Cylinder (engine) 1

Cylinder (engine)

Illustration of an engine cylinder with across-section view of the piston, connecting

rod, valves and spark plug.

A cylinder is the central working part of a reciprocating engine, the spacein which a piston travels. Multiple cylinders are commonly arranged sideby side in a bank, or engine block, which is typically cast from aluminumor cast iron before precision features are machined into it. The cylindersmay then be lined with sleeves or liners of some harder metal, or given awear-resistant coating such as Nikasil. Ceramic linings have also beentried, so far unsuccessfully, except with low-speed "oilless" steamengines.[1] A cylinder's displacement, or swept volume, is itscross-sectional area (the square of half the bore times pi ) times thedistance the piston travels within the cylinder (the stroke). The enginedisplacement is the swept volume of one cylinder times the number ofcylinders in the engine.

A piston is seated inside each cylinder by several metal piston rings whichfit around its outside surface in machined grooves; typically two forcompressional sealing and one to seal the oil (In steam engines onlycompressional sealing rings are used of which there can be from two tofive on the piston). A fine vapour of oil is usually maintained suspendedin the steam working in the cylinder. The rings make near contact with thehard walls of the liner, riding on a thin layer of lubricating oil which isessential to keep the engine from seizing up. This contact, and theresulting wear, explains the need for the hard lining on the inner surface of the cylinder. The breaking in or runningin of an engine is a process whereby tiny irregularities in the metals are encouraged to form congruent grooves. Anengine job or rebore is a process in which the cylinders are machined out to a slightly larger diameter, and newsleeves and piston rings installed.

Heat engines

Cylinder with piston in a double acting steamengine

Heat engines, including Stirling engines, are sealed machines usingpistons within cylinders to transfer energy from a heat source to acolder reservoir, often using steam or another gas as the workingsubstance. (See Carnot cycle.) The first illustration depicts alongitudinal section of a cylinder in a steam engine. The sliding part atthe bottom is the piston, and the upper sliding part is a distributionvalve (in this case of the D slide valve type) that directs steamalternately into either end of the cylinder. Refrigerators and airconditioners are heat engines driven in reverse cycle as pumps.

Cylinder (engine) 2

Internal combustion engines

Malossi air-cooled cylinder for two-stroke scooters. The exhaust portis visible to the right.

Four-stroke cycle (Otto cycle)

Internal combustion engines operate on the inherentvolume change accompanying oxidation of gasoline(petrol), diesel fuel (or some other hydrocarbon) orethanol, an expansion which is greatly enhanced by theheat produced. They are not classical heat engines sincethey expel the working substance, which is also thecombustion product, into the surroundings.

The reciprocating motion of the pistons is translatedinto crankshaft rotation via connecting rods. As apiston moves back and forth, a connecting rod changesits angle; its distal end has a rotating link to thecrankshaft. In addition to cylinder-piston engines, thereare also rotary turbines. The Wankel engine is a rotaryadaptation of the cylinder-piston concept which hasbeen used by Mazda and NSU in automobiles. Rotaryengines are relatively quiet because they lack the clatterof reciprocating motion.

Air-cooled engines generally use individual cases forthe cylinders to facilitate cooling. Inline motorcycleengines are an exception, having two-, three-, four-, oreven six-cylinder air-cooled units in a common block.Water-cooled engines with only a few cylinders mayalso use individual cylinder cases, though this makesthe cooling system more complex. The Ducatimotorcycle company, which for years used air-cooledmotors with individual cylinder cases, retained thebasic design of their V-twin engine while adapting it towater-cooling.

In some engines, especially French designs, thecylinders have "wet liners". They are formed separatelyfrom the main casting so that liquid coolant is free toflow around their outsides. Wet-lined cylinders havebetter cooling and a more even temperaturedistribution, but this design makes the engine as awhole somewhat less rigid.

A typical four-cylinder automobile engine has a singlerow of water-cooled cylinders. V engines (V6 or V8)use two angled cylinder banks. The "V" is designed to

minimize vibration through destructive interference of harmonic overtones. (The "straight-eight" engine is a thing ofthe past.) Many other engine configurations exist.

