ECU sI -fuel injection

The function of the SI Engine fuel supply system is, to mix the fuel with air at an efficient ratio for the effective combustion

1. Session: Electronic controlled fuel injection system for SI - Engine 4/24/2019 16MT407 - Theory of Automobile Engineering 1 MODULE 1

2. SESSION OBJECTIVES 4/24/2019 16MT407 - Theory of Automobile Engineering 2 On the completion of this session, the students might be able to understand, How the electronics system plays a role in SI Engine fuel supply system

3. Topics Function of Fuel supply system for SI Engine Types of Fuel supply system for SI Engine Electronic controlled fuel supply system for SI Engine Role of sensors 4/24/2019 16MT407 - Theory of Automobile Engineering 3

4. FUNCTION OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 4 Units of fuel supply system The Carburetor, Fuel Pump. Fuel filter Fuel tank Various fuel pipes connect them together Role of Carburetor is to mix Air & Fuel in proper ratio for begin the combustion process Carbureted Based Fuel supply system for SI Engine :

5. FUNCTION OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 5 The fuel supply function is controlled by an electronically controlled fuel injection system. The fuel supply pressure is much higher than carburetor system ECU Based Fuel supply system for SI Engine :

6. FUNCTION OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 6 To store fuel in a tank for running several hundred kilometers of vehicle. To deliver the fuel to the engine from the fuel tank To mix air with fuel in the proper ratio for efficient burning in the cylinder. Function of fuel supply system :

7. FUNCTION OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 7 Important terms used in combustion of fuel : Atomization : The process of breaking the fuel into fine drops is known as atomization. Vaporization : The process of changing the liquid fuel into vapours is know as vaporization. When gasoline evaporates, It changes into vapours state In order to mix fuel with air, the fuel is atomized during, which evaporation takes place.

8. TYPES OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 8 Types of Fuel supply system for SI Engine : Gravity feed system : Use the influence of gravity to feed the fuel to engine. Vacuum System : Suction stroke of the engine to suck the fuel from main tank to auxiliary tank & use gravity force to drawn into carburetor float chamber.

9. TYPES OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 9 Types of Fuel supply system for SI Engine : 3. Pressure feed system : Use air pump to pressurized the fuel to the carburetor 4. Pump System : High pressure fuel pump used to pressurized the fuel, run either mechanically or electrically.

10. TYPES OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 10 Types of Fuel supply system for SI Engine : 5. Fuel Injection system : Carburetor is replaced with fuel injector. The fuel injector supply fuel in atomized form into the intake manifold where it uniformly mixes with air the air stream The operation of f uel supply system is controlled by an ECU unit This is most accurate fuel supply system

11. TYPES OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 11 Types ECU Based SI Engine fuel injection : According to the location of injector 1. Throttle body Injection system : Initially carburetor were replace by this system only

12. TYPES OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 12 Types ECU Based SI Engine fuel injection : According to the location of injector 1. Throttle body Injection system : Injector located inside throttle body, sits on top of the inlet manifold Injector sprays fuel from above throttle valve ECU Controls Injector Opening

13. TYPES OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 13 Types ECU Based SI Engine fuel injection : According to the location of injector 2. Intake Port Fuel Injection system : An injector is placed near each cylinder The fuel is sprayed into each intake port on the manifold side of the inlet valve

14. TYPES OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 14 Types ECU Based SI Engine fuel injection : According to the location of injector 3. Direct Injection system: Also called gasoline direct injection system No air fuel pre mixing Optimal spray pattern is obtained, that breaks gasoline into smaller droplets Complete combustion is possible Compare to other system more costly. Injector should withstand High pressure & Heat Theme is High power & Less Pollution

15. TYPES OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 15 Types ECU Based SI Engine fuel injection : According to the Duration & Timing of injection 1. Continuous Injection Type: Fuel flows at all times from the fuel injectors but at variable flow rate. The continuous injection systems can be built multi point or single point. But not Direct

16. TYPES OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 16 Types ECU Based SI Engine fuel injection : According to the Duration & Timing of injection 2. Intermittent Injection Type: T he injector nozzles are opened only for the time period required. Also called the jerk type or batch type

17. TYPES OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 17 Types ECU Based SI Engine fuel injection : According to the Duration & Timing of injection 3. Sequential Injection Type: The fuel is injected at the exact moment when it will be most useful i.e Towards the opening of the intake stroke Advantage: Fast response time when driver makes the quick change. Less pollution & Even more Economy Disadvantage: More cost for providing additional control to ensure that the injector pulse sequentially occurs

18. TYPES OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 18 Types ECU Based SI Engine fuel injection : According to the number of injector: 1.Single point (or Central) Injection: Throttle Body Injection 2. Multi point (or Multiport injection): Separate injector for each cylinder mounted in intake port.

