Control Of Internal Combustion Engines Lecture PDF

Lecture (1) Prof A.E. Dr Magdy Riad  Air System Fuel System Lubricating System Cooling System Engine Exhaust System Starting System Governing System Internal Combustion Engine Systems  Types of Engine...

Lecture (1) Prof A.E. Dr Magdy Riad  Air System Fuel System Lubricating System Cooling System Engine Exhaust System Starting System Governing System Internal Combustion Engine Systems  Types of Engine Control Mechanical Electronic  Mechanical Control of Internal Combustion Engines The control of a diesel engine is accomplished through several components: The camshaft, provides the timing needed to properly inject the fuel, The fuel injector provides the component that meters and injects the fuel, and The governor regulates the amount of fuel that the injector is to inject. Together, these three major components ensure that the engine runs at the desired speed.  Electronic Control of Internal Combustion Engines Electronic sensors for registering operating conditions and changes. A wide array of physical inputs is converted into electrical signal outputs. Actuators or solenoids which convert the control unit's electrical output signal into mechanical control movement. ECM (Electronic Control Module ) or Engine ECU (Electronic Control Unit) with microprocessors which process information from various sensors in accordance with programmed software and outputs required electrical signals into actuators and solenoids. 11/5/2024 Prof A E Magdy Riad 5  Objectives Of ICE Control (1) Engine Performance Power, Torque and efficiency (2) Economy Fuel consumption and tribology parameters (3) Ecology Emissions; NOx, CO, HC, PM, noise and smog DIESEL COMBUSTION PROCESS PROCESS Liquid fuel injected into compressed charge (Heterogeneous mixture) Fuel evaporates and mixes with the hot air Auto-ignition with the rapid burning of the fuel/air that is “premixed” during the ignition delay period – Premixed burning is fuel rich As more fuel is injected, the combustion is controlled by the rate of diffusion of air into the flame (Turbulent diffusion flame) 5-Nov-24 Prof A E Magdy Riad Meseha 7 Processes occurring during Combustion Process Physical process Chemical process ▪ Atomization of the fuel ▪ Pre-combustion reactions ▪ Vaporization of the fuel ▪ Cracking of the larger ▪ Mixing of fuel vapor with air hydrocarbons Rate of Fuel Air Mixing Rate of fuel Vaporization ▪ Injector design ▪ Size of the droplets ▪ Combustion chamber design ▪ Droplet distribution ▪ Pre-chambers and swirl chambers ▪ Droplet velocity ▪ Number of injector nozzles ▪ Pressure and temperature inside ▪ Spatial arrangement of the nozzle injector the chamber holes ▪ Volatility of fuel ▪ Spray cone angle ▪ Injection pressure ▪ Air density  Factors Affecting Combustion in Diesel Engines o Fuel properties o Combustion chamber design o Degree of swirl and exhaust gas recirculation (EGR) o Fuel injection pressure o Rate of injection o Injection pattern Spray pattern of the diesel common-rail injector. o Number of injections o Injection timing o Speed and load 5-Nov-24 Prof A E Magdy Riad Meseha 9  Combustion stages of CIE Late combustion phase Part of combustion affected most by the charge motion TDC  Ignition Delay The time span between the start (Physio-Chemical nature) of injection and the start of ignition. ▪ Physical ignition delay depends upon the type of Preparatory phase of combustion fuel Interaction of fuel with air Determines the nature of the ▪ Chemical ignition delay preceding phases of combustion ▪ It is longer than physical Injection of more fuel during this delay phase leading to Diesel Knock ▪ A very strong function of causing shock waves temperature 5-Nov-24 Prof A E Magdy Riad Meseha 12  Premixed Combustion phase Rate of pressure rise is affected by: Main ignition event- The delay in the atomization