Ignition System Of IC Engine

Ignition System

· Air fuel mixture produced in carburetor is compressed in the cylinder by movement of piston during compression stroke, then fired by the spark plug.

· Very high voltage with very minimal current is needed for produce such high intensity spark.

· Ignition system generates high voltage unto required mark and ignites the air fuel mixture into the combustion chamber.  

Types Of Ignition System:

Ignition System are powered by either battery or a magneto.

Classification on the basis of power source:

Magneto Ignition:

1. Magneto ignition with contact ignition coil.

2. Alternative current with contact source coil.

3. Capacitor discharge ignition.

Battery Ignition:

1. Battery Ignition

2. Semi-transistor ignition

3. Full transistor ignition

4. Direct current-CDI ignition

5. Electronic control unit

Ignition Coil:

· The ignition coil generates sufficient high voltage which is necessary to produce electric spark in the spark plug.

· It’s similar to transformer utilizing self and mutual induction of the coil.

Secondary Voltage =number of turns in secondary coil/number of turns in primary coil*primary voltage

Function Of Ignition Coil:

· It consists of two windings primary as well as secondary wound on a soft iron core.  

· AC voltage is supplied to the primary winding which is input.

· Voltage develops across the secondary winding whose value is proportional to the ratio of the number of turns in secondary winding to the number of turns in primary winding.

Iron Core:

It consists of more than 10 iron sheets or wire insulated from each other for preventing the Eddy current losses.

Primary Coil:

· A copper wire 0.5~1 mm thick is wound a few hundred turns around a thick insulating film covering the secondary Coil.

· Drastic changes of current are made in the primary coil by continuous action of contact breaker or electric signals.

· 200~300 volts induced in the coil by the capacitor.

· Is raised up to 15000~20000 volts in the secondary winding by mutual induction in proportion to the ratio of number of windings.

· Hence it’s a kind of transformer.

Secondary Coil:

· A copper wire approximately 0.1 mm thick is wound more than 15000 times around the iron core.

· One end of the coil leads to high voltage terminal.

· Whether the other one is connected to the primary coil.