NUMERICAL STUDY ON THE EFFECTS OF CONTROL VALVE LEAKAGE ON CR INJECTOR PERFORMANCE

Abstract

The paper presents the results of numerical investigation of the effects of the control valve leakage on the performance of Common Rail (CR) injector. A numerical model of a CR injector 1-st generation was developed in AVL BOOST Hydsim environment to achieve the research tasks. It is revealed that the control valve leakage has the biggest effect on pressure changing behaviour in the control chamber and, in turn, on the amount of fuel injected per cycle. The amount of fuel injected increases with the increase in the control valve leakage. The effect of the control valve leakage is higher the higher rail pressure and the shorter the duration of fuel injection. Pressure in the control chamber drops dawn to the minimum value earlier after the start of opening the control valve and rises to the maximum value later in the cycle when the control valve closes the outlet orifice as the fuel leakage from the control chamber increases. When the control valve leakage increases, the nozzle needle-valve rises earlier and descends back to the seat later in the cycle.

Keywords: common rail, fuel injector, numerical simulation, ball valve, leakage, diesel engine.