Internal combustion engine
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An internal combustion engine is an engine in which the combustion
of a fuel occurs in a combustion chamber inside and integral to the
engine. In an internal combustion engine it is always the expansion
of the high temperature and pressure gases that are produced by the
combustion which apply force to the movable component of the engine,
such as the pistons or turbine blades.
The term internal combustion engine usually refers to an engine in
which combustion is intermittent, such as the more familiar
four-stroke and two-stroke piston engines, along with variants, such
as the Wankel rotary engine. A second class of internal combustion
engines use continuous combustion: jet engines (including gas
turbines) and most rockets, each of which are internal combustion
engines on the same principle as previously described. |
The internal combustion engine (or ICE) contrasts with the external
combustion engine, such as a steam or Stirling engine in which the
energy is delivered within a working fluid heated in a boiler by
fossil fuel, wood-burning, nuclear, solar etc.
A large number of different designs for ICEs have been developed and
built, with a variety of different strengths and weaknesses. While
there have been and still are many stationary applications, the real
strength of internal combustion engines is in mobile applications
and they completely dominate as a power supply for cars, aircraft,
and boats, from the smallest to the biggest. Only for hand-held
power tools do they share part of the market with battery powered
devices. Powered by an energy-dense fuel (nearly always liquid,
derived from fossil fuels) the ICE delivers an excellent
power-to-weight ratio with very few safety or other disadvantages.
Applications
A 1906 gasoline engineInternal combustion engines are most commonly
used for mobile propulsion in vehicles and portable machinery. In
mobile equipment, internal combustion is advantageous since it can
provide high power-to-weight ratios together with excellent fuel
energy density. Generally using fossil fuel (mainly petroleum),
these engines have appeared in transport in almost all vehicles
(automobiles, trucks, motorcycles, boats, and in a wide variety of
aircraft and locomotives).
Internal combustion engines appear in the form of gas turbines as
well where a very high power is required, such as in jet aircraft,
helicopters, and large ships. They are also frequently used for
electric generators and by industry.
Classification
At one time the word, "engine" (from Latin, via Old French, ingenium,
"ability") meant any piece of machinery—a sense that persists in
expressions such as siege engine. A "motor" (from Latin motor,
"mover") is any machine that produces mechanical power.
Traditionally, electric motors are not referred to as, "engines";
however, combustion engines are often referred to as, "motors." (An
electric engine refers to a locomotive operated by electricity).
However, many people consider[who?] engines as things which generate
their power from within, and motors as requiring an outside source
of energy to perform work.
Engines can and are classified in many different ways, by the engine
cycle used, by the layout of the engine, by the source of energy, by
the use of the engine, or by the cooling system employed. |
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