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Internal combustion engine

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An internal combustion engine (ICE) is a heat engine that converts chemical energy into kinetic energy.

Piston and connecting rod
Piston and connecting rod

This process occurs when a fuel source burns with an oxidizer, usually air, inside a combustion chamber. The chamber is an integral part of the working fluid flow circuit. When the fuel burns, it creates high-temperature and high-pressure gases. These gases expand and apply direct force to engine components. This force moves parts over a distance to power a machine. Depending on the design, this force might act on pistons, turbine blades, a rotor, or a nozzle.

4StrokeEngine Ortho 3D Small
4StrokeEngine Ortho 3D Small

In a reciprocating engine, the movement is based on parts sliding back and forth. The base of these engines is the engine block.

Clevelandblock
Clevelandblock

This block is typically made of cast iron or aluminum. It contains the cylinders where the combustion happens. Most engines arrange these cylinders in one row, known as a straight engine. They can also be in two rows, called a boxer or V engine. Some modern engines use three or four rows, known as a W engine.

Schemes
Schemes

To manage heat, water-cooled engines use a water jacket. This is a passage in the block where cooling fluid circulates. Other small engines are air-cooled. These use metal fins protruding from the block to transfer heat to the air.

Inside the cylinder, a piston acts as the primary moving part. The piston is a short cylindrical component that seals one end of the cylinder. It must seal against the high pressure of the combustion products. To prevent leaks, rings are fitted around the piston's circumference. These rings keep gases from escaping into the crankcase. The gas pressure hits the piston crown, which is the top surface. This force is transferred through the piston web to a gudgeon pin. The pin connects the piston to a connecting rod, which turns the motion into useful work.

Piston and connecting rod
Piston and connecting rod

Engineers classify these machines by how they ignite the fuel and how they move. One major group is reciprocating engines, which include two-stroke and four-stroke designs. For example, the Otto cycle is a four-stroke process. Some engines use spark-ignition (SI), which is common in gasoline engines. Others use compression-ignition (CI), which is common in diesel engines.

Diesel engine uniflow
Diesel engine uniflow

There are also rotary engines, such as the Wankel engine.

Wankel Cycle anim en
Wankel Cycle anim en

A different class uses continuous combustion. This includes gas turbines, jet engines, and most rocket engines. These engines do not use intermittent bursts of burning like a piston engine does.

History shows a long timeline of discovery for these machines. In 1791, John Barber developed the gas turbine. In 1807, Nicéphore Niépce and Claude Niépce ran a prototype called the Pyréolophore. This engine used controlled dust explosions to power a boat on the Saône river. In 1808, François Isaac de Rivaz invented a hydrogen-based engine using an electric spark.

Brayton walking beam engine 1872
Brayton walking beam engine 1872

Later, Nicolaus Otto designed the first modern internal combustion engine in 1876. This was the Otto engine. In 1892, Rudolf Diesel developed the compression ignition engine. These inventions paved the way for modern transport and industry.

Internal combustion engines are used in many different ways today. Most are used in mobile applications like cars, aircraft, and boats. These are often called internal-combustion-engine vehicles (ICEV). In the air, planes might use reciprocating engines or jet engines. Helicopters often use turboshafts, which are gas turbines optimized for torque. On land, engines drive motorcycles, cars, and even locomotives.

1970 AMX BBG-2part3
1970 AMX BBG-2part3

On a much larger scale, engines drive electric generators for the power grid. Some combustion turbines can produce 100 MW of electrical output. Combined cycle power plants even use the high-temperature exhaust to run a steam turbine. This can reach efficiencies of 50% to 60%.

Fuel choice is a major part of how these engines function. Most rely on hydrocarbon-based fuels like gasoline, diesel, or natural gas. They can also use renewable fuels. For example, biodiesel is used in compression ignition engines. Bioethanol is used in spark ignition engines. As early as 1900, Rudolf Diesel used peanut oil to run his engines.

Montreal power backup
Montreal power backup

While hydrogen is rarely used, it can be obtained from fossil fuels or renewable energy. This variety allows engines to be used in everything from small lawnmowers to massive ships.

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🖼️ Images & Media (24)
File:Four stroke engine diagram.jpg
Four stroke engine diagram.jpg
File:Brayton walking beam engine 1872.jpg
Brayton walking beam engine 1872.jpg
File:1970 AMX BBG-2part3.JPG
1970 AMX BBG-2part3.JPG
File:Montreal power backup.jpg
Montreal power backup.jpg
File:Clevelandblock.jpg
Clevelandblock.jpg
File:Piston and connecting rod.jpg
Piston and connecting rod.jpg
File:Diesel engine valve train.JPG
Diesel engine valve train.JPG
File:18XER engine block.jpg
18XER engine block.jpg
File:4StrokeEngine Ortho 3D Small.gif
4StrokeEngine Ortho 3D Small.gif
File:Two-Stroke Engine.gif
Two-Stroke Engine.gif
File:Diesel engine uniflow.svg
Diesel engine uniflow.svg
File:Bosch magneto (Army Service Corps Training, Mechanical Transport, 1911).jpg
Bosch magneto (Army Service Corps...

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