KR20100041622A - Step actuator - Google Patents

Abstract

PURPOSE: A step actuator is provided to reduce the frictional force which is generated between a bobbin, a magnet and a nut unit by forming a concave part which is recessed to a pre-set direction in a bobbin. CONSTITUTION: A stator is installed in housings(110, 120). A rotor is arranged in the inner side of the stator and includes a magnet and a nut unit, which is inserted in the magnet. The rotor rotates by interacting with the stator. A screw unit is combined to the rotor. A mounting unit(60) is supported by the housings. The screw unit linearly moves along the rotation direction of the rotor.

Description

Step Actuator {STEP ACTUATOR}

The present invention relates to a step actuator.

The step actuator has a rotor and a stator, and linearly drives an axis according to the rotation of the rotor.

For example, a step actuator may be connected to a member for driving a reflector of an automotive headlight system and used to change the lighting direction. In addition, the step actuator can be applied to a variety of electrical and mechanical devices that require linear motion by converting the rotational motion of the rotor into linear motion.

The embodiment provides a step actuator of the novel structure.

The embodiment provides a step actuator comprising a rotor of the novel structure.

The embodiment provides a step actuator with reduced friction between the rotor and the bearing.

The step actuator according to the embodiment includes a housing; A stator disposed inside the housing; A rotor disposed radially inward of the stator and rotating in interaction with the stator; A screw member coupled to the rotor and moving linearly in accordance with the rotation direction of the rotor; And a mounting member supported by the housing and supporting the screw member so as to be linearly movable, wherein the rotor is inserted into and coupled to the magnet disposed radially inward of the stator and coupled to the housing. It includes a nut member protruding through.

Embodiments can provide a step actuator of a novel structure.

Embodiments can provide a step actuator comprising a rotor of a novel structure.

Embodiments can provide a step actuator with reduced friction between the rotor and the bearing.

Hereinafter, a step actuator according to an embodiment will be described in detail with reference to the accompanying drawings.

In the drawings, the thickness or size of each component is exaggerated, omitted, or schematically illustrated for convenience and clarity of description. In addition, the size of each component does not necessarily reflect the actual size.

1 is a perspective view of a step actuator according to an embodiment, FIG. 2 is a cross-sectional view of a step actuator according to an embodiment, and FIGS. 3 and 4 are exploded perspective views of a step actuator according to an embodiment.

1 to 4, the step actuator according to the embodiment includes a stator, a rotor that is rotated by interaction with the stator, and the rotor is coupled to the rotor to rotate forward and reverse. And a screw member 10 which is linearly reciprocated in the first and second directions as it is rotated.

The stator includes first and second bobbins 130 and 140 and first and second yokes 150 and 160 disposed between the first housing 110 and the second housing 120.

The rotor includes a magnet 30 disposed inside the stator and rotated by interacting with the stator, and a nut member 20 coupled to the magnet 30.

The screw member 10 and the nut member 20 are coupled in a bolt and nut relationship. Therefore, when the nut member 20 is rotated, the screw member 10 is linearly moved.

In more detail, the first bobbin 130 and the second bobbin 140 are disposed in an internal space between the first housing 110 and the second housing 120, and the first bobbin 130 is disposed. ) And the first yoke 150 and the second yoke 160 are disposed between the second bobbin 140 and the second bobbin 140.

In addition, the magnet 30, the nut member 20, and the screw member 10 are disposed in the circumferential directions of the first bobbin 130 and the second bobbin 140.

In addition, a bearing 40, a bearing cover 50, and a mounting member 60 are disposed at one side of the second housing 120.

In more detail, the screw member 10 is linear in a first direction along an axial direction of the screw member 10 and in a second direction opposite to the first direction as the step actuator according to the embodiment is operated. Do a reciprocating motion.

In addition, the screw member 10 is supported by the first direction side is inserted into the protrusion tube 132 of the first bobbin 130 and the second direction side penetrates the protrusion 61 of the mounting member 60. Is supported. A joint 70 is coupled to the second directional end of the screw member 10.

