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Chapter 9Chapter 9
Ignition SystemsIgnition Systems
page 147page 147
Basic Ignition System Operation Basic Ignition System Operation
charge builds up in coil (12 volts in)charge builds up in coil (12 volts in)
creates a magnetic field (windings of wire)creates a magnetic field (windings of wire)
voltage is stepped up (secondary voltage is stepped up (secondary windings)windings)
switch open (magnetic field collapses)switch open (magnetic field collapses)
high voltage discharged (to plug)high voltage discharged (to plug)
Fundamental Electrical Fundamental Electrical PrinciplesPrinciples
Electricity is lazyElectricity is lazy
Electricity wants to go to groundElectricity wants to go to ground
electron theory (-) to (+)electron theory (-) to (+)
conventional theory (+) to (-)conventional theory (+) to (-)
ConductorsConductors
InsulatorsInsulators
The Electron TheoryThe Electron Theory
Electricity moves from – to +Electricity moves from – to +
Electrical Units of MeasurementElectrical Units of Measurement
Volts---- PushVolts---- Push VV
Current ---QuantityCurrent ---Quantity AA
Resistance ----Resistance to flowResistance ----Resistance to flow
Ohm’s LawOhm’s Law
E = I x R E = I x R
E / I = RE / I = R
E / R = IE / R = I E
I R
MagnetismMagnetism
Alike charges repel (-) (-)Alike charges repel (-) (-)
Dissimilar charges attract (-) (+)Dissimilar charges attract (-) (+)
Magnets & ElectricityMagnets & Electricity
Magnets can be used to for electricityMagnets can be used to for electricity
Electricity can be used to form magnetsElectricity can be used to form magnets
Electricity when applied to magnets make Electricity when applied to magnets make stronger magnetsstronger magnets
Ignition CoilsIgnition Coils
Coils of wire wrapped around an iron coreCoils of wire wrapped around an iron core
Step up transformerStep up transformer
Spark PlugsSpark Plugs
Spark plugs Spark plugs contain an air contain an air gap for gap for electricity to electricity to create a spark create a spark and make a and make a seal seal
Heat Heat RangesRanges
The difference between a "hot" and a "cold" spark plug is in the shape of the ceramic tip.
The manufacturers will select the right-temperature The manufacturers will select the right-temperature plug for each engine.plug for each engine.
Some engines with high-performance naturally Some engines with high-performance naturally generate more heat, so they need colder plugs.generate more heat, so they need colder plugs.
If the spark plug gets too hot, it could ignite the fuel If the spark plug gets too hot, it could ignite the fuel before the spark firesbefore the spark fires
It is important to stick with the right type of plugIt is important to stick with the right type of plug
Engine that burn oil may need hot plugsEngine that burn oil may need hot plugs
Measuring Spark Plug Measuring Spark Plug TemperatureTemperature
Types of ElectrodesTypes of Electrodes
Center electrodeCenter electrode
Side electrodeSide electrode
Switching DevicesSwitching DevicesBreaker pointsBreaker points
ElectronicElectronic
Breaker PointsBreaker Points
Ran by cam shaftRan by cam shaft
Electronic Switching DevicesElectronic Switching Devices
NO breaker pointsNO breaker points to burn or wear out to burn or wear out
The MBI Magneto SystemThe MBI Magneto System
Mechanical Breaker Point IgnitionMechanical Breaker Point Ignition
produce power without an outside power produce power without an outside power sourcesource
Condenser-prevents archingCondenser-prevents arching
The MBI Magneto CycleThe MBI Magneto Cycle
Magnets pass legsMagnets pass legs
CoilCoil
150 turns of large wire150 turns of large wire
20,000 turns of fine wire20,000 turns of fine wire
Iron coreIron core
The Stop SwitchThe Stop Switch
Plug only fires when points openPlug only fires when points open
Switch grounds pointsSwitch grounds points
Fasten metal to head boldFasten metal to head bold
Ignition Advance SystemsIgnition Advance Systems
Cause spark earlierCause spark earlier
BTDC BTDC
As engine warms upAs engine warms up
Speeds upSpeeds up
CentrifugalCentrifugal
VacuumVacuum
MechanicalMechanical
Dwell & Cam AnglesDwell & Cam Angles
Time points stay closedTime points stay closed
Lobes size = dwell timeLobes size = dwell time
Electronic IgnitionElectronic Ignition
Solid stateSolid stateNo maintenanceNo maintenanceNo points-burningNo points-burningSpark plug lifeSpark plug lifeEasy startingEasy startingHigher outputHigher outputStarts flooded engineStarts flooded engineHigher spark outputHigher spark output
Electronic IgnitionElectronic Ignition
Hermetically sealedHermetically sealed
Uniform performanceUniform performance
Good under adversityGood under adversity
Improved idlingImproved idling
Smoother power under loadSmoother power under load
Operation of Capacitive Operation of Capacitive Discharge Ignition ( CDI)Discharge Ignition ( CDI)
Solid StateSolid State
NewestNewest
NO Breaker pointsNO Breaker points
Magnets only moving partsMagnets only moving parts
Operation of Transistor Operation of Transistor Controlled Ignition (TCI) Controlled Ignition (TCI)
SystemsSystems
Magneto Ignition Systems Magneto Ignition Systems ComparedCompared
Battery Ignition SystemsBattery Ignition Systems
Low voltage primary circuitLow voltage primary circuit
High voltage secondary circuitHigh voltage secondary circuit
ignition switchignition switch
builds fieldbuilds field
field collapsesfield collapses
spark to plugspark to plug
High Voltage Secondary High Voltage Secondary CircuitsCircuits
Uses a step up transformerUses a step up transformer
Several winding of wire / iron coreSeveral winding of wire / iron core
Auto-Transformer Type Ignition Auto-Transformer Type Ignition CoilsCoils
The Lead Acid BatteryThe Lead Acid Battery
Vehicle batteriesVehicle batteries