JP2017067086A - Linear-motion actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear-motion actuator capable of suppressing degradation of a screw mechanism.SOLUTION: A linear-motion actuator 1 includes a nut member 25 which is arranged coaxially with a cylindrical rotor 20 which is rotated around a shaft center by a magnetic action with a stator 30, and is rotated accompanied with the rotation of the rotor 20; and a screw shaft 40 which is screwed to the nut member 25, and is advanced or retreated by the rotation of the nut member 25. A head section 45 which swingably connects a connection object T is provided to a front end of the screw shaft 40. Further the linear-motion actuator 1 includes, at the nut member 25, a female screw section 29 to which the screw shaft 40 is screwed, and a swinging section 27 which can swing in a direction crossing the shaft center 20a of the rotor 20.SELECTED DRAWING: Figure 11

Description

  The present invention relates to a linear motion actuator.

  A conventional linear actuator is disclosed in Patent Document 1. This linear motion actuator has an electric motor and a ball screw disposed coaxially with a hollow motor shaft of the electric motor. The ball screw has a nut fixed to the motor shaft, and a screw shaft that is inserted into the nut via a large number of balls and is disposed so as to advance and retract on the motor shaft.

  In this linear actuator, the nut rotates with the rotation of the motor shaft, and the rotation of the nut moves the screw shaft to move forward or backward in the axial direction, so that the screw shaft connected to the tip of the screw shaft is moved. The connected body is moved in a straight line.

JP 2008-298107 A

  However, when the above-mentioned connected body is arranged so as to be displaced from the axis of the screw shaft, the screw shaft is bent and attached, and this deflection causes the axis of the screw shaft and the axis of the nut to intersect in the ball screw. If a force is applied in the direction, the ball screw may be unevenly worn or galling, which may accelerate deterioration. The same applies to a configuration that employs another type of screw mechanism such as a slide screw instead of the ball screw.

  Then, an object of this invention is to provide the linear motion actuator which can suppress deterioration of a screw mechanism.

  In order to achieve the above object, the present invention provides a stator, a cylindrical rotor that is rotated around an axis by a magnetic action of the stator, and is arranged coaxially with the axis of the rotor. A nut member that is rotated along with the screw member, and a screw shaft that is screwed into the nut member and that is advanced or retracted by the rotation of the nut member. A head portion is provided that is swingably connected. The nut member has a female screw portion into which the screw shaft is screwed, and a swing portion that can swing in a direction intersecting the axis of the rotor is provided. It is a linear motion actuator characterized by being provided.

  According to the present invention, since the connected body can be swingably connected to the head portion provided at the front end of the screw shaft, the connected body is arranged so as to be displaced from the axis of the screw shaft. However, it is possible to connect to the head portion while maintaining the posture of the connected body. When the body to be connected is arranged so as to be displaced from the axis of the screw shaft, when the screw shaft is bent and attached to the body to be connected, force is applied to the swinging portion of the nut member by the deflection of the screw shaft. . With this force, the oscillating portion is oscillated in a direction intersecting with the axis of the rotor, and the axis of the female screw portion of the oscillating portion coincides with the axis of the screw shaft. Thereby, deterioration of a nut member or a screw shaft can be controlled.

  In the present invention, the nut member is formed in a spherical shape, and a groove extending in the rotational direction is provided at a position shifted rearward from the center of the spherical shape, and a portion closer to the front than the groove in the nut member However, it is preferable that the rotor is provided with a nut member accommodation space that is included in the spherical inner surface that constitutes the rocking portion and that is in sliding contact with the spherical surface of the rocking portion. By doing in this way, the part which provided the said groove | channel in a nut member becomes weak so that a deformation | transformation is possible, and a rocking | swiveling part is rock | fluctuated, without changing the attitude | position of the part nearer than the said groove | channel in a nut member. be able to. When the spherical surface of the swinging portion is in contact with the spherical inner surface surrounding the nut member housing space in which the nut member is housed, the swinging portion is positioned, and shaking of the swinging portion can be suppressed.

