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Reciprocating engine

From Wikipedia, in a visual modern way
Internal combustion piston engine Components of a typical, four-stroke cycle, internal combustion, gasoline piston engine. C. CrankshaftE. Exhaust camshaftI. Intake camshaftP. PistonR. Connecting rodS. Spark plugW. Water jacket for coolant flowV. Valves
Internal combustion piston engine
Components of a typical, four-stroke cycle, internal combustion, gasoline piston engine.
  1. C. Crankshaft
  2. E. Exhaust camshaft
  3. I. Intake camshaft
  4. P. Piston
  5. R. Connecting rod
  6. S. Spark plug
  7. W. Water jacket for coolant flow
  8. V. Valves

A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into a rotating motion. This article describes the common features of all types. The main types are: the internal combustion engine, used extensively in motor vehicles; the steam engine, the mainstay of the Industrial Revolution; and the Stirling engine for niche applications. Internal combustion engines are further classified in two ways: either a spark-ignition (SI) engine, where the spark plug initiates the combustion; or a compression-ignition (CI) engine, where the air within the cylinder is compressed, thus heating it, so that the heated air ignites fuel that is injected then or earlier.[1][2][3][4][5]

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Heat engine

Heat engine

In thermodynamics and engineering, a heat engine is a system that converts heat to usable energy, particularly mechanical energy, which can then be used to do mechanical work. While originally conceived in the context of mechanical energy, the concept of the heat engine has been applied to various other kinds of energy, particularly electrical, since at least the late 19th century. The heat engine does this by bringing a working substance from a higher state temperature to a lower state temperature. A heat source generates thermal energy that brings the working substance to the higher temperature state. The working substance generates work in the working body of the engine while transferring heat to the colder sink until it reaches a lower temperature state. During this process some of the thermal energy is converted into work by exploiting the properties of the working substance. The working substance can be any system with a non-zero heat capacity, but it usually is a gas or liquid. During this process, some heat is normally lost to the surroundings and is not converted to work. Also, some energy is unusable because of friction and drag.

Reciprocating motion

Reciprocating motion

Reciprocating motion, also called reciprocation, is a repetitive up-and-down or back-and-forth linear motion. It is found in a wide range of mechanisms, including reciprocating engines and pumps. The two opposite motions that comprise a single reciprocation cycle are called strokes.

Piston

Piston

A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the cylinder. In some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder.

Pressure

Pressure

Pressure is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure is the pressure relative to the ambient pressure.

Circular motion

Circular motion

In physics, circular motion is a movement of an object along the circumference of a circle or rotation along a circular path. It can be uniform, with constant angular rate of rotation and constant speed, or non-uniform with a changing rate of rotation. The rotation around a fixed axis of a three-dimensional body involves circular motion of its parts. The equations of motion describe the movement of the center of mass of a body. In circular motion, the distance between the body and a fixed point on the surface remains the same.

Internal combustion engine

Internal combustion engine

An internal combustion engine is a heat engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine. The force is typically applied to pistons, turbine blades, a rotor, or a nozzle. This force moves the component over a distance, transforming chemical energy into kinetic energy which is used to propel, move or power whatever the engine is attached to. This replaced the external combustion engine for applications where the weight or size of an engine were more important.

Motor vehicle

Motor vehicle

A motor vehicle, also known as motorized vehicle or automotive vehicle, is a self-propelled land vehicle, commonly wheeled, that does not operate on rails and is used for the transportation of people or cargo.

Steam engine

Steam engine

A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be transformed, by a connecting rod and crank, into rotational force for work. The term "steam engine" is generally applied only to reciprocating engines as just described, not to the steam turbine. Steam engines are external combustion engines, where the working fluid is separated from the combustion products. The ideal thermodynamic cycle used to analyze this process is called the Rankine cycle. In general usage, the term steam engine can refer to either complete steam plants, such as railway steam locomotives and portable engines, or may refer to the piston or turbine machinery alone, as in the beam engine and stationary steam engine.

Industrial Revolution

Industrial Revolution

The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going from hand production methods to machines; new chemical manufacturing and iron production processes; the increasing use of water power and steam power; the development of machine tools; and the rise of the mechanized factory system. Output greatly increased, and a result was an unprecedented rise in population and in the rate of population growth. The textile industry was the first to use modern production methods, and textiles became the dominant industry in terms of employment, value of output, and capital invested.

Spark-ignition engine

Spark-ignition engine

A spark-ignition engine is an internal combustion engine, generally a petrol engine, where the combustion process of the air-fuel mixture is ignited by a spark from a spark plug. This is in contrast to compression-ignition engines, typically diesel engines, where the heat generated from compression together with the injection of fuel is enough to initiate the combustion process, without needing any external spark.

