Design of Electronic Control Unit (ECU)for Automobiles Electronic Engine Management systemM. Tech. Project first stage report (EE 696)(Design Requirements, analysis and Proposed ideasfor design of Electronic Engine Management ECU)byVineet P. Aras(Roll No. 03307411)under the guidance ofProf. Kavi AryaProf. Dinesh SharmaDepartment of Electrical EngineeringIndian Institute of Technology BombayJuly 20041
AcknowledgementI express my gratitude to my guides, Prof. Kavi Arya and Prof. Dinesh Sharma,for their invaluable help, guidance and motivation, which effectively contributed insuccessful completion of the first stage of this project. The regular meetings anddiscussions with Prof. Kavi Arya helped a lot in carrying out a focused work. They wereinstrumental in providing technical, moral and administrative support. It is a privilege towork under their guidance. I also thank other professors including Prof ShashikanthSuryanarayanan, for their cooperation extended.2
AbstractThis report presents a detailed explanation of the Design requirements of Electroniccontrol Unit (ECU) for Engine Management. Due to the regulations demanding loweremissions, together with the need for better performance, fuel economy, continuousdiagnosis, Electronic systems form an inevitable part of Engine management. A systemsdesign approach has been used to break down the whole Engine management into threemain categories, namely Electronic Charging, Alternator, and Engine starting system;Electronic Ignition system; Electronic Fuel system. Design requirements of each of thesesections of engine management are explained thoroughly. The electronic starter is used tostart the engine. Once started, appropriate air-fuel mixture quantity is injected into thecylinder through proper electronic control, which depend on various factors like enginespeed, load, temperature, battery voltage, throttle position. Additionally, the electronicignition system should provide the spark to ignite the air-fuel vapour with proper timingdepending on speed, load, temperature etc. Moreover, the exhaust emissions should bekept at check and the fuel consumption should be minimum. Through out the report adesigner’s approach has been used by proposing self designed circuits, block diagramsand flowcharts, which would form the basis for design. Towards the end of the report, theactual design process of the ECU is started by designing the Input / Output circuit forElectronic Engine Management, which would be the basis for designing the actualelectronic system in the next stages of this project.3
CONTENTS1 INTRODUCTION61.1 Electronic Systems Design approach .62 ELECTRONIC CHARGING, ALTERNATOR ANDENGINE STARTING SYSTEM92.1 Battery .92.2 Electronic Charging circuit and system .92.3 Electronic Engine Starting circuit and system . .113 ELECTRONIC IGNITION SYSTEM’S DESIGN REQUIREMENTS153.1 Basic terms and types of Ignition systems 153.2 Proposed Block diagram and Design requirements ofElectronically programmed and distributed ignition system .173.2.1 Ignition switch .183.2.2 Ignition or Spark generation - Inductive / Capacitor Discharge type .183.2.3 Electronic Voltage Regulator .193.2.4 Pulse Generator – Crankshaft / Hall effect / optical type .193.2.5 Pulse Shaping circuit .203.2.6 Electronic Dwell control - Constant / Open loop /Constant Energy closed loop type .203.2.7 Electronics Spark Advance (ESA) timing control- speed, load,temperature, knock, idle, phase, anti-jerk and warm-up conditions .223.2.8 Analog and Digital Electronics Hardware and Proposed Flow Chart .243.2.9 Driving and output Switching .263.2.10 Electronic Distribution - Distributorless / Direct Ignition type .263.2.11 Spark Plug and High Voltage cables .274 ELECTRONIC FUEL SYSTEM’S DESIGN REQUIREMENTS284.1 Air-fuel mixture and Exhaust Emissions .284.2 Electronic fuel system’s Design requirements .294.2.1 Main relay operation .304
