4 stroke IC engine

The internal combustion engine is an engine in which the
combustion of a fuel (normally a fossil fuel ) occurs with an
oxidizer (usually air) in a combustion chamber that is an
integral part of the working fluid flow circuit. In an internal
combustion engine (ICE) the expansion of the high-
temperature and high- pressure gases produced by
combustion apply direct force to some component of the
engine. The force is applied typically to pistons, turbine
blades, or a nozzle. This force moves the component over
a distance, transforming chemical energy into useful
mechanical energy . The first commercially successful
internal combustion engine was created by Étienne Lenoir .
[1]
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 six-stroke piston engine
and the Wankel rotary engine. A second class of internal
combustion engines use continuous combustion: gas
turbines , jet engines and most rocket engines, each of
which are internal combustion engines on the same
principle as previously described.[1]
The ICE is quite different from external combustion
engines, such as steam or Stirling engines , in which the
energy is delivered to a working fluid not consisting of,
mixed with, or contaminated by combustion products.
Working fluids can be air, hot water, pressurized water or
even liquid sodium, heated in some kind of boiler . ICEs are
usually powered by energy-dense fuels such as gasoline or
diesel, liquids derived from fossil fuels . While there are
many stationary applications, most ICEs are used in mobile
applications and are the dominant power supply for cars,
aircraft, and boats.
A four-stroke engine (also known as four-cycle ) is an
internal combustion engine in which the piston completes
four separate strokes which comprise a single
thermodynamic cycle. A stroke refers to the full travel of
the piston along the cylinder, in either direction. While
risqué slang among some automotive enthusiasts names
these respectively the "suck," "squeeze," "bang" and "blow"
strokes. [1] they are more commonly termed
1. INTAKE: this stroke of the piston begins at top dead
center. The piston descends from the top of the
cylinder to the bottom of the cylinder, increasing the
volume of the cylinder. A mixture of fuel and air is
forced by atmospheric (or greater) pressure into the
cylinder through the intake port.
2. COMPRESSION: with both intake and exhaust valves
closed, the piston returns to the top of the cylinder
compressing the air or fuel-air mixture into the
cylinder head.
3. POWER: this is the start of the second revolution of
the cycle. While the piston is close to Top Dead
Centre, the compressed air–fuel mixture in a
gasoline engine is ignited, by a spark plug in gasoline
engines, or which ignites due to the heat generated
by compression in a diesel engine. The resulting
pressure from the combustion of the compressed
fuel-air mixture forces the piston back down toward
bottom dead centre.
4. EXHAUST: during the exhaust stroke, the piston once
again returns to top dead centre while the exhaust
valve is open. This action expels the spent fuel-air
mixture through the exhaust valve(s).