Adiabatic process

Adiabatic process

In thermodynamics, an adiabatic process is a type of thermodynamic process that occurs without transferring heat or mass between the thermodynamic system and its environment. Unlike an isothermal process, an adiabatic process transfers energy to the surroundings only as work. As a key concept in thermodynamics, the adiabatic process supports the theory that explains the first law of thermodynamics.

Diesel engine

Diesel engine

The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is called a compression-ignition engine. This contrasts with engines using spark plug-ignition of the air-fuel mixture, such as a petrol engine or a gas engine.

Common features in all types

Ray-traced image of a piston engine
Ray-traced image of a piston engine

There may be one or more pistons. Each piston is inside a cylinder, into which a gas is introduced, either already under pressure (e.g. steam engine), or heated inside the cylinder either by ignition of a fuel air mixture (internal combustion engine) or by contact with a hot heat exchanger in the cylinder (Stirling engine). The hot gases expand, pushing the piston to the bottom of the cylinder. This position is also known as the Bottom Dead Center (BDC), or where the piston forms the largest volume in the cylinder. The piston is returned to the cylinder top (Top Dead Center) (TDC) by a flywheel, the power from other pistons connected to the same shaft or (in a double acting cylinder) by the same process acting on the other side of the piston. This is where the piston forms the smallest volume in the cylinder. In most types the expanded or "exhausted" gases are removed from the cylinder by this stroke. The exception is the Stirling engine, which repeatedly heats and cools the same sealed quantity of gas. The stroke is simply the distance between the TDC and the BDC, or the greatest distance that the piston can travel in one direction.

In some designs the piston may be powered in both directions in the cylinder, in which case it is said to be double-acting.

Steam piston engineA labeled schematic diagram of a typical single-cylinder, simple expansion, double-acting high pressure steam engine. Power takeoff from the engine is by way of a belt. PistonPiston rodCrosshead bearingConnecting rodCrankEccentric valve motionFlywheelSliding valveCentrifugal governor
Steam piston engine
A labeled schematic diagram of a typical single-cylinder, simple expansion, double-acting high pressure steam engine. Power takeoff from the engine is by way of a belt.
  1. Piston
  2. Piston rod
  3. Crosshead bearing
  4. Connecting rod
  5. Crank
  6. Eccentric valve motion
  7. Flywheel
  8. Sliding valve
  9. Centrifugal governor

In most types, the linear movement of the piston is converted to a rotating movement via a connecting rod and a crankshaft or by a swashplate or other suitable mechanism. A flywheel is often used to ensure smooth rotation or to store energy to carry the engine through an un-powered part of the cycle. The more cylinders a reciprocating engine has, generally, the more vibration-free (smoothly) it can operate. The power of a reciprocating engine is proportional to the volume of the combined pistons' displacement.

A seal must be made between the sliding piston and the walls of the cylinder so that the high pressure gas above the piston does not leak past it and reduce the efficiency of the engine. This seal is usually provided by one or more piston rings. These are rings made of a hard metal, and are sprung into a circular groove in the piston head. The rings fit closely in the groove and press lightly against the cylinder wall to form a seal, and more heavily when higher combustion pressure moves around to their inner surfaces.

It is common to classify such engines by the number and alignment of cylinders and total volume of displacement of gas by the pistons moving in the cylinders usually measured in cubic centimetres (cm3 or cc) or litres (l) or (L) (US: liter). For example, for internal combustion engines, single and two-cylinder designs are common in smaller vehicles such as motorcycles, while automobiles typically have between four and eight, and locomotives and ships may have a dozen cylinders or more. Cylinder capacities may range from 10 cm3 or less in model engines up to thousands of liters in ships' engines.[6]

The compression ratio affects the performance in most types of reciprocating engine. It is the ratio between the volume of the cylinder, when the piston is at the bottom of its stroke, and the volume when the piston is at the top of its stroke.

The bore/stroke ratio is the ratio of the diameter of the piston, or "bore", to the length of travel within the cylinder, or "stroke". If this is around 1 the engine is said to be "square". If it is greater than 1, i.e. the bore is larger than the stroke, it is "oversquare". If it is less than 1, i.e. the stroke is larger than the bore, it is "undersquare".

Cylinders may be aligned in line, in a V configuration, horizontally opposite each other, or radially around the crankshaft. Opposed-piston engines put two pistons working at opposite ends of the same cylinder and this has been extended into triangular arrangements such as the Napier Deltic. Some designs have set the cylinders in motion around the shaft, such as the rotary engine.

