Sisäpolttoainekoneet

Sisäpolttoainekoneet, commonly known as internal combustion engines, are a type of heat engine where the combustion of fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. The expansion of the high-temperature and high-pressure gas products of the combustion process then applies direct force to some component of the engine, such as pistons or turbine blades, resulting in mechanical work. This process distinguishes internal combustion engines from external combustion engines, such as steam engines, where the heat is transferred to a working fluid by a separate combustion process.

The most common types of internal combustion engines are the piston engines, which are used in automobiles, motorcycles, aircraft, and many other applications. These engines operate on a cycle, typically the four-stroke cycle (intake, compression, power, exhaust) or the two-stroke cycle. In a piston engine, fuel is mixed with air and ignited inside a cylinder. The resulting explosion pushes a piston, which turns a crankshaft, generating rotational motion.

Another important type of internal combustion engine is the gas turbine, used in jet aircraft, power plants, and some high-performance vehicles. In a gas turbine, air is compressed, mixed with fuel, and then burned continuously. The hot, expanding gases drive a turbine, producing power. Wankel engines, which use a rotary design instead of pistons, are also a form of internal combustion engine, though less common.

Internal combustion engines are a fundamental technology for modern transportation and power generation, though their emissions and efficiency are ongoing areas of research and development.