GDI喷油器积碳理化特性和对喷雾特性的影响研究

发布时间：2018-05-27 21:44

本文选题：GDI + 喷油器积碳　；参考：《天津大学》2016年硕士论文

【摘要】：GDI汽车凭借其优越的动力性、燃油经济性和排放性能得到越来越多的普及。但是,相较于PFI汽油机,GDI汽油机直喷喷油器直接暴露于环境恶劣的燃烧室内而存在严重积碳的问题,会影响到在用车发动机的性能。本文针对GDI喷油器积碳问题,开展了喷油器积碳理化特性研究和喷油器积碳对喷雾性能的影响研究,为认识喷油器积碳的本质提供了依据,丰富和发展了喷油器积碳形成机理,为进一步采取措施降低积碳提供理论依据。因此,本文研究具有一定的基础研究意义。本研究开发了一套模拟喷油器积碳形成的装置,借助于SEM、X射线能谱分析、FTIR分别对实车喷油器积碳和模拟喷油器积碳进行理化分析对比。基于纹影法原理搭建了一套喷雾高速摄影台架,分别对清净喷油器、积碳喷油器、清洗后喷油器在喷油压力6MPa、12MPa、15MPa下进行喷雾摄影,然后利用喷雾图像处理软件对喷雾锥角、贯穿距、喷雾投影面积进行对比分析。喷油器积碳理化特性研究结果表明,多孔喷油器喷孔积碳相差较大。对于模拟喷油器积碳,在模拟时间段里内孔积碳呈孤立的颗粒状,外孔积碳沿着喷孔周边铺展开来。实车积碳和模拟积碳X射线光谱趋势具有一致性,前者含有C、O、Na、Mg、Al、Si、P、S、K、Ca、Cr、Mn、Fe、Zn等元素,后者含有C、O、Na、P、S、K、Ca、Fe等元素。FTIR分析结果显示,实车积碳和模拟积碳红外光谱类似,两者都有羟基官能团、伸缩振荡亚甲基官能团、碳氧双键官能团、烯烃类官能团、伸缩振荡甲基官能团、硫化合物官能团,但是各个官能团含量不同。喷油器积碳对喷雾特性的研究结果表明,对于喷雾贯穿距,在喷雾油束惯性力和破碎的综合相互作用下,积碳喷油器喷雾油束有的变长,有的变短,使整个喷雾呈现不对称性特点,积碳喷油器清洗后喷雾油束贯穿距接近清净喷油器,整个喷雾骨架也接近清净喷油器;对于喷雾锥角,积碳喷油器不管在任何喷油压力下,其喷雾锥角都小于清净喷油器喷雾锥角,清洗后喷油器喷雾锥角介于两者之间。积碳喷油器喷雾锥角随喷油压力增加的幅度变化比较小,而清净喷油器在一定喷油压力范围内,喷雾锥角增加幅度随喷油压力增大而增大,超过这个压力范围时,其喷雾锥角增加幅度降低;对于喷雾投影面积,积碳喷油器喷雾投影面积始终小于清净喷油器喷雾投影面积,清洗后喷油器喷雾投影面积非常接近后者。
[Abstract]:With its superior power, fuel economy and emission performance, GDI vehicles are becoming more and more popular. However, compared with the direct injector of PFI gasoline engine, there is a serious problem of carbon deposition, which will affect the performance of in-use engine. Aiming at the problem of carbon deposition in GDI injector, the physical and chemical characteristics of carbon deposition in injector and the effect of carbon deposition on spray performance are studied in this paper, which provides a basis for understanding the essence of carbon deposition in injector, and enriches and develops the formation mechanism of carbon deposition in injector. It provides a theoretical basis for further measures to reduce carbon deposition. Therefore, this study has certain basic research significance. In this paper, a set of apparatus for simulating the formation of carbon deposits in injectors has been developed. The physical and chemical analysis and comparison of carbon deposits in real vehicle injectors and simulated injectors have been carried out by means of SEMX ray energy spectrum analysis and FTIR, respectively. Based on the principle of schlieren method, a set of spray high speed photography bench was set up. The clean injector, the carbon accumulator and the cleaned injector were sprayed under the injection pressure of 6 MPA and 12 MPA, and the spray coning angle was analyzed by using the spray image processing software. The penetration distance and spray projection area were compared and analyzed. The results show that there is a big difference in carbon deposition between the holes of the porous injector. For the simulated fuel injector, the carbon deposits in the internal holes are isolated particles in the simulation period, and the carbon deposits in the outer holes spread along the periphery of the nozzle holes. The results of FTIR and FTIR analysis showed that the infrared spectra of solid carbon deposits and simulated carbon deposits were similar to those of simulated carbon deposits, and both of them had hydroxyl functional groups, and the latter contained elements such as C _ (O) O _ (Na) P _ (+) P _ (+) P _ (+) (K _ (+) K _ (+) Ca _ (Fe) and so on. The results of FTIR analysis showed that the infrared spectra of solid and simulated carbon deposits were similar to those of simulated carbon deposits, and both of them had hydroxyl functional groups, and the latter had hydroxyl functional groups. Telescopic oscillating methylene functional groups, carbon-oxygen double bond functional groups, olefin functional groups, telescopic oscillating methyl functional groups, sulfur functional groups, but the content of each functional group is different. The results of the study on the spray characteristics of the fuel injector show that, for the spray penetration, under the combined interaction of the inertial force and the breakage of the spray fuel beam, the spray fuel beam of the carbon accumulator becomes longer or shorter. The whole spray is asymmetrical. After cleaning, the spray jet penetration distance is close to the clean injector, and the whole spray skeleton is close to the clean injector. For the spray cone angle, no matter under any injection pressure, The spray cone angle of the injector is smaller than that of the clean injector, and the spray cone angle of the injector after cleaning is between the two. The spray cone angle of the carbon injector varies slightly with the increase of the injection pressure, while the increase of the spray cone angle increases with the increase of the injection pressure in a certain range of fuel injection pressure. For the spray projection area, the spray projection area of the carbon accumulator is always smaller than that of the clean injector, and the spray projection area of the injector after cleaning is very close to the latter.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U464.171

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