Step actuator

1. A step actuator comprising:

a housing;

a stator in the housing;

a rotor including a magnet provided radially inward of the stator and a nut member inserted into the magnet and protruding through one side of the housing;

a bearing rotatably supporting the nut member;

a screw member coupled with the nut member to linearly move as the rotor rotates; and

a mounting member supported on one side of the housing to support the screw member in such a manner that the screw member is linearly movable,

wherein the nut member includes an end portion passing through the bearing and a coupling portion extending from the end portion to couple with the bearing, and

wherein the end portion of the nut member has an outer circumferential surface coupled with an inner circumferential surface of an inner race of the bearing, and the coupling portion is coupled with a lateral surface of the inner race of the bearing.

2. The step actuator of claim 1 , wherein the coupling portion includes a bearing coupling portion which is coupled with the bearing and formed by performing a swaging process with respect to the end portion of the nut member after applying heat or an ultrasonic wave to the end portion of the nut member.

3. The step actuator of claim 1 , wherein the coupling portion includes a hook portion formed in the end portion of the nut member.

4. The step actuator of claim 3 , further comprising an elastic member interposed in at least one of: a position between the hook portion and the bearing, a position between the bearing and the magnet, and a position between the magnet and the nut member.

5. A step actuator comprising:

a housing;

a stator in the housing;

a magnet provided radially inward of the stator;

a nut member inserted into the magnet and protruding through one side of the housing;

a bearing rotatably supporting the nut member;

a coupling member coupled with the nut member while interposing the bearing therebetween;

a screw member coupled with the nut member to linearly move as the nut member rotates; and

a mounting member supported on one side of the housing to support the screw member in such a manner that the screw member is linearly movable.

6. The step actuator of claim 5 , wherein the nut member includes an end portion passing through the bearing and a coupling groove formed in the end portion, and the coupling member is coupled with the coupling groove while making contact with an inner race of the bearing.

7. The step actuator of claim 6 , wherein the coupling member includes a snap ring fitted into the coupling groove.

8. The step actuator of claim 6 , wherein the coupling member includes a bush coupled with the coupling groove and fixed to the coupling groove through a caulking process.

9. The step actuator of claim 5 , further comprising an elastic member interposed in at least one of a position between the coupling member and the bearing, a position between the bearing and the magnet, and a position between the magnet and the nut member.

10. The step actuator of claim 5 , wherein the coupling member includes a nut member stopper inserted into the nut member while making contact with an inner race of the bearing.

11. A step actuator comprising:

a housing;

a stator in the housing;

a rotor including a magnet provided radially inward of the stator and a nut member inserted into the magnet and protruding through one side of the housing;

a bearing provided outside the housing to rotatably support the nut member;

a bearing cover coupled with the housing to support the bearing;

a screw member coupled with the nut member to linearly move as the rotor rotates; and

a mounting member coupled with the bearing cover to support the screw member in such a manner that the screw member is linearly movable.

12. The step actuator of claim 11 , wherein the nut member includes a coupling portion coupled with the bearing.

13. The step actuator of claim 12 , wherein the coupling portion overlaps with the bearing in a direction parallel to an axial direction of the screw member.

14. The step actuator of claim 11 , wherein the bearing has an outer race coupled with the bearing cover and an inner race coupled with the nut member.