4.2.2 Air mass flow measurement – Flap / Hot wire type .304.2.3 Engine speed measurement – Idle, Overrun and Overspeed conditions 304.2.4 Temperature Measurements – Engine, Fuel (Hot start) and Air 314.2.5 Throttle position measurement –Idle, Accelerate, Decelerate and Full load conditions 324.2.6 Exhaust gas oxygen (EGO) measurement –Closed loop Lambda control and Catalytic converter .334.2.7 Battery Voltage correction 344.2.8 Idle or fast idle control – idle air control motor actuator .344.2.9 Exhaust gas recirculation (EGR) .344.2.10 Fuel supply – tank, pump, pressure regulator and tank emissions 354.2.11 Fuel Injection – Simultaneous / Sequential /Gasoline Direct Injection (GDI) 364.2.12 Calculation of basic Injection time - Air flow / Speed - density method.404.2.13 Proposed Electronic Fuel Injection system Flow Chart .404.2.14 Other fuel injections – DMI / Diesel / alternative fuels 425 ELECTRONIC ENGINE MANAGEMENT ECU WITHON-BOARD DIAGNOSTICS - DESIGN PROCESS STARTED435.1 Proposed ‘Engine Management ECU’s’ Input / Output circuit diagram .435.2 On – Board Diagnostics (OBD) 455.3 Designed and tested EGO Lambda Control ADC circuit module .466 CONCLUSIONS AND WORK AHEAD . . . 48REFERENCES .505
Chapter 1INTRODUCTIONSince the electronics explosion in the automotive field, electronic solutions have provento be reliable over time and have enabled to solve problems otherwise unsolvable. Theelectronics in today’s vehicles have made the transition from simple components tocomplex semiconductor chips, incorporating in the process the interfacing capability ofanalog electronics, and proven reliability and flexibility of digital electronics. The contentand complexity of electronics for circuit design, processing, power control sensing, signalconditioning and transient suppression are destined to increase even more in futurevehicles.Automobile electronic systems can be broken down into four main categories ‘PowertrainDrive’ consisting of electronic engine management, electronic transmission, electronicnetworks; ‘Safety systems’ such as Antilock Brake systems, air bag triggering, anti–theft,suspension, steering, skid systems; ‘Comfort body systems’ such as Air conditioner, seatadjusting, dashboard displays; ‘Communication systems’ such as Global positioningsystem, radio reception, information systems. Each of these systems requires ElectronicControl Unit (ECU) for efficient performance.‘Electronic Engine Management’ is the science of electronically equipping, controllingand calibrating an engine to maintain top performance and fuel economy while achievingcleanest possible exhaust stream, and continuously diagnosing system faults. Due to therequirement of lower emissions, together with the need for better performance, Electronicsystems form an important part of Engine management [1].1.1 The Electronic Systems design approachElectronic Systems can be defined as a group of electronic and electrical devices workingto perform a specific task, with optimum and efficient results. The steps in the design ofan Electronic System are surveying the Design Requirements, Analysis andConceptualization of design i.e. proposing ideas for design, followed by actual designbased on the proposed ideas, verification, implementation and testing. In the I stage of6
this project, the Design Requirements, Analysis and proposing ideas for design have beencompleted. And the actual design has also started.Fig.1. Steps in the design of an Electronic systemThe Electronic Systems design approach at the earliest stages will provide reduced designcycle time and cost-performance optimization to enable Electronically operated vehicles[7]. In this approach an Electronic system is broken into parts for ease of design. Systemboundaries may or may not overlap. Thus the Engine management ECU can be thought asan electronic system comprising of the following sections.(1) Electronic Charging, Alternator, and Engine starting system(2) Electronic Ignition system(3) Electronic Fuel system7
The design would incorporate both analog and digital design. The main processing andcontrolling would be done using microcontroller technology that improves reliability,efficiency, accuracy and control. There would be other interfacing circuits for both analogand digital hardware. Thus after the design of Engine management ECU, this singlePrinted Circuit Board (PCB) when connected to the required sensors and actuators wouldbe used as engine starter, ignition and fuel system to provide optimum and efficientElectronic engine management.Through out the report a designer’s approach has been used by proposing self designedcircuits, block diagrams and flowcharts, which would be the basis for design of theelectronic system in the next stages. In Chapter 2, the electronic charging, alternator andengine starting has been discussed. Chapter 3 defines the design requirements for theElectronic Ignition system. In Chapter 4, requirements for design of the Electronic Fuelsystem are explained. In Chapter 5 the actual design process of Electronic Enginemanagement is started by designing the ECU Input / output circuit. Summery and workneeded to be done in further stages is discussed in the last section.8
