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Small Engines

Small Engines. How do engines work?. What goes inside of an engine?. Fuel What happens to the gas? Combustion – a chemical reaction between a fuel and oxygen with the result of heat. A spark plug is used to light the fuel and create combustion. Compression. What happens when fuel is lit?

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Small Engines

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  1. Small Engines How do engines work?

  2. What goes inside of an engine? • Fuel • What happens to the gas? • Combustion – a chemical reaction between a fuel and oxygen with the result of heat. • A spark plug is used to light the fuel and create combustion.

  3. Compression • What happens when fuel is lit? • Compression - raising the pressure and reducing the volume of gases • An engine must have three things to run • Fuel • Spark • Compression

  4. Conversion of Energy and Motion • Converts chemical energy to mechanical energy. • Burning fuel to moving parts in the engine • Converts reciprocating motion to rotary motion. • Up and down to rotational

  5. A Firecracker in the Garbage

  6. Cylinder and Piston • Cylinder - the empty space in which a piston travels. • Piston -sliding plug that fits closely inside the diameter of a cylinder. • Its purpose is either to change the volume enclosed by the cylinder, or to compress a gas inside the cylinder.

  7. Connecting Rod and Crankshaft • The connecting rod attaches to the piston • The crankshaft changes the up and down motion to rotational motion • This is where you would hook up your lawn mower blade

  8. Valves • Intake valve- allows fuel and air to enter the combustion chamber • Exhaust valve- allows the exhaust gases to escape the combustion chamber

  9. Four Stroke Cycle • Stroke- a movement of the piston; either up or down • Cycle- a repetitive process • The engine will run through each stroke and then repeat

  10. Four Stroke Cycle • Intake Stroke • The piston moves down in the cylinder • This creates a vacuum that sucks the fuel and air mixture into the engine • The intake valve is open and exhaust valve is closed

  11. Four Stroke Cycle • Compression Stroke • The piston moves up in the cylinder • The piston compresses the fuel/air mixture in the combustion chamber to make it more volatile • Both valves are closed

  12. Four Stroke Cycle • Power Stroke • A spark occurs • The piston moves down in the cylinder due to combustion • Both valves are closed

  13. Four Stroke Cycle • Exhaust Stroke • The piston moves up in the cylinder • The piston will push out the exhaust gases that are created from combustion • The intake valve is closed and exhaust valve is open

  14. Four Stroke Cycle

  15. Other Important Parts • Muffler- an exhaust component that decreases the noise of the engine. • Starter- a small electric motor is used to turn the engine until it runs by itself. • Fuel Tank- holds the fuel

  16. Other Important Parts • Carburetor- controls the air/fuel mixture that enters the engine • Flywheel- is a heavy rotating disk used as a storage device for motion. It helps keep momentum for the four stroke cycle. • Camshaft- opens and closes the by pressing on the valve, or on some intermediate mechanism, as they rotate.

  17. What Does Oil Do? Oil lubricates the engine for smoother operation A lubricant provides a protective film which allows for two touching surfaces to be separated, thus lessening the friction between them Will an engine run w/out oil?

  18. Review • What are the steps of a 4 stroke engine cycle in order? • What is needed for combustion? • What is a piston? • What controls the timing of the valves? • How does oil reduce friction?

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