Stirling piston engine Rhombic Drive – Beta Stirling Engine Design, showing the second displacer piston (green) within the cylinder, which shunts the working gas between the hot and cold ends, but produces no power itself. .mw-parser-output .legend{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .legend-color{display:inline-block;min-width:1.25em;height:1.25em;line-height:1.25;margin:1px 0;text-align:center;border:1px solid black;background-color:transparent;color:black}.mw-parser-output .legend-text{}  Hot cylinder wall  Cold cylinder wall  Displacer piston  Power piston  Flywheels
Stirling piston engine Rhombic Drive – Beta Stirling Engine Design, showing the second displacer piston (green) within the cylinder, which shunts the working gas between the hot and cold ends, but produces no power itself.
  1.   Hot cylinder wall
  2.   Cold cylinder wall
  1.   Displacer piston
  2.   Power piston
  3.   Flywheels

In some steam engines, the cylinders may be of varying size with the smallest bore cylinder working the highest pressure steam. This is then fed through one or more, increasingly larger bore cylinders successively, to extract power from the steam at increasingly lower pressures. These engines are called compound engines.

Aside from looking at the power that the engine can produce, the mean effective pressure (MEP), can also be used in comparing the power output and performance of reciprocating engines of the same size. The mean effective pressure is the fictitious pressure which would produce the same amount of net work that was produced during the power stroke cycle. This is shown by:

where is the total piston area of the engine, is the stroke length of the pistons, and is the total displacement volume of the engine. Therefore:

Whichever engine with the larger value of MEP produces more net work per cycle and performs more efficiently.[1]

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Cylinder (engine)

Cylinder (engine)

In a reciprocating engine, the cylinder is the space in which a piston travels.

Steam engine

Steam engine

A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be transformed, by a connecting rod and crank, into rotational force for work. The term "steam engine" is generally applied only to reciprocating engines as just described, not to the steam turbine. Steam engines are external combustion engines, where the working fluid is separated from the combustion products. The ideal thermodynamic cycle used to analyze this process is called the Rankine cycle. In general usage, the term steam engine can refer to either complete steam plants, such as railway steam locomotives and portable engines, or may refer to the piston or turbine machinery alone, as in the beam engine and stationary steam engine.

Ignition system

Ignition system

An ignition system generates a spark or heats an electrode to a high temperature to ignite a fuel-air mixture in spark ignition internal combustion engines, oil-fired and gas-fired boilers, rocket engines, etc. The widest application for spark ignition internal combustion engines is in petrol (gasoline) road vehicles such as cars and motorcycles.

Internal combustion engine

Internal combustion engine

An internal combustion engine is a heat engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine. The force is typically applied to pistons, turbine blades, a rotor, or a nozzle. This force moves the component over a distance, transforming chemical energy into kinetic energy which is used to propel, move or power whatever the engine is attached to. This replaced the external combustion engine for applications where the weight or size of an engine were more important.

Dead centre (engineering)

Dead centre (engineering)

In a reciprocating engine, the dead centre is the position of a piston in which it is either farthest from, or nearest to, the crankshaft. The former is known as Top Dead Centre (TDC) while the latter is known as Bottom Dead Centre (BDC).

Flywheel

Flywheel

A flywheel is a mechanical device which uses the conservation of angular momentum to store rotational energy; a form of kinetic energy proportional to the product of its moment of inertia and the square of its rotational speed. In particular, assuming the flywheel's moment of inertia is constant then the stored (rotational) energy is directly associated with the square of its rotational speed.

Exhaust gas

Exhaust gas

Exhaust gas or flue gas is emitted as a result of the combustion of fuels such as natural gas, gasoline (petrol), diesel fuel, fuel oil, biodiesel blends, or coal. According to the type of engine, it is discharged into the atmosphere through an exhaust pipe, flue gas stack, or propelling nozzle. It often disperses downwind in a pattern called an exhaust plume.

Connecting rod

Connecting rod

A connecting rod, also called a 'con rod', is the part of a piston engine which connects the piston to the crankshaft. Together with the crank, the connecting rod converts the reciprocating motion of the piston into the rotation of the crankshaft. The connecting rod is required to transmit the compressive and tensile forces from the piston. In its most common form, in an internal combustion engine, it allows pivoting on the piston end and rotation on the shaft end.

Crankshaft

Crankshaft

A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecting rods.

Piston

Piston

A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the cylinder. In some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder.

Piston ring

Piston ring

A piston ring is a metallic split ring that is attached to the outer diameter of a piston in an internal combustion engine or steam engine.