  In the present invention, it is preferable that a portion of the nut member closer to the rear than the groove constitutes a rotation receiving portion in which the rotational movement around the axis of the rotor is restricted with respect to the rotor. By doing in this way, a rotation receiving part is combined with a rotor, without changing the attitude | position, and rotation of a rotor is transmitted more reliably.

  In this invention, it is preferable that the said nut member is arrange | positioned at the front-end part of the said rotor. By doing so, for example, the protrusion length of the screw shaft from the rotor when the screw shaft is advanced as much as possible as compared with the configuration in which the nut member is arranged at the center portion or the rear end portion of the rotor. Can be larger.

  In this invention, it is preferable that the said nut member is further arrange | positioned inside the said rotor, and also has a bearing part which pivotally supports the location in which the said nut member is arrange | positioned in the said rotor. By doing in this way, since a nut member faces a bearing part on both sides of a rotor, much force added to a nut member is transmitted to a bearing part, without being absorbed by a rotor. Therefore, it is possible to suppress the force applied to the nut member from being absorbed by the rotor, for example, to suppress the deflection of the rotor as compared with a configuration in which a portion where the nut member is not disposed in the rotor is supported by the bearing portion. it can.

  In the present invention, it is preferable that the head portion is formed in a spherical shape, and a head portion groove extending in the rotation direction of the rotor is provided at a position shifted forward from the center of the spherical shape. By doing in this way, the part which provided the head part groove | channel in the head part becomes weak so that a deformation | transformation is possible, and the part nearer than the head part groove | channel in a head part can be rock | fluctuated. Therefore, even when the connected body is fixed to the front portion of the head portion in the head portion groove, the connected body can be swung, and the maintenance of the posture of the connected body can be suppressed.

  The linear motion actuator of the present invention can suppress deterioration of the screw mechanism.

It is a perspective view of the linear motion actuator which concerns on one Embodiment of this invention. It is a front view of the linear motion actuator of FIG. It is a perspective view of the rotor which the linear motion actuator of FIG. 1 has. It is sectional drawing which follows the II-II line | wire of FIG. It is sectional drawing which follows the III-III line of FIG. FIG. 6 is an enlarged cross-sectional view in which a part of FIG. 5 is enlarged. It is sectional drawing which follows the IV-IV line of FIG. It is sectional drawing of the nut member which the linear motion actuator of FIG. 1 has. It is the figure which expanded a part of screw shaft which the linear motion actuator of FIG. 1 has. It is a figure explaining the case where a to-be-connected body is arrange | positioned on the axial center of a rotor. It is a figure explaining the case where a to-be-connected body has shifted | deviated from the axial center of a rotor, and is arrange | positioned. It is sectional drawing which shows the structure of the modification of the linear motion actuator of FIG.

  Below, the structure of the linear motion actuator which is one Embodiment of this invention is demonstrated with reference to FIGS.

  FIG. 1 is a perspective view of a linear actuator according to an embodiment of the present invention. FIG. 2 is a front view of the linear motion actuator of FIG. FIG. 3 is a perspective view of a rotor included in the linear motion actuator of FIG. 4 is a cross-sectional view taken along the line II-II in FIG. FIG. 5 is a sectional view taken along line III-III in FIG. FIG. 6 is an enlarged cross-sectional view in which a part of FIG. 5 is enlarged. 7 is a cross-sectional view taken along line IV-IV in FIG. FIG. 8 is a cross-sectional view of a nut member included in the linear motion actuator of FIG. FIG. 9 is an enlarged view of a part of a screw shaft included in the linear motion actuator of FIG.

  As shown in the drawings, the linear actuator (hereinafter simply referred to as “actuator 1”) includes a case 10, a rotor 20, a nut member 25, a stator 30, and a screw shaft 40. .

