Flame-Front Precombustion Engine

an internal combustion engine in which the air-fuel mixture in the main combustion chamber is ignited by a flame front issuing from a precombustion chamber; the volume of the latter is approximately equal to 2 percent of the volume of the main combustion chamber. In the precombustion chamber are located a spark plug and an inlet valve through which a rich air-fuel mixture enters from a separate carburetor. A lean mixture from another carburetor enters the main combustion chamber through another inlet valve. The two inlet valves open simultaneously. Ignition by the flame issuing from the precombustion chamber ensures that the air-fuel mixture in the main chamber is burned with a coefficient of excess air α = 1.6–1.7. The engine is thus more economical than conventional spark-ignition engines when operating under partial loads, the tendency to knock is reduced, and the exhaust gases produced are less toxic. However, such engines are more complicated than conventional designs.