Engine displacement

Engine displacement

Engine displacement is the measure of the cylinder volume swept by all of the pistons of a piston engine, excluding the combustion chambers. It is commonly used as an expression of an engine's size, and by extension as a loose indicator of the power an engine might be capable of producing and the amount of fuel it should be expected to consume. For this reason displacement is one of the measures often used in advertising, as well as regulating, motor vehicles.

Operations

In steam engines and internal combustion engines, valves are required to allow the entry and exit of gases at the correct times in the piston's cycle. These are worked by cams, eccentrics or cranks driven by the shaft of the engine. Early designs used the D slide valve but this has been largely superseded by piston valve or poppet valve designs. In steam engines the point in the piston cycle at which the steam inlet valve closes is called the cutoff and this can often be controlled to adjust the torque supplied by the engine and improve efficiency. In some steam engines, the action of the valves can be replaced by an oscillating cylinder.

Internal combustion engines operate through a sequence of strokes that admit and remove gases to and from the cylinder. These operations are repeated cyclically and an engine is said to be 2-stroke, 4-stroke or 6-stroke depending on the number of strokes it takes to complete a cycle.

The most common type is 4-stroke, which has following cycles.

  1. Intake: Also known as induction or suction. This stroke of the piston begins at top dead center (T.D.C.) and ends at bottom dead center (B.D.C.). In this stroke the intake valve must be in the open position while the piston pulls an air-fuel mixture into the cylinder by producing vacuum pressure into the cylinder through its downward motion. The piston is moving down as air is being sucked in by the downward motion against the piston.
  2. Compression: This stroke begins at B.D.C, or just at the end of the suction stroke, and ends at T.D.C. In this stroke the piston compresses the air-fuel mixture in preparation for ignition during the power stroke (below). Both the intake and exhaust valves are closed during this stage.
  3. Combustion: Also known as power or ignition. This is the start of the second revolution of the four stroke cycle. At this point the crankshaft has completed a full 360 degree revolution. While the piston is at T.D.C. (the end of the compression stroke) the compressed air-fuel mixture is ignited by a spark plug (in a gasoline engine) or by heat generated by high compression (diesel engines), forcefully returning the piston to B.D.C. This stroke produces mechanical work from the engine to turn the crankshaft.
  4. Exhaust: Also known as outlet. During the exhaust stroke, the piston, once again, returns from B.D.C. to T.D.C. while the exhaust valve is open. This action expels the spent air-fuel mixture through the exhaust valve.

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Piston valve

Piston valve

A "piston valve" is a device used to control the motion of a fluid along a tube or pipe by means of the linear motion of a piston within a chamber or cylinder.

Poppet valve

Poppet valve

A poppet valve is a valve typically used to control the timing and quantity of gas or vapor flow into an engine.

Cutoff (steam engine)

Cutoff (steam engine)

In a steam engine, cutoff is the point in the piston stroke at which the inlet valve is closed. On a steam locomotive, the cutoff is controlled by the reversing gear.

Torque

Torque

In physics and mechanics, torque is the rotational equivalent of linear force. It is also referred to as the moment of force. It represents the capability of a force to produce change in the rotational motion of the body. The concept originated with the studies by Archimedes of the usage of levers, which is reflected in his famous quote: "Give me a lever and a place to stand and I will move the Earth". Just as a linear force is a push or a pull, a torque can be thought of as a twist to an object around a specific axis. Torque is defined as the product of the magnitude of the perpendicular component of the force and the distance of the line of action of a force from the point around which it is being determined. The law of conservation of energy can also be used to understand torque. The symbol for torque is typically , the lowercase Greek letter tau. When being referred to as moment of force, it is commonly denoted by M.

Spark plug

Spark plug

A spark plug is a device for delivering electric current from an ignition system to the combustion chamber of a spark-ignition engine to ignite the compressed fuel/air mixture by an electric spark, while containing combustion pressure within the engine. A spark plug has a metal threaded shell, electrically isolated from a central electrode by a ceramic insulator. The central electrode, which may contain a resistor, is connected by a heavily insulated wire to the output terminal of an ignition coil or magneto. The spark plug's metal shell is screwed into the engine's cylinder head and thus electrically grounded. The central electrode protrudes through the porcelain insulator into the combustion chamber, forming one or more spark gaps between the inner end of the central electrode and usually one or more protuberances or structures attached to the inner end of the threaded shell and designated the side, earth, or ground electrode(s).

