面向可调喷油速率的超高压共轨系统建模及仿真分析

Modeling and simulation analysis of ultra high pressure common rail system for adjustable fuel injection rate

针对常规高压共轨系统在喷射过程内喷油压力较低、无法灵活实现喷油速率改变等问题,提出并设计了立足国内加工能力和技术工艺的面向可调喷油速率的超高压共轨系统。在介绍其工作原理的基础上,基于AMEsim软件建立了系统的仿真模型,并利用试验验证了模型的准确性;通过模型研究了系统的压力特性和喷油控制特性,同时分析了电控增压器的关键结构参数对系统性能的影响规律。结果表明:面向可调喷油速率的超高压共轨系统可以将燃油压力放大至超高压状态,并且通过改变系统内电控增压器和喷油器各自电磁阀的控制信号作用时间,能够实现灵活可控的喷油速率曲线形状。相比于控制室容积和阀芯质量,出油孔直径和阀芯位移对系统性能的影响较大,随着出油孔直径和阀芯位移的增加,增压室压力和喷油速率峰值增大,而燃油泄漏率先上升后下降。

Aiming at the problems of low fuel injection pressure and inability to flexibly change the fuel injection rate in the injection process of conventional high pressure common rail system,an ultra high pressure common rail system for adjustable fuel injection rate based on domestic processing capacity and technology was proposed and designed.On the basis of introducing the working principle of this system,the simulation model of system was established via AMEsim software,the accuracy of this model was verified by experiment,and the pressure characteristics and fuel injection control characteristics of the system were studied through the model.A at the same time,the influence of the key structural parameters of the electric-controlled pressure amplifier on the system performance were analyzed.Results show that the ultra high pressure common rail system for adjustable fuel injection rate can magnify fuel pressure to the ultra high pressure state,and by changing the control signal working time of electric-controlled pressure amplifier and injector solenoid valve in system,the flexible and controllable fuel injection rate curve shape can be achieved.Compared with the control chamber volume and spool mass,the fuel outlet diameter and spool displacement have greater influence on the performance of this system,with the increase of fuel outlet diameter and spool displacement,the pressurization pressure and fuel injection rate peak value both increase,while the fuel leakage rate increases first and then decreases.