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在过去的1～2年中,全球开展了进一步控制柴油车辆排放的运动。关于重型车辆,欧盟在1999年后期提出了在2008年前分阶段实施欧3、欧4、欧5排放标准的要求。预计要达到这些标准需要引入先进的PM和NO_x控制。美国环保局(EPA)已经通过了将在2007年实施的更为严格的排放标准,同时要求采用含硫量(<15ppm)很低的柴油。日本正在进行一项严格的复审程序,可能在2005年前要求燃油的含硫量至少降到50ppm,并提出相当低的PM要求。他们还在实施一项重大的柴油机改进计划。关于轻型车辆,加州大气资源局(CARB)已原则上确定柴油车辆应采用与汽油车辆相同的标准,而美国EPA也仿照提出了阶段2(Tier2)计划。本文将阐述在这些方面所做的工作。
Over the past 1-2 years, there has been a worldwide campaign to further control the emission of diesel vehicles. With regard to heavy vehicles, the EU proposed in late 1999 the phased implementation of Euro 3, Euro 4 and Euro 5 emission standards by 2008. It is expected that achieving these standards requires the introduction of advanced PM and NO_x control. The US Environmental Protection Agency (EPA) has passed tighter emission standards to be implemented in 2007, while requiring diesel fuel with very low sulfur content (<15ppm). Japan is conducting a rigorous reexamination process that may require the sulfur content of fuel to be reduced to at least 50ppm by 2005 and place rather low PM requirements. They are also implementing a major diesel improvement program. Regarding light vehicles, CARB has determined, in principle, that diesel vehicles should use the same standards as gasoline vehicles, and the U.S. EPA has also modeled the Tier 2 plan. This article explains the work done in these areas.