Coil pack is useful on gasoline engines; ignition allows the fuel/oxidizer mixture to be ignited in the combustion chamber. Because of the diesel engines do not need it as the pressure/heat auto-ignition; gasoline needs to trigger combustion by means of spark plugs (therefore ignition). In addition, with the presence of several spark plugs (as many as there are cylinders), the system must also know which one to supply with juice. It is also necessary to take into account that the spark must be produced at a very precise moment in each cylinder, according to the position of the piston and the current engine speed.
Version with a mechanical switch
Here are two phases of the ignition cycle. To better understand the relationship between the breaker and the distributor, it is necessary to know how the coil works. Generally speaking, the battery supplies current to the coil. This coil will have the role of sending an intense current towards the spark plugs using a process similar to a transformer. However, not all of the spark plugs in an engine coil pack have to be lit at the same time. So something is needed that chooses which spark plug is to be illuminated. It will then be the role of the coil pack for car that will therefore have the task of distributing the spark to the right spark plug. It is then a simple rotary mechanism which will generate connections on the terminals (connected to each of the spark plugs) that it crosses.
What is Coil pack:
Car coil pack takes care of transforming the 12v of the battery into something punchier: the goal is to cause a spark on the electrodes of the spark plugs. The latter is crossed by two circuits of coils of different gauges. When the primary circuit (red) is cut at the breaker (so-called open circuit), this induces a high voltage on the secondary circuit (blue wire which starts from the centre of the coil). This high voltage is obtained thanks to the help of electromagnetic forces induced by electricity.
The system ensures that the spark is produced at the right time, depending on the engine speed. Indeed, the more we go up in the towers, the more advance the ignition is required, i.e. trigger the spark a little earlier compared to the moment when the piston reaches the highest possible point (when the compression, of the 4-stroke engine). This highest point is called TDC for the initials of Top Dead Center (when the piston is all the way up). Note, however, that if the advance is too important, the motor will be subjected to great stresses which will damage it. The symptom is the appearance of clicking sounds, and the result is bent pistons.
Another preferred assembly on modern engines: “coil on the spark plug.”
On modern assemblies, there are mainly systems where there are as many coil pack as there are cylinders. Indeed, instead of having a distributor which distributes the “force” of a single-coil, there are several complete assemblies. Basically, it’s like each cylinder is an independent engine that has its own ignition system.
The code remains similar apart from that the system is not mechanical but also that it is this time controlled by the computer, which can then choose the best rhythm to have. Finally, this system optimizes combustion and therefore reduces fuel consumption.