What is the function of automobile ignition coil?

The ignition coil is actually a transformer (with primary winding, secondary winding, iron core, insulation, etc.). ).

12 volt car voltage is converted into 20-30 kV voltage, and the car ignition system uses this high voltage to ignite the mixture in the cylinder.

The function of the automobile ignition controller is to distribute the ignition high voltage according to the ignition sequence of each cylinder. The function of the ignition coil is to change the low-voltage direct current into high-voltage electricity, and the voltage can reach tens of thousands of volts. The spark plug in the cylinder penetrates the air and ionizes to produce sparks.

Extended data:

principle

The usual ignition coil has two groups of coils, primary coil and secondary coil. Thick enameled wire is used for primary coil, generally with 0.5- 1 mm enameled wire for about 200-500 turns; Fine enamelled wire for secondary coil is generally 0. 1mm, about 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 (circuit 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 electricity. The reason why the ignition coil can change the low-voltage electricity on the car into high voltage is because it is the same as the ordinary transformer, and the turn ratio of the primary coil is greater than that of the secondary coil. However, the working mode of ignition coil is different from that of ordinary transformer.

The working frequency of ordinary transformer is fixed at 50Hz, which is also called power frequency transformer, while the ignition coil works in pulse form, which can be regarded as a pulse transformer, which repeatedly stores and releases energy at different frequencies according to different engine speeds. After the primary coil is connected to the power supply, with the increase of current, a strong magnetic field is generated around it, and the magnetic field energy is stored in the iron core.

When the switching device disconnects the circuit of the primary coil, the magnetic field of the primary coil decays rapidly, and the secondary coil will induce high voltage. The faster the magnetic field of the primary coil disappears, the greater the current at the moment of current disconnection, the greater the turn ratio of the two coils, and the higher the voltage induced by the secondary coil.

Extended source: Baidu Encyclopedia-Ignition coil