10.4.7 Spark plug
The element, which ignites the fuel-air mixture inside the cylinder, is called the spark plug. The arrangement of this element is very simple (see figure 10.7): the casing with a cut thread and an electrode (negative as contacts with "ground" – cylinder head), the insulator in which the positive electrode passes. A high-voltage wire of the ignition system is connected to this electrode on one side through a tip. The positive electrode is located next to the negative electrode (the air gap between them is 0.8-1.2 mm - depending on the model of the spark plug). When a high-voltage discharge is applied to the positive electrode from the ignition distributor, an air gap breaks through, that is, a spark appears - powerful enough to ignite the fuel-air mixture.
Figure 10.7 Spark plug.
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