Engine

Source: Wikipedia, the free encyclopedia.
For other uses, see Engine (disambiguation). "Motor" redirects here. For other uses, see Motor (disambiguation).
An animation showing the four stages of the four-stroke gasoline-fueled internal combustion cycle with electrical ignition source:
  1. Induction (Fuel enters)
  2. Compression
  3. Ignition (Fuel is burnt)
  4. Emission (Exhaust out)
hydraulic systems can be taken from the turbine shaft, but thrust
is produced by expelled exhaust gas.

An engine or motor is a

mechanical energy.[1][2]

Available energy sources include

transportation
, but also plays a role in many industrial processes such as cutting, grinding, crushing, and mixing.

Mechanical heat engines convert

Newton's third law of motion
.

Apart from heat engines,

clockwork motors in wind-up toys use elastic energy. In biological systems, molecular motors, like myosins in muscles, use chemical energy
to create forces and ultimately motion (a chemical engine, but not a heat engine).

Chemical heat engines which employ air (ambient atmospheric gas) as a part of the fuel reaction are regarded as airbreathing engines. Chemical heat engines designed to operate outside of Earth's atmosphere (e.g.

oxidizer (although there exist super-oxidizers suitable for use in rockets, such as fluorine, a more powerful oxidant than oxygen itself); or the application needs to obtain heat by non-chemical means, such as by means of nuclear reactions
.

Emission/Byproducts

All chemically fueled heat engines emit exhaust gases. The cleanest engines emit water only. Strict

zero-emissions generally means zero emissions other than water and water vapour. Only heat engines which combust pure hydrogen (fuel) and pure oxygen (oxidizer) achieve zero-emission by a strict definition (in practice, one type of rocket engine). If hydrogen is burnt in combination with air (all airbreathing engines), a side reaction occurs between atmospheric oxygen and atmospheric nitrogen resulting in small emissions of NOx, which is adverse even in small quantities. If a hydrocarbon (such as alcohol or gasoline) is burnt as fuel, large quantities of CO2 are emitted, a potent greenhouse gas. Hydrogen and oxygen from air can be reacted into water by a fuel cell without side production of NOx, but this is an electrochemical
engine not a heat engine.

Terminology

The word engine derives from

industrial revolution were described as engines—the steam engine being a notable example. However, the original steam engines, such as those by Thomas Savery, were not mechanical engines but pumps. In this manner, a fire engine in its original form was merely a water pump, with the engine being transported to the fire by horses.[3]

In modern usage, the term engine typically describes devices, like steam engines and internal combustion engines, that burn or otherwise consume fuel to perform

mechanical work by exerting a torque or linear force (usually in the form of thrust). Devices converting heat energy into motion are commonly referred to simply as engines.[4] Examples of engines which exert a torque include the familiar automobile gasoline and diesel engines, as well as turboshafts. Examples of engines which produce thrust include turbofans and rockets
.

When the internal combustion engine was invented, the term motor was initially used to distinguish it from the steam engine—which was in wide use at the time, powering locomotives and other vehicles such as steam rollers. The term motor derives from the Latin verb moto which means 'to set in motion', or 'maintain motion'. Thus a motor is a device that imparts motion.

Motor and engine are interchangeable in standard English.[5] In some engineering jargons, the two words have different meanings, in which engine is a device that burns or otherwise consumes fuel, changing its chemical composition, and a motor is a device driven by electricity, air, or hydraulic pressure, which does not change the chemical composition of its energy source.[6][7] However, rocketry uses the term rocket motor, even though they consume fuel.

A heat engine may also serve as a

better source needed
]

History

Antiquity

siege engines in Ancient Rome. The writers of those times, including Vitruvius, Frontinus and Pliny the Elder, treat these engines as commonplace, so their invention may be more ancient. By the 1st century AD, cattle and horses were used in mills
, driving machines similar to those powered by humans in earlier times.

According to

Antikythera Mechanism used complex trains of gears and dials to act as calendars or predict astronomical events. In a poem by Ausonius in the 4th century AD, he mentions a stone-cutting saw powered by water. Hero of Alexandria is credited with many such wind and steam powered machines in the 1st century AD, including the Aeolipile and the vending machine
, often these machines were associated with worship, such as animated altars and automated temple doors.