A thread 11 is formed on the first outer side surface of the screw member 10, and a stopper 12 is formed between the screw 11 and the end portion of the second direction side.

The thread 11 of the screw member 10 is coupled to the thread 21 formed on the inner circumferential surface of the nut member 20. Thus, as the nut member 20 is rotated, the screw member 10 is moved in the first direction and the second direction.

The stopper 12 limits the range of movement of the screw member 10 in the second direction. As the screw member 10 is moved in the second direction, the stopper 12 is caught by the protrusion 61 of the mounting member 60 so that the screw member 10 is no longer moved in the second direction. . In addition, a blocking part 133 is formed at an end of the first direction side of the protruding tube 132 of the first bobbin 130 to limit the movement range of the screw member 10 in the first direction.

Limiting the range of movement of the screw member 10 in the second direction is the diameter of the through-hole 62 of the protrusion 61 formed in the mounting member 60 screw thread 11 of the screw member 10 It may be achieved by forming small so that it does not pass, and likewise limiting the range of movement in the first direction of the screw member 10 is the diameter of the end of the first direction side of the protruding pipe 132 the screw member It may be achieved by forming small so that the thread 11 of (10) does not pass. Therefore, the blocking part 133 and the stopper 12 may be selectively formed according to the design.

On the other hand, as described above, the screw member 10 is installed to be linearly movable in the first direction and the second direction through the mounting member 60, it is limited to rotate about the axis. That is, the screw member 10 is limited to the rotation by the protrusion 61 of the mounting member 60.

For example, the second direction side of the screw member 10 is formed by cutting in a D-shape, the through hole 62 of the mounting member 60 and the second direction side cross section of the screw member 10 and the It may be formed in a corresponding shape.

Therefore, since the screw member 10 cannot be rotated, the screw member 10 is linearly moved in the first direction and the second direction when the nut member 20 coupled to the screw member 10 is rotated. do.

The nut member 20 is inserted into and coupled to the magnet 30 and a second direction side end portion 22 protrudes in the second direction through the magnet 30. The outer peripheral surface of the nut member 20 is formed with a protrusion 23 extending in the axial direction, the groove 31 of the shape corresponding to the protrusion 23 is coupled to the magnet 30 formed on the inner peripheral surface.

The nut member 20 and the magnet 30 are partially overlapped in the circumferential direction by the protrusion 23 and the groove 31, and are alternately arranged. Therefore, the force acting in the circumferential direction by the rotation of the magnet 30 is transmitted to the nut member 20 and the nut member 20 is rotated together as the magnet 30 is rotated.

For example, the protrusion 23 and the groove 31 may be formed in a curved surface, in which case the groove 31 of the magnet 30 may be more easily processed.

The second directional end 22 of the nut member 20 is engaged with the inner ring of the bearing 40. Thus, the nut member 20 may be freely rotated while being supported by the bearing 40.

In addition, the nut member 20 has a screw thread 21 formed on the inner circumferential surface of the central portion thereof and is coupled to the screw thread 11 of the screw member 10. In addition, the nut member 20 is rotatably supported by the inner circumferential surface of the first direction is coupled to the protruding tube 132 of the first bobbin 130. That is, the first direction side inner circumferential surface of the nut member 20 is in contact with and supported by the outer circumferential surface of the protruding tube 132.

The magnet 30 may be formed of a permanent magnet in which the N side and the S pole are alternately magnetized at equal intervals in the circumferential direction. As described above, the nut member 20 is inserted into and coupled to the magnet 30, so that the nut member 20 also rotates as the magnet 30 is rotated.

Meanwhile, the second direction side end portion 32 of the magnet 30 may protrude in a second direction to contact the inner ring of the bearing 40. The magnet 30 may rotate smoothly without contact with the outer ring of the bearing 40 by the second direction side end 32 of the magnet 30.

The first bobbin 130 on which the first coil 131 is wound and the second bobbin 140 on which the second coil 141 is wound are disposed outside the circumferential direction of the magnet 30. In addition, the first yoke 150 and the second yoke 160 are disposed between the first bobbin 130 and the second bobbin 140.

