Basic Properties of an Internal Combustion Engine by EEJ0k6


									Basic Properties of an
 Internal Combustion
     By: Todd Conrado
Why is it important to understand
   the operation of engines?
Why is it important to understand
   the operation of engines?
                 • General knowledge.
                 • Understanding what
                   your working with.
                 • To be a better
                 • To be able to
                   troubleshoot more
The Basics
       • Internal combustion
         engines are a direct
         descendent of external
         combustion engines.
       • The switch over to internal
         combustion was difficult
         but resulted in much
         greater efficiency, smaller
         engine size, ease of use,
         and adaptability.
The basics
     • Today’s modern
       engines are relatively
       safe, efficient,
       inexpensive, and easy
       to refuel.
Engines and Potato Guns
            • To understand the basic
              idea of how an internal
              combustion engine works,
              it is helpful to have a good
              mental picture of how
              “internal combustion”
              works. A good example is
              the potato gun.
Engines and Potato Guns
            • Say you take an enclosed
              cylinder and place a small
              amount of gasoline in it.
            • You then take a potato and
              seal the end of the
            • Now you ignite the fuel.
            • What happens?
Engines and Potato Guns
            • Correct - The potato is
              expelled out the cylinder
              with great force.
            • This small amount of fuel
              produced a tremendous
              amount of force. This is
              the energy harnessed by
              the internal combustion
Engines and Potato Guns
            • The internal combustion
              engine uses the basic
              principles behind the
              potato canon.
            • To be more efficient
              though the engine needs to
              perform the loading
              operations automatically.
              It does this through the
              operation cycles.
Engine Cycles
       • The vast majority of
         engines use the four stroke
         cycle (Otto Cycle) to
         convert gasoline into
       • The four strokes are
          –   Intake
          –   Compression
          –   Power
          –   Exhaust
Engine Cycles
       • The potato in our example
         is replaced by the piston.
       • The piston is connected to
         the crankshaft by the
         connecting rod.
       • As the crankshaft rotates it
         actuates the valves in
         effect reloading the
Intake Stroke
       • The piston starts at the top
         of the cylinder and moves
       • The intake valve opens
         allowing a fresh charge of
         mixed fuel and air into the
       • This is the intake stroke.
Compression Stroke
         • Once reaching bottom the
           piston moves back up.
         • The intake valve closes
           sealing the mixture inside
           the cylinder.
         • The mixture compresses
           making the soon to come
           explosion more powerful
           and efficient.
         • This is the compression
Power Stroke
      • When the piston reaches
        the top of its stroke the
        fuel mixture is ignited by
        the spark plug.
      • The gasoline charge in the
        cylinder explodes with
        great power.
      • This is the power stroke
Exhaust Stroke
       • Once the piston reaches
         the bottom of its stroke the
         piston again moves
       • The exhaust valve opens
         and the burnt gasses are
         forced out of the cylinder.
       • This is the exhaust stroke
         and the engine is ready to
         begin the cycle again.
The basis for understanding
              • All engines need three
                basic functions to operate.
              • They are
                 – Fuel
                 – Ignition
                 – compression
              • The Four Cycle process
                provides these three
                functions continuously
                and automatically for
                efficient engine operation.
Key Points
     • Internal Combustion is
       combustion inside the
     • The cycle order is
        –   Intake
        –   Compression
        –   Power
        –   Exhaust
     • The basic parts of the
       internal combustion

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