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Internal Combustion Engines

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... pump a gallon of gas vs. several hours to recharge batteries (i.e. electric cars) ... an engine to create movement of cars and other gas powered machines. ... – PowerPoint PPT presentation

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Title: Internal Combustion Engines


1
Internal Combustion Engines
  • Introduction
  • Fuels
  • Four Stroke Engine
  • Parts of a four stroke engine

2
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.

3
Introduction
4
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

5
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)

6
Fuels
  • What are other types of fuels that can be used?
  • Wood- steam engines
  • Coal- steam engines
  • Oil
  • Electricity

7
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.

8
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.

9
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.

10
The four-stroke cycle
  • The four stroke combustion cycle consists of
  • 1. Intake
  • 2. Compression
  • 3. Combustion
  • 4. Exhaust

11
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.

12
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.

13
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.

14
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

15
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

16
Parts of an engine
17
Source
  • www.howstuffworks.com
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