Ignition Systems

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
Ohms 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
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