Fig. 21. Magnetic force: comparison of the standard and pressure-balanced pilot-valve.Figure optionsDownload full-size imageDownload as PowerPoint slide
A detailed analysis of the new generation of solenoid injectors equipped with pressure-balanced pilot-valves has been performed. An integrated numerical-experimental approach has been proposed to examine both the mechanical and hydraulic performance of the innovative pilot-valve setup.
As far as the mechanical performance AC 264613 concerned, a ring contact surface exists, between the armature and the valve seat, on which the fuel pressure acts and tends to open the pressure balanced pilot-valve. The reduction in radial thickness s of this surface has been proved to decrease the NCD, as a direct consequence of the variation in the needle lift peak value. The main result of the analysis is that s should be reduced as much as possible, in a correct injector design, in order to improve both needle dynamics and pilot-valve static leakages.