Chapter 2ELECTRONIC CHARGING, ALTERNATOR ANDENGINE STARTING SYSTEM2.1 BatteryThe vehicle battery is used as a source of energy when the engine, and hence thealternator is not running. It is a power storage device required to operate the engine startermotor.Types of batteries are lead-acid, alkaline, ZEBRA, Ultra-capacitors, cells, sodium sulphur,swing batteries. The lead-acid batteries have been the most suitable choice. Some ofbattery ratings are in Ampere hour (AH) capacity, Reserve capacity, cold crankingcapacity. Some characteristics are internal resistance, efficiency and self-discharge. Thenominal 12V battery consists of six 2V cells connected in series [2].2.2 Electronic Charging circuit and systemThe charging is done by the alternator of the vehicle, which produces voltage whenengine is running, supplied to battery and loads. When engine is not running current flowsfrom battery to loads. The state of charge should not fall below 70 %, to prevent difficultrecharging. Constant voltage charging is done where the charger is at a constant level andthe state of charge will determine how much current flows. Typically 14.2 0.2 V isaccepted constant voltage for 12 V batteries. In boost charging, the battery temperatureshould not exceed 43oC [6].The alternator is a generator producing 3-phase AC voltage when the electromagneticrotor (initially magnetized by battery when start relay switch closed by starting system)rotates between the three stator windings connected in Star (or Delta). The frequency isf pn / 60, where p number of poles, n alternator speed rev/min.9
Fig.2. Electronic Charging and Engine Starting circuit diagramThere could be third harmonic(3f) at the neutral point. There is a fixed drive ratio ofalternator speed to engine speed determined from maximum allowable alternator speed tomaximum allowable engine speed, sometimes 3:1.This AC is rectified by a 3-phase full wave diode bridge rectifier circuit, to produce DCused for charging the battery and running electronic circuits. Charge warning light bulbindicates charging in progress. This charge warning light is extinguished when the batterycharges to the alternator DC voltage, as equipotential.Additional three diodes along with negative diodes form another 3-phase full wave diodebridge rectifier circuit, which produce DC voltage used for rotor electromagnetization(now battery not used for magnetization). Two extra diodes are employed to remove thirdharmonic.Overvoltage protection can be provided by a zener diode across the field winding willprevent voltage from exceeding limit (20V)Voltage Regulator IC is used to obtain constant voltage irrespective of changes in load,supply, temperature and also have overload and overvoltage protections.10
Charging system demands and solutionsThe loads on the alternator can be classified as continuous, prolonged and intermittent,which keep increasing, thus increasing the power supply demand of the alternator. Ironlosses, copper losses and mechanical friction lead to inefficiency. There are varioussolutions for the high power demand [8].Larger alternator is the easiest, or alternators with higher maximum speed, thus allowinggreater drive ratio.Power management technique is used wherein certain loads like headlights, fog lights areswitched off when vehicle not moving [19].Two-speed drive technique, which uses a drive ratio of 5:1 for engine speeds under 1200rev/min and 2.5 at higher speeds [4].Increase Idle speed but this increases fuel consumption and emissions.Dual power supply technique is used wherein, each of two 12 V supplies are used forsmaller loads, while both 12 V, i.e. 24 V is used for heavier loads [18].Water-cooled and Integrated alternators / starters called ‘dynastart’ are also being used.2.3 Electronic Engine Starting circuit and systemIn order to start the engine a minimum starting speed (typically about 100 rev/min) shouldbe achieved. This is achieved with the help of an engine starter. Once this is achieved theengine would use the combustible mixture, compression stroke and ignition to continuerunning. The starting torque should be more than the engine torque at the time of starting.As the speed increases, and after the cranking speed, the engine torque takes over, and thestarter is disengaged mechanically. The cranking speed decreases with increase intemperature [5].11
