Patent ID: 7509946
Filing Date: 2009-03-31
Classification: F02D,F02M

Abstract:
1. A method for controlling the voltage across a direct acting piezoelectric fuel injector in accordance with a voltage or charge vs. time waveform that defines: (a) a first gradient during a first portion of a fuel injection cycle that extends from a time at which a nozzle of the injector is fully closed to a time at which the nozzle is partially open; and (b) a second gradient during a second portion of the fuel injection cycle that extends from a time at which the nozzle is partially open to a time at which the nozzle is fully open; wherein: (i) the magnitude of the first gradient is greater than the magnitude of the second gradient; (ii) the first portion of the injection cycle terminates at a predetermined voltage point; and the predetermined voltage point is the point at which the voltage across the injector is less than or equal to that required to cause the injector to switch to a hydraulic lift amplification mode.