The first bobbin 130 is formed with a first coil winding part 134 in which the first coil 131 is wound in a circumferential direction, and includes a first terminal part for electrically connecting the first coil 131 ( 135) is formed. Similarly, the second bobbin 140 is formed with a second coil winding 144 in which the second coil 141 is wound in a circumferential direction, and a second for electrically connecting the second coil 141. The terminal portion 145 is formed.

As described above, the first bobbin 130 is provided with the protrusion tube 132 through which the screw member 10 is inserted and supported, and the third tooth 111 of the first housing 110 is inserted therein. Slits 136 are formed. The first bobbin 130 faces the magnet 30 and the nut member 20 in a first direction, and the first bobbin 130 is provided with a recessed portion 134 recessed in the first direction to form the magnet. As the 30 and the nut member 20 flow in the first direction and the second direction, the friction force that may be generated between the first bobbin 130 and the magnet 30 and the nut member 20 may be reduced. Can be.

The first yoke 150 protrudes toward the first housing 110 from an inner circumference of the ring-shaped first body portion 151 and the first body portion 151 and the first bobbin 130. A first tooth 152 disposed between the magnets 30 and a first ground terminal 153 for grounding the first body 151 are included. In addition, the second yoke 160 protrudes toward the second housing 120 from an inner circumference of the ring-shaped second body portion 161 and the second body portion 161 and the second bobbin 140. ) And a second tooth 162 disposed between the magnet 30 and a second ground terminal portion 163 for grounding the second body portion 161.

Meanwhile, the third tooth 111 protruding toward the second housing 120 is formed in the first housing 110 to penetrate the slit 136 of the first bobbin 152 to pass through the first bobbin. It is disposed between the 130 and the magnet 30. The third tooth 111 and the first tooth 152 are alternately disposed along the outer circumference of the magnet 30.

The first housing 110 is formed with a first rim 112 protruding radially inward from the cylindrical body, and the third tooth 111 is in a second direction from the first rim 112. Extends. One side of the first bobbin 130 is inserted into and coupled to the first opening 113 formed by the first rim 112.

In addition, a fourth tooth 121 protruding in the direction of the first housing 110 is formed in the second housing 120 and disposed between the second bobbin 140 and the magnet 30. The fourth tooth 121 and the second tooth 162 are alternately disposed along the outer circumference of the magnet 30.

The second housing 120 is formed with a second rim 122 protruding radially inward from the cylindrical body, and the fourth tooth 121 extends in the first direction from the second rim 122. do.

On the other hand, the first housing 110 is formed with a first cut portion 114 is a part of the first rim 112 is cut, the second housing 120 is a part of the second rim 122 is cut The second cut portion 124 is formed. The first cut part 114 and the second cut part 124 may include a first terminal part 135 formed on the first bobbin 130, a first ground terminal part 153 formed on the first yoke 150, The second ground terminal part 163 formed on the second yoke 160 and the second terminal part 145 formed on the second bobbin 140 may form an opening to protrude outward.

The bearing 40 is disposed on the second direction side of the second housing 120, and the bearing cover 50 supporting the bearing 40 is installed. That is, the bearing cover 50 is coupled to the second housing 120 to constrain the bearing 40. For example, the second housing 120 and the bearing cover 50 may be coupled by spot welding or laser welding.

As described above, the inner ring of the bearing 40 is coupled to and supported by the second direction side end 22 of the nut member 20.

In addition, the bearing 40 is limited in the first direction by the second rim portion 122 of the second housing 120 and is moved in the second direction by the bearing cover 50. Movement is restricted.

The diameter of the second opening 123 formed by the second rim portion 122 is larger than the diameter of the magnet 30 and smaller than the diameter of the bearing 40. Therefore, it is possible to prevent the friction force from occurring between the magnet 30 and the second housing 120, it is possible to limit the movement of the bearing 40 in the first direction.

5 is a view showing that the second housing supports the bearing in the first direction in the step actuator according to the embodiment.

