What Is an Ignition Coil?

As the core component of the automobile engine ignition system, the ignition coil plays a key role in converting the low-voltage power supply commonly used in vehicles (such as the common 12 volts) into high-voltage electricity (voltage can reach 15 to 20 kilovolts or higher) sufficient to ignite the mixture. This conversion process relies on the basic principle of electromagnetic induction. The internal structure of the ignition coil consists of two parts: the primary coil and the secondary coil: the primary coil has fewer turns and thicker wires, which are directly connected to the low-voltage power supply of the vehicle; while the secondary coil has more turns and thinner wires, one end of which is connected to the primary coil and the other end is connected to the high-voltage line output end, responsible for outputting high-voltage electricity.

However, the working mode of the ignition coil is different from that of a common transformer. Ordinary transformers usually work continuously, but the ignition coil works in an intermittent manner, which frequently stores and releases energy according to the engine speed. When the primary coil is connected to the power supply, a magnetic field is generated; when the power supply is disconnected, the secondary coil will sense and generate extremely high voltage due to the rapid disappearance or attenuation of the magnetic field.

There are various types of ignition coils, the most common of which include open magnetic and closed magnetic coils. They may differ in structure and application environment, but their core function is to provide enough energy to the spark plug to generate electric sparks, thereby igniting the combustible mixture in the engine cylinder, ensuring that the engine can operate normally and efficiently.