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提出了1种氮氧化物(NOx)储存和还原(NSR)功能的切换控制策略,该控制策略是将传统的浓燃去除NOx转化为通过吸附中间还原物的柴油机NOx后处理方式(DiAir),介绍了在除硫过程中采用碳氢喷射器(HCI)的额外好处。瞬态循环下的试验研究显示,采用DiAir时的NOx转化性能主要受NSR催化器中NOx初始储存状态的影响。为避免在DiAir方式中,碳氢喷射开始后出现NOx临界值,采用浓燃还原储存的NOx尤为重要,在瞬态循环下采用这种控制策略可以达到较高的NOx转化性能。另外,将HCI和缸内后喷相结合,可使NSR除氧化硫(SOx)的浓燃状态扩展到更宽广的发动机转速和负荷范围。由于在高温条件下采用DiAir(包括柴油机颗粒捕集器的再生)时的NOx转化效率较高,在低负荷行驶工况下的NOx储存功能和除SOx过程中碳氢喷射的有益作用,显示了该控制策略在实际行驶工况下降低NOx排放的潜力。
A switching control strategy for nitrogen oxide (NOx) storage and reduction (NSR) function is proposed. The control strategy is to convert the traditional rich combustion NOx removal into diesel NOx after-treatment (DiAir) through adsorption of intermediate reductant, Describes the additional benefits of using a hydrocarbon injector (HCI) during sulfur removal. Experimental studies under transient cycling show that the NOx conversion performance with DiAir is primarily affected by the initial storage of NOx in the NSR catalyst. In order to avoid the occurrence of NOx threshold after the start of hydrocarbon injection in the DiAir process, it is particularly important to reduce the stored NOx with rich fuel. This control strategy can achieve higher NOx conversion performance under transient conditions. In addition, the combination of HCI and in-cylinder post injection expands the rich state of the NSR in addition to sulfur dioxide (SOx) to a broader engine speed and load range. The NOx storage efficiency at low load conditions and the beneficial effect of hydrocarbon injection in addition to the SOx process are shown due to the higher NOx conversion efficiency at high temperature conditions with DiAir (including regeneration of diesel particulate traps) The control strategy reduces the potential of NOx emissions under actual driving conditions.