Internal Combustion Engines *Introduction *Fuels *Four Stroke Engine *Parts of a four stroke engine About this Lesson This lesson contains hypertext links to www.howstuffworks.com. If you are connected.
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Transcript Internal Combustion Engines *Introduction *Fuels *Four Stroke Engine *Parts of a four stroke engine About this Lesson This lesson contains hypertext links to www.howstuffworks.com. If you are connected.
Internal Combustion
Engines
*Introduction
*Fuels
*Four Stroke Engine
*Parts of a four stroke engine
About this Lesson
This lesson contains hypertext links to
www.howstuffworks.com.
If you are connected to the internet, click
on the link icon and scroll to the
animation at the sight.
Introduction
Fuels
Why are nearly all vehicles and engines
powered by gasoline?
extremely high energy density
cheap (relative to other sources)
easy and safe to move around
Fuels
Why not use other fuels?
Size of engines needed to utilize these
fuels is impractical for automobiles
lawnmowers etc.
Convenience
it takes 15 seconds to pump a gallon of gas
vs. several hours to recharge batteries (i.e.
electric cars)
Fuels
What are other types of fuels that can be
used?
Wood- steam engines
Coal- steam engines
Oil
Electricity
Internal Combustion
Where do we get internal combustion?
The idea here is to take a fuel (gasoline for
example) and burn it in an engine to create
movement of cars and other gas powered
machines. This is where we get internal
combustion engines.
Internal Combustion
A cannon uses the basic
principles of internal
combustion engines. If
you take a small amount
of high energy fuel (like
gasoline) in a small,
enclosed space and ignite
it, an incredible amount
of energy is released in
the form of expanding
gas.
The four-stroke cycle
Almost all engines use a four-stroke
combustion cycle to convert gasoline into
motion.
This is also known as the Otto cycle in honor
of Nikolaus Otto who invented it in 1867.
This process takes the basic example of a
cannon several steps further.
The four-stroke cycle
The four stroke
combustion cycle
consists of:
1.
2.
3.
4.
Intake
Compression
Combustion
Exhaust
The four-stroke cycle
The piston starts at
the top, the intake
valve opens and the
piston moves down to
let the engine take in
a full cylinder of air
and gasoline during
the intake stroke
The piston then
moves up to
compress the
air/gasoline mixture.
This makes the
explosion more
powerful.
The four-stroke cycle
When the piston
reaches the top, the
spark plug emits a
spark to ignite the
gasoline/air mixture.
The gasoline/air
mixture explodes
driving the piston
down.
The the piston
reaches the bottom of
its stroke the exhaust
valve opens and the
exhaust leaves out of
the tailpipe.
The engine is ready
for another cycle.
Parts of an engine
Cylinder- where the piston moves up and
down. Most lawnmowers are 1 cylinder
while automobiles are 4,6,8, and 10.
Spark plug- supplies spark for the fuel/air
mixture.
Valves- let air in and exhaust out.
Note: both valves are closed during the
compression stroke.
Parts of an engine
Piston- cylindrical piece of metal that moves up
and down the cylinder.
Piston rings- rings provide a sliding seal between
the piston and cylinder.
Rings serve two purposes:
prevent fuel/air from leaking into the sump
prevent oil from entering the combustion
chamber
Parts of an engine
Combustion chamber- area where combustion
and compression takes place.
Connecting rod- connects the piston to the
crankshaft.
Crankshaft- the crankshaft turns the up and
down motion of the piston into circular motion
Sump- (oil pan) contains and collects oil for
lubrication
Parts of an engine
Source
www.howstuffworks.com