History

An early known example of rotary to reciprocating motion is the crank mechanism. The earlier hand-operated cranks appeared in China during the Han Dynasty (202 BC–220 AD).[7] The Chinese used the crank-and-connecting rod for operating querns as far back as the Western Han dynasty (202 BC–9 AD). Eventually crank-and-connecting rods were used in the inter-conversion of rotary and reciprocating motion for other applications such as flour-sifting, silk-reeling machines, treadle spinning wheels, and furnace bellows driven either by horses or waterwheels. [8][7] Several saw mills in Roman Asia and Byzantine Syria during the 3rd–6th centuries AD had a crank and connecting rod mechanism which converted the rotary motion of a water wheel into the linear movement of saw blades.[9] In 1206, Arab engineer Al-Jazari invented a crankshaft.[10]

The reciprocating engine developed in Europe during the 18th century, first as the atmospheric engine then later as the steam engine. These were followed by the Stirling engine and internal combustion engine in the 19th century. Today the most common form of reciprocating engine is the internal combustion engine running on the combustion of petrol, diesel, liquefied petroleum gas (LPG) or compressed natural gas (CNG) and used to power motor vehicles and engine power plants.

One notable reciprocating engine from the World War II era was the 28-cylinder, 3,500 hp (2,600 kW) Pratt & Whitney R-4360 Wasp Major radial engine. It powered the last generation of large piston-engined planes before jet engines and turboprops took over from 1944 onward. It had a total engine capacity of 71.5 L (4,360 cu in), and a high power-to-weight ratio.

The largest reciprocating engine in production at present, but not the largest ever built, is the Wärtsilä-Sulzer RTA96-C turbocharged two-stroke diesel engine of 2006 built by Wärtsilä. It is used to power the largest modern container ships such as the Emma Mærsk. It is five stories high (13.5 m or 44 ft), 27 m (89 ft) long, and weighs over 2,300 metric tons (2,500 short tons) in its largest 14 cylinders version producing more than 84.42 MW (114,800 bhp). Each cylinder has a capacity of 1,820 L (64 cu ft), making a total capacity of 25,480 L (900 cu ft) for the largest versions.

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History of the steam engine

History of the steam engine

The first recorded rudimentary steam engine was the aeolipile mentioned by Vitruvius between 30 and 15 BC and, described by Heron of Alexandria in 1st-century Roman Egypt. Several steam-powered devices were later experimented with or proposed, such as Taqi al-Din's steam jack, a steam turbine in 16th-century Ottoman Egypt, and Thomas Savery's steam pump in 17th-century England. In 1712, Thomas Newcomen's atmospheric engine became the first commercially successful engine using the principle of the piston and cylinder, which was the fundamental type of steam engine used until the early 20th century. The steam engine was used to pump water out of coal mines.

History of the internal combustion engine

History of the internal combustion engine

Internal combustion engines date back to between the 10th and 13th centuries, when the first rocket engines were invented in China. Following the first commercial steam engine in 1698, various efforts were made during the 18th century to develop equivalent internal combustion engines. In 1791, the English inventor John Barber patented a gas turbine. In 1794, Thomas Mead patented a gas engine. Also in 1794, Robert Street patented an internal-combustion engine, which was also the first to use liquid fuel (petroleum) and built an engine around that time. In 1798, John Stevens designed the first American internal combustion engine. In 1807, French engineers Nicéphore and Claude Niépce ran a prototype internal combustion engine, using controlled dust explosions, the Pyréolophore. This engine powered a boat on the river in France. The same year, the Swiss engineer François Isaac de Rivaz built and patented a hydrogen and oxygen-powered internal-combustion engine. Fitted to a crude four-wheeled wagon, François Isaac de Rivaz first drove it 100 meters in 1813, thus making history as the first car-like vehicle known to have been powered by an internal-combustion engine.

Crank (mechanism)

Crank (mechanism)

A crank is an arm attached at a right angle to a rotating shaft by which circular motion is imparted to or received from the shaft. When combined with a connecting rod, it can be used to convert circular motion into reciprocating motion, or vice versa. The arm may be a bent portion of the shaft, or a separate arm or disk attached to it. Attached to the end of the crank by a pivot is a rod, usually called a connecting rod (conrod).

China

China

China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and borders fourteen countries by land, the most of any country in the world, tied with Russia. With an area of approximately 9.6 million square kilometres (3,700,000 sq mi), it is the world's third largest country by total land area. The country consists of 22 provinces, five autonomous regions, four municipalities, and two special administrative regions. The national capital is Beijing, and the most populous city and largest financial center is Shanghai.