of the Uncontrolled fuel. It depends on the design of combustion design of the injection system The amount of fuel evaporated during Characterized by an the delay period increase in The extend of distribution and mixing temperature and of the fuel throughout the cylinder, longer delay periods and high engine pressure speed will increase the mixing Determines the The quantity of fuel injected during maximum in-cylinder the delay period pressure Mixing controlled Late combustion phase (After combustion phase Burning): Controlled phase of Factors responsible are: combustion Slow burning Depends Upon: High viscosity The rate of fuel injected High density Type and intensity of air High carbon content of the fuel motion Excessive after burning can result in: Piston Motion Higher exhaust temperature resulting in increased heat transfer losses and reduced thermal efficiency  Diesel Fuel Injection Systems Air Solid Injection Injection Mechanically Electronically Controlled Injection Controlled Injection Direct Direct Indirect Injection Injection Injection Pre-chamber Swirl Chamber 5-Nov-24 Prof A E Magdy Riad Meseha 15  For Efficient Fuel Delay period is Burning about 0.4 ms at 1400 rpm Excess Air Quick Efficient Mixing 50-100% at full load Time available for (Reduces the engine mixing is 0.1 ms at 1400 power) rpm Finely Atomized and Air Motion distributed Fuel Swirl, Tumble and Squish, 5- 40 micron Role of Role of Combustion Chamber Design Injection System 5-Nov-24 Prof A E Magdy Riad Meseha 16  Air Motion Swirl, Tumble and Squish, 5-Nov-24 Prof A E Magdy Riad Meseha 17  Methods of Fuel Mixture Formation Two fuel distribution methods are commonly used. 1- The air distributed method (Space mixture) The mixture formation is achieved by mixing fuel particles with air particles surrounding them. 2- The wall distribution method (Film mixture) The fuel is injected with a single-hole nozzle at relatively low pressure towards the walls of the combustion chamber. The fuel evaporates from the combustion chamber walls and is picked up by the swirling air. 5-Nov-24 Prof A E Magdy Riad Meseha 18  air distributed system (space mixture) wall distributed system (Film mixture) 5-Nov-24 Prof A E Magdy Riad Meseha 19  Diesel Fuel Injection Systems  Functions of Fuel Injection Systems (1) Metering (2) Timing (3) Injection Pressure and Rate Control (4) Atomization (5) Distribution (penetration and dispersion) (6) Quick Start & Stop (7) Mixing (in case of non turbulent chamber) (8) Prevention of wall impingement 5/11/2024 Prof E Dr Magdy Riad Meseha 21  Types of Fuel Injection Systems 1). Mechanical fuel injection system a) In-line fuel injection pump b) Distributor-type fuel pump c) Unit injector d) PT fuel injection system 2). Electronically controlled Fuel injection a) Electronically controlled in-line pump b) Electronically controlled distributor pump c) Electronically controlled unit injector d) Common rail fuel injection system e) Hydraulically Actuated Electronically Controlled Unit 5/11/2024 Injector (HEUI) Prof E Dr Magdy Riad Meseha 22  In-line fuel injection pump system 5-Nov-24 Prof A E Magdy Riad Meseha 23  In Line Injection System Injection Pump Port and Helix Method 5-Nov-24 Prof A E Magdy Riad Meseha 24  Distributor-type fuel pump system 5-Nov-24 Prof A E Magdy Riad Meseha 25  Unit injector system Detroit Diesel General Motors 5-Nov-24 Prof A E Magdy Riad Meseha 26  PT fuel injection system Cummins 5-Nov-24 Prof A E Magdy Riad Meseha 27  Common rail fuel injection system The EDU allows precise control of the injection timing of highly pressurised and finely atomised fuel which decreases emissions. 5-Nov-24 Prof A E Magdy Riad Meseha 28  Hydraulically Actuated Electronically Controlled Unit Injector (HEUI) CATERPILLAR INJECTOR 5-Nov-24 Prof A E Magdy Riad Meseha 29  Questions ? 5-Nov-24 Prof A E Magdy Riad Meseha 30