关键结构参数对压电式喷油器喷射特性的影响

Influence of Key Structural Parameters on Fuel Injection Characteristics of Piezoelectric Injectors

利用Matlab/Simulink软件,建立了压电驱动器非线性动力学模型,同时耦合其他机-液部分,建立了完整的压电喷油器电-机-液模型,并试验验证了模型的准确性.系统分析了驱动器预紧力、进/出油孔直径、旁通油孔直径、控制腔容积、控制活塞直径和针阀弹簧预紧力等参数对喷油特性和针阀响应特性的影响,并建立了结构参数灵敏度量化指标,对各部件结构参数进行灵敏度量化分析.结果表明:该喷油器特有的旁通油道可有效地减少针阀关闭延迟,下降时间缩短了0.2 ms,有利于喷油器快速断油;适当增大进/出油孔的孔径比可提高针阀开启速度、缩短针阀下降时间;在各结构参数的许可范围内,针阀控制活塞直径和进/出油孔直径在喷油器喷油量以及针阀响应过程的各个时期影响权重最大,旁通油孔直径和控制腔容积主要影响针阀的回位阶段,喷孔直径对针阀上升和下降过程影响较小,但更大程度上改变了循环喷油量.

A nonlinear dynamic model of piezoelectric actuator was established by using Matlab/Simulink software.Then,a complete piezoelectric injector model was established by coupling other mechanism-liquid parts. The accuracy of the models was verified by a test result. The influences of parameters such as actuator spring preload,inlet/outlet orifice diameters,bypass orifice diameter,control-chamber volume,control-piston diameter,needle spring preload on injection characteristics and needle valve response characteristics were analyzed. An index of structural parameter sensitivity was established. The results show that,the specific bypass orifice can effectively reduce the closing delay of the needle valve,shorten the fall time,and help the injector to quickly cut off the oil. Appropriate increase of the aperture ratio of the inlet and outlet orifice can increase the opening speed of the needle valve and shorten its closing time. The diameter of the control-piston and the inlet and outlet orifice have the most influence on the fuel injection quantity and various stages of the needle valve response process within the allowable range of structural parameters. Diameter of the oil bypass and volume of control-chamber mainly affect the needle valve return stage.The diameter of the injection hole has slight influence on the needle valve rising and falling process,but it changes the circulation injection quantity to a greater extent.