Four Stroke Engines

1
Four Stroke Engines

• How does a canon work?

2
Engine Operation

• Gasoline diesel engines convert chemical energy
  into mechanical energy

3
1st stroke Intake stroke

• Gasoline and diesel engines have to go through 4
  strokes to create power to move the car
• the intake valve opens
• the piston moves down

4
Intake Stroke Continued

• As the piston moves down the cylinder
• a mixture of gas and air enters the cylinder
• this mixture is 15 parts air to 1 part gas (151
  air fuel ratio)
• the air fuel is mixed delivered by the fuel
  system either a carburetor or fuel injection
  system

5
2nd Stroke Compression Stroke

• Intake valve closes
• Piston moves up the cylinder
• When the piston reaches the top of the cylinder,
  the air fuel has been squeezed to 150psi

6
3rd Stroke Power Stroke

• a spark created by the ignition system, jumps the
  gap at the spark plug ignites the air/fuel
  mixture
• This causes the burning gases to expand and drive
  the piston down the cylinder

7
4th Stroke Exhaust Stroke

• Once the piston reaches the bottom of the
  cylinder from the power stroke
• The exhaust valve opens
• The piston moves up
• The burnt gases are pushed out of the cylinder

8
Then what happens?

• After the exhaust stroke, the piston begins
  moving down on another intake stroke, continually
  repeating the 4 strokes

9
Interesting Facts

• the burning air-fuel mixture can reach 1200C
  or more
• the crankshaft spins 750 times per minute at
  idle
• it spins 3000 times per minute at freeway
  speeds
• this equals 50 times per second!
• the force on the piston during the power stroke
  is 1700kgs
• a well maintained engine can last 300,000 km or
  more!
• the design of a 4 stroke engine hasnt changed
  very much over the last 100
  years