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Homogeneous charge compression ignition (HCCI) is a form of internal combustion in which well-mixed fuel and oxidizer (typically air) are compressed to the point of auto-ignition. As in other forms of combustion, this exothermic reaction releases chemical energy into a sensible form that can be transformed in an engine into work and heat. HCCI combines characteristics of conventional gasoline engine and diesel engines. Gasoline engines combine ''homogeneous charge'' (HC) with ''spark ignition'' (SI), abbreviated as HCSI. Diesel engines combine ''stratified charge'' (SC) with ''compression ignition'' (CI), abbreviated as SCCI. As in HCSI, HCCI injects fuel during the intake stroke. However, rather than using an electric discharge (spark) to ignite a portion of the mixture, HCCI raises density and temperature by compression until the entire mixture reacts spontaneously. Stratified charge compression ignition also relies on temperature and density increase resulting from compression. However, it injects fuel later, during the compression stroke. Combustion occurs at the boundary of the fuel and air, producing higher emissions, but allowing a leaner and higher compression burn, producing greater efficiency. Controlling HCCI requires microprocessor control and physical understanding of the ignition process. HCCI designs achieve gasoline engine-like emissions with diesel engine-like efficiency. HCCI engines achieve extremely low levels of Nitrogen oxide emissions () without a catalytic converter. Unburned hydrocarbon and carbon monoxide emissions still require treatment to meet automotive emission regulations. Recent research has shown that the hybrid fuels combining different reactivities (such as gasoline and diesel) can help in controlling HCCI ignition and burn rates. RCCI or Reactivity Controlled Compression Ignition has been demonstrated to provide highly efficient, low emissions operation over wide load and speed ranges.〔(【引用サイトリンク】title=College of Engineering @ The University of Wisconsin-Madison, initiatives in energy, health, nanotechnology, security, and information technology )〕 == History == HCCI engines have a long history, even though HCCI has not been as widely implemented as spark ignition or diesel injection. It is essentially an Otto combustion cycle. HCCI was popular before electronic spark ignition was used. One example is the hot-bulb engine which used a hot vaporization chamber to help mix fuel with air. The extra heat combined with compression induced the conditions for combustion. Another example is the "diesel" model aircraft engine. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Homogeneous charge compression ignition」の詳細全文を読む スポンサード リンク
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