Electronic ignition system

The function of an Electronic ignition system is to produce the spark to ignite the air-fuel mixture in a timely manner for maintaining the effective combustion

1. Session: Electronic Ignition System 1/18/2019 16MT407 - Theory of Automobile Engineering 1 MODULE 1

2. SESSION OBJECTIVES 1/18/2019 16MT407 - Theory of Automobile Engineering 2 On the completion of this session, the students might be able to understand, How the electronic Ignition system works

3. Topics Function of Ignition system Types of Ignition system Types of Electronic Ignition system 1/18/2019 16MT407 - Theory of Automobile Engineering 3

4. FUNCTION OF IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 4 Function of ignition system: To generate an electrical spark with enough heat to ignite the air-fuel mixture in the combustion chamber. To maintain the spark long enough to allow for combustion of all the air & fuel in the cylinder. To delivery the spark to each cylinder To properly time the spark so that the combustion can be started at right time during the combustion stroke of the each cylinder

5. TYPES OF IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 5 Types of Ignition system: Conventional Ignition system Battery Ignition system Magneto Ignition system Electronic Ignition system Transistorized Ignition system Capacitor discharge ignition system Fully electronic (i.e. Computer controlled) direct ignition system .

6. TYPES OF IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 6 Battery ignition system: Components Battery Ignition switch Ammeter Ignition coil Contact breaker Condenser Distributor sparkplugs

7. TYPES OF IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 7 Battery ignition system: Components Battery : Main source of electrical energy Supplies current to primary circuit One terminal is connected with earth Other with Ignition switch, Ammeter, Primary Coil of high tension wire, contact breaker points and then to earth.

8. TYPES OF IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 8 Battery ignition system: Components Ignition Switch : The ignition switch when closed, allows the flow of current from battery to the primary circuit of the ignition coil.

9. TYPES OF IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 9 Battery ignition system: Components Ammeter: It is a gauge It indicates the flow of electrical current through the system.

10. TYPES OF IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 10 Battery ignition system: Components Ignition coil: It is a type of induction coil which steps up low voltage current to high voltage current.

11. TYPES OF IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 11 Battery ignition system: Components Contact Breaker: It is the mechanism by means of which make or break of the contact is affected in the primary circuit of the ignition system for obtaining high voltage current.

12. TYPES OF IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 12 Battery ignition system: Components Condenser: The condenser is connected across the contact breaker. Prevents the arcing at the contact breaker points at the time of break in the primary circuit

13. TYPES OF IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 13 Battery ignition system: Components Distributor: The distributor is used to distribute the high voltage impulses to each of the spark plug at regularly timed intervals in the sequence of the engine’s firing order.

14. TYPES OF IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 14 Battery ignition system: Components Spark Plugs: The spark plugs are fitted in the combustion chamber to provide spark which cause the compressed air-fuel mixture to burn . Working : The induced voltage in the secondary coil directly proportional to the rate of collapse of magnetic field

15. TYPES OF IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 15 Pros & Cons of Battery Ignition system: Advantages Disadvantages 1. Good spark is available at engine start & Low speed 1. Engine speed increases means battery energy gets reduced & more time taken for building current 2.Auxiliary components utilized the battery energy (Head light, Indicator Light) 2. Mechanical & Electrical wear of contact breaker leads to short interval maintenance 3.Less cost 3.Not reliable at high speed

16. TYPES OF IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 16 MAGNETO IGNITION SYSTEM: (ROTATING MAGNET TYPE) Magneto is basically an electrical generator which is turned to create a periodic high voltage pulse rather than continuous current. An electrical generator is the reverse of an electromagnet. It is classified into two types. Rotating magnet type Rotating Armature type

17. TYPES OF IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 17 MAGNETO IGNITION SYSTEM: (ROTATING ARMATURE TYPE) Rotating Armature Type: In rotating armature type magneto, the armature along with the primary and secondary coils revolves in the magnetic field set up by the permanent magnets.