Fig.3. Starting, engine torque and Starter Motor Characteristics [4]A typical cranking current of 150A to 500A is required to provide the initial stalledtorque. In a motor, when current is passed through the armature coil rotor (typically wavewound) placed in magnetic field stator (typically four-pole four-brush), a force is createdacting on rotor coils, causing it to rotate. A series wound DC motor, wherein the fieldwinding (electromagnet) is in series with the armature, is used for starting, because it hasa high initial torque (produced due to high current, low resistance and no back EMF),which is required to overcome the stall torque. Sometime, shunt wound, compoundwound or permanent magnet DC motors can also be used [1].Different types of starters are used like Inertia, Pre-engaged, Permanent magnet (smallsize) starters. Owing to the very high speeds at no load (0A), there is possibility ofdamage. Maximum power is at mid range speed and maximum torque at zero speed.Stall torque T BilrZ, where, B magnetic field in Wb/m2, I Current (V- EMF)/R, l length of conductor in field in m, r armature radius in m, Z number of armatureconductors [2].Power consumed P Torque x angular velocity. Typical efficiency is 60 %.The starter motor is the main load on the battery, thus to prevent power loss heavyconductors are used, with less voltage drop.Electronic engine starting circuit diagramThe circuit diagram is same as shown in the charging system. When the starter relayswitch closes, the hold-on and pull-in windings of the relay are energized. The current12
through pull-in winding flows through the starter motor, which slowly engages itself withthe engine, and at same, time the main contact to the starter motor closes. Thus the motoris now supplied by battery voltage, thus rotating and starting the engine. The pull inwinding switches off as equipotential. When the engine starts and start relay switch isreleased, the main contact opens and starter motor stops rotating and the starter isdisengaged from engine. This is the control circuit for the start relay switch.Fig.5. Circuit for controlling the start relay switch (used by Ford Motor Company Ltd) [8]13
The start relay switch (i.e. the starter) turns on only when the Ignition switch is at the startposition and either the Automatic transmission switch is at Park, Neutral position or theClutch pedal switch is at depressed position. Only under the above conditions will therelay coil activating the start relay switch is connected to earth through the Electronictransistorized Power control module (PCM). To prevent start operation when engine is on,the PCM does not complete the earth path.ECU controlled starter will have features such as starter torque evaluated in real time totell the precise instant of starting, so as to shut starter off after cranking speed, so as toreduce unnecessary wear and tear. The ECU will provide thermal and short circuitprotection.14
Chapter 3ELECTRONIC IGNITION SYSTEM’S DESIGNREQUIREMENTSHere it has been tried to propose a block diagram (which would be the basis on which theelectronic circuit would be designed) and flow chart, and hence the requirements, for thedesign of Ignition system section of Engine Management ECU. The fundamental purposeof ignition systems is to supply a spark inside the cylinder , near the end of thecompression stroke to ignite the compressed charge of air- fuel vapour.3.1 Basic terms and types of Ignition systemsFollowing are the four main factors considered for broadly classifying types of Ignitionsystems.Ignition coil and generation of High Tension (HT)For a spark to jump across an air gap of 0.6 mm in an engine cylinder under compression,a voltage of 2 to 3 kV is required. For higher compression ratios and weaker mixtures,voltage up to 20 kV or even 40 kV is required. Thus the ignition system has to transformthe normal battery voltage of 12 V to approximately 8 to 20 kV and in addition, has todeliver this high voltage to the right cylinder at the right time. By transformer action,primary winding of a coil is switched on and off causing a high voltage to be induced inthe secondary winding with more number of turns than the primary coil. The value of thismutually induced voltage depends on the primary current, turns ratio and rate of changeof magnetism [4].Advance angle (timing)The ignition timing (or the time at which the spark occurs) has a significant effect on fuelconsumption, torque, drivability and exhaust emissions. For optimum efficiency theignition advance angle should be such as to cause the maximum combustion pressure tooccur just after the Top Dead Centre (TDC) i.e. when the engine piston is at maximumcompression point [2]. The graph shows the effect of timing changes on emissions,15