Medieval

Medieval Muslim engineers employed gears in mills and water-raising machines, and used dams as a source of water power to provide additional power to watermills and water-raising machines.[10] In the medieval Islamic world, such advances made it possible to mechanize many industrial tasks previously carried out by manual labour.

In 1206,

Taqi al-Din[11] in 1551 and by Giovanni Branca[12] in 1629.[13]

In the 13th century, the solid

rocket motor was invented in China. Driven by gunpowder, this simplest form of internal combustion engine was unable to deliver sustained power, but was useful for propelling weaponry at high speeds towards enemies in battle and for fireworks
. After invention, this innovation spread throughout Europe.

Industrial Revolution

Boulton & Watt engine of 1788

The

Newcomen steam engine, the Watt steam engine, developed sporadically from 1763 to 1775, was a great step in the development of the steam engine. Offering a dramatic increase in fuel efficiency, James Watt's design became synonymous with steam engines, due in no small part to his business partner, Matthew Boulton. It enabled rapid development of efficient semi-automated factories on a previously unimaginable scale in places where waterpower was not available. Later development led to steam locomotives and great expansion of railway transportation
.

As for internal combustion

de Rivaz and independently, by the Niépce brothers. They were theoretically advanced by Carnot in 1824.[citation needed] In 1853–57 Eugenio Barsanti and Felice Matteucci invented and patented an engine using the free-piston principle that was possibly the first 4-cycle engine.[14]

The invention of an

Etienne Lenoir.[15]

In 1877, the Otto cycle was capable of giving a far higher power-to-weight ratio than steam engines and worked much better for many transportation applications such as cars and aircraft.

A V6 internal combustion engine from a Mercedes-Benz

Automobiles

The first commercially successful automobile, created by

Karl Benz, added to the interest in light and powerful engines. The lightweight gasoline internal combustion engine, operating on a four-stroke Otto cycle, has been the most successful for light automobiles, while the more efficient Diesel engine
is used for trucks and buses. However, in recent years, turbo Diesel engines have become increasingly popular, especially outside of the United States, even for quite small cars.

Horizontally-opposed pistons

In 1896, Karl Benz was granted a patent for his design of the first engine with horizontally opposed pistons. His design created an engine in which the corresponding pistons move in horizontal cylinders and reach top dead center simultaneously, thus automatically balancing each other with respect to their individual momentum. Engines of this design are often referred to as flat engines because of their shape and lower profile. They were used in the Volkswagen Beetle, the Citroën 2CV, some Porsche and Subaru cars, many BMW and Honda motorcycles, and propeller aircraft engines.

Advancement

Continuance of the use of the internal combustion engine for automobiles is partly due to the improvement of engine control systems (onboard computers providing engine management processes, and electronically controlled fuel injection). Forced air induction by turbocharging and supercharging have increased power outputs and engine efficiencies. Similar changes have been applied to smaller diesel engines giving them almost the same power characteristics as gasoline engines. This is especially evident with the popularity of smaller diesel engine propelled cars in Europe. Larger diesel engines are still often used in trucks and heavy machinery, although they require special machining not available in most factories. Diesel engines produce lower

particulate and NOx pollution, than gasoline engines.[16] Diesel engines are also 40% more fuel efficient than comparable gasoline engines.[16]

Increasing power

In the first half of the 20th century, a trend of increasing engine power occurred, particularly in the U.S models.[clarification needed] Design changes incorporated all known methods of increasing engine capacity, including increasing the pressure in the cylinders to improve efficiency, increasing the size of the engine, and increasing the rate at which the engine produces work. The higher forces and pressures created by these changes created engine vibration and size problems that led to stiffer, more compact engines with V and opposed cylinder layouts replacing longer straight-line arrangements.

