main page

PHYSICS

JARGON

4 STEPS

PV DIAGRAM

RATIOS & EFFICIENCIES

Bibliography

The Four steps of a Otto's Four-stoke Engine

INTAKE COMPRESSION POWER EXHAUST

Kenai Halvorson

University of Alaska Fairbanks

March 24, 2005

Physics 212x
with David Newman

"Intake
     
During the intake stroke, the piston moves downward, drawing a fresh charge of vaporized fuel/air mixture.  The illustrated engine features a 'poppet' intake valve which is drawn open by the vacuum produced by the intake stroke. 

Compression
    
As the piston rises the poppet valve is forced shut by the increased cylinder pressure.  Flywheel momentum drives the piston upward, compressing the fuel/air mixture.

Power
    
At the top of the compression stroke the spark plug fires, igniting the compressed fuel.  As the fuel burns it expands, driving the piston downward.

Exhaust
     
At the bottom of the power stroke, the exhaust valve is opened by the cam/lifter mechanism.  The upward stroke of the piston drives the exhausted fuel out of the cylinder."

http://www.keveney.com/otto.html