柴油机电控喷油器关键匹配技术研究

发布时间：2019-05-19 17:22

【摘要】：燃油喷射系统对柴油机的动力性、经济性、排放性和NVH具有十分重要的影响。作为燃油系统的核心部件,电控喷油器的结构与性能参数选择对喷油过程、喷雾质量、以及混合气的形成和燃烧有重要的影响。本文基于生产实践中高压共轨系统电控喷油器匹配的技术需求展开研究,旨在使电控喷油器的选型评估更加全面、细致,使电控喷油器的匹配更加高效、精确。对结构尺寸相同,由不同厂家加工的两组喷油器进行测试,两组喷油器的组内喷油器间油量差异区别较大。发动机外特性试验结果表明两组喷油器油量特征差异导致了发动机性能的不同。负荷特性试验结果表明发动机采用厂家1喷油器时的油耗低于采用厂家2喷油器时的油耗,该优势在小负荷区域更加明显。在大部分外特性工况点采用厂家2喷油器时的烟度值均高于采用厂家1喷油器时的烟度值。针对四种不同的电控喷油器,在不同轨压、不同加电时间下测量了喷油持续期,分析了喷油持续期与加电时间之差,得出相同工况下、不同喷油器的喷油持续期和加电时间之差差别不大,并对四种喷油持续期做了平均。采用基于最小二乘法的曲面拟合方法对平均后的喷油持续器进行拟合,得到喷油持续期关于轨压和加电时间的表达式,结果表明:93.9%的喷油持续期试验数据点同拟合结果的差异在±120?s的范围内。采用理论计算评估燃油喷射功耗,将燃油喷射功耗分为雾化功耗和压力损失功耗,对影响计算精度的喷孔流量系数做了深入分析。对静态泄漏功耗进行了理论和试验分析,结果表明理论结果与试验结果在重点关注的高轨压区域保持了很好的一致性。采用理论结合试验的方法评估液力控制功耗和电力驱动功耗。对某柴油机大扭矩点和额定点喷油器功耗的评估显示用于雾化功耗约占总功耗的40%,通过喷油器结构优化可以使发动机油耗降低的幅度小于1.0g/(kWh)。通过试验研究了电控喷油器多次喷射油量特征,结果表明燃油压力波动导致了两次喷射模式下第二次喷射油量随两次喷射间隔的变化。每个轨压下都存在多次喷射油量偏差幅度最大的情况,最大接近±50%。绝对油量偏差幅度随第二次喷射标准油量和轨压的增大而增大;相对偏差范围随第二次喷射标准油量的增大而减小。喷油器入口处压力波动与第二次喷射油量随两次喷射间隔变化的周期相同。结构尺寸不同的两种喷油器的第二次喷射油量偏差幅度差异较大。
[Abstract]:Fuel injection system has a very important influence on the power, economy, emission and NVH of diesel engine. As the core component of the fuel system, the structure and performance parameters of the electronic control injector have an important influence on the injection process, spray quality, and the formation and combustion of the mixture. In this paper, based on the technical requirements of electronic control injector matching in high pressure common rail system, the purpose of this paper is to make the selection and evaluation of electronic control injector more comprehensive and detailed, and to make the matching of electronic control injector more efficient and accurate. The two groups of injectors processed by different manufacturers are tested for the same structure size, and the oil quantity difference between the two groups of injectors is quite different. The results of engine external characteristic test show that the difference of fuel quantity characteristics between the two groups of injectors leads to the difference of engine performance. The results of load characteristic test show that the fuel consumption of the engine with manufacturer 1 injector is lower than that when manufacturer 2 injector is used, and the advantage is more obvious in the low load area. When the manufacturer 2 injector is used in most of the external characteristic working conditions, the smoke value is higher than that when the manufacturer 1 injector is used. According to four different kinds of electronic control injectors, the injection duration is measured under different rail pressure and different power-up time, the difference between injection duration and power-up time is analyzed, and the same working conditions are obtained. There is no significant difference between the injection duration and the charging time of different injectors, and the four injection duration are averaged. The surface fitting method based on the least square method is used to fit the average fuel injector, and the expressions of the fuel injection duration about rail pressure and power up time are obtained. The results show that the difference between 93.9% of the fuel injection duration test data points and the fitting results is in the range of 卤120 鈮，

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