扭矩储备系数对非道路直喷式柴油机排放性能的影响

Effects of Torque Backup on Exhaust Emissions from an Off-Road Direct Injection Diesel Engine

以一台非道路直喷式柴油机为样机,研究了扭矩储备系数φtq和供油提前角对其排放和经济性能的影响。排放试验参照欧盟非道路柴油机八工况法,测取了该机PM、NOx、HC、CO排放量和油耗等参数。根据该机的工作需求,对φtq为18％和20％时不同供油提前角下的性能进行了研究。结果表明。该机在φtq为18％,供油提前角为12℃A时的排放完全满足欧-II排放标准;φtq为20％时,PM和NOx排放不能同时满足欧-II排放标准。φtq由18％增加到20％后,PM排放量有较大幅度的上升,并且对供油提前角的变化变得敏感,CO有所上升, NOx有所下降,对HC排放影响最小。随着供油提前角的增加,该机PM和CO排放量显著下降,NOx排放上升明显,HC排放变化幅度不大,油耗下降,φtq为18％、供油提前角为12．5℃A时的油耗最低为218．1 g／(kW·h)。

The effects of torque backup φtq and injection timing on regulated exhaust emissions of an off-road diesel engine was studied. According to the EU Directive 97/68/EC and ISO 8178-C1 eight-mode test cycle, concentrations of the four regulated emissions, particulate matter （PM）, NOx, HC. CO and SFC of the diesel engine were measured. The results show that the four emissions concentrations completely meet Euro-Ⅱ standard when φtq is 0.18 and the fuel suppy advance angle is 12°CA, but the PM and NOx could not meet Euro- Ⅱ standard simultaneously when φtq is 0.20. The concentration of PM emissions rises remarkably with φtq increase from 0.18 to 0.20, and varies rapidly with the fuel supply advance angle changing when φtq is 0.20. The concentrations of PM emissions decrease with the increase in the torque backup, the CO has some decrease, and the NOx and HC vary slightly. The concentrations of PM and CO decrease markedly with the advanced fuel supply advance angle increasing, the NOx increase observably, and the HC have a little change. The lowest SFC of 218. 1 g/（kW-h） occurs when φtq is 0.18 and fuel supply advance angle is 12.5 °CA.