Decoupling Analysis on Pressure Fluctuation and Needle Valve Response for High Pressure Common Rail Injector

In the process of multiple injections, the influence of different injections makes the controlling of cycle fuel injection quantity more difficult. The high pressure common rail (HPCR) simulation model is established in AMESim environment. Through the method of combining numerical simulation and experiment test, it is found that the strong coupling of pressure fluctuation and needle valve response is the fundamental reason, which leads to the fluctuation of main injection fuel quantity (MIFQ) with dwell time (DT). The result shows that the largest fluctuation quantity is 3.6mm3 when the reference value of main injection is 60.0mm3. Non-damping LC hydraulic system model is also established. Through the analysis of the model, reducing the length-diameter ratio of internal oil duct and the delivery chamber volume are decoupling methods to the strong coupling.