  As shown in FIGS. 1 and 2, the case 10 is formed in a rectangular parallelepiped hollow box shape in which the size in the height direction Z is smaller than the size in the width direction X. As shown in FIG. 4, the case 10 includes a case body 11 made of metal such as stainless steel, and a front bearing 16 and a rear bearing 17 made of ball bearings.

  As shown in FIGS. 4 and 5, the case main body 11 includes a rectangular tube-shaped peripheral wall 12 having a rectangular cross section, a rectangular plate-shaped front wall 13 that covers the front side end of the peripheral wall 12, and a peripheral wall. 12 and a rectangular plate-like back wall portion 14 that closes the back-side end portions. The front wall portion 13 is integral with the peripheral wall portion 12, and the back wall portion 14 is detachable from the peripheral wall portion 12. The case main body 11 has a size in the height direction Z of the internal space of the case main body 11 so that the inner surface facing the height direction Z does not contact the outer peripheral surface of the rotor 20 when the rotor 20 described later is accommodated. Is formed to be slightly larger than the diameter D of the rotor 20.

  A circular front shaft insertion hole 13 a is formed at the center of the front wall portion 13. A front bearing 16 is fixedly attached to the inner surface of the front wall portion 13 so as to be coaxial with the front shaft insertion hole 13a. Similarly, a circular rear shaft insertion hole 14 a is formed at the center of the rear wall portion 14. A rear bearing 17 is fixedly attached to the inner surface of the rear wall portion 14 so as to be coaxial with the rear shaft insertion hole 14a.

  As illustrated in FIG. 3, the rotor 20 includes a rotor shaft 21, a magnet 22, an N pole rotor core 23, and an S pole rotor core 24.

  The rotor shaft 21 is formed in a cylindrical shape as a whole using, for example, metal or hard resin as a material. As shown in FIG. 4, the large-diameter portion 21a, the shaft main body portion 21b, The small-diameter portion 21c is coaxial and is configured in succession in the length direction Y (that is, the axial direction P of the rotor 20).

  The large-diameter portion 21a has an outer diameter that is the same as the inner diameter of the front bearing 16, and a flange 21d that protrudes over the entire circumference is integrally provided at the rear end portion of the outer peripheral surface. Inside the large-diameter portion 21a, a spherical nut member accommodating space 21e for accommodating a nut member 25 described later with the front end portion exposed is formed. In addition, in this specification, in addition to the exact spherical shape, the spherical shape includes, for example, a substantially spherical shape partially cut off by a plane.

  The shaft main body portion 21b is formed in a cylindrical shape whose outer diameter is smaller than the outer diameter of the large diameter portion 21a, and the large diameter portion 21a is coaxially connected to the front end portion thereof. The small diameter portion 21c is formed in a cylindrical shape having an outer diameter smaller than the outer diameter of the shaft main body portion 21b and the same as the inner diameter of the rear bearing 17, and is coaxially connected to the rear side end portion of the shaft main body portion 21b. . The inner diameter of the shaft main body portion 21b and the inner diameter of the small diameter portion 21c are the same size and slightly larger than the outer diameter of the screw shaft 40 described later.

  The rotor shaft 21 is rotatably supported with a large diameter portion 21a inserted through the front bearing 16 of the case 10 and a small diameter portion 21c inserted through the rear bearing 17. The rotor shaft 21 is formed to be separable so that a nut member 25 described later can be accommodated in the nut member accommodating space 21e.

  The magnet 22 is made of, for example, a permanent magnet such as an alnico magnet or a rare earth magnet, and is formed in a cylindrical shape having an inner diameter that is the same as the outer diameter of the shaft body 21 b of the rotor shaft 21. The magnet 22 is magnetized so that the front side end is an N pole and the back side end is an S pole. The magnet 22 has a shaft main body portion 21b of the rotor shaft 21 inserted therein, and is fixedly attached to a central portion of the shaft main body portion 21b.

