Patent ID: 6880417

Claim:
An electric actuator comprising: a frame; a rotary driving source which is disposed inside or outside said frame; a feed screw shaft which is connected to a drive shaft of said rotary driving source for receiving rotary driving force from said rotary driving source; a displacement mechanism which is engaged with said feed screw shaft, which converts rotary motion of said feed screw shaft into rectilinear motion, and which is displaceable in an axial direction of said feed screw shaft; and a spline guide mechanism which is connected to said displacement mechanism, which guides said displacement mechanism in said axial direction of said feed screw shaft, an which absorbs loads applied to said displacement mechanism in a substantially vertical direction, in a circumferential direction about a center of an axis of said feed screw shaft, in a circumferential direction about a center of a horizontal line substantially perpendicular to said axis of said feed screw shaft, in a circumferential direction about a center of a vertical line substantially perpendicular to said axis of said feed screw shaft, and in a direction obtained by compositively combining said directions, wherein said spline guide mechanism includes a splined bore which has a plurality of adjacent splines provided in a longitudinal direction formed over an entire inner wall circumferential surface of said frame, and a pair of spline pistons each of which has a plurality of adjacent spline teeth, formed over an entire outer circumferential surface, to be fitted to said splined bore.