Small Engines . ppt
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Transcript Small Engines . ppt
SMALL ENGINES
ENGINE
OPERATION FOR
A FOUR STROKE
ENGINE
SMALL ENGINES
An engine is a device which
converts energy into mechanical
motion to do work.
Small engines are described as
internal combustion engines rated up to
25 horsepower.
A small engine has either a
spark ignition or a compression ignition
based on how the fuel is ignited.
Small engines are classified as either
four-stroke cycle engines or two-stroke
cycle engines.
PARTS OF THE ENGINE
CYLINDER BLOCK
Engine component which
consists of the cylinder bore,
cooling fins, and valve train
components.
CYLINDER
HEADMade of cast
aluminum alloy that are
Engine component made out of
lightweight and dissipate heat
cast aluminum alloy fastened
rapidly.
to the end
of the cylinder block
COOLING
FINS
farthest
fromthin
the cast
crankshaft.
An integral
strip
designed to provide efficient
HEAD
airGASKET
circulation and
A filler material placed
dissipation of heat away from
between the cylinder block
the engine cylinder block
and PLUG
cylinder head to seal
SPARK
into the
air stream.
the
combustion
Component thatchamber.
isolates
Made
of
soft
metals
the electricity and and
graphite
together.
produceslayered
the spark
for the
engine
PARTS OF THE ENGINE
PISTON
A cylindrical engine component
that slides back and forth in the
cylinder bore
CONNECTING
ROD by forces produced
during the combustion process.
Engine component that
transfers motion from the
CRANKSHAFT
piston to the crankshaft and
functions
a lever arm.
An engineascomponent
that
converts linear (reciprocating)
motion of the piston into rotary
FLYWHEEL
motion.
A cast iron disk that is
mounted at one end of the
COUNTERWEIGHTS
crankshaft to provide inertia
A protruding
for
the engine.mass cast into the
crankshaft which partially
balances the forces of a
reciprocating piston.
PARTS OF THE ENGINE
PISTON
PISTON: A cylindrical engine component that
slides back and forth in the cylinder
bore by forces produced during the
combustion process.
PARTS OF THE ENGINE
PISTON
PISTON:
DIFFERENT PISTON TYPES:
FLAT
DOMED
IRREGULAR
DISHED
PARTS OF THE ENGINE
PISTON
PISTON RINGS:
Three types:
An expandable split ring used to provide a
seal between the piston and the cylinder
wall
1.
COMPRESSION RING
2.
WIPER RING
3.
OIL RING
1
2
3
PARTS OF THE ENGINE
VALVE TRAIN
VALVE HEAD
MARGIN
VALVE FACE
VALVE SEAT
VALVE NECK
VALVE GUIDE
VALVE SPRING
VALVE ROTATOR
VALVE SPRING RETAINER
FOUR STROKE CYCLE ENGINE
INTAKE STROKE
COMPRESSION STROKE
POWER STROKE
EXHAUST STROKE
INTAKE STROKE
Occurs from TDC to BDC
Intake valve opens
Air-Fuel that was previously
mixed in the carburetor is now
sucked into the combustion
chamber due to the low pressure
created inside.
COMPRESSION
STROKE
Compresses the Air-Fuel
mixture
By compressing the Air-Fuel
mixture:
Allows for more energy to
be released.
Increases fuel
vaporization
Allows for more complete
burning
POWER
STROKE
Spark occurs igniting
compressed air-fuel mixture
Spark occurs 20 degrees before
TDC so the flame front can
spread throughout combustion
chamber
Gases ignite pushing piston
away from the cylinder head
Linear motion from the
piston is transferred into a
rotary motion on the
crankshaft
EXHAUST
STROKE
Exhaust valve opens
Inertia from the flywheel
and other parts push the
piston back up toward TDC,
pushing the spent gases out of
the combustion chamber.
THE END