7.7 Introduction Direct injection spark-ignition (DISI) injector technologies Homogeneous-charge direct injection