Ignition Coil Typesby Jamie Rankin
An ignition coil is actually two coils of wire wrapped around an iron core. The primary coil is made of heavy wire and is connected to two terminals on the top of the coil. The secondary coil is made of fine wire and connects to the high-tension connection, also on the top of the coil. There are three main types of ignition systems, hence three main types of ignition coils.
The conventional breaker point-type ignition system has been in use since the early 1900s. In this system, the primary circuit of the ignition coil receives power from the battery through a resistor. The power is grounded through closed ignition points in the distributor. Current flows through the windings of the primary coil, creating a magnetic field. When the points are opened by the rotation of the distributor cam, the current's electrical circuit is broken, collapsing the magnetic field. The force from the collapse crosses the windings of the secondary coil and creates an electrical current within them. The current flows into the distributor cap and eventually into the spark plugs, all in a split second.
Electronic ignition systems were popular in the mid-1970s and were developed to be more reliable and produce fewer emissions. This type of ignition is very similar to the conventional system, with the same configuration in the secondary circuit of the ignition coil. From the battery to the coil terminal, the primary circuit is also the same. But instead of a distributor cam and points, the electronic system uses a pickup coil to signal the control module, which then fires the ignition coil. On some electronic systems, the ignition coil is located inside the distributor cap.
In a distributorless ignition system, which came out in the 1980s, its design allowed more energy to be available from the coils. Instead of two coils, there are typically three or more mounted together in a coil pack, each responsible for firing either one spark plug or a pair. This system uses a magnetic triggering device to determine engine speed and crankshaft position. The triggering device sends a signal to the engine control module or the ignition control module which, in turn, sends energy to the coil.
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