Investigation On Injection Characteristics Of Electronic Control Injector With Micro Dynamic Leakage

With the continuous improvement of fuel injection pressure of marine high-power diesel engine's fuel system,fuel leakage of the traditional electronic fuel injector is rising gradually,which leading to the reduction of the hydraulic efficiency and limitation of fuel injection pressure's further improvement.The current international advanced electronic control injectors can achieve zero static leakage,while the dynamic leakage in the process of transient state control of injector is still considerable.Especially the large flow injector has lower hydraulic efficiency,which consequently limits further enhancement of fuel injection pressure.This paper designed an electronic control injector with micro dynamic leakage,the influence law of different parameters on it's fuel injection characteristics were analyzed,optimizing its performance and researching on its fuel injection characteristics provide theoretical guidance and engineering applications value for the self-design and development of fuel injector.Firstly,the conceptual design of micro dynamic leakage electronic control injector was carried out.Numerical simulation model was established in AMESim environment,electromagnetic force calculation model was established in Ansoft Maxwell finite element simulation software,and the modeling methods were calibrated by comparing and analyzing the relevant data,it showed that the modeling method is accurate and reliable,and the model established can meet performance requirements of high-power diesel engine.Next,the influential factors of micro dynamic leakage electronic control injector's fuel injection characteristics was studied.The influence laws along with generation mechanism of needle valve response characteristics and cycle fuel injection quantity caused by variations of different structural parameters such as accumulator cavity,flow-limiting valve,high speed solenoid valve,micro dynamic leakage module and nozzle were analyzed thoroughly by single-factor analysis method,and the reference design values of parameters are obtained roughly.Then parameters having distinct influence on the response characteristics and cycle fuel injection quantity were obtained by quantitative analysis method,and come to the conclusion that the structure parameters such as nozzle diameter,needle valve diameter,inlet and outlet throttle orifice diameter are important factors affect the fuel injection characteristics.Finally,fuel injection characteristics of micro dynamic leakage electronic control injector were investigated.Multi-objective optimization of fuel return quantity and response characteristics was carried out,after optimizing,the opening response time of the new injector can be decreased by 7.58%,the closing response time of the needle can be decreased by 18.11%,and fuel return quantity of single injection can be decreased by 12.69%.Besides,hydraulic efficiency of micro dynamic leakage electronic control injector under overall working conditions were analyzed,the change regulation of hydraulic efficiency with control pulse width and rail pressure were obtained.Meanwhile,fluctuation characteristic of multiple injection fuel injection quantity was researched,the main influence factors of fuel injection quantity fluctuation in multiple injection processes were revealed,it showed that the pressure wave caused by pilot injection in the fuel tank is the fundamental reason what leads to fluctuation of main injection quantity.