Referring to FIG. 5, the nut member 20 is inserted into the magnet 30 and engaged with the inner ring of the bearing 40.

The bearing cover 50 is coupled to the second housing 120 in a second direction, and the mounting member 60 is coupled to the bearing cover 50 in a second direction.

The bearing 40 is installed between the bearing cover 50 and the second housing 120, which is in the first direction by the second rim 122 of the second housing 120. Movement is restricted.

In FIG. 5, the bearing 40 is partially exposed between the second rim 122 and the magnet 30, and an unexposed portion of the bearing 40 is exposed to the second rim 122. This is a portion where movement in the first direction is limited.

6 to 8 are views showing another example of the rotor in the step actuator according to the embodiment.

Unlike the rotors described in FIGS. 1 to 5, the rotors described in FIGS. 6 to 8 include nut members 20, magnets 30, and magnet covers 25.

The nut member 20 is coupled to the magnet 30 in a first direction to protrude in a second direction, and the magnet cover 25 is formed in a ring shape to be coupled to the nut member 20 in a second direction. The nut member 20 penetrates through the inner circumference of the magnet cover 25.

As described above, the nut member 20 is inserted into and coupled to the inside of the magnet 30 in a first direction, and a second direction side end portion 22 penetrates through the magnet 30 in a second direction. Protrudes. A protrusion 23 extending along the axial direction is formed on an outer circumferential surface of the nut member 20 to be coupled to the magnet 30 in which a groove 31 having a shape corresponding to the protrusion 23 is formed. Thus, the nut member 20 is rotated together as the magnet 30 is rotated.

The second directional end 22 of the nut member 20 is engaged with the inner ring of the bearing 40. Thus, the nut member 20 may be freely rotated while being supported by the bearing 40.

In addition, a thread 21 is formed on an inner circumferential surface of the nut member 20 to be coupled to the thread 11 of the screw member 10. In addition, the nut member 20 is rotatably supported in combination with the protruding tube 132 of the first bobbin 130. That is, the inner circumferential surface of the nut member 20 is in contact with and supported by the outer circumferential surface of the protruding tube 132.

The magnet 30 may be formed of a permanent magnet in which the N side and the S pole are alternately magnetized at equal intervals in the circumferential direction. As described above, the nut member 20 is inserted into and coupled to the magnet 30, so that the nut member 20 also rotates as the magnet 30 is rotated.

Meanwhile, a plurality of penetrating nut holes 24 extending in the axial direction are formed between the inner circumferential surface and the outer circumferential surface of the nut member 20, and the magnet cover 25 is coupled through the nut holes 24. .

That is, the magnet cover 25 is coupled to the nut member 20 in a second direction, and a cover protrusion 25a protruding from the magnet cover 25 in the first direction is inserted into the nut hole 24. Is fixed. As a result, the magnet 30 is constrained between the nut member 20 and the magnet cover 25.

Therefore, the rotor including the magnet 30, the nut member 20 and the magnet cover 25 can be firmly integrally coupled.

Meanwhile, the magnet cover 25 may have an inner circumference protruding in a second direction to contact the inner ring of the bearing 40. As the magnet cover 25 protrudes in the second direction, the magnet cover 25 may be smoothly rotated without being in contact with the outer ring of the bearing 40.

9 and 10 illustrate another example of a bearing cover in the step actuator according to the embodiment.

A fastening part 54 may be formed in the bearing cover 50. The fastening part 54 is bent radially inward from the bearing cover 50 to limit the movement of the bearing 40 in the first direction. The fastening part 54 may be disposed in a first direction of the outer ring of the bearing 40 by a caulking process.

In the step actuators described with reference to FIGS. 1 to 5, the movement of the bearing 40 in the first direction and the second direction by the second housing 120 and the bearing cover 50 is limited, but FIGS. 9 and 10. In the step actuator described in the above, the bearing 40 is limited to move in the first direction and the second direction by the bearing cover 50.

