| 主权项 |
1. An electric actuator comprising:
an operation member that is a bar-like member, and that has a first helical groove on its outer peripheral surface on one end; a rotor that is a cylindrical member having a hollow portion into which the operation member is arranged, the hollow portion having a second helical groove, corresponding to the first groove, on a part of its inner peripheral surface, and an opening from which the other end of the operation member projects from the hollow portion; plural balls arranged between the first groove and the second groove; a circulating member mounted to the rotor for circulating the balls; a stator that is arranged at the outside of the rotor in the diameter direction and that rotates the rotor about an axis of the rotor in order to move the operation member in the direction of the axis; and a rotation preventing member that is engaged with a part of the operation member for preventing the rotation of the operation member about the axis, wherein a direction of a load in the direction of the axis is the same on the portion of the operation member where the first groove is formed and on the portion of the rotor where the second groove is formed, the operation member has a cylindrical screw shaft, having the first groove on its outer peripheral surface, on the outer periphery on one end, the screw shaft is mounted on one end of the operation member, the rotor is mounted such that the portion where the opening is formed is supported to be rotatable to a housing, to which the stator is mounted, via a rolling bearing, an input position of a load to the screw shaft is arranged on a position apart from the rolling bearing from a center of a region where the plural balls are arranged in the direction of the axis, and the load input position of the screw shaft and the load operation position of the rolling bearing are on both sides of the region where the plural balls are arranged. |
