Single cylinder research engine multi-spark ignition system Andreas Lius Master of Science Thesis TRITA-ITM-EX 2018:498 KTH Industrial Engineering and Management Machine Design SE-100 44 STOCKHOLM Examensarbete TRITA-ITM-EX 2018:498 Encylindrig forskningsmotor med konfigurerbart tändsystem Andreas Lius Godkänt Examinator Handledare 2018-06-19 Andreas Cronhjort Ola Stenlåås, Richard Adolfsson Uppdragsgivare Kontaktperson Scania CV AB Ola Stenlåås Sammanfattning I detta projekt presenteras ett arbete där en serieproducerad 5 cylindrig motor med gasdrift modifieras till drift på enbart en cylinder. En konceptstudie genomförs där för och nackdelar vägs mot varandra där sedan ett koncept implementeras. Tidigare lösningar har använts där avaktivering av cylindrar uppnåtts genom att ta bort komponenter till gasväxlingssystemet och med hål borrade i kolvarna. Motorn är tänkt att vid ett senare skede installeras i en test-cell på avdelningen för förbränningsmotorteknik på Kungliga Tekniska Högskolan. Oönskat kompressionsarbete i avaktiverade cylindrar minimeras genom att låta dessa ventilera mot atmosfären. Detta sker genom att plocka bort insugsventilerna och igentäppning av ventilstyrningar. Ventilation mot atmosfären sker med hjälp av ett modifierat insug. Ett system för att ta hand om olja som annars skulle ha förbränts i de avaktiverade cylindrarna konstrueras. Med denna lösning behöver inte den roterande massan modifieras vilket annars hade påverkat motorns balansering. Ett kapacitivt tändsystem där gnistenergi kan ändras under drift implementeras. Tändsystemet är uppbyggt av två stycken tändenheter och tändspolar som är kopplade till samma tändstift. Denna lösning tillåter bättre kontroll när multipla gnistor under en cykel är önskvärt. Motorn är tänkt att använda en experimentell styrning av tändning vilket kräver att tiden från när en gnista önskas till gnistinitiering minimeras. För kontroll av bränsle och tändning i ett initialt skede installeras ett eftermarknads motorstyrsystem. Detta styrsystem ansluts till motorns standard sensorer. Styrsystemet kan ändra relevanta driftparametrar under drift genom ett grafiskt gränssnitt, systemet inkluderar återkoppling för luft-bränsleblandning samt skyddsfunktioner för okontrollerad självantändning. Standardsystemet för avgasåterledning modifieras för att kunna styras av tidigare nämnt styrsystem. Hjälpaggregat och andra komponenter ej nödvändiga för drift i testcell demonteras. Motorn förbereds även så att en högtryckspump för direktinsprutning kan monteras i framtiden. 1 2 Master of Science Thesis TRITA-ITM-EX 2018:498 Single cylinder research engine multi-spark ignition system Andreas Lius Approved Examiner Supervisor 2018-06-19 Dr. Andreas Cronhjort Dr. Ola Stenlåås, Richard Adolfsson Commissioner Contact person Scania CV AB Dr. Ola Stenlåås Abstract In this project, a 5-cylinder SI port-injected engine is converted to single cylinder operation by deactivating four of the cylinders. A concept generation process resulted in four different concepts where one of them was chosen to be implemented. Previous setups have been used before where cylinders have been deactivated by drilling holes in the piston. Unwanted compression work for the deactivated cylinders is minimized by allowing ventilation to the atmosphere. The inlet valves are removed and the inlet guides plugged. A modified intake connects the deactivated cylinders to the atmosphere. To manage the oil in the deactivated cylinders which otherwise would be combusted is routed to a manifold and finally a catch tank. With this setup, the rotating assembly is untouched thereby retaining the stock engine balance. A capacitive ignition system where the spark energy can be altered during operation is implemented. The ignition system is comprised of two separate ignition units and coils which is connected to the same spark plug. This setup allows full control of when the second spark is released when operated in a multi-spark mode. The system has been designed to minimize the time from spark demand to spark initiation. This is to prepare for future use where an experimental control algorithm will be used which doesn’t use traditional look-up tables. In an initial stage, the fuel and spark will be controlled by an aftermarket engine control unit. The system is installed using the standard sensors on the engine. The control unit can alter relevant parameters during operation using a graphical user interface. The system incorporates closed- looped lambda and knock control for safe operation. The stock exhaust gas recirculation system is incorporated with the engine control unit. Auxiliary units and other components not necessary for single operate are removed. The engine is also prepared to accommodate a high-pressure pump for future direct injection. 