Inhibition of pressure fluctuation and multi-injection fuel mass deviation in high pressure common rail system

Pressure fluctuation in high pressure common rail has great influence on injection quantity deviation of multiple injections. To eliminate the pressure fluctuation at the inlet of the injector, a new damping filter with damping hole and vessel to inhibit pressure fluctuation is studied. Through the uniform design method, it is found that the amplitude of pressure fluctuation is the minimum when the damping hole diameter is 0.4 mm and volume of the cavity is 1720 mm³. Based on this, experiments are conducted to verify the filter performance under different rail pressure and control strategy of multi-injection. Results show that, when the common rail pressures are 40, 60 and 100 MPa, respectively, the filter can decrease the amplitude of pressure fluctuation by 51% to 54% under single injection with a pulse width of 0.4 ms. In pre-injection mode, the filter can decrease the fluctuation amplitude of fuel injection quantity by 62.4% to 715. In main-post mode, accordingly, it can be reduced by 86% to 86.3%. Therefore, the filter can suppress fuel quantity deviation and provide reference to optimize the control precision of the common rail fuel injection system.