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Ignition coil
An ignition coil is used in the ignition system of a spark-ignition engine to transform the battery voltage to the much higher voltages required to operate the spark plug(s). The spark plugs then use this burst of high-voltage electricity to ignite the air-fuel mixture.
The ignition coil is constructed of two sets of coils wound around an iron core. Older engines often use a single ignition coil which has its output directed to each cylinder by a distributor, a design which is still used by various small engines (such as lawnmower engines). Modern car engines often use a distributor-less system (such as coil-on-plug), whereby every cylinder has its own ignition coil.
Diesel engines use compression ignition and therefore do not have ignition coils.
An ignition coil consists of an iron core surrounded by two coils (windings) made from copper wire. The primary winding has relatively few turns of heavy wire, while the secondary winding consists of thousands of turns of smaller wire and is insulated from the high voltage by enamel on the wires and layers of oiled paper insulation.
When the electrical circuit connected from the power source (e.g. the car's battery) to the primary winding is closed (by a contact breaker or transistor), current flows through the primary winding, which produces a magnetic field around the core. This current flow lasts for a period of time to build up energy in the coil. Once the coil is charged, the circuit is opened, and the resulting oscillation in the magnetic field induces a high voltage in the secondary winding. This high-voltage electricity travels through several components (such as a distributor and spark plug wires), before reaching the spark plug, where it is used to ignite the air/fuel mixture.
The timing of the circuit opening must be coordinated with the rotation of the engine, so that the burst of high-voltage electricity is produced at the optimal time to ignite the air/fuel mixture.
Modern electronic ignition systems operate using the same principle of charging an electric circuit, however they use a capacitor charged to around 400 volts,[citation needed] rather than using the induction charging of an ignition coil. Typical output voltages for modern ignition coils vary from 15 kV (for a lawnmower engine) to 40 kV (for a larger engine).
A modern single-spark system has one coil per spark plug. To prevent premature sparking at the start of the primary pulse, a diode or secondary spark gap is installed in the coil to block the reverse pulse that would otherwise form. In older wasted spark systems for four-stroke engines, the secondary winding of the ignition coil has two output terminals, both of which connect to a spark plug. The reverse pulse triggers the spark plug in a cylinder containing no air/fuel mixture (since that cylinder is out of phase by 180 degrees).
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Ignition coil AI simulator
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Ignition coil
An ignition coil is used in the ignition system of a spark-ignition engine to transform the battery voltage to the much higher voltages required to operate the spark plug(s). The spark plugs then use this burst of high-voltage electricity to ignite the air-fuel mixture.
The ignition coil is constructed of two sets of coils wound around an iron core. Older engines often use a single ignition coil which has its output directed to each cylinder by a distributor, a design which is still used by various small engines (such as lawnmower engines). Modern car engines often use a distributor-less system (such as coil-on-plug), whereby every cylinder has its own ignition coil.
Diesel engines use compression ignition and therefore do not have ignition coils.
An ignition coil consists of an iron core surrounded by two coils (windings) made from copper wire. The primary winding has relatively few turns of heavy wire, while the secondary winding consists of thousands of turns of smaller wire and is insulated from the high voltage by enamel on the wires and layers of oiled paper insulation.
When the electrical circuit connected from the power source (e.g. the car's battery) to the primary winding is closed (by a contact breaker or transistor), current flows through the primary winding, which produces a magnetic field around the core. This current flow lasts for a period of time to build up energy in the coil. Once the coil is charged, the circuit is opened, and the resulting oscillation in the magnetic field induces a high voltage in the secondary winding. This high-voltage electricity travels through several components (such as a distributor and spark plug wires), before reaching the spark plug, where it is used to ignite the air/fuel mixture.
The timing of the circuit opening must be coordinated with the rotation of the engine, so that the burst of high-voltage electricity is produced at the optimal time to ignite the air/fuel mixture.
Modern electronic ignition systems operate using the same principle of charging an electric circuit, however they use a capacitor charged to around 400 volts,[citation needed] rather than using the induction charging of an ignition coil. Typical output voltages for modern ignition coils vary from 15 kV (for a lawnmower engine) to 40 kV (for a larger engine).
A modern single-spark system has one coil per spark plug. To prevent premature sparking at the start of the primary pulse, a diode or secondary spark gap is installed in the coil to block the reverse pulse that would otherwise form. In older wasted spark systems for four-stroke engines, the secondary winding of the ignition coil has two output terminals, both of which connect to a spark plug. The reverse pulse triggers the spark plug in a cylinder containing no air/fuel mixture (since that cylinder is out of phase by 180 degrees).