performance and consumption. The quality of the spark determines its ability to ignite themixture. The stronger the spark, the less the likelihood of a misfire, which can causemassive increase in production of hydrocarbons. It is clear from the graph that acompromise on fuel consumption and emissions has to be done while choosing theadvance timing. The ideal ignition timing is dependent on factors to be discussed later.Fig.6. Effect of changes in ignition timing.DwellThe energy storage takes place in the ignition coil in the form of magnetic field. Thecharge on the coil before ignition point depend on dwell period. Ignition spark occurs is atthe end of dwell period. The term dwell is a measure of the tike during which the ignitioncoil is charging i.e. the primary current is flowing. It is often expressed as a percentage ofone charge – discharge cycle.DistributionDirects the spark from the secondary coil to each cylinder in a pre-set sequence. In a 4stroke 4 cylinder engine, it will distribute four sparks, one to each cylinder in tworevolutions.Thus depending on these factors the ignition system can be broadly classified as16
allyProgrammedProgrammed –ElectronicallyDistributedInductive /Inductive /Inductive cIgnitionInductiveDwell controlAdvancecontrolDistribution3.2 Proposed Block diagram and Design requirements ofElectronically programmed and distributed ignition systemFor obtaining the design requirements of ECU – Engine Management, we will considerthe Electronically Programmed and Distributed Ignition systems. The following is theproposed block diagram for designing the Ignition system part of the Engine ManagementECU. This diagram would be the basis on which the electronic circuit would be designed.Fig.7. Proposed Block diagram of Electronically Programmed and Distributed IgnitionSystem17
3.2.1 Ignition switchProvides driver control of the ignition system and is also used for starting the engine instarting phase.3.2.2Ignition or Spark generation - Inductive / Capacitor DischargetypeTypes of spark generation1. Inductive Charging of Ignition coilThe ignition coil stores energy in the form of magnetism. Te instantaneous value ofprimary current is given byi V (1 – e –Rt/L)RWhere i instantaneous primary current, R total primary resistance, L inductance ofprimary winding, t instantaneous time.The energy stored in the magnetic field of the ignition coil is given byE 1 (L x i2)2where E energy, L inductance of primary winding, I instantaneous primary current.The rate of increase of primary current determines the value of current when the circuit isbroken in order to produce the collapse of the magnetic field, thereby producing a highvoltage spike at the secondary.2. Capacitor discharge ignition (CDI)The CDI works by first stepping up the battery voltage to about 400 V DC, using an DCto AC converter (oscillator), amplifying it with a transformer, followed by a rectifier toobtain high voltage DC. This high voltage charges the capacitor, which is discharged atthe point of ignition through the primary coil by a thyristor, producing a high voltagespike at the secondary. The disadvantage is that since the spark duration is short, it cancause problems during starting, overcomed by multi-sparking [9].18
3.2.3 Electronic Voltage RegulatorThis circuit is used to provide a constant voltage supply to the ECU irrespective of thechanges in the supply and load, so as to provide accurate ignition control.3.2.4 Pulse Generator – Crankshaft / Hall effect / optical typeA pulse generator is used to provide the timing signal in correspondence to the speed andposition of the engine, so as to accurately control the turning on and off of the primarycoil, thereby providing spark at the desired time. Types of Pulse generators are1. Inductive pulse generator (Engine speed and position – crankshaft sensor)This device consists of a magnet, a winding and a soft iron core. It is mounted inproximity