Four-Stroke Engine Basics Cars Trucks Semis Tractors Airplanes Motorcycles Lawnmowers.
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Transcript of Four-Stroke Engine Basics Cars Trucks Semis Tractors Airplanes Motorcycles Lawnmowers.
Four-Stroke Engine Basics
• 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 ComponentsIntake Valve
Valve Cover
Intake Port
Head
Coolant
Engine Block
Oil PanOil Sump
Crankshaft
Camshaft
Exhaust Valve
Spark Plug
Exhaust Port
Piston
Connecting Rod
Rod Bearings
The 4-Stroke Cycle
• 1. • 2. • 3. • 4.
Intake
Compression
Combustion
Exhaust
Back Next
Intakeprocess of filling the cylinder with the proper air-fuel mixture through the intake valve.
Back
Compression the process of compressing the air-fuel mixture in the cylinder to make it more combustible
Back
Combustionthe process of igniting the compressed air-fuel mixture to create motion and the over all power of the engine.
Back
Exhaustthe 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
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Valve Guide• Controls the position of the valves
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 Pluga device, inserted into the combustion chamber for firing an electrical spark to ignite air-fuel mixture
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Cylinder
• Three types– Cast aluminum– Cast aluminum with cast
iron sleeve– Cast iron
• Usually use a cross-hatch finish to improves ring lubrication
Pistonthe 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
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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.
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
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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.
Application
• Now that you understand the basics of four-stroke 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. headb. valvesc. coolantd. connecting rod
2. The _____ Cycle is the ignition of the compressed fuel-air mixture.
a. Exhaustb. Combustionc. Compressiond. Intake
3. The most common type of engine?a. diesel enginesb. 2-stroke enginesc. rotary enginesd. 4-stroke engines
4. What part of the engine converts up and down motion into a rotation motion?
a. crankshaftb. pistonc. valve coverd. camshaft
5. What is the name of the part listed?
a. intake valveb. piston c. oil pand. 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