18. TYPES OF IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 18 Pros & Cons of Magneto Ignition system: Advantages Disadvantages 1. It is more useful at medium and high speed 1.Starting problem because of Low speed 2. No battery is required 2.Little more cost than the battery ignition system 3. It requires less maintenance 3.Chance s of miss fire, due voltage leakage in the wire

19. TYPES OF IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 19 Difference between Battery and Magneto Ignition system: Battery Magneto 1. Battery supplies current to primary circuit 1. Magneto generates current 2. Strong spark at starting & Low speed of engine 2. Weak spark at starting & Low speed 3. Easy engine starting 3. The starting of engine is difficult 4. If battery dried out means, engine never starts 4. No battery needed, no such kind of difficulty in here 5. The spark strength decreases with increase of speeds 5. The spark strength increases with increase in speeds. 6. This system requires more space This system requires less space 7. The wiring is quite complicated The wiring is comparatively simple 8. This system is used in cars, heavy vehicle likes buses & trucks It is used in motor cycles, scooters and racing cars

20. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 20 ELECTRONIC IGNITION SYSTEM: It overcomes the draw backs in the conventional ignition system. Easy control of ignition is possible Accurate ignition timing for all operating condition. TYPES ELECTRONIC IGNITION SYSTEM: Transistorized Ignition system Capacitor discharge ignition system Computer controlled direct ignition system (Without distributor)

21. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 21 Transistorized ignition system: It improves the ignition performance & reliability. No contact points required to open or close the ignition primary circuit Therefore no possibility of point of arc. Staring & Low speed characteristics are improved Transistorized ignition system : Components i.) Distributor, ii.) Igniter iii.) Ignition coil, iv.) Spark plug

22. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 22 Non Transistorized system: Ignition coil and spark plugs are called non-transistorized ignition system. Transistorized system: Distributor & Igniters are called transistorized systems.

23. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 23 Transistorized ignition system: Distributor: It consist solid state signal generator & Spark plug distributor. When the signal rotor is rotates, an AC voltage is induced in the pick up coil. The igniter is activated by these AC signals, Which connects & disconnects the primary circuit.

24. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 24 Transistorized ignition system: Distributor advance controllers are the same as used in Non transistorized system. Centrifugal governor advance mechanism control the signal rotor & causes to rotate Breaker plate rotate by vacuum advance mechanism . The above two mechanism helps the magnet & pick up coil fitted

25. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 25 SPARK ADVANCE MECHANISM: NEED Ignition begins at the end of the compression stroke in the combustion chamber at an appropriate time – Ignition Time If the spark occurs too early or too late in the engine cycle, it results in excessive vibration – Knocking Also affects engine power, Torque, Fuel economy, Engine life So ignition should be occurs at exact time in the cylinder.

26. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 26 SPARK ADVANCE MECHANISM: NEED At the end of compression stroke, maximum pressure is developed inside the combustion chamber. It results in Increasing engine speed. So spark occurs need to be advanced Modern engine control rely on electronics to control the timing precisely & accurately. Earlier speed sensing mechanism are used to control the spark timing Centrifugal Governor mechanism Vacuum advance mechanism

27. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 27 Centrifugal Governor Advance M echanism: It is used to regulate the ignition timing in response to the engine rpm. When the engine is running the distributor shaft and weight assembly rotate. As the engine speed increases, the two weights moves outwards from the centrifugal force, turning the breaker cam in advance direction

28. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 28 Centrifugal Governor Advance M echanism: Under this condition, the quantity of mixed air entering the cylinder is reduced. Set the air fuel mixture as lean – Lean mixture This causes it to burn slowly So spark advance is required for proper combustion

29. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 29 Centrifugal Governor Advance Mechanism : This results in cam lobes on the breaker cam to contact the rubbing block on the contact set earlier. This will cause the early spark on spark plug. The maximum advance can limit by stopper pin Stopper Pin

30. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 30 Vacuum advance mechanism: During light load in Engine, The Air/Fuel Mixture drawn inside combustion chamber is very small. So high vacuum is developed in the intake manifold. It may be noted that inertia force of the incoming gases to expel the burnt gases becomes weak, allowing the mixture to diluted with residual gas. It means mixes with reaming gas in the combustion chamber Results in power combustion So the engine vacuum is used to provide earlier ignition in combustion chamber.

31. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 31 Vacuum advance mechanism: Idle condition No vacuum at Intake manifold. Partial open of Throttle: Vacuum pressure at Diaphragm shield chamber Wider & Full open no vacuum pressure at intake manifold So not suits for high engine load

32. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 32 Transistorized ignition system : Igniter : Detects the signal from distributor pick up coil output. It is a component to amplify the signal & switch on/off the current in the primary circuit. It is Simply a transistor unit

33. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 33 Transistorized ignition system : Function Enables the generation of high performance spark over all speed ranges from high to low. The time control circuit controls the charging time to the ignition coil according to engine speed. It will helps the electric power consumption at low speed. Prevent the secondary voltage drop at high speed.

34. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 34 Transistorized ignition system : Function Ignition Switch on: Pickup coil & signal rotor aligned, Therefore no magnetic flux change The base voltage of the transistor at point p becomes high. Base current flow happen, transistor state is gets on – While primary current flows to the ignition coil.

35. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 35 Transistorized ignition system : Function 2. Staring Engine: The AC current overlaps with the DC Voltage (i.e. Battery Voltage) at point p and is applied in-between the transistor base & emitter When the applied AC current & DC voltage or on the plus side the transistor is turned on and primary current flows to the ignition coil.

36. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 36 Transistorized ignition system : Function 2. Staring Engine: However when the signal rotor rotates generating a minus voltage, this voltage will reduce the DC voltage at Point P. Hence the electrical potential drops below the operational voltage of the transistor, thus current will not flow to the base.

37. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 37 Transistorized ignition system : Function 2. Staring Engine: This cause the transistor to turn off, cutting off the primary current while the secondary coil generates high voltage.

38. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 38 Capacitor Discharge ignition system : Most of the vehicles follows inductive ignition system Which depends on electric inductance of the coil. Mean breaking the primary circuit & trigger the secondary circuit In this method capacitor is used to store the electrical energy, which is then discharged into the primary coil when required. The amount of stored energy depends on the rating of capacitor & charging voltage of the capacitor.

39. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 39 Capacitor Discharge ignition system : Booster circuits converts 12V from battery into 200 V by the booster circuit. The pulse generator allows the control circuit to send the current to the thyristor to on. When the thyristor receives the signal from the control circuit, the current charged in the capacitor flow to the ignition coil and high voltage is supplied to the spark plug.

40. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 40 Capacitor Discharge ignition system : Booster circuits converts 12V from battery into 200 V by the booster circuit. The pulse generator allows the control circuit to send the current to the thyristor to on. When the thyristor receives the signal from the control circuit, the current charged in the capacitor flow to the ignition coil and high voltage is supplied to the spark plug.

41. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 41 Capacitor Discharge ignition system : Advantage: Fast voltage rise. Short spark duration – Suits high speed vehicle. Full burning of Rich mixture Disadvantage : Insufficient energy for the long spark duration. Not suits for lean mixture

42. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 42 HALL EFFECT SWITCH: Replace the signal generator. (Signal rotor & Pick-up coil) According to hall effect, when a thin semi – conductor chip carrying current is cut by a magnetic field at right angles A voltage is produced at the edges of the switch.

43. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 43 HALL EFFECT SWITCH: Advantage: High Accuracy Extremely precise which results in optimum performance. High fuel efficiency & Low emissions.

44. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 44 Computer controlled direct ignition system: (Distributor less ignition system) Each spark plug has an ignition coil built in the spark plug cap. Ignition takes place when the primary current is supplied from the ignition control module to each coil. By replace the distributor & Wires reduce the power loss

45. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 45 Computer controlled direct ignition system: (Distributor less ignition system) Timing diagram of Distributor less ignition system

46. TYPES OF ELECTRONIC IGNITION SYSTEM 1/18/2019 16MT407 - Theory of Automobile Engineering 46 Advantages of Electronic Ignition system: No moving parts like previous types No maintenance required Spark plug life is increased Combustion efficiency is increased 90-95% More output power & More fuel economy.

47. 1/18/2019 16MT407 - Theory of Automobile Engineering 47 END