to the reluctor disc, which has 34 teeth, spaced 10o intervals around theperiphery of the disc as shown in the block diagram. It has two missing teeth , 180o apartat known positions before TDC and BTDC. As a tooth from the reluctor coupled with theengine passes the core of the sensor, it induces a voltage in the winding, the frequency ofthe waveform being proportional to the engine speed. The missing tooth causes a no pulseat those positions, so that the ECU can determine the engine positions.Fig.8. Typical inductive pulse generator (Engine speed and position crankshaft sensor)output [10]2. Hall effect pulse generatorThe principle of working of a Hall effect transducer is tat if a strip of conducting materialcarries a current in the presence of a transverse magnetic field, a difference of potential isproduced between the opposite edges of the conductor.19
EH KH IB/t , where KH Hall effect coefficient; Vm3/Awb, I current, B magneticfield, t thickness of hall stripAs the engine rotates, the vanes attached under the rotor arm alternately covers anduncovers the hall chip. Thus the chip produces almost a square wave output (0 to 7 V),which can easily be used to switch further electronic circuits.Fig.9. Hall effect pulse output [10]3. Optical pulse generatorThis involves a focused beam of light from an LED and sensed by a phototransistor. Therotating vane coupled with the engine interrupts the light, thereby forming a square waveoutput3.2.5 Pulse Shaping circuitA circuit within the ECU ( Schmitt trigger) converts the pulse generator signal into a puresquare wave.3.2.6 Electronic Dwell control - Constant / Open loop / ConstantEnergy closed loop typeTypes of Dwell control1. Constant Dwell systemsIn this type, the dwell percentage or dwell angle (ratio of the time for which the primaryis on to the time for which it is off) remains constant. Now as engine speed increases, the20
actual on and off times reduce, thus the time available to charge the coil reduces, therebyproducing a lower power spark.2.Open loop Dwell controlIn this type the dwell increases with engine speed. This will only be benefit, if the ignitioncoil can charge up to its full capacity in very short time. This figure shows the circuitdiagram of a transistorized ignition module.Fig.10. Circuit diagram of a transistorized ignition ECU module [9]Diode D1 acts a reverse polarity protection. The first part is a voltage stabilizer. Zenerdiode ZD1 provides a constant known voltage for the rest of the circuit. The pulsegenerator output is given as the trigger input to the Schmitt Trigger pulse shaping circuit.The diode D4, Transistors T1 and T2 act as a Schmitt trigger providing a square wave atthe collector of T2 with pulse position and frequency same as the pulse generated input,thus providing information of the position and speed of the engine. When T2 is off,capacitor C5 charges via R9 and T3. At low engine speed the capacitor has sufficient timeto charge. T3, T4, T5, T6 turn on, so is the ignition coil. T5, T6 is a Darlington pair outputswitching stage. At ignition point, T2 switches on, and C5 discharges and ignition coil is21
switched off suddenly thereby inducing a spike at secondary. As engine speed increases,the charge time available for C5 decreases, thus reaching a lower voltage and dischargingquickly, thus increasing dwell. ZD4 and D6 protect against back EMF of coil.3. Constant energy Closed loop systemThis is the type shown in the block diagram. Constant energy means that, within limits,the energy available to the spark plug remains constant under all operating conditions.Stationary engine primary cut-offDue to the high-energy nature of constant energy ignition coils, the coil cannot beallowed to remain switched on for more than a certain time, as when the ignition isswitched on but the engine is not running. This is known as ‘Stationary engine primarycurrent cut-off’ achieved by a timer. The sensing of current causes the feedback [14].Current limitingA very low resistance, high power precision resistor is connected in series with the powertransistor and primary of ignition coil, that causes the output stage to hold the primarycurrent at a constant value after the current exceeds as preset value.Battery voltage correctionCorrection to dwell settings, stored in the memory, is required if battery voltage falls, aslarger dwell is required. A three dimensional graph of the dwell against speed (forconstant energy output) and battery voltage is stored.3.2.7Electronics Spark Advance (ESA) timing control - speed, load,temperature, knock, idle, phase, anti-jerk, warm-up conditionsThe problems of mechanical centrifugal advance and vacuum advance are overcome byusing Digital electronics programmed timing advance. The ideal ignition timing to ensuremaximum pressure in the cylinder just after TDC, depend on two main factors, enginespeed and engine load followed by many other corrections.Engine speed and positionAt higher engine speeds the time taken for the piston to travel the same distance (i.e. pointof ignition) reduces. Advancing the time of the spark ensures full burning is achieved.22
Similarly at lower speeds spark timing is retarded. The ECU uses the pulse generator(crankshaft sensor) to obtain engine speed and position inputsEngine load measurement– manifold absolute pressure (MAP) sensorWeaker mixture is used on low load conditions, which burn at slower rate and requiresfurther ignition advance. Similarly for lower loads, richer mixtures, retardation is requiredas the mixture burns rapidly. Engine load is proportional to manifold absolute pressure.Thus Load / Pressure sensor connected to the ECU, is a silicon diaphragm withpiezoresistors connected in a Wheatstone Bridge and filter arrangement, to sense pressure.A lot of information is held in the ROM. The basic timing three-dimensional graphconsists of the correct ignition advance for 16 engine speeds and 16 engine loadconditions.Engine temperature measurement – coolant sensorCoolant temperature measurement is carried out by a thermistor, which is also used by theElectronic fuel system. Timing may be retarded when the engine is cold to assist in morerapid warm up. A three dimensional graph is used that has 8 speed and 8 temperature tothe timing settings.Detonation detection – knock sensorDetonation is caused due to the pressure wave traveling at high velocity causing impacton the cylinder walls setting them into vibration or ringing knock [8]. These knock aresensed by the knock sensor, which generate piezoelectric voltage when the seismic massvibrates. The resonant frequency is given asF 1/(2π)(k/m)1/2, where f frequency, k spring constant, m seismic massThe vehicle knock sensor has a frequency response of 15 kHz and a sensitivity of 20mV/g. The engine will run at its most efficient when the timing is advanced as far aspossible, but just below the knock range. To achieve this, the ECU responds to signalsfrom the knock sensor (accelerometer) in the engines knock window for each
Mar 02, 2010 · 1.1 The Electronic Systems design approach Electronic Systems can be defined as a group of electronic and electrical devices working to perform a specific task, with optimum and efficient results. The steps in the design of an Electronic System are surveying the Design Requirements, Analysis and Conceptualization of design i.e. proposing ideas .
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BASIC WIRING TABLE OF CONTENTS Unit I: Occupational Introduction 1 Unit II: General Safety 15 Unit III: Electrical Safety 71 Unit IV: Hand Tools 101 Unit V: Specialty Tools and Equipment 195 Unit VI: Using Trade Information 307 Unit VII: Basic Equipment 343 Unit VIII: Basic Theory 415 Unit IX: DC Circuits 469 Unit X: AC Circuits 533 Unit XI: Wiring Methods 641 Unit XII: Conductors 685
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CONTENTS Page Thank you page 3 About the book 4 UNIT 1: About Academic IELTS Task 1 6 UNIT 2: Line Graphs – Language of Change 8 UNIT 3: Introducing a graph 20 UNIT 4: Grouping Information 26 UNIT 5: A More Complicated Line Graph 29 UNI T 6: Describing Bar Charts 36 UNIT 7: Describing Pie Charts 44 UNIT 8: Describing Tables 49
1 M70 Engine 2 ABS Hydraulic Unit 3 ASC T Hydraulic Unit 4 PWG Pot 5 ASC ON/OFF Switch The ASC T control unit receives throttle valve position information via an interface with the EML control unit. Communication between the EML control unit and the ASC T control unit is in the form of pulse width modulated signals.
on the work of its forty-seventh session, which was held in New York, from 7-18 July 2014, and the action thereon by the United Nations Conference on Trade and Development (UNCTAD) and by the General Assembly. In part two, most of the documents considered at the forty-seventh session of the Commission are reproduced. These documents include .