Electronic actuator for fan clutch

An electronic actuator for a fan clutch, the electronic actuator comprising:

• a shaft rotated by a rotational force transferred from an engine crankshaft;
• an armature plate positioned over the shaft, the armature plate having a through hole in a middle portion thereof;
• a bobbin disposed to surround a middle portion of the shaft, the bobbin being provided with a coil wound therein;
• a nut formed of a magnetic material and disposed to surround one longitudinal side of the shaft, the nut screwed to a clutch;
• an upper bushing formed of a nonmagnetic material and press-fit between the one longitudinal side of the shaft and the nut, the upper bushing integrally connecting the shaft to the nut;
• a housing formed of a magnetic material and provided with a bottom plate and a side wall to surround the other longitudinal side of the shaft, the side wall extending to partially overlap the nut;
• a bearing mounted on an outer peripheral surface of the other longitudinal side of the shaft positioned inside the housing, the bearing positioned inside the housing;
• a lower bushing formed of a nonmagnetic material and press-fit into, and fully filling, a space surrounded by the bearing, the housing, and the bobbin, the lower bushing integrally connecting the bearing to the housing,
• wherein the lower bushing has a first internal projecting edge, a second internal projecting edge, and a seating groove between the first internal projecting edge and the second internal projecting edge, wherein at least part of the bearing fits into the seating groove with the first internal projecting edge and the second internal projecting edge, respectively, positioned over and under the part of the bearing, wherein the bobbin filled with the coil is disposed to surround a whole outer peripheral surface of the shaft exposed between the upper bushing and the bearing which are positioned inside the housing to allow magnetic field lines generated from the coil to form a loop passing along the upper bushing, the shaft, the bearing, and the housing.