Wiring Fundamentals: Ignition Coil Types
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Ignition Coil Types
02.28
| 00:00 | - To ignite the combustion charge in the cylinder, the ECU controls an ignition coil which provides enough electrical energy to a spark plug to generate a spark across its electrode gap, initiating the combustion process. |
| 00:12 | Your ECU will have dedicated ignition output pins for controlling ignition coils and these will be listed in your ECU's documentation. |
| 00:19 | We can break down the common types of ignition coils and their required wiring into three main groups, conventional distributed, conventional direct fire, and internally amplified direct fire. |
| 00:30 | There is another type you may come across periodically known as capacitive discharge ignition or CDI ignition coils. |
| 00:36 | But they're usually only used in high level motorsport and are outside the scope of this course. |
| 00:41 | A conventional ignition coil works by converting a low voltage, high current input into a high voltage low current output. |
| 00:49 | Ignition coils consist internally of a primary and a secondary winding. |
| 00:53 | And they operate by taking advantage of the inductive load principal we discussed in the electrical fundamentals section of the course. |
| 01:01 | The primary winding of the ignition coil is the part your ECU interacts with via its ignition output channels and is simply a coil of wire with a terminal at either end. |
| 01:10 | Your ECU allows current to pass through the primary winding and when it requires a spark to occur it removes the ground connection from the circuit, stopping the flow of current abruptly. |
| 01:21 | As this primary winding is an inductive load, this generates a voltage spike, typically in the range of 200-300 volts. |
| 01:28 | The secondary winding of the coil then converts this voltage spike up to a much larger voltage. |
| 01:34 | Typically in the range of 20000 to 40000 volts which it then applies to the spark plug gap. |
| 01:40 | This voltage is high enough for a spark to jump across the gap which ignites the combustion charge. |
| 01:45 | The primary winding of the ignition coil requires a large current to flow through it to build up enough energy for the secondary winding to generate a spark. |
| 01:53 | Generally the ECU is not capable of handling this level of current directly and will use a device called an ignition amplifier. |
| 02:00 | These are sometimes known as igniters or ignition modules but they all perform the same task. |
| 02:05 | You can think of them in the same way as a relay except that their solid state electronics are capable of switching on and off much faster than the mechanical switch system in a conventional relay. |
| 02:15 | The ECU provides the control signal to the ignition amplifier, which in turn then handles the switching of the current passing through the primary winding of the ignition coil. |
