Patent ID: 7954729
Filing Date: 2011-06-07
Classification: F02M

Abstract:
1. A metering servovalve for a fuel injector of an internal combustion engine, the metering servovalve comprising: a fixed valve body having a control chamber communicating with an inlet channel and an outlet channel having at least one calibrated restriction; a stem extending along an axis and having a lateral surface, said outlet channel exiting at an opening in said lateral surface; a sleeve coupled to said lateral surface in a substantially fluid-tight manner that allows slidable movement along said axis between a closed position in which a first end portion of said sleeve closes said opening and an open position in which said opening is open, thereby varying pressure in said control chamber; said sleeve comprising an armature at a second end portion of said sleeve that is axially opposite said first end portion and an annular shoulder such that an outer diameter of said second end portion is greater than an outer diameter of said first end portion, said annular shoulder located axially between said first end portion and said armature; an electro-actuator operably coupled to said sleeve to facilitate said slidable movement; and said first end portion having geometric characteristics that allow said first end portion to elastically deform in a radially outward direction under a force of a fuel pressure at said opening to generate an axial unbalancing force on said sleeve in a direction of the open position when said sleeve is in the closed position.