Combustion efficiency

Optimal combustion efficiency in passenger vehicles is reached with a coolant temperature of around 110 °C (230 °F).[17]

Engine configuration

Earlier automobile engine development produced a much larger range of engines than is in common use today. Engines have ranged from 1- to 16-cylinder designs with corresponding differences in overall size, weight, engine displacement, and cylinder bores. Four cylinders and power ratings from 19 to 120 hp (14 to 90 kW) were followed in a majority of the models. Several three-cylinder, two-stroke-cycle models were built while most engines had straight or in-line cylinders. There were several V-type models and horizontally opposed two- and four-cylinder makes too. Overhead camshafts were frequently employed. The smaller engines were commonly air-cooled and located at the rear of the vehicle; compression ratios were relatively low. The 1970s and 1980s saw an increased interest in improved fuel economy, which caused a return to smaller V-6 and four-cylinder layouts, with as many as five valves per cylinder to improve efficiency. The Bugatti Veyron 16.4 operates with a W16 engine, meaning that two V8 cylinder layouts are positioned next to each other to create the W shape sharing the same crankshaft.

The largest internal combustion engine ever built is the Wärtsilä-Sulzer RTA96-C, a 14-cylinder, 2-stroke turbocharged diesel engine that was designed to power the Emma Mærsk, the largest container ship in the world when launched in 2006. This engine has a mass of 2,300 tonnes, and when running at 102 rpm (1.7 Hz) produces over 80 MW, and can use up to 250 tonnes of fuel per day.

Types

An engine can be put into a category according to two criteria: the form of energy it accepts in order to create motion, and the type of motion it outputs.

Heat engine

Main article: Heat engine

Combustion engine

Combustion engines are heat engines driven by the heat of a combustion process.

Internal combustion engine

A three-horsepower internal combustion engine that ran on coal gas
Main article:
nozzle, and by moving it over a distance, generates mechanical work.[18][19][20][21]

External combustion engine

Main article: External combustion engine

An external combustion engine (EC engine) is a

work.[22]
The fluid is then cooled, compressed and reused (closed cycle), or (less commonly) dumped, and cool fluid pulled in (open cycle air engine).

"

oxidizer
, to supply the heat. Engines of similar (or even identical) configuration and operation may use a supply of heat from other sources such as nuclear, solar, geothermal or exothermic reactions not involving combustion; but are not then strictly classed as external combustion engines, but as external thermal engines.

The working fluid can be a gas as in a Stirling engine, or steam as in a steam engine or an organic liquid such as n-pentane in an Organic Rankine cycle. The fluid can be of any composition; gas is by far the most common, although even single-phase liquid is sometimes used. In the case of the steam engine, the fluid changes phases between liquid and gas.

Air-breathing combustion engines

Air-breathing combustion engines are combustion engines that use the

oxidiser, as in a rocket. Theoretically, this should result in a better specific impulse
than for rocket engines.

A continuous stream of air flows through the air-breathing engine. This air is compressed, mixed with fuel, ignited and expelled as the exhaust gas. In reaction engines, the majority of the combustion energy (heat) exits the engine as exhaust gas, which provides thrust directly.

Examples

Typical air-breathing engines include:

Environmental effects

The operation of engines typically has a negative impact upon

air quality and ambient sound levels. There has been a growing emphasis on the pollution producing features of automotive power systems. This has created new interest in alternate power sources and internal-combustion engine refinements. Though a few limited-production battery-powered electric vehicles have appeared, they have not proved competitive owing to costs and operating characteristics.[citation needed] In the 21st century the diesel engine has been increasing in popularity with automobile owners. However, the gasoline engine and the Diesel engine, with their new emission-control devices to improve emission performance, have not yet been significantly challenged.[citation needed
] A number of manufacturers have introduced hybrid engines, mainly involving a small gasoline engine coupled with an electric motor and with a large battery bank, these are starting to become a popular option because of their environment awareness.

Air quality

global warming
.

Non-combusting heat engines

Main article: heat engine

Some engines convert heat from noncombustive processes into mechanical work, for example a nuclear power plant uses the heat from the nuclear reaction to produce steam and drive a steam engine, or a gas turbine in a rocket engine may be driven by decomposing hydrogen peroxide. Apart from the different energy source, the engine is often engineered much the same as an internal or external combustion engine.

