Sisäistysmoottori

Sisäistysmoottori, often referred to in English as an internal combustion engine, is a heat engine where the combustion of a fuel occurs with an oxidizer (usually atmospheric air) in a combustion chamber that is an integral part of the working fluid flow circuit. The expansion of the superheated gases produced by combustion applies direct force to some element of the engine, such as a piston, turbine blade, or nozzle. This force moves the element, which in turn does useful work.

The term "internal combustion" is used to distinguish this type of engine from external combustion engines, such as steam engines, where the heat source is outside the engine. In an internal combustion engine, the high-temperature, high-pressure gas produced by combustion expands and pushes directly on a moving part, such as a piston. This movement is then converted into a useful output, typically rotational motion.

Common examples of internal combustion engines include gasoline engines and diesel engines, which power most automobiles, motorcycles, and many other vehicles and machines. Gas turbines and jet engines are also types of internal combustion engines, although they operate differently by using a continuous combustion process. The fundamental principle, however, remains the same: burning fuel internally to generate power. These engines are crucial to modern transportation and industry due to their power density and relatively simple operation.