Connecting rod

Connecting rod

A connecting rod, also called a 'con rod', is the part of a piston engine which connects the piston to the crankshaft. Together with the crank, the connecting rod converts the reciprocating motion of the piston into the rotation of the crankshaft. The connecting rod is required to transmit the compressive and tensile forces from the piston. In its most common form, in an internal combustion engine, it allows pivoting on the piston end and rotation on the shaft end.

Crankshaft

Crankshaft

A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecting rods.

Steam engine

Steam engine

A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be transformed, by a connecting rod and crank, into rotational force for work. The term "steam engine" is generally applied only to reciprocating engines as just described, not to the steam turbine. Steam engines are external combustion engines, where the working fluid is separated from the combustion products. The ideal thermodynamic cycle used to analyze this process is called the Rankine cycle. In general usage, the term steam engine can refer to either complete steam plants, such as railway steam locomotives and portable engines, or may refer to the piston or turbine machinery alone, as in the beam engine and stationary steam engine.

Stirling engine

Stirling engine

A Stirling engine is a heat engine that is operated by the cyclic compression and expansion of air or other gas between different temperatures, resulting in a net conversion of heat energy to mechanical work.

Internal combustion engine

Internal combustion engine

An internal combustion engine is a heat engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine. The force is typically applied to pistons, turbine blades, a rotor, or a nozzle. This force moves the component over a distance, transforming chemical energy into kinetic energy which is used to propel, move or power whatever the engine is attached to. This replaced the external combustion engine for applications where the weight or size of an engine were more important.

Diesel fuel

Diesel fuel

Diesel fuel, also called diesel oil or historically heavy oil, is any liquid fuel specifically designed for use in a diesel engine, a type of internal combustion engine in which fuel ignition takes place without a spark as a result of compression of the inlet air and then injection of fuel. Therefore, diesel fuel needs good compression ignition characteristics.

Liquefied petroleum gas

Liquefied petroleum gas

Liquefied petroleum gas is a fuel gas which contains a flammable mixture of hydrocarbon gases, specifically propane, propylene, butylene, isobutane and n-butane.

Compressed natural gas

Compressed natural gas

Compressed natural gas (CNG) is a fuel gas mainly composed of methane (CH4), compressed to less than 1% of the volume it occupies at standard atmospheric pressure. It is stored and distributed in hard containers at a pressure of 20–25 megapascals (2,900–3,600 psi), usually in cylindrical or spherical shapes.

Engine capacity

For piston engines, an engine's capacity is the engine displacement, in other words the volume swept by all the pistons of an engine in a single movement. It is generally measured in litres (l) or cubic inches (c.i.d., cu in, or in3) for larger engines, and cubic centimetres (abbreviated cc) for smaller engines. All else being equal, engines with greater capacities are more powerful and consumption of fuel increases accordingly (although this is not true of every reciprocating engine), although power and fuel consumption are affected by many factors outside of engine displacement.

Power

Reciprocating engines can be characterized by their specific power, which is typically given in kilowatts per litre of engine displacement (in the U.S. also horsepower per cubic inch). The result offers an approximation of the peak power output of an engine. This is not to be confused with fuel efficiency, since high efficiency often requires a lean fuel-air ratio, and thus lower power density. A modern high-performance car engine makes in excess of 75 kW/L (1.65 hp/in3).

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Power density

Power density

Power density is the amount of power per unit volume.

Engine displacement

Engine displacement

Engine displacement is the measure of the cylinder volume swept by all of the pistons of a piston engine, excluding the combustion chambers. It is commonly used as an expression of an engine's size, and by extension as a loose indicator of the power an engine might be capable of producing and the amount of fuel it should be expected to consume. For this reason displacement is one of the measures often used in advertising, as well as regulating, motor vehicles.

Horsepower

Horsepower

Horsepower (hp) is a unit of measurement of power, or the rate at which work is done, usually in reference to the output of engines or motors. There are many different standards and types of horsepower. Two common definitions used today are the mechanical horsepower, which is about 745.7 watts, and the metric horsepower, which is approximately 735.5 watts.

Fuel efficiency

Fuel efficiency

Fuel efficiency is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical potential energy contained in a carrier (fuel) into kinetic energy or work. Overall fuel efficiency may vary per device, which in turn may vary per application, and this spectrum of variance is often illustrated as a continuous energy profile. Non-transportation applications, such as industry, benefit from increased fuel efficiency, especially fossil fuel power plants or industries dealing with combustion, such as ammonia production during the Haber process.

Other modern non-internal combustion types

Reciprocating engines that are powered by compressed air, steam or other hot gases are still used in some applications such as to drive many modern torpedoes or as pollution-free motive power. Most steam-driven applications use steam turbines, which are more efficient than piston engines.

