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Ignition and Electrical Systems

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  1. City & Guilds 3905 / IVQ in Motor Vehicle Engineering Unit 1 Engine Systems 1 Ignition and Electrical Systems Module (b)

  2. Table of Content • Introduction to Basic Electricity • 1.1b & 1.2b Spark ignition systems • 1.3b Ignition Timing • 1.4b Electrical Systems

  3. Introduction to basic Electricity

  4. Introduction to basic Electricity • After studying this chapter you will know about: • Electrons & their flow • Electricity • Current, its flow & types • Voltage • Resistance • Ohm’s Law

  5. Introduction to basic Electricity • Everything in the world is made of matter • Matter is anything that has mass (weight) and occupies space

  6. Introduction to basic Electricity • All matter (solid, liquid & gas) have molecules • All molecules can be further divided into atoms • Each atom has a nucleus which contains: • Neutron (no charge) • Proton (positive charge) • Electron (negative charge)Moves around nucleus Inside Nucleus

  7. Introduction to basic Electricity • Element • A chemical element is a pure chemical substance consisting of one type of atom O Cu

  8. Introduction to basic Electricity • Compound • A chemical compound is a pure chemical substance consisting of two or more different elements CH4

  9. Introduction to basic Electricity • Atom • Molecules Atom is the smallest particle into which an element or substance can be divided, without losing its property O

  10. Introduction to basic Electricity • Atom Construction

  11. Introduction to basic Electricity • Electrons • They have (–)ve charge • Free to move around nucleus, unlike protons and neutrons which are fixed in the center • (+)ve charge in the nucleus by proton attracts (–)ve electron • The closer, the stronger force of attraction

  12. Introduction to basic Electricity • Simplest atom of hydrogen

  13. Introduction to basic Electricity • Now lets see a more complex atom of copper

  14. Introduction to basic Electricity • Copper • Most commonly used • Atomic number is 29 (i.e. 29 protons & 29 electrons) • 2, 8, 18, 1 electrons in 1st to 4th ring • Conductors have < 4 electrons in outer ring • Insulators have > 4 electrons in outer ring • Semi-conductors = 4 electrons in outer ring

  15. Introduction to basic Electricity • Electron Flow • Electrons farther from the nucleus are loosely held • They start moving freely from atom to atom • They are also called free electrons • When atom looses electron, it gains another one from the adjacent atom

  16. Introduction to basic Electricity • Current & Electricity • The directed flow of electron from one atom to another in a conductor • Measured in amperes (A) • Free electrons, unless directed, can not produce current

  17. Introduction to basic Electricity • Current Flow • Conventional (we will study this type) • Positive to negative • Electron theory • Negative to positive

  18. Introduction to basic Electricity • Current flow • Types • A.C • D.C

  19. Introduction to basic Electricity • Voltage • A force that causes electrons to move in an electrical circuit • Also called • EMF (electromotive force) • Electrical pressure • Potential difference (Difference in potential between two points)

  20. Introduction to basic Electricity • Resistance (Ohms) • Resistance restricts the flow of electric current. • Energy is used up as the voltage drives the current through the resistor • This energy appears as heat in the component.

  21. Introduction to basic Electricity • Ohm’s Law

  22. Introduction to basic Electricity • Ohm’s Law

  23. Introduction to basic Electricity • Ohm’s Law

  24. Introduction to basic Electricity • Ohm’s Law

  25. 1.1b & 1.2bSpark Ignition Systems(Identification, Components & Function)

  26. 1.1b & 1.2b Spark ignition systems • In this section we will study about: • Spark ignition system components • Contact Breaker • Contact Breakerless • Ignition switch • Ignition coil • Ballast resistor • Spark advance devices • Spark plugs

  27. Spark ignition systems 1.1b & 1.2b • Ignition System

  28. 1.1b & 1.2b Spark ignition systems • Ignition System • Provides high-intensity sparks at the spark plugs to ignite the air-fuel mixture in the combustion chamber • Spark should be at the right time • Energy is obtained from the battery & alternator • Can produce 40,000 or more volts by the ignition coil

  29. 1.1b & 1.2b Spark ignition systems • Components • Battery • Low-tension cables • Ignition coil • Distributor • Coil high-tension cable • Spark plug cables • Spark plugs