3 4 FOREWORD This project has been a journey where many lessons was learned. The learning outcomes from this project stretches far beyond the scope of the project. As a gearhead where engines have been a central part of my life since childhood I am very thankful for doing my thesis at Scania. I would like to thank my main supervisor Ola Stenlåås for the support during the project. I would also like to thank Richard Adolfsson for the support and all the interesting discussions regarding engines. The project has been carried out at the NMEG/NMEO group and I would like to thank both groups. A special recognition goes to Anders Forslund who always made time available to discuss various problems. A big thank also goes to my fellow friends and thesis workers here at Scania, Rohan Sharad Kittur, Sotirios Tsironas, Jacob Arimboor Chinnan, Laura Horváth, Marcus Holmgren, Arvid Isaksson and Jonas Johansson. Andreas Lius Södertälje, May 2018 5 6 NOMENCLATURE Notations Symbol Description λ Air-fuel equivalence ratio Abbreviations AFR Air Fuel Ratio CAD Crank Angle Degree(s) CAN Controller Area Network CDI Capacitive Discharge Ignition CI Compression Ignition CNG Compressed Natural Gas DIY Do-It-Yourself DPF Diesel Particulate Filter ECU Engine Control Unit EGR Exhaust Gas Recirculation EMC Electromagnetic compatibility FPGA Field Programmable Gate Array LNG Liquefied Natural Gas NOx Nitrogen Oxides OEM Original Equipment Manufacturer OHV Over Head Valve PID Proportional Integral Derivative (controller) PTFE Polytetrafluoroethylene PWM Pulse Width Modulation RFI Radio Frequency Interference SAE Society of Automotive Engineers SCR Selective Catalytic Reduction SI Spark Ignition TIG Tungsten Inert Gas XML Extensible Markup Language 7 8 TABLE OF CONTENTS SAMMANFATTNING (SWEDISH) 1 ABSTRACT 3 FOREWORD 5 NOMENCLATURE 7 TABLE OF CONTENTS 9 1 INTRODUCTION 13 1.1 Background 13 1.2 Purpose 15 1.3 Research questions 15 1.4 Deliverables 15 1.5 Delimitations 16 2 FRAME OF REFERENCE 17 2.1 Ignition system 17 2.1.1 Inductive ignition 17 2.1.2 Capacitive-discharge ignition 19 2.1.3 Inductive and capacitive ignition system comparison 20 2.2 Engine knock 20 2.3 Engine Control Unit 21 2.3.1 Aftermarket engine control units 21 2.3.2 Aftermarket ignition units 22 2.4 Air charge measurement 22 2.4.1 Thermal sensing 22 2.4.2 Speed-density 23 2.4.3 Other methods 23 9 2.5 Exhaust gas recirculation 23 2.6 Single-cylinder engine for research purposes 24 2.6.1 Cylinder deactivation & decompression 25 3 IMPLEMENTATION 26 3.1 Base engine specifications 26 3.2 Requirements 27 3.2.1 Cylinder deactivation requirements 27 3.2.2 Ignition requirements 27 3.2.3 Engine control unit requirements 27 3.2.4 Air handling requirements 27 3.3 Concept selection 28 3.3.1 Cylinder deactivation concept selection 28 3.3.2 Ignition system concept selection 33 3.3.3 Engine control unit concept selection 38 3.4 Concept implementation 39 3.4.1 Cylinder deactivation implementation 39 3.4.2 Ignition system implementation 40 3.4.3 ECU synchronisation 43 3.4.4 Air handling modifications 43 3.4.5 ECU implementation 45 3.4.5.1 ECU configuration 45 3.4.5.2 CAN & Heat release preparation 47 3.4.6 EGR preparation 47 3.4.7 Other modifications 49 3.4.7.1 Cooling system 50 10 3.4.7.2 Transmission plate 50 4 VERIFICATION 52 4.1 Ignition system 52 4.2 Synchronisation 53 4.3 Oil pressure 54 5 DISCUSSION AND CONCLUSIONS 55 5.1 Discussion 55 5.1.1 Cylinder deactivation 55 5.1.2 Ignition system 55 5.1.3 Engine control 55 5.1.4 Scope of thesis project 56 5.2 Conclusions 56 6 RECOMMENDATIONS AND FUTURE WORK 57 6.1 Recommendations 57 6.1.1 Oil pressure relief valve 57 6.1.2 Knock calibration 57 6.1.3 Manifold pressure sensor 57 6.1.4 Spark plug wear 57 6.1.5 Crankcase ventilation 57 6.1.5 Piston ring-pack 58 6.2 Future work 58 6.2.1 Oxygen sensor pressure correction 58 6.2.2 In-cycle spark event control 58 6.2.3 EGR system 59 7 REFERENCES 60 11 12 1 INTRODUCTION 1.1 Background The internal combustion engine in its current form has been used extensively due its relatively simple design and the availability of a suitable fuel source to run it. During its infancy, the development focused on power output and reliability, but in modern times with higher fuel prices the focus has shifted to efficiency and emissions (Heywood, 1988). The reciprocating internal combustion engine can be differentiated into two groups depending on the inherent combustion process and how the fuel is introduced. Both groups can also be used in either two or four stroke applications (Johansson, 2014). The first type relies on heat to initiate the combustion process, this heat is generated during the compression stroke. The engines are typically called compression ignited (CI) engines (Johansson, 2014). Modern engines based on this combustion process can under certain circumstances achieve a fuel efficiency close to 50% (EMMA-MAERSK, 2018). The other type of engine is the spark ignited (SI) engine where an electrical discharge in the combustion chamber ignites the fuel mixture. While the combustion process limits the fuel efficiency to a lower level compared to the CI engine, it is widely used as it can be made in various sizes suitable for personal transport.