Editing Diesel engine (section)

===Diesel's idea===
[[File:Lumbar patent dieselengine.jpg|thumb|right|[[Rudolf Diesel]]'s 1893 patent on a rational heat motor]]
[[File:Experimental Diesel Engine.jpg|thumb|right|Diesel's second prototype. It is a modification of the first experimental engine. On 17 February 1894, this engine ran under its own power for the first time.<ref name="Diesel_1913_22" /><br /><br />Effective efficiency 16.6% <br />Fuel consumption 519&nbsp;g·kW<sup>−1</sup>·h<sup>−1</sup>]]
[[File:Historical Diesel engine in Deutsches Museum.jpg|thumb|right|First fully functional diesel engine, designed by Imanuel Lauster, built from scratch, and finished by October 1896.<ref name="Diesel_1913_64" /><ref name="Diesel_1913_75" /><ref name="Diesel_1913_78" /><br /><br />Rated power 13.1&nbsp;kW<br />Effective efficiency 26.2% <br />Fuel consumption 324&nbsp;g·kW<sup>−1</sup>·h<sup>−1</sup>.]]

In 1878, [[Rudolf Diesel]], who was a student at the [[Technical University of Munich#Foundation of "Polytechnische Schule München"|"Polytechnikum"]] in [[Munich]], attended the lectures of [[Carl von Linde]]. Linde explained that steam engines are capable of converting just 6–10% of the heat energy into work, but that the [[Carnot cycle]] allows conversion of much more of the heat energy into work by means of isothermal change in condition. According to Diesel, this ignited the idea of creating a highly efficient engine that could work on the Carnot cycle.<ref name="Diesel_1913_1" /> Diesel was also introduced to a [[fire piston]], a traditional [[fire making|fire starter]] using rapid [[adiabatic]] compression principles which Linde had acquired from [[Southeast Asia]].<ref name="ogata">{{Cite web |last1=Ogata |first1=Masanori |last2=Shimotsuma |first2=Yorikazu |date=October 20–21, 2002 |title=Origin of Diesel Engine is in Fire Piston of Mountainous People Lived in Southeast Asia |url=http://inet.museum.kyoto-u.ac.jp/conference02/MasanoriOGATA.html |url-status=dead |archive-url=https://web.archive.org/web/20070523214754/http://inet.museum.kyoto-u.ac.jp/conference02/MasanoriOGATA.html |archive-date=May 23, 2007 |access-date=2007-05-28 |website=First International Conference on Business and technology Transfer |publisher=Japan Society of Mechanical Engineers}}</ref> After several years of working on his ideas, Diesel published them in 1893 in the essay ''[[Theory and Construction of a Rational Heat Motor]]''.<ref name="Diesel_1913_1" />

====Constant temperature====
Diesel was heavily criticised for his essay, but only a few found the mistake that he made;<ref name="Sittauer_1990_70" /> his ''rational heat motor'' was supposed to utilise a constant temperature cycle (with isothermal compression) that would require a much higher level of compression than that needed for compression ignition. Diesel's idea was to compress the air so tightly that the temperature of the air would exceed that of combustion. However, such an engine could never perform any usable work.<ref name="Sittauer_1990_71" /><ref name="Sass_1962_398" /><ref name="Sass_1962_399" /> In his 1892 US patent (granted in 1895) #542846, Diesel describes the compression required for his cycle:<ref name="Diesel_1895" />

{{blockquote|pure atmospheric air is compressed, according to curve 1 2, to such a degree that, before ignition or combustion takes place, the highest pressure of the diagram and the highest temperature are obtained-that is to say, the temperature at which the subsequent combustion has to take place, not the burning or igniting point. To make this more clear, let it be assumed that the subsequent combustion shall take place at a temperature of 700°. Then in that case the initial pressure must be sixty-four atmospheres, or for 800° centigrade the pressure must be ninety atmospheres, and so on. Into the air thus compressed is then gradually introduced from the exterior finely divided fuel, which ignites on introduction, since the air is at a temperature far above the igniting-point of the fuel. The characteristic features of the cycle according to my present invention are therefore, increase of pressure and temperature up to the maximum, not by combustion, but prior to combustion by mechanical compression of air, and there upon the subsequent performance of work without increase of pressure and temperature by gradual combustion during a prescribed part of the stroke determined by the cut-oil.}}

====Constant pressure====
By June 1893, Diesel had realised his original cycle would not work, and he adopted the constant pressure cycle.<ref name="Sass_1962_402" /> Diesel describes the cycle in his 1895 patent application. Notice that there is no longer a mention of compression temperatures exceeding the temperature of combustion. Now it is simply stated that the compression must be sufficient to trigger ignition.<ref name="Diesel_1898" /><ref name="Diesel_1893" /><ref name="e-rara.ch" />

{{blockquote|1. In an internal-combustion engine, the combination of a cylinder and piston constructed and arranged to compress air to a degree producing a temperature above the igniting-point of the fuel, a supply for compressed air or gas; a fuel-supply; a distributing-valve for fuel, a passage from the air supply to the cylinder in communication with the fuel-distributing valve, an inlet to the cylinder in communication with the air-supply and with the fuel-valve, and a cut-oil, substantially as described.}}

In 1892, Diesel received patents in [[German Empire|Germany]], [[Switzerland]], the [[United Kingdom of Great Britain and Ireland|United Kingdom]], and the [[United States]] for "Method of and Apparatus for Converting Heat into Work".<ref name="Diesel_1892" /> In 1894 and 1895, he filed patents and addenda in various countries for his engine; the first patents were issued in [[Spain]] (No.&nbsp;16,654),<ref>{{patent|ES|16654|"Perfeccionamientos en los motores de combustión interior."}}</ref> [[France]] (No.&nbsp;243,531) and [[Belgium]] (No.&nbsp;113,139) in December 1894, and in [[Germany]] (No.&nbsp;86,633) in 1895 and the [[United States]] (No.&nbsp;608,845) in 1898.<ref name="Diesel_1895_2" />

Diesel was attacked and criticised over several years. Critics claimed that Diesel never invented a new motor and that the invention of the diesel engine is fraud. Otto Köhler and {{ill|Emil Capitaine|de}} were two of the most prominent critics of Diesel's time.<ref name="Sass_1962_486" /> Köhler had published an essay in 1887, in which he describes an engine similar to the engine Diesel describes in his 1893 essay. Köhler figured that such an engine could not perform any work.<ref name="Sass_1962_399" /><ref name="Sass_1962_400" /> Emil Capitaine had built a petroleum engine with glow-tube ignition in the early 1890s;<ref name="Sass_1962_412" /> he claimed against his own better judgement that his glow-tube ignition engine worked the same way Diesel's engine did. His claims were unfounded and he lost a patent lawsuit against Diesel.<ref name="Sass_1962_487" /> Other engines, such as the [[Hot-bulb engine|Akroyd engine]] and the [[Brayton engine]], also use an operating cycle that is different from the diesel engine cycle.<ref name="Sass_1962_400" /><ref name="Sass_1962_414" /> [[Friedrich Sass]] says that the diesel engine is Diesel's "very own work" and that any "Diesel myth" is "[[falsification of history]]".<ref name="Sass_1962_518" />