  The N-pole rotor core 23 is formed in a substantially cylindrical shape by laminating thin electromagnetic steel plates in the axial direction P. As shown in FIG. 5, on the outer peripheral surface of the N-pole rotor core 23, core small teeth 23a that extend in the axial direction P and are arranged at an equal pitch (7.2 degrees in the present embodiment) in the circumferential direction Q over the entire circumference. Is formed. The N-pole rotor core 23 is provided with a through-hole 23 b that penetrates in the axial direction P. The through-hole 23 b has a large-diameter portion 23 c having the same inner diameter as the outer diameter of the magnet 22 and the shaft main body portion 21 b of the rotor shaft 21. It has a small-diameter portion 23d having the same inner diameter as the outer diameter. The front end which is the N pole of the magnet 22 is inserted and fixed in the large diameter portion 23c, and the shaft main body portion 21b protruding from the front end surface of the magnet 22 is inserted and fixed in the small diameter portion 23d. Thereby, the N pole rotor core 23 is magnetized to the N pole.

  Similar to the N-pole rotor core 23, the S-pole rotor core 24 is formed in a substantially cylindrical shape by laminating thin electromagnetic steel plates in the axial direction P. On the outer peripheral surface of the S pole rotor core 24, core small teeth 24a are formed that extend in the axial direction P and are arranged at an equal pitch (7.2 degrees in the present embodiment) in the circumferential direction Q over the entire circumference. The S-pole rotor core 24 is provided with a through hole 24b penetrating in the axial direction P. The through hole 24b has a large diameter portion 24c having an inner diameter that is the same as the outer diameter of the magnet 22 and a shaft main body portion of the rotor shaft 21 having an inner diameter. It has the same small diameter part 24d as the outer diameter of 21b. The large-diameter portion 24c is inserted and fixed at the back end, which is the south pole of the magnet 22, and the small-diameter portion 24d is fixedly inserted into the shaft main body 21b protruding from the back-side end surface of the magnet 22. Thereby, the S pole rotor core is magnetized to the S pole.

  The N-pole rotor core 23 and the S-pole rotor core 24 are fixed so that the core small teeth 23a and the core small teeth 24a are shifted by a half pitch (3.6 degrees in this embodiment) in the circumferential direction Q. The diameters of the N-pole rotor core 23 and the S-pole rotor core 24 are the diameter D of the rotor 20.

  The nut member 25 is formed in a spherical shape using, for example, a resin such as polytetrafluoroethylene (PTFE). As shown in FIG. 8, the nut member 25 is provided with a groove 25 b that extends around the entire circumference in the rotational direction around the axis 25 a of the nut member 25 at a position closer to the rear than the spherical center. The nut member 25 is housed in the nut member housing space 21e of the rotor shaft 21 so that the shaft center 25a of the nut member 25 and the shaft center 20a of the rotor 20 coincide.

  A portion of the nut member 25 closer to the rear than the groove 25 b constitutes the rotation receiving portion 26, and a portion of the nut member 25 closer to the front than the groove 25 b constitutes the swinging portion 27. The rotation receiving portion 26 and the swinging portion 27 are connected by a connection portion 28 located at the bottom of the groove 25b. The groove 25b is formed so as to be brittle to such an extent that the connecting portion 28 can be elastically deformed.

  The nut member 25 is provided with a through hole 25c penetrating in the direction of the axis 25a. The through hole 25c is formed such that the diameter of the portion 25d corresponding to the rotation receiving portion 26 and the connecting portion 28 in the through hole 25c is larger than the outer diameter of the screw shaft 40 described later. Further, a female screw portion 29 to which the screw shaft 40 is screwed is formed at a location 25e corresponding to the swinging portion 27 in the through hole 25c. In other words, the rocking portion 27 is provided with the female screw portion 29.