Another group of noncombustive engines includes thermoacoustic heat engines (sometimes called "TA engines") which are thermoacoustic devices that use high-amplitude sound waves to pump heat from one place to another, or conversely use a heat difference to induce high-amplitude sound waves. In general, thermoacoustic engines can be divided into standing wave and travelling wave devices.[24]

Stirling engines can be another form of non-combustive heat engine. They use the Stirling thermodynamic cycle to convert heat into work. An example is the alpha type Stirling engine, whereby gas flows, via a recuperator, between a hot cylinder and a cold cylinder, which are attached to reciprocating pistons 90° out of phase. The gas receives heat at the hot cylinder and expands, driving the piston that turns the crankshaft. After expanding and flowing through the recuperator, the gas rejects heat at the cold cylinder and the ensuing pressure drop leads to its compression by the other (displacement) piston, which forces it back to the hot cylinder.[25]

Non-thermal chemically powered motor

Non-thermal motors usually are powered by a chemical reaction, but are not heat engines. Examples include:

Electric motor

Main articles: Electric motor and Electric vehicle

An electric motor uses

generator or dynamo. Traction motors
used on vehicles often perform both tasks. Electric motors can be run as generators and vice versa, although this is not always practical. Electric motors are ubiquitous, being found in applications as diverse as industrial fans, blowers and pumps, machine tools, household appliances,
kilowatts
. Electric motors may be classified by the source of electric power, by their internal construction, and by their application.

Electric motor

The physical principle of production of mechanical force by the interactions of an electric current and a magnetic field was known as early as 1821. Electric motors of increasing efficiency were constructed throughout the 19th century, but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks.

To reduce the electric

aerodynamics of motors to reduce mechanical windage losses, 5) improving bearings to reduce friction losses, and 6) minimizing manufacturing tolerances. For further discussion on this subject, see Premium efficiency
).

By convention, electric engine refers to a railroad electric locomotive, rather than an electric motor.

Physically powered motor

Some motors are powered by potential or kinetic energy, for example some

elastic bands
.

Historic

siege engines included large catapults, trebuchets, and (to some extent) battering rams
were powered by potential energy.

Pneumatic motor

Main article: Pneumatic motor

A pneumatic motor is a machine that converts potential energy in the form of

mechanical work
. Pneumatic motors generally convert the compressed air to mechanical work through either linear or rotary motion. Linear motion can come from either a diaphragm or piston actuator, while rotary motion is supplied by either a vane type air motor or piston air motor. Pneumatic motors have found widespread success in the hand-held tool industry and continual attempts are being made to expand their use to the transportation industry. However, pneumatic motors must overcome efficiency deficiencies before being seen as a viable option in the transportation industry.

Hydraulic motor

Main article: Hydraulic motor

A hydraulic motor derives its power from a pressurized liquid. This type of engine is used to move heavy loads and drive machinery.[27]

Hybrid

Some motor units can have multiple sources of energy. For example, a

fossil fuels
inputs via an internal combustion engine and a generator.

Performance

The following are used in the assessment of the performance of an engine.

Speed

Speed refers to crankshaft rotation in piston engines and the speed of compressor/turbine rotors and electric motor rotors. It is measured in revolutions per minute (rpm).

Thrust

Thrust is the force exerted on an airplane as a consequence of its propeller or jet engine accelerating the air passing through it. It is also the force exerted on a ship as a consequence of its propeller accelerating the water passing through it.

Torque

Torque is a turning moment on a shaft and is calculated by multiplying the force causing the moment by its distance from the shaft.

Power

Power is the measure of how fast work is done.

Efficiency

Main article: Engine efficiency

Efficiency is a proportion of useful energy output compared to total input.

Sound levels

Vehicle noise is predominantly from the engine at low vehicle speeds and from tires and the air flowing past the vehicle at higher speeds.[28] Electric motors are quieter than internal combustion engines. Thrust-producing engines, such as turbofans, turbojets and rockets emit the greatest amount of noise due to the way their thrust-producing, high-velocity exhaust streams interact with the surrounding stationary air. Noise reduction technology includes intake and exhaust system mufflers (silencers) on gasoline and diesel engines and noise attenuation liners in turbofan inlets.