19. TYPES OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 19 Types ECU Based SI Engine fuel injection : According to the Control Methods: 1.Mechanical Fuel injection system: Fuel injection are by mechanical means Timing, Pressure and distribution were all controlled by Mechanical means. Disadvantage: It had only throttle opening & RPM Control Engine output was linear. Fuel requirement by an IC Engine at different condition are against linear. This will results in wide mixture variation.

20. TYPES OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 20 Types ECU Based SI Engine fuel injection : According to the Control Methods: 1.Mechanical Fuel injection system: Fuel injection are by mechanical means Timing, Pressure and distribution were all controlled by Mechanical means. Disadvantage: It had only throttle opening & RPM Control Engine output was linear. Fuel requirement by an IC Engine at different condition are against linear. This will results in wide mixture variation.

21. TYPES OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 21 Types ECU Based SI Engine fuel injection : According to the Control Methods: 2.Electronic fuel injection system: All modern electronic fuel injection works in same way Sensors converts the various physical conditions both inside & outside the engine into electrical voltage. Based on the signal CPU find the fuel requirement for the engine.

22. TYPES OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 22 Types ECU Based SI Engine fuel injection : According to the Control Methods: 2.Electronic fuel injection system: The computer converts the final calculation of fuel requirement into timed voltage pulse which prompts the injector to open at a specific time and for a specific duration. The injector through its one or more holes, forces the very fine atomized fuel, making it more thoroughly vaporized & therefore more readily combustible

23. TYPES OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 23 Types ECU Based SI Engine fuel injection : According to the Control Methods: 2.Electronic fuel injection system: Purpose To Regulate the engine. To regulate the other engine devices to maintain smooth & stable operation Maintain optimum air-fuel mixture is supplied at appropriate timing, based on driver accelerator inputs & other sensor inputs.

24. TYPES OF FUEL SUPPLY SYSTEM FOR SI ENGINE 4/24/2019 16MT407 - Theory of Automobile Engineering 24 Types ECU Based SI Engine fuel injection : According to the Control Methods: 2.Electronic fuel injection system: Layout:

25. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 25

26. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 26 What is engine control unit/Electronic control unit: Brain of the electronic fuel injection fuel injection system. Microprocessor is most important unit It is relayed on different sensors & data stored in its memory ECU Function : i.) Produce the relevant control output signal ii.) Determines the actuator control amounts

27. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 27 Function of ECU: Fail safe function : When an abnormality occurs in a signal from a sensor, the ECU Ignores that the signal assume a pre – programmed value that allows to continue to operate. Backup Function : When an abnormality occurs in the ECU itself, the injectors are controlled by a backup circuit independent of the system in order to permit minimum driving. Self diagnosis Function: When an abnormality occurs in a signal from a sensor, the ECU lights up the check engine warning light & indicates the faulty system with codes any time when ignition is on.

28. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 28 Some important terminology in SI Engine Fuel control: Swept volume or displacement Volume: It is the volume swept through by the piston in moving between TDC & BDC A – Area of the cylinder L – Length of the cylinder D- Diameter of the cylinder  

29. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 29 Some important terminology in SI Engine Fuel control: Clearance Volume: It is the volume contained in the cylinder above the top of the piston, when the piston at TDC, It tells how much original volume is compressed.

30. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 30 Some important terminology in SI Engine Fuel control: Volumetric Displacement: Engine displacement is the swept volume for all piston inside the cylinders of a reciprocating engine in a single movement from TOP Dead center(TDC) to Bottom dead center (BDC). It is commonly specified in cubic centimeters (cc or cm 3 ), liters or cubic inches

31. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 31 Some important terminology in SI Engine Fuel control: Volumetric Displacement: For eg : 1000 cc 1000 cm3 = 1Litre = 1.0L Similarly 800cc = 800cm3 = 0.8 Liter = 0.8 L How to measure the capacity of the Engine volume V – Volume, D – Bore Dia, H – Stroke Length, N- No of Cylinders.  

32. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 32 Some important terminology in SI Engine Fuel control: Volumetric Efficiency: Volumetric Efficiency (VE) in internal combustion engine engineering is defined as the ratio of the mass density of the air fuel mixture drawn into the cylinder at atmospheric pressure (during intake stroke) to the mass density of the same volume of air in the intake manifold.

33. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 33 Some important terminology in SI Engine Fuel control: Volume flow rate of air:   Role of fuel injection: Mass flow rate of air: Where ,   Note: Volume flow rate mainly rely on Throttle angle RPM: A look table is formed in ECU for    

34. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 34 Some important terminology in SI Engine Fuel control: Role of fuel injection: Mass flow rate of fuel: 14.7:1 = stoichiometric air fuel mixture ratio  

35. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 35 Electronic controlled fuel injection for SI Engine: Schematic Layout

36. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 36 Manifold absolute pressure sensor (MAP): Pressure sensing element is silicon chip with an integral sensing diaphragm and Piezo electric resistor. The sensor converts the manifold absolute pressure to a voltage signal & transmits it to the ECU. The voltage signal & Engine revolution signal determines the fuel injection

37. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 37 TDC,CKP,CYP - SENSOR: These sensors provide the accurate information of engine position. Which determine the Injection & Ignition timing. Each sensors comprises of a pickup coil and a rotor which rotates in unison with either crankshaft or a camshaft. A signal is generated whenever one rotor teeth is passes by the pick up coil

38. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 38 TDC SENSOR: (TOP Dead C enter Sensor) Indicates the position of the piston at TOP Dead center. TDC generates the four pulses per cam/Crank shaft rotation To determine injection timing & ignition timing

39. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 39 CKP SENSOR: (Crankshaft Position Sensor) Indicates the crankshaft’s rotation angle. The output voltage signal from the sensor determine the Injection & Ignition timing & Duration

40. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 40 CYP SENSOR: (Cylinder Position Sensor) Indicates which cylinder at TDC For sequential fuel injection first cylinder will be the reference for fuel injection.

41. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 41 Barometric Pressure Sensor: The sensor converts the atmospheric pressure into voltage signal. For changes in atmospheric pressure, the discharge duration can be modified.

42. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 42 Vehicle speed Sensor: The sensor detects speed of the vehicle by taking account of gear shaft revolution. It contains a rotor within the rotating mechanism and a magnetic sensor among other components. The vehicle speed sensor converts the basic voltage signal basic ON/OFF signal & send it to cpu. To determine fuel injection & Ignition timing & Duration

43. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 43 Throttle position sensor: The sensor is made of potentiometer connected to the throttle shaft. The sensor detects the throttle valve opening angle as a resistance value. Converts it to a voltage signal. The signal increase during acceleration Cut it off during deceleration.

44. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 44 Intake air temperature sensor: It is temperature dependent resistor (i.e thermistor) The resistance of sensor decrease with rise of intake air temperature. It converts air temperature into a voltage signal & send this to ECU. This will modified the injection duration

45. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 45 Engine coolant temperature sensor : It is temperature dependent resistor (i.e thermistor) Mounted in the cylinder block The resistance of sensor decrease with rise of Engine coolant temperature. It converts engine coolant temperature into a voltage signal & send this to ECU. This will modified the injection duration

46. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 46 Oxygen Sensor: The oxygen sensor uses hollow closed end shaft of zirconia with platinum plated inner & outer surface. The inner surface is open to the atmosphere and the outer surface is exposed to the exhausted gas. It generates the voltage signal for oxygen density difference between atmospheric & Exhaust. This will determine the fuel injection duration.

47. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 47 Knock sensor: This sensor is mounted on the cylinder block and it detects knocking by sensing vibration. It converts the engine knock vibration into voltage signal. Knocking happen because of incorrect air fuel mixture. Which leads to burn the fuel into uneven packets rather than uniform bursts.

48. ECU FOR SI ENGINE FUEL SUPPLY SYSTEM 4/24/2019 16MT407 - Theory of Automobile Engineering 48 Battery voltage sensor: The battery voltage is used to power the ECU If voltage drop occurs, the ECU initiates the control to correct the corresponding delay in the fuel injector operation.

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