  The rotation receiving portion 26 has a flat surface 26b facing rearward and two bosses 26a and 26a projecting rearward from the flat surface 26b. The two bosses 26a, 26a are fitted into boss holes formed in the rotor shaft 21 corresponding to these. As a result, the rotation receiving portion 26 is rotated together with the rotor shaft 21 while the rotational movement about the shaft center 20 a is restricted with respect to the rotor shaft 21.

  The swing part 27 is formed in a substantially hemispherical shape. The swinging portion 27 can swing in the direction in which the shaft center 29 a of the female screw portion 29 intersects the shaft center 25 a by the deformation of the connecting portion 28. When the oscillating portion 27 oscillates in the nut member accommodating space 21e, the spherical surface of the oscillating portion 27 is in sliding contact with the inner surface 21f (FIGS. 10 and 11) of the rotor shaft 21 surrounding the nut member accommodating space 21e. .

  As shown in FIG. 5, the stator 30 has two stator cores 31, 31, an A-phase winding 35 and a B-phase winding 36.

  Each of the two stator cores 31, 31 is formed by laminating thin electromagnetic steel plates in the axial direction P. In the case 10, the width direction X (that is, in the axial direction P of the rotor 20) with the rotor 20 interposed therebetween is formed. (Directions orthogonal to each other) so as to face each other. Each of the two stator cores 31, 31 integrally includes a stator core main body portion 32, an A-phase stator tooth 33, and a B-phase stator tooth 34.

  As shown in FIGS. 4 and 7, the stator core main body 32 is shorter than the length in the length direction Y in the internal space of the case main body 11 and the S pole rotor core from the front end face of the N pole rotor core 23 in the rotor 20. 24 is formed in a column shape longer than the length to the rear side end face. The size in the height direction Z of the stator core body 32 is formed to be the same as the size in the height direction Z of the inner space of the case body 11 as shown in FIG. On the outer peripheral surface of the stator core main body 32, there are provided a facing surface 32a facing the other stator core main body 32 and flat surfaces 32b, 32c, 32d in contact with the inner surface of the case main body 11. The facing surface 32 a is formed in a concave curved surface shape along an arc centered on the axis 20 a of the rotor 20. The facing surface 32a may be a flat surface.

  The A-phase stator teeth 33 protrude from the facing surface 32a toward the outer peripheral surface of the rotor 20 (that is, the outer peripheral surfaces of the magnet 22, the N-pole rotor core 23, and the S-pole rotor core 24) and in the length direction Y, the stator core main body 32. It is formed to extend to the same length. As shown in FIG. 6, the A-phase stator teeth 33 include a shaft portion 33 a and a tip portion 33 b wider than the shaft portion 33 a in the circumferential direction Q of the rotor 20. The tip 33b is formed with a plurality of protruding stator small teeth 33c extending in the axial direction P and arranged in the circumferential direction Q at an equal pitch (7.5 degrees in the present embodiment). The plurality of small stator teeth 33c are arranged so as to face the outer peripheral surface of the rotor 20 with a space therebetween.

  Similarly to the A-phase stator teeth 33, the B-phase stator teeth 34 protrude from the facing surface 32 a toward the outer peripheral surface of the rotor 20 and extend in the length direction Y to the same length as the stator core body 32. Has been. As shown in FIG. 6, the B-phase stator tooth 34 includes a shaft portion 34 a and a tip portion 34 b wider than the shaft portion 34 a in the circumferential direction Q of the rotor 20. A plurality of protruding stator small teeth 34c extending in the axial direction P and arranged in the circumferential direction Q at an equal pitch (7.5 degrees in the present embodiment) are formed on the distal end portion 34b. The plurality of stator small teeth 34c are arranged so as to face the outer peripheral surface of the rotor 20 with a space therebetween.

  The A-phase stator teeth 33 and the B-phase stator teeth 34 are arranged at an interval in the circumferential direction Q of the rotor 20 so as to be positioned 45 degrees apart from each other about the axis 20a of the rotor 20. Yes.

