Patent ID: 6409094
Filing Date: 2002-06-25
Classification: F02M

Abstract:
A fuel injector comprising:a nozzle having formed therein a spray hole from which fuel is sprayed; a nozzle valve selectively opening and closing the spray hole; an injector body supporting therein said nozzle valve slidably, said injector body having formed therein a fuel sump supplied with the fuel from an inlet formed in said injector body to produce fuel pressure urging said nozzle valve in a spray hole-opening direction, a pressure chamber supplied with the fuel from the inlet to produce fuel pressure urging said nozzle valve in a spray hole-closing direction, and a valve hole establishing fluid communication between the pressure chamber and a drain port formed in said injector body; a control valve selectively opening and closing the valve hole formed in said injector body; a first urging mechanism urging said control valve in a valve hole-closing direction for closing the valve hole to block the fluid communication between the pressure chamber and the drain port; a control valve moving mechanism made up of a stationary portion and a movable portion, the stationary portion including a stator and a coil, the movable portion including an armature which is connected fixedly to said control valve and spaced from the stator through a given air gap, the coil being energized electrically to produce an attractive force through the stator for attracting the armature to move said control valve in a valve hole-opening direction, thereby opening the valve hole to establish the fluid communication between the pressure chamber and the drain port; a second urging mechanism urging the stationary portion of said control valve moving mechanism in a first direction identical with the valve hole-opening direction; and an air gap adjusting member disposed around the stationary portion of said control valve moving mechanism in engagement with said injector body so as to urge the stationary portion of said control valve moving mechanism in a second direction opposite the first direction against an urging pressure produced by said second urging mechanism to keep the air gap between the stator and the armature, said air gap adjusting member being designed to be movable selectively in said first direction and second direction for changing the air gap.