In the step actuator according to the embodiment, since the bearing 40 is constrained by the second housing 120 and the bearing cover 50, the mounting member 60 restrains the bearing 40 at a constant position. There is no need to function. Therefore, the mounting member 60 may be designed in more various forms.

In addition, in the step actuator according to the embodiment, the bearing 40 is constrained by the bearing cover 50, so that the second housing 120 and the mounting member 60 is in a fixed position It does not have to be a restraining function. Therefore, the second housing 120 and the mounting member 60 may be designed in more various forms.

11 to 15 are views for explaining the structure and the coupling relationship between the bearing cover and the mounting member.

The bearing cover 50 illustrated in FIGS. 11 to 15 is an example in which a fastening part 54 as described with reference to FIGS. 9 and 10 is formed. However, except for the fastening part 54 structure, the structure of the bearing cover 50 described with reference to FIGS. 1 to 5 is the same as that of the bearing cover 50 described with reference to FIGS. 11 to 15.

Referring to FIG. 11, the bearing cover 50 includes a coupling frame 51, a coupling pipe 52, a hook frame 53, a fastening portion 54, a support piece 55, a rotation preventing protrusion 56, and The first contact piece 57 is included.

The coupling frame 51 is formed in a ring shape having a predetermined width and is coupled to the second rim portion 122 of the second housing 120. For example, the coupling frame 51 and the second rim portion 122 may be coupled by welding.

The coupling pipe 52 extends in the second direction from the inner circumference of the coupling frame 51 and has an inner circumferential surface in contact with the outer ring of the bearing 40.

The hook frame 53 is formed to protrude radially inward from the second direction side end of the coupling pipe 52, and contacts the outer ring of the bearing (40). The latch frame 53 restricts the bearing 40 from moving in the second direction.

As described above, the fastening part 54 restricts the bearing 40 from moving in the first direction. The fastening part 54 is bent vertically to support the bearing 40, and faces the engaging frame 53 with the bearing 40 interposed therebetween.

The support piece 55 extends in the second direction from the outer circumference of the coupling frame 51 and is provided with a plurality of spaced apart from each other. At this time, the imaginary line connecting the support piece 55 is approximately circular.

The anti-rotation protrusion 56 extends radially outward from the support piece 55, and a first bending piece 56a and a second bending piece 56b are formed in the circumferential direction, respectively. The first bending piece 56a and the second bending piece 56b are mounted to the mounting member 60 so that the mounting member 60 does not rotate in the circumferential direction when the mounting member 60 is coupled to the bearing cover 50. It is supported by the locking piece 64 and the locking protrusion 65 of 60, respectively.

The first bending piece 56a and the second bending piece 56b increase the contact area of the anti-rotation protrusion 56 so that the anti-rotation protrusion 56 stops the locking piece 64 and the locking protrusion 65. To be firmly supported.

The first contact piece 57 extends radially outward from the second direction side end portion of the support piece 55, and contacts the second contact piece 67 of the mounting member 60 to mount the mounting piece. The member 60 is prevented from flowing in the axial direction.

The mounting member 60 includes a protrusion 61, a housing tube 63, a locking piece 64, a locking protrusion 65, an extension frame 66, and a second contact piece 67.

The protrusion 61 and the receiving tube 63 form a body of the mounting member 60. The protrusion 61 supports the screw member 10 so as to be movable in the first direction and the second direction, and the housing tube 63 has the bearing 40 and the bearing cover 50 disposed therein. Provide space for The protrusion 61 is formed to protrude in a second direction from the accommodation tube 63.

The accommodating tube 63 has a first direction end portion inserted between the support piece 55 of the bearing cover 50 and the coupling tube 52. Therefore, the outer circumference of the first direction side end portion of the housing tube 63 is in contact with the inner circumference of the support piece 55, and the inner circumference of the first direction side end of the housing tube 63 is the coupling tube 52. Contact with the outer periphery of the

The extension frame 66 extends radially outward from the outer circumferential surface of the housing tube 63 to form a ring shape, and the anti-rotation protrusion 56 and the first contact piece 57 of the bearing cover 50 are formed. To face.

