A spark plug produces current through a process involving an electrical discharge that jumps across a gap between two electrodes inside the combustion chamber of an engine. When the ignition coil generates a high-voltage pulse, typically from 12,000 to 45,000 volts depending on the engine, this voltage is applied to the spark plug. The high voltage creates an electric field strong enough to ionize the air-fuel mixture present between the electrodes. This ionization allows current to flow as a spark, which ignites the air-fuel mixture in the combustion chamber, initiating the combustion process in an internal combustion engine.
The current produced by a spark plug is not AC (alternating current) or DC (direct current) in the conventional sense. Instead, it is a brief pulse of current that flows as a result of the high-voltage discharge from the ignition coil. This discharge is typically in the form of a high-energy pulse that jumps the gap between the electrodes in the spark plug. The duration of this current pulse is very short, lasting only a fraction of a millisecond, but it is crucial for igniting the air-fuel mixture in the engine cylinder.
The amount of current flowing through a spark plug during operation is relatively low compared to other electrical components. Typically, the current ranges from a few milliamperes (mA) to tens of milliamperes, depending on the design of the ignition system and the engine’s characteristics. The current pulse is sufficient to generate the spark needed to ignite the compressed air-fuel mixture in the engine cylinder.
A spark plug generates high voltage through the process of electromagnetic induction. When the ignition coil rapidly switches off, it induces a high-voltage pulse in the secondary winding of the coil. This high voltage is transferred to the center electrode of the spark plug. The gap between the center electrode and the ground electrode creates a high-resistance path. As the voltage across this gap increases, it eventually ionizes the air-fuel mixture, allowing current to flow in the form of a spark. The voltage required to jump the gap can be as high as 20,000 to 30,000 volts or more, depending on the engine and ignition system design.
A spark plug produces electricity that burns the air-fuel mixture through the ignition process. When the high-voltage pulse from the ignition coil creates a spark across the electrodes of the spark plug, it ignites the compressed air-fuel mixture in the engine cylinder. This ignition initiates the combustion process, where the mixture rapidly burns, releasing energy in the form of heat and expanding gases. The resulting combustion generates the force that drives the piston, powering the engine and producing mechanical work. The spark plug plays a critical role in ensuring reliable ignition and efficient combustion in internal combustion engines.