Ottomotor

Ottomotor is the term used in German for a spark-ignition internal combustion engine that operates on the Otto cycle. In English, such engines are commonly called gasoline or spark-ignition engines and are the dominant form of piston engine in light vehicles. The Ottomotor is named after Nikolaus August Otto, whose development of a practical four-stroke engine in the 1870s established the basis for modern gasoline-powered propulsion. It is distinguished from Diesel engines, which operate on the diesel cycle and rely on compression ignition.

Operation and cycle: The Otto cycle consists of four piston strokes within the engine cylinder: intake, compression, power, and exhaust. During intake, air and typically fuel enter the cylinder via the intake valve. In the compression stroke, the mixture is compressed by the rising piston. A spark plug then ignites the mixture near top dead center, causing rapid expansion that drives the piston in the power stroke. Finally, the exhaust stroke expels spent gases. The cycle repeats rapidly to produce continuous power. Modern Ottomotors use electronic ignition, fuel injection (port or direct), and various efficiency- and emissions-improving technologies such as turbocharging and variable valve timing.

History and characteristics: The first practical four-stroke Otto engine was developed by Nikolaus Otto and Eugen Langen in 1876. The four-stroke concept was described earlier by Beau de Rochas, whose ideas shaped the cycle. Otto engines became dominant in automotive powertrains for much of the 20th century, evolving with advanced ignition systems, fuel delivery, combustion control, turbocharging, and emissions technologies. The term Ottomotor remains common in German-language contexts to refer to gasoline-powered engines.