Turbo Petrol Automobile Ignition Coil 31422117 S60 MK2

According to the magnetic circuit, the ignition coil is divided into two types: open magnetic type and closed magnetic type.

Open magnetic circuit ignition coil

The open magnetic circuit ignition coil is generally a pot-shaped structure. It is composed of several silicon steel sheets to form a rod-shaped iron core, and the secondary coil and the primary coil are respectively wound on the outside of the iron core. The secondary coil is an enameled wire with a wire diameter of 0.05 to 1 mm, and the number of turns is 20,000 to 30,000. The wire diameter of the primary coil is 0.5 to 1.0 mm, which is thicker than the secondary coil, and the number of turns is only 150 to 300. The primary coil is wound on the outside of the secondary coil, so the magnetic flux change produced by the secondary coil is exactly the same as that of the primary coil. The winding directions of the primary coil and the secondary coil are the same. The start of the secondary coil is connected to the high-voltage output connector, and the end of the secondary coil is connected to the start of the primary coil and connected to the "+" terminal of the housing. The end of the primary coil is connected to the housing. The "one" post is connected to the collector of the power transistor in the igniter, and the igniter controls the on and off of the primary coil current.

Closed magnetic circuit ignition coil

The closed magnetic circuit ignition coil is designed with a closed iron core that allows for the magnetic flux to pass through it. The magnetic permeability of the iron core is significantly higher than that of air, which means that the open magnetic circuit ignition coil requires a larger magnetomotive force to obtain the same magnetic flux as the closed magnetic circuit ignition coil. To achieve this, the primary coil of the open magnetic circuit ignition coil needs a larger number of turns and a larger wire diameter. As a result, the secondary coil also needs to have an increased number of turns to maintain the same turns ratio. This makes it difficult to miniaturize the open magnetic circuit ignition coil.

On the other hand, the closed magnetic circuit ignition coil has a lower magnetic resistance, which allows for effective reduction of the magnetomotive force and miniaturization of the ignition coil. The closed magnetic circuit ignition coil can be combined with an igniter or even integrated into a spark plug, making it very compact.

The traditional ignition coil is an open magnetic type and has an iron core laminated with silicon steel sheets of about 0.3 mm. The iron core is wound with secondary and primary coils. In contrast, the closed magnetic type uses an iron core shaped like the letter "III" to wind the primary coil and then the secondary coil is wound outside. The magnetic line of force is formed by the iron core to create a closed magnetic circuit.

The advantages of closed magnetic ignition coils include less magnetic leakage, low energy loss, and small size. Therefore, closed magnetic ignition coils are commonly used in electronic ignition systems.