The role of the ignition coil

With the development of automobile gasoline engine to the direction of high speed, high compression ratio, high power, low fuel consumption and low emission, the traditional ignition device has been unable to meet the requirements of use. The core components of the ignition device are the ignition coil and the switching device, improve the energy of the ignition coil, the spark plug can produce enough energy spark, which is the basic condition of the ignition device to adapt to the operation of modern engines.

There are usually two sets of coils inside the ignition coil, the primary coil and the secondary coil. The primary coil uses a thicker enamelled wire, usually about 0.5-1 mm enamelled wire around 200-500 turns; The secondary coil uses a thinner enamelled wire, usually about 0.1 mm enamelled wire around 15000-25000 turns. One end of the primary coil is connected to the low-voltage power supply (+) on the vehicle, and the other end is connected to the switching device (breaker). One end of the secondary coil is connected with the primary coil, and the other end is connected with the output end of the high voltage line to output high voltage.

The reason why the ignition coil can turn the low voltage into high voltage on the car is that it has the same form as the ordinary transformer, and the primary coil has a larger turn ratio than the secondary coil. But the ignition coil working mode is different from the ordinary transformer, the ordinary transformer working frequency is fixed 50Hz, also known as power frequency transformer, and the ignition coil is in the form of pulse work, can be regarded as a pulse transformer, it according to the different speed of the engine at different frequencies of repeated energy storage and discharge.

When the primary coil is powered on, a strong magnetic field is generated around it as the current increases, and the magnetic field energy is stored in the iron core. When the switching device disconnects the primary coil circuit, the magnetic field of the primary coil decays rapidly, and the secondary coil senses a high voltage. The faster the magnetic field of the primary coil disappears, the greater the current at the moment of current disconnection, and the greater the turn ratio of the two coils, the higher the voltage induced by the secondary coil.