The locking pieces 64 extend in the first direction from the outer circumference of the extension frame 66 and are provided with a plurality of spaced apart from each other. The inner circumferential surface of the engaging piece 64 faces the outer circumferential surface of the coupling frame 51 of the bearing cover 50.

When the mounting member 60 is rotated in the clockwise direction while the locking piece 64 is positioned between the support piece 55 and the support piece 55 of the bearing cover 50, the first bending piece 56a is caught by the circumferential end of the engaging piece 64. Thus, the mounting member 60 no longer rotates clockwise.

The locking protrusion 65 is formed on the extension frame 66 between the locking piece 64 and the locking piece 64 and has elasticity. The locking protrusion 65 is formed in a cantilever shape, and the free end side contacts the second bending piece 56b of the anti-rotation protrusion 56.

That is, the locking projection 65 is located between the support piece 55 and the support piece 55 adjacent to each other, and as the mounting member 60 rotates in the clockwise direction, the anti-rotation protrusion 56 ) Is caught by the second bending piece 56b of the anti-rotation protrusion 56. Then, the mounting member 60 is no longer rotated counterclockwise.

The free end side of the locking protrusion 65 is formed to be inclined so that the locking protrusion 65 can smoothly cross the anti-rotation protrusion 56.

The second contact piece 67 extends radially inward from the first direction end portion of the locking piece 64 and is spaced apart from the extension frame 66 by a predetermined distance. The first contact piece 57 is inserted between the second contact piece 67 and the extension frame 66.

The mounting member 60 is located in the second direction of the bearing cover 50. Therefore, when the mounting member 60 is coupled to the bearing cover 50, the second contact piece 67 integrally formed with the mounting member 60 may include the first integrally formed with the bearing cover 50. Since it is located in the first direction of the contact piece 57, the mounting member 60 does not flow in the first direction and the second direction.

In order for the bearing cover 50 and the mounting member 60 to be in close contact with each other, an embossing 57a is formed on a surface of the first contact piece 57 that is in contact with the second contact piece 67. . The embossing 57a is connected to the second contact piece 67 when the mounting member 60 is rotated so that the locking piece 64 and the locking protrusion 65 are caught by the rotation preventing protrusion 56, respectively. In close contact, the second contact piece 67 is supported in the first direction.

A method of coupling the mounting member 60 to the bearing cover 50 will be described with reference to FIGS. 12 to 15.

As shown in FIG. 12, the mounting member 60 is inserted between the support piece 55 of the bearing cover 50 and the coupling tube 52 while the housing tube 63 of the mounting member 60 is inserted. The locking piece 64 and the locking protrusion 65 are positioned between the anti-rotation protrusion 56 and the anti-rotation protrusion 56 of the bearing cover 50.

In the state shown in FIG. 12, as shown in FIG. 13, the first contact piece 57 of the bearing cover 50 and the second contact piece 67 of the mounting member 60 overlap each other in the axial direction. It is not a condition.

12 and 13, when the mounting member 60 is rotated in the clockwise direction, as shown in FIG. 14, the locking piece 64 is in contact with and supported by the first bending piece 56a. The locking protrusion 65 is supported by the free end portion of the second bending piece 56b beyond the anti-rotation protrusion 56. Thus, the mounting member 60 does not rotate.

In the state shown in FIG. 14, as shown in FIG. 15, the first contact piece 57 and the second contact piece 67 overlap each other in the axial direction. The second contact piece 67 is in contact. By the way, since the embossing 57a is formed in the first contact piece 57, the embossing 57a is in close contact with the second contact piece 67 so that the second contact piece 67 is in the first direction. To support it. Therefore, the bearing cover 50 and the mounting member 60 are firmly coupled without flowing in the axial direction.

When the mounting member 60 is to be separated, the free end side of the locking protrusion 165 may be lifted in the second direction, and then the mounting member 60 may be rotated counterclockwise.

