Download - Ignition System. Purpose Distribute high voltage pulses to spark plugs in correct sequence
Ignition System
Purpose • Distribute high voltage
pulses to spark plugs in correct sequence.
Basic operation
• Ignition switch on
–Switching device closed
• Piston moves close to TDC
–Ignition trigger device opens
–Ignition coil charges
Basic operation
• Current stops going to ignition coil
• Lack of current causes a high voltage surge, ignition coil discharges
Basic operation
• Surge flows across spark plug gap, creating an arc
• Arc ignites air/fuel mixture
Basic operation• Ignition trigger device
closes, recharging coil
–Electricity flows to the coil
–High voltage surge stops
Parts • Battery
• Ignition switch
• Bypass circuit
• Resistance circuit
• Primary circuit
Parts
• Secondary circuit
• Ignition coil
• Spark plugs
• Ignition system wires
Battery-Supply voltage
• Battery supplies voltage at start up
• Battery and alternator supply voltage during operation
Ignition switch
• Hot Switch, one side is connected to the battery and the other side is connected to the ignition system
Primary circuit • Low voltage
• Does not exceed 12.5 volts
• Conventional wires
Secondary circuit • High Voltage
• 4000 – 30 000 volts
• Heavy wire that prevents electrical leakage
Bypass circuit • Makes sure there is enough
voltage for start up• Starts engine using a lot of
voltage
Resistance circuit
• A resistor or resistor wire that makes sure the system can not exceed 9.5 10.5 Volts
Resistance circuit• Newer computer control cars
have computer controlled voltage regulators
• Resistor circuit not needed today
Distributor
• Sends voltage to appropriate spark plugs
• Tells magnetic field inside of coil when to collapse
Spark plug wires
• Cary high voltage from distributor to spark plugs
• 1000 -4000 ohms resistance per foot
Spark plugs
• Provide a spark for ignition
• Is a ground for primary circuit
• Insulated to stop electrical leakage
Ignition coil
• A transformer
• Creates short bursts of high voltage
Ignition coil • Older vehicles
–Small spark plug gaps –Less voltage 4000 – 8000 volts
Ignition coil• Newer vehicles
–Leaner fuel mixture
–Larger spark plug gap
–Voltage ranges from 4000 – 30 000 volts
–Average of 15 000 volts
Ignition coil parts
• 2 sets of windings
• 2 Primary terminals (low voltage)
• Iron core inside of windings • 1 High voltage out put
connection
Primary Windings
• Several hundred turns of heavy gage wire
Secondary windings
• Several thousand turns of light gauge wire
Ignition coil operation
• Current from the battery flows through the secondary windings, creating a magnetic field.
Ignition coil operation
• When current flow is interrupted the magnetic field collapses And sends its current through the secondary windings.
Ignition coil operation
• Because of the high number of secondary windings voltage is increased and current is decreased