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often called flat engines. Engines of two different cylinder arrangements have
been classified as W-type engines in the technical literature. An opposed-pis-
ton engine has two pistons in each cylinder with the combustion chamber in
the centre between the pistons. Radial engines
are engines with pistons posi-
tioned in a circular plane around a circular crankshaft. The connecting rods of
the pistons
are connected to a master rod, which in turn, is connected to the
crankshaft.
A rotary engine is made of a large non-concentric rotor with a built-in
gearwheel, moving around a stationary block (stator). The moving combus-
tion chambers are formed by the corners of the rotor sliding against the inner
surface of the non-rotating block (housing). A number of experimental engines
have been tested using this concept, but the only
design that has ever become
common in an automobile is the Wankel engine which has one, two, and three
rotors.
Вy
method of fuel input, spark-ignition engines are divided into
four types:
carburetted engines in which air and fuel are mixed to facilitate the combustion
process; multipoint port fuel injection engines in which one or more injectors
at each cylinder intake; throttle body fuel injection engines in which injectors
upstream in intake manifold; gasoline direct injection engines in which injec-
tors are mounted in combustion chambers with injection directly into cylinders.
By method of fuel input, compression-ignition engines are divided into
three types: direct injection engines in which fuel is injected into the main
combustion chamber; indirect injection engines in which fuel is injected into
the secondary combustion chamber; homogeneous charge compression igni-
tion engines in which well-mixed fuel and oxidizer (typically, air) are com-
pressed to the point of auto-ignition.
Besides, different kinds of fuel are used in engines: diesel oil, motor oil,
naphta; kerosene
or benzol-oil mixtures; gas, natural gas methane; alcohol-
ethyl, methyl; dual fuel. There are several engines that use a combination of
two or more fuels.
Several or all of these classifications can be used at the same time to iden-
tify a given engine. Thus, a modern engine might be called a reciprocating,
spark-ignition, four-stroke cycle, I-head, water-cooled, gasoline, multipoint
port fuel injection automobile engine.
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