IGNITION COIL

In a gasoline engine, where the combustion is initiated by a spark, the ignition coil supplies the required voltage to the spark-plug to combust the fuel. The ignition coil transforms the 12V battery voltage into very high voltage (10kV and more) which creates a spark across the plug which ignites the air-fuel mixture in the combustion chamber. By the principle of electromagnetic induction, the coil stores energy in the primary winding and then discharges it to the secondary winding. The charging and discharging period is controlled by the ECU by means of electrical interrupts. The voltage amplification and energy transfer from the primary winding to the secondary winding is determined by the relative numbers of coil windings (turns ratio) of the two. The magnitude of the primary current and the coil’s primary inductance determine the amount of energy stored in the coil.