As described above, the step actuator according to the embodiment restrains the position of the bearing 40 and supports and supports the linear movement of the screw member 10 and the bearing cover 50 for supporting the mounting member 60. And a mounting member 60. Therefore, the design of the mounting member 60 can be freely modified, and can be easily coupled with the bearing cover 50.

In the step actuator as described above, an electric field is generated when the power is applied to the first terminal 135 and the second terminal 145, respectively, and the magnet 30 is rotated in the forward and reverse directions.

As the magnet 30 is rotated, the nut member 20 coupled with the magnet 30 is rotated, and the screw member 10 having the thread 11 engaged with the thread 21 of the nut member 20. ) Moves in a first direction and a second direction according to the rotation direction of the magnet 30.

Although the above description has been made based on the embodiments, these are merely examples and are not intended to limit the present invention. Those skilled in the art to which the present invention pertains may not have been exemplified above without departing from the essential characteristics of the present embodiments. It will be appreciated that many variations and applications are possible. For example, each component specifically shown in the embodiment can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

1 is a perspective view of a step actuator according to an embodiment.

2 is a sectional view of a step actuator according to an embodiment;

3 and 4 are exploded perspective views of the step actuator according to the embodiment.

5 shows a second housing supporting a bearing in a first direction in a step actuator according to an embodiment.

6 to 8 show another example of the rotor in the step actuator according to the embodiment;

9 and 10 show another example of a bearing cover in the step actuator according to the embodiment.

11 to 15 illustrate the structure and the coupling relationship between the bearing cover and the mounting member.

Claims (15)

housing; A stator disposed inside the housing; A rotor disposed radially inward of the stator and rotating in interaction with the stator; A screw member coupled to the rotor and moving linearly in accordance with the rotation direction of the rotor; And A mounting member supported by the housing and supporting the screw member to be linearly movable; And the rotor includes a magnet disposed radially inward of the stator, and a nut member inserted into and coupled to the inside of the magnet and protruding through the housing. The method of claim 1, And a bearing for rotatably supporting the nut member. The method of claim 1, And said at least part of said magnet and said nut member are overlapped in a circumferential direction. The method of claim 1, The magnet has a groove formed on an inner circumferential surface, and the nut member has a step portion corresponding to the groove formed on an outer circumferential surface thereof so that the groove and the protrusion are coupled to each other. The method of claim 4, wherein And the groove and the protrusion are formed extending in the axial direction. 3. The method of claim 2, The magnet is a step actuator in which a portion facing the inner ring of the bearing protrudes in the bearing direction. 3. The method of claim 2, And a bearing cover coupled to the housing to constrain the bearing, wherein the mounting member is coupled to the bearing cover. The method of claim 1, The nut member has a thread formed on the inner circumferential surface and the screw member is formed a thread on the outer circumferential surface, the screw member is linear movement in the first direction and the second direction according to the rotation direction of the nut member. The method of claim 1, The housing includes a first housing and a second housing coupled with the first housing, The stator is disposed between the first bobbin and the second bobbin disposed between the first housing and the second housing, and the first bobbin and the second bobbin, and disposed between the first bobbin and the second bobbin and the magnet. A first yoke and a second yoke having a first tooth and a second tooth formed therein, A third tooth is formed in the first housing alternately with the first tooth along the outer circumference of the magnet, and a fourth tooth is alternately disposed with the second tooth along the outer circumference of the magnet. The step actuator is formed. The method of claim 9, And a protruding tube in which the screw member is inserted and supported by the first bobbin. The method of claim 10, And a step actuator in contact with an outer circumferential surface of the protruding tube. The method of claim 1, And a magnet cover coupled to the nut member to restrain the magnet. The method of claim 12, And the nut member and the magnet cover are coupled to each other with the magnet interposed therebetween. The method of claim 12, The nut member is formed with a nut hole extending in the axial direction, the magnet cover is a step actuator formed with a cover projection is inserted into the nut hole is coupled. 3. The method of claim 2, A magnet cover coupled to the nut member to constrain the magnet; The magnet cover has a step actuator in which a portion facing the inner ring of the bearing protrudes in the bearing direction.

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