Dictionary

Surface ignition is a premature self-ignition of the fuel-air mixture from a hot substance, such as soot, which is formed inside the combustion chamber, or from overheated (more than 700- 800 ° C) parts: spark plugs, heads, exhaust valves, etc. Surface ignition disrupts the process of normal combustion of gasoline, because it is directly related to the development or occurrence of knocking. Fuel combustion in case of surface ignition is similar in its physical nature to normal combustion, but it starts earlier, on a larger area and goes faster. Premature ignition is a self-developing process. Thus, the moment of self-ignition occurs earlier and earlier. The pressure and temperature rise inside the combustion chamber, the maximums of which can be reached before the arrival of the piston in TDC. All this causes an increase in the load on the parts of the cylinder-piston group and the crankshaft. It causes increase of the noise of the engine, including the knocking of the muffled tone, which is quite difficult to distinguish from a number of engine sounds. But most importantly - surface ignition leads to a significant increase in thermal loads on the surface forming the combustion chamber. As a rule, the piston melts and/or burns out and the spark plug electrodes melt.