  Further, when the stator small teeth 33c at the center of the A-phase stator teeth 33 are at positions facing the core small teeth 23a of the N-pole rotor core 23, the stator small teeth 33c at the center of the B-phase stator teeth 34 are The A-phase stator teeth 33 and the B-phase stator teeth 34 are positioned so as to be shifted from the core small teeth 23a of the N-pole rotor core 23 in the circumferential direction Q (position shifted by 1.8 degrees in this embodiment). Has been placed. For example, the number and pitch of the core small teeth 23a, core small teeth 24a, stator small teeth 33a, stator small teeth 34a, the number of A-phase stator teeth 33 and B-phase stator teeth 34, and the center of each other. The angle formed by the passing line is arbitrary as long as the object of the present invention is not violated.

  In the A-phase winding 35, one enamel-coated copper wire is concentratedly wound around the shaft portion 33 a of the A-phase stator tooth 33 of one stator core 31 and the shaft portion 33 a of the A-phase stator tooth 33 of the other stator core 31. Wrapped and configured.

  In the B-phase winding 36, another enamel-coated copper wire independent of the A-phase winding 35 is used for the shaft portion 34 a of the B-phase stator tooth 34 of one stator core 31 and the B-phase of the other stator core 31. The shaft 34a of the stator tooth 34 is wound around the shaft 34a by concentrated winding.

  The screw shaft 40 is formed in a rod shape having a circular cross section using, for example, a metal such as stainless steel. As shown in FIG. 9, the screw shaft 40 integrally includes a shaft main body 41 and a head portion 45 provided at a front end portion of the shaft main body 41.

  The shaft main body 41 is formed with a male screw portion 41a that is screwed with a female screw portion 29 provided on the swinging portion 27 of the nut member 25 over the entire outer peripheral surface.

  The head portion 45 is formed in a spherical shape, and is accommodated in a spherical head portion accommodation space Te provided in a later-described connected body T (FIGS. 10 and 11). Is connected so that it can swing. The head portion 45 is formed in a spherical shape, and is located at a position closer to the rear than the center of the spherical shape in the circumferential direction around the axis 40a (that is, the rotational direction around the axis 20a of the rotor 20). ) Over the head portion groove 45b.

  A portion of the head portion 45 closer to the front than the head portion groove 45 b constitutes a disc portion 46, and a portion of the head portion 45 closer to the rear than the head portion groove 45 b constitutes a hemispherical portion 47. The disc part 46 and the hemispherical part 47 are connected by a connection part 48 located at the bottom of the head part groove 45b. The head groove 45b is formed so as to be fragile to such an extent that the connecting portion 48 can be elastically deformed.

  When the to-be-connected body T is fixed to the disk part 46, and the rotational movement centering on the centerline Ta parallel to the shaft center 20a of the rotor 20 in this to-be-connected body T is controlled by this, the disk part 46 will be. That is, the rotational movement of the screw shaft 40 is also restricted. Therefore, when the nut member 25 is rotated and the rotational movement of the screw shaft 40 is restricted, the screw shaft 40 is advanced or retracted by the screw mechanism of the female screw portion 29 and the male screw portion 41a. Further, the disk portion 46 swings in a direction intersecting the axis 40 a with respect to the hemispherical portion 47 as the connecting portion 48 is deformed in response to the swing of the connected body T. In the hemispherical portion 47, when the connected body T swings, the spherical surface of the hemispherical portion 47 is brought into sliding contact with the inner surface Tf of the connected body T surrounding the head portion accommodating space Te.

  Next, the operation of the above-described linear motion actuator will be described with reference to FIGS. FIG. 10 is a cross-sectional view illustrating a case where the connected body is disposed on the axis of the rotor, and FIG. 11 illustrates a case where the connected body is displaced from the axis of the rotor. It is sectional drawing.

