Transcript Four-Stroke Engine Basics

Four-Stroke Engine Basics
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Cars
Trucks
Semis
Tractors
Airplanes
Motorcycles
Lawnmowers
The Basics
• A four-stroke engine:
– Is an internal combustion engine
– Converts gasoline into motion
– Is the most common car engine type
– Is relatively efficient 20%
– 4 piston strokes per cycle
– 2 crankshaft revolutions per cycle
Basic Components
Camshaft
Intake Valve
Valve Cover
Intake Port
Head
Exhaust Valve
Spark Plug
Exhaust Port
Piston
Connecting Rod
Coolant
Rod Bearings
Engine Block
Crankshaft
Oil Pan
Oil Sump
The 4-Stroke Cycle
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1.
Intake
2. Compression
3. Combustion
4.
Exhaust
Back
Next
Intake
process of filling the
cylinder with the
proper air-fuel mixture
through the intake
valve.
Back
Compression
the process of
compressing the airfuel mixture in the
cylinder to make it
more combustible
Back
Combustion
the process of igniting
the compressed airfuel mixture to create
motion and the over
all power of the
engine.
Back
Exhaust
the process of releasing
the exhaust out of the
cylinder through the
exhaust valve.
How Stuff Works Animation
• http://auto.howstuffworks.com/engine1.htm
• Engine Block- cast in one piece. The basis for
most of the parts of the engine.
Back
• Valve Cover- Protects the valves and the valve
springs. Keeps dirt out and lubricating oil in.
• Head- a platform containing most of the parts
of the combustion chamber.
• Intake Valve- opens at the
proper time to let in air and
fuel.
• Intake Port- the passageway
in a cylinder head for the
fuel and air to pass through.
Exhaust Valve- open
at the proper time to
release the exhaust
Exhaust Port- the
passageway in a
cylinder head, for
the exhaust to pass
through
Valve Guide
• Controls the position of the valves
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Lubrication
• Oil Pan where the oil is collected and
recirculated primarily for lubricating the
crankshaft and rod bearing
• Oil Sump where the oil is stored for lubrication
Camshaft- a round shaft with lobes, that rotates
to open and close the fuel and exhaust valves.
Aligned with crankshaft gear for proper timing
Spark Plug
a device, inserted
into the combustion
chamber for firing
an electrical spark
to ignite air-fuel
mixture
Cylinder
• Three types
– Cast aluminum
– Cast aluminum with cast
iron sleeve
– Cast iron
• Usually use a crosshatch finish to improves
ring lubrication
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Piston
the part of the engine that moves up and down
in the cylinder converting the gasoline into
motion
• Piston Rings-Keep tight seal against cylinder wall
Ring Grooves
• Ring grooves are
machined grooves in the
piston designed to hold
the rings.
• Ring lands are the areas
of the piston between
the ring grooves.
• The clearance between
the rings and the ring
lands is critical.
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Connecting Rod- links the piston to the
crankshaft.
Rod Bearing- used to reduce friction to the rod
and crankshaft
Crankshaft- converts the up and down (linear)
motion of the piston into a turning, or rotating
motion
Crankcase Breather
• Maintains pressure in the
crankcase at less than ambient
pressure to assist in the
control of oil consumption.
• Excessive blow by renders the
breather useless.
• Old engines vent to the
atmosphere.
• New engines vent to the
carburetor.
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Application
• Now that you understand the basics of fourstroke engines, how can you use this
information in the real world?
Back
Quiz
• Lets take a quiz to see what you have learned!
Back
Quiz
1. The ____ controls the amount of intake and
the release of exhaust.
a. head
b. valves
c. coolant
d. connecting rod
2. The _____ Cycle is the ignition of the
compressed fuel-air mixture.
a. Exhaust
b. Combustion
c. Compression
d. Intake
3. The most common type of engine?
a. diesel engines
b. 2-stroke engines
c. rotary engines
d. 4-stroke engines
4. What part of the engine converts up and
down motion into a rotation motion?
a. crankshaft
b. piston
c. valve cover
d. camshaft
5. What is the name of
the part listed?
a. intake valve
b. piston
c. oil pan
d. spark plug
• Congratulations! That is the end of your quiz,
and the end of your lesson on four-stroke
engines.
Next
Four Stroke Chart
Stroke
Piston Movement
Intake Valve
Exhaust Valve
Compare & Contrast 2 & 4 Cycle
Engines