Engine
An engine is a machine designed to convert one or more forms of energy into mechanical energy. Dictionary.com defines it as any device that converts another form of energy into mechanical energy so as to produce motion. Available energy sources include potential energy, heat energy, chemical energy, electric potential and nuclear energy. Many processes generate heat as an intermediate form, making heat engines particularly important. Mechanical energy drives transportation but also powers industrial tasks like cutting, grinding, crushing, and mixing. A heat engine may serve as a prime mover that transforms fluid flow or pressure changes into mechanical energy. An automobile powered by an internal combustion engine uses various motors and pumps, yet all derive power from the engine itself.
Simple machines such as the club and oar date back to prehistoric times. More complex engines using human power, animal power, water power, wind power and even steam power existed in antiquity. By the 1st century AD, cattle and horses drove mills in Ancient Rome. Strabo recorded a water-powered mill built in Kaberia during the 1st century BC. These early systems used aqueducts, dams, sluices, and gear trains made of wood and metal. Hero of Alexandria created wind and steam powered machines in the 1st century AD including the Aeolipile. In medieval Islamic engineering, gears appeared in mills and water-raising machines. Al-Jazari employed a crank-conrod system for two water-raising machines in 1206. Taqi al-Din described a rudimentary steam turbine device in 1551 while Giovanni Branca did so again in 1629. The solid rocket motor was invented in China during the 13th century driven by gunpowder.
The Watt steam engine became the first type to use steam at pressure just above atmospheric levels. James Watt developed his design sporadically from 1763 to 1775 improving upon Thomas Newcomen's 1712 engine. Matthew Boulton served as business partner helping make the design synonymous with steam engines. This innovation enabled rapid development of efficient semi-automated factories where waterpower was unavailable. Later developments led to steam locomotives and great expansion of railway transportation. Internal combustion piston engines were tested in France in 1807 by de Rivaz and independently by the Niépce brothers. Eugenio Barsanti and Felice Matteucci patented an engine using the free-piston principle between 1853 and 1857. Etienne Lenoir created an internally successful internal combustion engine during 1860. The Otto cycle achieved far higher power-to-weight ratios than steam engines in 1877 making it suitable for cars and aircraft.
Karl Benz created the first commercially successful automobile adding interest in light and powerful engines. The lightweight gasoline internal combustion engine operating on a four-stroke Otto cycle proved most successful for light automobiles. Diesel engines offer greater thermal efficiency used primarily for trucks and buses. Turbocharged diesel engines became increasingly popular in automobiles especially outside the United States. Karl Benz received a patent in 1896 for his horizontally opposed pistons design. These flat or boxer engines automatically balanced momentum since corresponding pistons moved simultaneously in horizontal cylinders. Volkswagen Beetles, Citroën 2CV models, Porsche and Subaru cars utilized this configuration. Opposed four- and six-cylinder engines remain common power sources in small propeller-driven aircraft. Engine control systems improved through onboard computers providing management processes and electronically controlled fuel injection. Forced air induction via turbocharging increased power output of smaller displacement engines while maintaining weight and fuel efficiency.
Engines categorize by form of energy accepted to create motion and type of motion output. Heat engines convert heat into work via thermodynamic processes like the Stirling cycle. Internal combustion engines burn fossil fuels with oxidizers usually air inside a combustion chamber. External combustion engines heat an internal working fluid through an external source like steam engines. Electric motors use electrical energy producing mechanical energy through magnetic field interactions known as early as 1821. Pneumatic motors convert compressed air potential energy into linear or rotary motion. Hydraulic motors derive power from pressurized liquid moving heavy loads and driving machinery. Hybrid units combine multiple energy sources such as plug-in hybrid electric vehicles using batteries or fossil fuels. Molecular motors found in living things use chemical energy creating forces and ultimately motion without being heat engines. Thermoacoustic devices use high-amplitude sound waves to pump heat from one place to another.
Exhaust gas from spark ignition engines contains nitrogen 70 to 75 percent water vapor 10 to 12 percent carbon dioxide 10 to 13.5 percent. Carbon monoxide ranges from 0.1 to 6 percent while unburnt hydrocarbons reach 0.5 to 1 percent. Nitrogen monoxide measures between 0.01 to 0.4 percent and sulfur dioxide reaches 15 to 60 ppm. Catalytic converters reduce toxic emissions but cannot eliminate them entirely. Widespread engine use contributes significantly to global greenhouse effects causing primary concerns regarding global warming. Diesel engines produce lower hydrocarbon and carbon dioxide emissions yet generate greater particulate and nitrogen oxide pollution. Electric motors offer quieter operation than internal combustion engines with potential for over 90 percent efficiency conversion. Regulatory authorities introduced legislation encouraging higher efficiency electric motor manufacturing throughout many countries. Hybrid engines combining small gasoline engines with electric motors and large battery banks are becoming popular options due to environmental awareness.
Common questions
What is the definition of an engine according to Dictionary.com?
Dictionary.com defines an engine as any device that converts another form of energy into mechanical energy so as to produce motion. Available energy sources include potential energy, heat energy, chemical energy, electric potential and nuclear energy.
When did Hero of Alexandria create wind and steam powered machines?
Hero of Alexandria created wind and steam powered machines in the 1st century AD including the Aeolipile. These early systems used aqueducts, dams, sluices, and gear trains made of wood and metal.
Who developed the Watt steam engine between 1763 and 1775?
James Watt developed his design sporadically from 1763 to 1775 improving upon Thomas Newcomen's 1712 engine. Matthew Boulton served as business partner helping make the design synonymous with steam engines.
Which year did Karl Benz receive a patent for horizontally opposed pistons?
Karl Benz received a patent in 1896 for his horizontally opposed pistons design. These flat or boxer engines automatically balanced momentum since corresponding pistons moved simultaneously in horizontal cylinders.
What percentage of exhaust gas from spark ignition engines is nitrogen?
Exhaust gas from spark ignition engines contains nitrogen 70 to 75 percent water vapor 10 to 12 percent carbon dioxide 10 to 13.5 percent. Carbon monoxide ranges from 0.1 to 6 percent while unburnt hydrocarbons reach 0.5 to 1 percent.