  As shown in FIG. 10, when the center line Ta of the connected body T is arranged so as to coincide with the axis 20 a of the rotor 20, the connected body T does not swing with respect to the screw shaft 40. It is connected to the head unit 45 while maintaining the above. Then, the screw shaft 40 is screwed together without the swinging portion 27 of the nut member 25 swinging. Therefore, the shaft center 20a of the rotor 20, the shaft center 29a of the female thread portion 29 of the nut member 25, and the shaft center 40a of the screw shaft 40 are arranged in a straight line.

  On the other hand, as shown in FIG. 11, when the center line Ta of the body to be connected T is shifted downward in the figure with respect to the axis 20 a of the rotor 20, the body to be connected T is in relation to the screw shaft 40. By relatively swinging, the head portion 45 is connected while maintaining the posture. At this time, the head portion 45 of the screw shaft 40 moves downward in the drawing, the screw shaft 40 bends, and the axis 40 a of the screw shaft 40 intersects the axis 20 a of the rotor 20. When the screw shaft 40 is bent and a force is applied to the swinging portion 27 of the nut member 25, the swinging portion 27 swings, and the shaft center 29a of the female screw portion 29 of the nut member 25 and the shaft center 40a of the screw shaft 40 are swung. Matches.

  As described above, according to the present embodiment, the connected body T can be swingably connected to the head portion 45 provided at the front end portion of the screw shaft 40, so that the connected body T is connected to the screw shaft 40. Even if it is displaced from the axis 40a, it can be connected to the head portion 45 while maintaining the posture of the connected body T. And when the screw shaft 40 is bent and attached to the to-be-connected body T because the to-be-connected body T is displaced from the axis 40a of the screw shaft 40, the nut member 25 is bent by the deflection of the screw shaft 40. A force is applied to the swing part 27. With this force, the oscillating portion 27 is oscillated in a direction intersecting the axis 20 a of the rotor 20, and the axis 29 a of the female screw portion 29 of the oscillating portion 27 and the axis 40 a of the screw shaft 40 coincide. Thereby, deterioration of the nut member 25 and the screw shaft 40 can be suppressed.

  In the present embodiment, the nut member 25 is formed in a spherical shape, and a groove 25b extending in the rotational direction is provided at a position shifted rearward from the center of the spherical shape, and closer to the front than the groove 25b in the nut member 25. This portion constitutes the swinging portion 27. The rotor 20 is provided with a nut member accommodation space 21e surrounded by a spherical inner surface with which the spherical surface of the swinging portion 27 is slidably contacted. By doing in this way, the connection part 28 which is the part which provided the groove | channel 25b in the nut member 25 becomes weak so that a deformation | transformation is possible, and the attitude | position of the rotation receiving part 26 which is a part nearer than the groove | channel 25b in the nut member 25 The swinging portion 27 can be swung without changing the angle. The oscillating portion 27 is positioned by contacting the spherical surface of the oscillating portion 27 with the spherical inner surface surrounding the nut member accommodating space 21e in which the nut member 25 is accommodated, and the shaking of the oscillating portion 27 can be suppressed. .

  In the present embodiment, the portion of the nut member 25 closer to the rear than the groove 25 b constitutes the rotation receiving portion 26 in which the rotational movement around the axis 20 a of the rotor 20 is restricted with respect to the rotor 20. By doing in this way, the rotation receiving part 26 is couple | bonded with the rotor 20 without changing the attitude | position, and rotation of the rotor 20 is transmitted more reliably.

  In the present embodiment, the nut member 25 is disposed at the front end portion of the rotor 20. By doing in this way, for example, compared to the configuration in which the nut member 25 is disposed at the center portion or the rear end portion of the rotor 20, the screw shaft 40 can be moved forward as much as possible from the rotor 20 in the screw shaft 40. The protruding length of can be made larger.