The French-designed FlowAIR vehicles use compressed air stored in a cylinder to drive a reciprocating engine in a local-pollution-free urban vehicle.[11]

Torpedoes may use a working gas produced by high test peroxide or Otto fuel II, which pressurize without combustion. The 230 kg (510 lb) Mark 46 torpedo, for example, can travel 11 km (6.8 mi) underwater at 74 km/h (46 mph) fuelled by Otto fuel without oxidant.

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Steam turbine

Steam turbine

A steam turbine is a machine that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Its modern manifestation was invented by Charles Parsons in 1884. Fabrication of a modern steam turbine involves advanced metalwork to form high-grade steel alloys into precision parts using technologies that first became available in the 20th century; continued advances in durability and efficiency of steam turbines remains central to the energy economics of the 21st century.

Otto fuel II

Otto fuel II

Otto fuel II is a monopropellant used to drive torpedoes and other weapon systems. It is not related to the Otto cycle. Otto fuel II was developed by US Navy in the 1960s for use as fuel in torpedoes. Otto fuel II was invented by Otto Reitlinger in 1963 ; it is named after Reitlinger and for being the second iteration of the fuel. The first torpedo to use it was the Mark 48 torpedo in the 1960s.

Mark 46 torpedo

Mark 46 torpedo

The Mark 46 torpedo is the backbone of the United States Navy's lightweight anti-submarine warfare torpedo inventory and is the NATO standard. These aerial torpedoes are designed to attack high-performance submarines. In 1989, an improvement program for the Mod 5 to the Mod 5A and Mod 5A(S) increased its shallow-water performance. The Mark 46 was initially developed as Research Torpedo Concept I, one of several weapons recommended for implementation by Project Nobska, a 1956 summer study on submarine warfare.

Reciprocating quantum heat engine

Quantum heat engines are devices that generate power from heat that flows from a hot to a cold reservoir. The mechanism of operation of the engine can be described by the laws of quantum mechanics. Quantum refrigerators are devices that consume power with the purpose to pump heat from a cold to a hot reservoir.

In a reciprocating quantum heat engine, the working medium is a quantum system such as spin systems or a harmonic oscillator. The Carnot cycle and Otto cycle are the ones most studied.[12] The quantum versions obey the laws of thermodynamics. In addition, these models can justify the assumptions of endoreversible thermodynamics. A theoretical study has shown that it is possible and practical to build a reciprocating engine that is composed of a single oscillating atom. This is an area for future research and could have applications in nanotechnology.[13]

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Quantum mechanics

Quantum mechanics

Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, quantum field theory, quantum technology, and quantum information science.

Carnot cycle

Carnot cycle

A Carnot cycle is an ideal thermodynamic cycle proposed by French physicist Sadi Carnot in 1824 and expanded upon by others in the 1830s and 1840s. By Carnot's theorem, it provides an upper limit on the efficiency of any classical thermodynamic engine during the conversion of heat into work, or conversely, the efficiency of a refrigeration system in creating a temperature difference through the application of work to the system.

Otto cycle

Otto cycle

An Otto cycle is an idealized thermodynamic cycle that describes the functioning of a typical spark ignition piston engine. It is the thermodynamic cycle most commonly found in automobile engines.

Thermodynamics

Thermodynamics

Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of thermodynamics which convey a quantitative description using measurable macroscopic physical quantities, but may be explained in terms of microscopic constituents by statistical mechanics. Thermodynamics applies to a wide variety of topics in science and engineering, especially physical chemistry, biochemistry, chemical engineering and mechanical engineering, but also in other complex fields such as meteorology.

Endoreversible thermodynamics

Endoreversible thermodynamics

Endoreversible thermodynamics is a subset of irreversible thermodynamics aimed at making more realistic assumptions about heat transfer than are typically made in reversible thermodynamics. It gives an upper bound on the energy that can be derived from a real process that is lower than that predicted by Carnot for a Carnot cycle, and accommodates the exergy destruction occurring as heat is transferred irreversibly.

Nanotechnology

Nanotechnology

Nanotechnology, also shortened to nanotech, is the use of matter on an atomic, molecular, and supramolecular scale for industrial purposes. The earliest, widespread description of nanotechnology referred to the particular technological goal of precisely manipulating atoms and molecules for fabrication of macroscale products, also now referred to as molecular nanotechnology. A more generalized description of nanotechnology was subsequently established by the National Nanotechnology Initiative, which defined nanotechnology as the manipulation of matter with at least one dimension sized from 1 to 100 nanometers (nm). This definition reflects the fact that quantum mechanical effects are important at this quantum-realm scale, and so the definition shifted from a particular technological goal to a research category inclusive of all types of research and technologies that deal with the special properties of matter which occur below the given size threshold. It is therefore common to see the plural form "nanotechnologies" as well as "nanoscale technologies" to refer to the broad range of research and applications whose common trait is size.

