internal-combustion engine

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Cross section showing one cylinder of a four-stroke internal-combustion engine. In the first stroke …
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Any engine in which a fuel-air mixture is burned in the engine proper so that the hot gaseous products of combustion act directly on the surfaces of its moving parts, such as those of pistons (see piston and cylinder) or turbine rotor blades.

Internal-combustion engines include gasoline engines, diesel engines, gas turbine engines, pure jet engines, and rocket engines and motors, and are one class of heat engines. They are commonly divided into continuous-combustion engines and intermittent-combustion engines. In the first type (e.g., jet engines) fuel and air flow steadily into the engine, where a stable flame is maintained for continuous combustion. In the second (e.g., gasoline–reciprocating-piston engines), discrete quantities of fuel and air are periodically ignited. See also automobile industry, machine, steam engine.

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More on "internal-combustion engine" from Britannica Concise:

engine - Machine that can convert any of various forms of energy into mechanical power or motion.

diesel engine - Internal-combustion engine in which air is compressed to a temperature sufficiently high to ignite fuel injected into the cylinder, where combustion and expansion activate a piston (see piston and cylinder).

radial engine - Type of internal-combustion engine used mainly in small airplanes, in which the cylinders (ranging from five to as many as 28, depending on engine size) are mounted in a circle around the crankshaft, sometimes in banks of two or more.

rotary engine - Internal-combustion engine in which the combustion chambers and cylinders rotate with the driven shaft around a fixed control shaft to which pistons are attached.

jet engine - Any of a class of internal-combustion engines that propel aircraft by means of the rearward discharge of a jet of fluid, usually hot exhaust gases generated by burning fuel with air drawn in from the atmosphere.

More on "internal-combustion engine" from the 32 Volume Encyclopædia Britannica:

internal-combustion engine - any of a group of devices in which the reactants of combustion (oxidizer and fuel) and the products of combustion serve as the working fluids of the engine. Such an engine gains its energy from heat released during the combustion of the nonreacted working fluids, the oxidizer-fuel mixture. This process occurs within the engine and is part of the thermodynamic cycle of the device. Useful work ...

engine - a machine that can convert any of various forms of energy into mechanical power or motion. See diesel engine; gasoline engine; internal-combustion engine; jet engine; rocket; rotary engine; steam engine.

jet engine - any of a class of internal-combustion engines that propel aircraft by means of the rearward discharge of a jet of fluid, usually hot exhaust gases generated by burning fuel with air drawn in from the atmosphere.

diesel engine - any internal-combustion engine in which air is compressed to a sufficiently high temperature to ignite diesel fuel injected into the cylinder, where combustion and expansion actuate a piston. It converts the chemical energy stored in the fuel into mechanical energy, which can be used to power freight trucks, large tractors, locomotives, and marine vessels. A limited number of automobiles also are ...

gasoline engine - any of a class of internal-combustion engines that generate power by burning a volatile liquid fuel (gasoline or a gasoline mixture such as ethanol) with ignition initiated by an electric spark. Gasoline engines can be built to meet the requirements of practically any conceivable power-plant application, the most important being passenger automobiles, small trucks and buses, general aviation ...

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