How does an Internal Combustion Engine Work?

Michael Anissimov
Michael Anissimov

The internal combustion engine is used to power nearly all land vehicles and many water-based and air-based vehicles as well. In an internal combustion engine, a fuel, such as gasoline, fills a chamber and then is ignited by a spark plug, causing a small explosion which generates work.

A spark plug, part of an internal combustion engine.
A spark plug, part of an internal combustion engine.

The superheated expanding gas created by the explosion pushes a piston, which drives a crankshaft usually connected to an axle. The axle is connected to wheels which turn to drive a vehicle, such as an automobile, forward.

Cylinders that are connected to and drive a crank shaft are fired up and down by exploding fuel/air mixtures in an internal combustion engine.
Cylinders that are connected to and drive a crank shaft are fired up and down by exploding fuel/air mixtures in an internal combustion engine.

The entire assemblage of a chamber, spark plug, piston, crankshaft, and valves that allow in fuel and air is known as a cylinder. Whereas small appliances such as chainsaws only use one cylinder, autmobiles generally use four to eight. Historic aircraft have had as many as 28 cylinders to provide the power to drive their propellers.

The superheated expanding gas created by the explosion pushes a piston, which drives a crankshaft usually connected to an axle.
The superheated expanding gas created by the explosion pushes a piston, which drives a crankshaft usually connected to an axle.

The internal combustion engine is distinct from external combustion engines (such as steam engines), in that the energy generated from the combustion of fuel is efficiently contained within a cylinder. In steam engines, fuel is used to transform water into steam which then moves through a mechanism and provides work. Internal combustion engines took some time to perfect because the cylinder must be able to withstand the wear and tear of many thousands of explosions over the course of its operating lifetime.

Although engineers have been experimenting with automobiles driven by various types of engines since the 18th century, it wasn't until the late 19th century that Germans Daimler and Benz created internal combustion engines suited for mass production and commercialization. This ushered in the modern era of internal combustion engines used for a vast variety of purposes. In common use for more than a century, it could be a while before our engineers devise a new standard of engine for powering our multitude of machines.

Steam engines are a type of external combustion engine.
Steam engines are a type of external combustion engine.
Michael Anissimov
Michael Anissimov

Michael is a longtime wiseGEEK contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.

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Discussion Comments

anon134157

thank you! saved my life man!

anon89082

That is cool. I have been looking all over for explanations of how my engine works. The explanation really makes it easier to understand what is going on under my hood.

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