Miscellaneous engines

There are a large number of unusual varieties of piston engines that have various claimed advantages, many of which see little if any current use:

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Free-piston engine

Free-piston engine

A free-piston engine is a linear, 'crankless' internal combustion engine, in which the piston motion is not controlled by a crankshaft but determined by the interaction of forces from the combustion chamber gases, a rebound device and a load device.

Opposed-piston engine

Opposed-piston engine

An opposed-piston engine is a piston engine in which each cylinder has a piston at both ends, and no cylinder head. Petrol and diesel opposed-piston engines have been used mostly in large-scale applications such as ships, military tanks, and factories. Current manufacturers of opposed-piston engines include Fairbanks-Morse, Cummins and Achates Power.

Swing-piston engine

Swing-piston engine

A swing-piston engine is a type of internal combustion engine in which the pistons move in a circular motion inside a ring-shaped "cylinder", moving closer and further from each other to provide compression and expansion. Generally two sets of pistons are used, geared to move in a fixed relationship as they rotate around the cylinder. In some versions the pistons oscillate around a fixed center, as opposed to rotating around the entire engine. The design has also been referred to as a oscillating piston engine, vibratory engine when the pistons oscillate instead of rotate, or toroidal engine based on the shape of the "cylinder".

IRIS engine

IRIS engine

The IRIS Engine is a design for a new type of internal combustion engine. Its inventors say that engines constructed using this design can be smaller, lighter and significantly more efficient than traditional engines of comparable horsepower and displacement. The design replaces the piston and cylinder architecture of conventional engines with a purportedly novel mechanism called the Internally Radiating Impulse Structure, or IRIS.

Bourke engine

Bourke engine

The Bourke engine was an attempt by Russell Bourke, in the 1920s, to improve the two-stroke internal combustion engine. Despite finishing his design and building several working engines, the onset of World War II, lack of test results, and the poor health of his wife compounded to prevent his engine from ever coming successfully to market. The main claimed virtues of the design are that it has only two moving parts, is lightweight, has two power pulses per revolution, and does not need oil mixed into the fuel.

Thermo-magnetic motor

Thermo-magnetic motor

Thermomagnetic motors convert heat into kinetic energy using the thermomagnetic effect, i.e., the influence of temperature on the magnetic material magnetization.

Source: "Reciprocating engine", Wikipedia, Wikimedia Foundation, (2023, March 14th), https://en.wikipedia.org/wiki/Reciprocating_engine.

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See also
Notes
  1. ^ a b Thermodynamics: An Engineering Approach by Yunus A. Cengal and Michael A. Boles
  2. ^ "Piston Engine Basics". 4 February 2016.
  3. ^ "What is a Piston Engine? (With pictures)".
  4. ^ "Beginner's Guide: What is a Piston (And What Does It Do)?". 16 March 2018.
  5. ^ "The Basics of How a Piston-Driven Engine Works".
  6. ^ Hanlon, Mike. Most powerful diesel engine in the world GizMag. Accessed: 14 April 2017.
  7. ^ a b Needham, Joseph. (1986). Science and Civilization in China: Volume 4, Part 2, Mechanical Engineering. Taipei: Caves Books, Ltd. Pages 118–119.
  8. ^ Hong-Sen Yan, Marco Ceccarelli (2009). International Symposium on History of Machines and Mechanisms. Springer Science and Business Media. pp. 235–249. ISBN 978-1-4020-9484-2.
  9. ^ Ritti, Tullia; Grewe, Klaus; Kessener, Paul (2007), "A Relief of a Water-powered Stone Saw Mill on a Sarcophagus at Hierapolis and its Implications", Journal of Roman Archaeology, 20: 138–163, doi:10.1017/S1047759400005341, S2CID 161937987
  10. ^ Sally Ganchy, Sarah Gancher (2009), Islam and Science, Medicine, and Technology, The Rosen Publishing Group, p. 41, ISBN 978-1-4358-5066-8
  11. ^ AIRPod manufactured by MDI SA. Accessed February 19, 2015
  12. ^ [1] Irreversible performance of a quantum harmonic heat engine, Rezek and Kosloff, New J. Phys. 8 (2006) 83
  13. ^ Can a car engine be built out of a single particle? Physorg, November 30, 2012 by Lisa Zyga. Accessed 01-12-12
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