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Chapter 9

Chapter 9. Ignition Systems page 147. Basic Ignition System Operation. charge builds up in coil (12 volts in) creates a magnetic field (windings of wire) voltage is stepped up (secondary windings) switch open (magnetic field collapses) high voltage discharged (to plug).

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Chapter 9

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  1. Chapter 9 Ignition Systems page 147

  2. Basic Ignition System Operation • charge builds up in coil (12 volts in) • creates a magnetic field (windings of wire) • voltage is stepped up (secondary windings) • switch open (magnetic field collapses) • high voltage discharged (to plug)

  3. Fundamental Electrical Principles • Electricity is lazy • Electricity wants to go to ground • electron theory (-) to (+) • conventional theory (+) to (-) • Conductors • Insulators

  4. The Electron Theory • Electricity moves from – to +

  5. Electrical Units of Measurement • Volts---- Push V • Current ---Quantity A • Resistance ----Resistance to flow 

  6. Ohm’s Law • E = I x R • E / I = R • E / R = I E I R

  7. Magnetism • Alike charges repel (-) (-) • Dissimilar charges attract (-) (+)

  8. Magnets & Electricity • Magnets can be used to for electricity • Electricity can be used to form magnets • Electricity when applied to magnets make stronger magnets

  9. Ignition Coils • Coils of wire wrapped around an iron core • Step up transformer

  10. Spark Plugs • Spark plugs contain an air gap for electricity to create a spark and make a seal

  11. The difference between a "hot" and a "cold" spark plug is in the shape of the ceramic tip. Heat Ranges • The manufacturers will select the right-temperature plug for each engine. • Some engines with high-performance naturally generate more heat, so they need colder plugs. • If the spark plug gets too hot, it could ignite the fuel before the spark fires • It is important to stick with the right type of plug • Engine that burn oil may need hot plugs

  12. Measuring Spark Plug Temperature

  13. Types of Electrodes • Center electrode • Side electrode

  14. Switching Devices • Breaker points • Electronic

  15. Breaker Points • Ran by cam shaft

  16. Electronic Switching Devices • NO breaker points to burn or wear out

  17. The MBI Magneto System • Mechanical Breaker Point Ignition • produce power without an outside power source • Condenser-prevents arching

  18. The MBI Magneto Cycle • Magnets pass legs

  19. Coil • 150 turns of large wire • 20,000 turns of fine wire • Iron core

  20. The Stop Switch • Plug only fires when points open • Switch grounds points • Fasten metal to head bold

  21. Ignition Advance Systems • Cause spark earlier • BTDC • As engine warms up • Speeds up • Centrifugal • Vacuum • Mechanical

  22. Dwell & Cam Angles • Time points stay closed • Lobes size = dwell time

  23. Electronic Ignition • Solid state • No maintenance • No points-burning • Spark plug life • Easy starting • Higher output • Starts flooded engine • Higher spark output

  24. Electronic Ignition • Hermetically sealed • Uniform performance • Good under adversity • Improved idling • Smoother power under load

  25. Operation of Capacitive Discharge Ignition ( CDI) • Solid State • Newest • NO Breaker points • Magnets only moving parts

  26. Operation of Transistor Controlled Ignition (TCI) Systems

  27. Magneto Ignition Systems Compared

  28. Battery Ignition Systems • Low voltage primary circuit • High voltage secondary circuit • ignition switch • builds field • field collapses • spark to plug

  29. High Voltage Secondary Circuits • Uses a step up transformer • Several winding of wire / iron core

  30. Auto-Transformer Type Ignition Coils

  31. The Lead Acid Battery

  32. Vehicle batteries

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