Cylinder (engine) 3

Air-cooled boxer engine on a 1954 BMWmotorcycle

During use, the cylinder is subject to wear from the rubbing action ofthe piston rings and piston skirt. This is minimized by the thin oil filmwhich coats the cylinder walls, but eventually the cylinder becomesworn and slightly oval in shape, usually necessitating a rebore to anoversize diameter and the fitting of new, oversize pistons. The cylinderdoes not wear above the highest point reached by the top compressionring of the piston, which can result in a detectable ridge. If an engine isonly operated at low rpm for its early life (e.g. in a gently drivenautomobile) then abruptly used in the higher rpm range (e.g. by a newowner), the slight stretching of the connecting rods at high speed canenable the top compression ring to contact the wear ridge, breaking thering. For this reason it is important that all engines, once initiallyrun-in, are occasionally "exercised" through their full speed range to develop a tapered wear profile rather than asharp ridge.

Cylinder Sleeving, Cylinder walls can become very worn or damaged from use. In such cases the use of a sleeve canrestore proper clearances to an engine. Sleeves are made out of iron alloys and are very reliable. A sleeve is installedby a machinist at a machine shop. The engine block is mounted on a precision boring machine where the cylinder isthen bored to a size much larger than normal and a new cast-iron sleeve can be inserted. The sleeves can be pressedinto place, or they can be held in by an interference fit. The interference fit is done by boring the cylinder (between.003-.006 thousandths of an inch) smaller than the sleeve being installed, then heating the engine block and whilehot, the cold sleeve can be inserted easily. When the engine block cools down it shrink fits around the sleeve holdingit into place. Once a sleeve has been installed the cylinder needs to be finish bored and honed to match the piston.

References[1] http:/ / www. www. spilling. de/ uk/ index-steamengines. htm. com

External links• The Long History of Reverse-Cylinder Engine Designs (http:/ / motocrossactionmag. com/ Main/ News/

THE-LONG-HISTORY-OF-REVERSECYLINDER-ENGINE-DESIGNS-7056. aspx) -motocrossactionmag.com

Article Sources and Contributors 4

Article Sources and ContributorsCylinder (engine)  Source: http://en.wikipedia.org/w/index.php?oldid=383044267  Contributors: Ahoerstemeier, Akerans, Alynna Kasmira, Andy Dingley, Ardonik, Ashawley, Axium,Biscuittin, Bongwarrior, Bonás, CRGreathouse, CarinaT, Conscious, D. Recorder, David Shear, DeLarge, DerHexer, Discospinster, ExtraBold, Feuerspiegel, Fish and karate, Gasheadsteve,GregorB, H92, Hooperbloob, Jagged 85, JerrySteal, Jkeaton, John of Paris, Kallemax, Longhair, Lumos3, Luna Santin, MER-C, Maniadis, Mgros, Mike Rosoft, Motorrad-67, Nikkimaria,Nimbus227, Palmiped, Pil56, Piotrus, Qxz, R'n'B, Rogerzilla, RottweilerCS, Shaun F, Sonett72, Steve Pucci, SteveBaker, Subversive.sound, Trevor MacInnis, Typ932, Wizard191, Wtshymanski,Yamazuki3, Zephyris, 39 ,ילארשי יסוי anonymous edits

Image Sources, Licenses and ContributorsFile:Cylinder 2 (PSF).png  Source: http://en.wikipedia.org/w/index.php?title=File:Cylinder_2_(PSF).png  License: unknown  Contributors: Andy Dingley, Ariadacapo, Bastique, CarolSpears,PatríciaRImage:Cylinder-NF.png  Source: http://en.wikipedia.org/w/index.php?title=File:Cylinder-NF.png  License: Public Domain  Contributors: Users Ericd, Koyaanis Qatsi on en.wikipediaImage:Malossi 70cc Morini cylinder.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Malossi_70cc_Morini_cylinder.jpg  License: Public Domain  Contributors: Original uploaderwas Kallemax at en.wikipediaFile:4StrokeEngine Ortho 3D Small.gif  Source: http://en.wikipedia.org/w/index.php?title=File:4StrokeEngine_Ortho_3D_Small.gif  License: GNU Free Documentation License  Contributors:User:ZephyrisFile:R68-opposed-cylinders.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:R68-opposed-cylinders.jpg  License: Attribution  Contributors: Original uploader was Motorrad-67 aten.wikipedia Later versions were uploaded by Liftarn at en.wikipedia.

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