Ignition coil (VAZ-2107, 1982-2012)

The ignition coil is used to convert a low voltage current of 12 V into a high voltage current of 11-20 kV, necessary for the breakdown of the air gap between the spark plug electrodes and the formation of a spark that ignites the working mixture. In the contact ignition system, an ignition coil of type B-117A is used. The coil is installed in the engine compartment and fastened with nuts on two studs to the left mudguard. It is a transformer with a magnetic circuit, consisting of a core and an external magnetic circuit, and two windings - primary and secondary. The core is made of plates of electrical steel and is located in a frame on which the secondary winding is wound. The primary winding is wound through the insulator over the secondary winding.

The outer magnetic circuit consists of a coiled strip of electrical steel. The coil body is steel, it has a cylindrical shape. The top of the housing is hermetically sealed with a lid made of insulating material. To improve cooling and insulation, transformer oil is poured into the housing. The coil cover has a high-voltage and two low-voltage terminals. The high-voltage output is connected to the secondary winding and, through a contact bolt and spring, to the core. The end of the primary winding is connected to one low-voltage output of the coil, connected by a wire to the contact group of the ignition distributor. Conclusion "+B" coils are energized by the ignition switch.

The current flowing through the primary winding of the ignition coil creates a magnetic field around the turns of the coil. When the breaker contacts are opened, the current in the primary coil circuit disappears, the magnetic field is sharply reduced and, crossing the turns of the primary and secondary windings, induces an electromotive force in them (EMF), proportional to the number of turns. In the secondary winding, the EMF reaches 12000-24000 V, and in the primary - 200-300 V.

Contactless system uses coils type 27.3705 (open-circuit, oil-filled) or type 3122.3705 (with a closed magnetic circuit, dry).