Engines by use

Particularly notable kinds of engines include:

See also

References

Citations

  1. ^ "Motor". Dictionary.reference.com. Archived from the original on 2008-04-07. Retrieved 2011-05-09. a person or thing that imparts motion, esp. a contrivance, as a steam engine, that receives and modifies energy from some source in order to use it in driving machinery.
  2. Archive-It
    "3. any device that converts another form of energy into mechanical energy so as to produce motion"
  3. ^ "World Wide Words: Engine and Motor". World Wide Words. Archived from the original on 2019-04-25. Retrieved 2020-04-30.
  4. ^ "Engine". Collins English Dictionary. Archived from the original on 2012-08-29. Retrieved 2012-09-03.
  5. ^ Dictionary definitions:
  6. ^ "Engine", McGraw-Hill Concise Encyclopedia of Science and Technology, Third Edition, Sybil P. Parker, ed. McGraw-Hill, Inc., 1994, p. 714.
  7. ^ Quinion, Michael. "World Wide Words: Engine and Motor". Worldwide Words. Archived from the original on 2019-04-25. Retrieved 2018-02-03.
  8. ^ "Prime mover", McGraw-Hill Concise Encyclopedia of Science and Technology, Third Edition, Sybil P. Parker, ed. McGraw-Hill, Inc., 1994, p. 1498.
  9. ISBN 978-0-465-00489-8
    .
  10. Hassan, Ahmad Y. "Transmission of Islamic Engineering". Transfer of Islamic Technology to the West, Part II. Archived from the original
    on 2008-02-18.
  11. Hassan, Ahmad Y. (1976). Taqi al-Din and Arabic Mechanical Engineering, pp. 34–35. Institute for the History of Arabic Science, University of Aleppo
    .
  12. ^ "University of Rochester, NY, The growth of the steam engine online history resource, chapter one". History.rochester.edu. Archived from the original on 2012-02-04. Retrieved 2010-02-03.
  13. ISBN 0-07-043599-5
    .
  14. ^ "La documentazione essenziale per l'attribuzione della scoperta". Archived from the original on 25 February 2017. Retrieved 24 February 2014. A later request was presented to the Patent Office of the Reign of Piedmont, under No. 700 of Volume VII of that Office. The text of this patent request is not available, only a photo of the table containing a drawing of the engine. This may have been either a new patent or an extension of a patent granted three days earlier, on 30 December 1857, at Turin.
  15. ISBN 0-7487-8082-3
    [Retrieved 2016-06-16]
  16. ^
    ISBN 978-0-85404-621-8
  17. ^ McKnight, Bill (August 2017). "The Electrically Assisted Thermostat". Motor.com. Archived from the original on 2021-05-03. Retrieved 2021-03-13.
  18. ^ Proctor, Charles Lafayette II. "Internal Combustion engines". Encyclopædia Britannica Online. Retrieved 2011-05-09.
  19. ^ "Internal combustion engine". Answers.com. Archived from the original on 2011-06-28. Retrieved 2011-05-09.
  20. ^ "Columbia encyclopedia: Internal combustion engine". Inventors.about.com. Archived from the original on 2012-07-21. Retrieved 2011-05-09.
  21. ^ "Internal-combustion engine". Infoplease.com. 2007. Archived from the original on 2011-05-15. Retrieved 2011-05-09.
  22. ^ "External combustion". Merriam-Webster Online Dictionary. 2010-08-13. Archived from the original on 2018-06-27. Retrieved 2011-05-09.
  23. ^ Paul Degobert, Society of Automotive Engineers (1995), Automobiles and Pollution
  24. ^ Emam, Mahmoud (2013). Experimental Investigations on a Standing-Wave Thermoacoustic Engine, M.Sc. Thesis. Egypt: Cairo University. Archived from the original on 2013-09-28. Retrieved 2013-09-26.
  25. ISSN 2214-157X
    .
  26. ^ "Motors". American Council for an Energy-Efficient Economy. Archived from the original on 2012-10-23.
  27. ^ "Howstuffworks "Engineering"". Reference.howstuffworks.com. 2006-01-29. Archived from the original on 2009-08-21. Retrieved 2011-05-09.
  28. S2CID 109914430
    .

Sources

External links

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