| Abstract from DBPedia | 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 a so-called compression-ignition engine (CI engine). This contrasts with engines using spark plug-ignition of the air-fuel mixture, such as a petrol engine (gasoline engine) or a gas engine (using a gaseous fuel like natural gas or liquefied petroleum gas). Diesel engines work by compressing only air, or air plus residual combustion gases from the exhaust (known as exhaust gas recirculation (EGR)). Air is inducted into the chamber during the intake stroke, and compressed during the compression stroke. This increases the air temperature inside the cylinder to such a high degree that atomised diesel fuel injected into the combustion chamber ignites. With the fuel being injected into the air just before combustion, the dispersion of the fuel is uneven; this is called a heterogeneous air-fuel mixture. The torque a diesel engine produces is controlled by manipulating the air-fuel ratio (λ); instead of throttling the intake air, the diesel engine relies on altering the amount of fuel that is injected, and the air-fuel ratio is usually high. The diesel engine has the highest thermal efficiency (engine efficiency) of any practical internal or external combustion engine due to its very high expansion ratio and inherent lean burn which enables heat dissipation by the excess air. A small efficiency loss is also avoided compared with non-direct-injection gasoline engines since unburned fuel is not present during valve overlap and therefore no fuel goes directly from the intake/injection to the exhaust. Low-speed diesel engines (as used in ships and other applications where overall engine weight is relatively unimportant) can reach effective efficiencies of up to 55%. The combined cycle gas turbine (Brayton and Rankin cycle) is a combustion engine that is more efficient than a diesel engine, but it is, due to its mass and dimensions, unsuited for vehicles, watercraft, or aircraft.The world's largest diesel engines put in service are 14-cylinder, two-stroke marine diesel engines; they produce a peak power of almost 100 MW each. Diesel engines may be designed as either two-stroke or four-stroke cycles. They were originally used as a more efficient replacement for stationary steam engines. Since the 1910s, they have been used in submarines and ships. Use in locomotives, buses, trucks, heavy equipment, agricultural equipment and electricity generation plants followed later. In the 1930s, they slowly began to be used in a few automobiles. Since the 1970s energy crisis, demand for higher fuel efficiency has resulted in most major automakers, at some point, offering diesel-powered models, even in very small cars. According to Konrad Reif (2012), the EU average for diesel cars at the time accounted for half of newly registered cars. However, air pollution emissions are harder to control in diesel engines than in gasoline engines, so the use of diesel auto engines in the U.S. is now largely relegated to larger on-road and off-road vehicles, Though aviation has traditionally avoided diesel engines, aircraft diesel engines have become increasingly available in the 21st Century. Since the late 1990s, for various reasons -- including the diesel's normal advantages over gasoline engines, but also for recent issues peculiar to aviation -- development and production of diesel engines for aircraft has surged, with over 5000 such engines delivered worldwide between 2002 and 2018, particularly for light airplanes and unmanned aerial vehicles.ディーゼルエンジン（英: Diesel engine）は、ディーゼル機関とも呼ばれる内燃機関であり、ドイツの技術者ルドルフ・ディーゼルが発明した往復ピストンエンジン（レシプロエンジン）である。1892年に発明され、1893年2月23日に特許が取得された。 ディーゼルエンジンは点火方法が圧縮着火である「圧縮着火機関」に分類され、ピストンによって圧縮加熱した空気に液体燃料を噴射することで着火させる。液体燃料は発火点を超えた圧縮空気内に噴射されるため自己発火する。 実用化された単体の熱機関としては最も効率に優れる種類のエンジンであり、また軽油・重油などの石油系の他にも、発火点が225 ℃程度の液体燃料であればスクワレン、エステル系など広範囲に使用可能である。汎用性が高く、小型高速機関から巨大な船舶用低速機関までさまざまなバリエーションが存在する。 エンジンの名称は発明者にちなむ。日本語表記では一般的な「ディーゼル」のほか、かつては「ヂーゼル」「ジーゼル」「デイゼル」とも表記された。日本の自動車整備士国家試験ではジーゼルエンジンと表記している。 (Source: http://dbpedia.org/resource/Diesel_engine) |