  30. 1.1b & 1.2b Spark ignition systems

  31. 1.1b & 1.2b Spark ignition systems • Types We will only talk about the contact-breaker & contact-breakerless types in detail

  32. 1.1b & 1.2b Spark ignition systems • Contact Breaker Ignition Systems

  33. 1.1b & 1.2b Spark ignition systems • Contact Breaker Ignition Systems • There are two parts to the system • Primary Section • Battery • Ignition switch • Ballast resistor • Primary winding of the ignition coil • Primary section of the distributor

  34. 1.1b & 1.2b Spark ignition systems • Contact Breaker Ignition Systems • Secondary Section • Secondary windings of the ignition coil • Secondary side of the distributor • Spark plug cables • Spark plugs

  35. Spark ignition systems 1.1b & 1.2b • Contact Breaker Ignition Systems

  36. 1.1b & 1.2b Spark ignition systems • Contact Breaker Ignition Systems • Activity in the primary section • Step 1 • Battery is connected to terminal B of the ignition switch • Ignition switch is turned to S for starting • Ignition switch is turned to IG once the engine is running

  37. 1.1b & 1.2b Spark ignition systems • Contact Breaker Ignition Systems • Activity in the primary section • Step 2 • Breaker points are closed • To energies primary windings, current flows from:

  38. 1.1b & 1.2b Spark ignition systems • Contact Breaker Ignition Systems • Activity in the primary section • Step 3 • Breaker points are opened and closed by the action of cam in the distributor as it rotates • Primary windings are de-energized when points are open, and a high voltage is induced in the secondary windings

  39. 1.1b & 1.2b Spark ignition systems • Contact Breaker Ignition Systems • Activity in the Secondary Section • Step 1 • Secondary winding of the coil are connected to the rotor of the distributor by the coil high-tension cable • The rotor rotates to distribute the high-tension voltage to the segments in the distributor cap

  40. 1.1b & 1.2b Spark ignition systems • Contact Breaker Ignition Systems • Activity in the Secondary Section • Step 2 • Spark plug cables connect the segments of the distributor cap to the spark plug • The cable should be connected in correct firing order

  41. 1.1b & 1.2b Spark ignition systems • Contact Breaker Ignition Systems • Activity in the Secondary Section • Step 3 • High voltage from coil causes a spark at the spark plug electrodes • This ignites the air-fuel mixture in the combustion chamber • Process is repeated for each power stroke of engine

  42. 1.1b & 1.2b Spark ignition systems • Contact Breaker Ignition Systems • Ignition Switch • It controls the power by preventing accessories from running down the car's battery when the car is parked for a long period of time • The ignition switch connects the starter to the battery, allowing the battery to send a powerful surge of electricity to the starter when the car is being started.

  43. Spark ignition systems 1.1b & 1.2b • Contact Breaker Ignition Systems • Ignition Switch

  44. 1.1b & 1.2b Spark ignition systems • Contact Breaker Ignition Systems • Ignition Coil • Primary winding consists of a few hundred turns of heavy wire • Secondary winding consists of thousands of turns of fine wire • Soft-iron core in the centre of the coil • 12 volts of the battery are stepped up to the high voltage

  45. 1.1b & 1.2b Spark ignition systems • Contact Breaker Ignition Systems • Ignition Coil

  46. 1.1b & 1.2b Spark ignition systems Types of Ignition Coil (a) conventional coil (b) coil-on-plug

  47. 1.1b & 1.2b Spark ignition systems Types of Ignition Coil (c) direct ignition, dual-spark coil (d) coil with exposed core

  48. 1.1b & 1.2b Spark ignition systems • Contact Breaker Ignition Systems • Ballast Resistor • Fitted between the ignition switch and the ignition coil • Reduces voltage at the coil • Coil is designed to operate on lower-than-battery voltage

  49. 1.1b & 1.2b Spark ignition systems • Contact Breaker Ignition Systems • Ballast Resistor

  50. Spark ignition systems 1.1b & 1.2b • Contact Breaker Ignition Systems • Distributor parts • Housing • Shaft with a cam • Advance mechanism • Breaker contact points • Capacitor • Rotor • Cap