What Is The Function Of The Ignition Coil Of A Car

Ignition coils are transformers capable of delivering high voltage pulses.

The purpose of these pulses is to create a spark (arc) between the electrodes of the spark plug of the internal combustion engine, the strength and duration of which is sufficient to properly start the internal combustion of the air-gasoline mixture.

The working principle of the coil consists of a primary winding that is driven by an electronic switch until the required current is reached. At the moment of power failure, a high voltage of 20~30Kv is generated at the secondary output to ensure spark ignition.

Over the years, the types of coils associated with the development of the engine have been more or less complex:

- Oil bath coil: this is the most outdated technology. Facet has decided not to produce them because they are heavily polluting and have limited production, recommending a newer generation of coils as an alternative (see below).

- Electromechanical distribution coils (first generation): these are single coils, high voltage is "distributed" by a special cable from a rotary distributor installed on the distributor to a spark plug, inside the "cap".

- Misfire coil (second generation): This coil is called a misfire coil because there is a normal ignition spark in the cylinder in the compression phase and a spark of small intensity in the cylinder in the exhaust stage. Ignition systems that use these coils are called "static dispensing" or "dispenserless" because they eliminate distributors, caps, and high-voltage cables, making the ignition system more reliable. The electronic control system of these coils is more precise and can manage the intensity of the primary current by controlling the pulse duration, so that the current reaches a given value.

This type of coil also includes some multi-plug type coils.

- Direct coils (3rd generation): These coils are mounted on an all-electronic ignition system.

In these coils, the negative output of the secondary circuit is connected directly to a single spark plug, while the other end is grounded by a low-voltage connection, or connected to the positive terminal of the primary circuit within the coil. Therefore, we have prepared a coil for each candle.

Each direct coil consumes half the power consumed by the lost spark coil: this advantage is important because the direct coil mounted on the spark plug operates at a higher temperature. These coils can be "pencil" type with axial windings on the spark plug to form a typical "pencil" shape, or "plug top" type, where the coils are assembled in a single block mounted on the motor head, or located below a direct coil pack connected to the spark plug by a high-voltage cable. Direct coils can be equipped with built-in control electronics.