How an Engine Works

· Different types of engines
o Diesel
o Gas turbine engines
o Internal combustion engines
§ Gas is burned on the inside
§ The main idea/theory
· If you put a high power fuel (gasoline) in a small confined space, massive energy will emit by expanding gas.
o If you can create a cycle of this hundreds of times a minute, you have the core of a car engine.
§ Almost all cars use the four stroke combustion cycle
· Think of a potato gun. Now, replace the potato with a piston.
o The piston is connected to the crankshaft by a connecting rod
§ As the crankshaft revolves, it has the effect of “resetting the cannon”
o Intake stroke
§ The piston starts at the top, the intake valve opens, and the piston drops
· This allows the engine to take in a cylinder full of air and gasoline.
· This is the Intake stroke
· Only a tiny amount of gasoline is needed
o Compression stroke
§ The piston moves back up to compress the air/fuel
· Compression makes the explosion more powerful
o Combustion stroke
§ The spark plug emits a spark, lighting the gasoline
· The gasoline charge explodes, driving the piston down
o Exhaust stroke
§ Once the piston hits the bottom, the exhaust valve opens and the exhaust leaves the tailpipe.
· Now the engine is ready for its next cycle, so it repeats over and over again.
§ Parts of the engine
· Cylinder
o The core of the engine is the cylinder
o Pistons move up and down inside
o The above is a single cylinder, common in a lawn mower
o Most cars are 4, 6, or 8 cylinder
§ The higher the cylinder, the better performance
o Types of cylinder formation
§ L (line) formed in a line
§ V (angled) Shaped like a V
· Spark plug
o Provides the spark in the air/fuel compression
o Must spark at just the right time for proper function
· Valves
o Open and close for the intake stroke and for exhaust excretion
· Piston
o The grey shapes in the above pictures.
o Move up and down in the cylinder
· Piston rings
o Provides a sliding seal between the piston and cylinder.
o Provides two major purposes
§ Prevent excretion of the fuel/air mixture during compression and combustion strokes
§ Keep oil out of the space in the cylinder
· Connecting Rod
o Connects the piston to the crankshaft
o Can rotate at both ends so that piston can move and the crankshaft can rotate
· Crankshaft
o Works like a Jack-in-the-box, only the clown is the piston
· Sump
o Surrounds the crankshaft, containing oil
§ Oil used to lubricate and minimize temperature of the entire cycle
o Steam engines
§ External combustion engine