The car ignition coil is a transformer capable of providing high-voltage pulses.
The purpose of these pulses is to create a spark (arc) between the electrodes of the spark plug of an internal combustion engine, of sufficient strength and duration to properly initiate 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 desired current is reached. At the moment of power failure, the secondary output terminal generates a high voltage of 20~30Kv to ensure spark ignition.
Over the years, the types of coils related to the development of engines are more or less complex:
- Oil Bath Coil: This is the most outdated technology. Facet has decided not to produce them as they are highly polluting and limited in production, suggesting a newer generation of coils as an alternative (see below).
- Electromechanical distribution coils (1st generation): these are single coils, and the high voltage is "distributed" to the spark plugs via special cables from a rotary distributor mounted on the distributor, inside the "cap".
- Misfire coil (2nd generation): This type of coil is called a misfire coil because there is a normal ignition spark in the cylinder during the compression phase and a spark of small intensity in the cylinder during the exhaust phase. Ignition systems using these coils are called "static distribution" or "distributors" 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 manages the strength of the primary current by controlling the pulse duration so that the current reaches a set value.
This type of coil also includes some multi-plug coils.
- Direct coils (3rd generation): These coils are installed on the fully 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 connected to the ground through a low-voltage connection, or to the positive terminal of the primary circuit within the coil. Therefore, we prepared a coil for each candle.
Each direct coil consumes half the power of a missinga spark coil: this advantage is important because direct coils mounted on spark plugs operate at a higher temperature. These coils can be of the "pencil" type, with axial windings on the spark plug, forming the typical "pencil" shape, or of the "plug top" type, where the coils are assembled in a single block mounted on the motor head, or Located below the direct coil pack connected to the spark plug by a high voltage cable. Direct coils can be equipped with built-in control electronics.