  In the present embodiment, the nut member 25 is disposed inside the rotor 20, and further includes a front bearing 16 that rotatably supports a portion of the rotor 20 where the nut member 25 is disposed. By doing so, the nut member 25 faces the front bearing 16 with the rotor 20 interposed therebetween, so that most of the force applied to the nut member 25 is transmitted to the front bearing 16 without being absorbed by the rotor 20. Therefore, it is possible to suppress the force applied to the nut member 25 from being absorbed by the rotor 20. For example, as compared with a configuration in which a portion of the rotor 20 where the nut member 25 is not disposed is pivotally supported by the front bearing 16. Deflection can be suppressed.

  In the present embodiment, the head portion 45 is formed in a spherical shape, and a head portion groove 45b extending in the rotational direction of the rotor 20 is provided at a position shifted forward from the center of the spherical shape. By doing in this way, the connection part 48 which is the part which provided the head part groove | channel 45b in the head part 45 becomes fragile so that a deformation | transformation is possible, and the disk which is a part near the front part from the head part groove | channel 45b in the head part 45 The portion 46 can be made swingable. Therefore, even when the connected body T is fixed to the disc portion 46, the connected body T can be swung, and the maintenance of the posture of the connected body T can be suppressed.

  Therefore, the linear motion actuator of this embodiment can suppress deterioration of the screw mechanism between the nut member 25 and the screw shaft 40.

  In the embodiment described above, the nut member 25 is provided inside the rotor shaft 21, but the present invention is not limited to this. For example, the nut member 25 may be coaxially connected to the front end portion of the rotor shaft 21 and provided outside the rotor shaft 21. Further, the nut member 25 may have a shape other than a spherical shape as long as a swinging portion that can swing in a direction intersecting the axis 20a of the rotor 20 is provided.

  In the above-described embodiment, the groove 25b of the nut member 25 and the head portion groove 45b of the head portion 45 of the screw shaft 40 are formed over the entire circumference in the rotational direction centering on the axis 20a of the rotor 20. However, the present invention is not limited to this. The groove 25b and the head part groove 45b only need to extend at least in the rotational direction so that the swinging part 27 and the disk part 46 can swing according to the displacement direction of the connected body T. .

  In the above-described embodiment, the case 10 is formed in the shape of a rectangular parallelepiped hollow box whose size in the height direction Z is smaller than the size in the width direction X, and the width direction X with the rotor 20 interposed in the case 10. The stator 30 has two stator cores 31 and 31 arranged so as to face each other. However, the present invention is not limited to this. For example, as shown in FIG. 12, it has a case 10A formed in a hollow rectangular parallelepiped shape having the same size in the width direction X and the size in the height direction Z, and accommodates the rotor 20 inside the case 10A. The linear motion actuator 2 may be configured to include the stator 30A having one stator core 31A arranged in this manner.

  The stator core 31A is formed by laminating thin electromagnetic steel plates in the axial direction P (front-rear direction in FIG. 12). The stator core main body 32A is formed in a square tube shape, and the inner peripheral surface of the stator core main body 32A. It has four A-phase stator teeth 33 and four B-phase stator teeth 34 arranged at 32A1. The stator core main body portion 32A has a cross-sectional shape orthogonal to the axial direction P so that the outer peripheral edge is square and the inner peripheral edge is circular. The four A-phase stator teeth 33 and the four B-phase stator teeth 34 are alternately arranged at equal intervals in the circumferential direction on the inner peripheral surface 32A1 of the stator core main body portion 32A. That is, the rotor 20 is surrounded by the four A-phase stator teeth 33 and the four B-phase stator teeth 34. By doing in this way, torque can be applied to the rotor 20 from the entire circumferential direction. The configuration of the rotor and the stator in such a linear motion actuator is arbitrary as long as it does not contradict the purpose of the present invention.

  Although this embodiment of the present invention has been described above, the present invention is not limited to these examples. As long as a person skilled in the art appropriately adds, deletes, and modifies the design of each of the above-described embodiments, and appropriately combines the features of each of the embodiments, the gist of the present invention is included. And within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1, 2 ... Linear motion actuator 10, 10A ... Case, 11 ... Case main-body part, 12 ... Perimeter wall part, 13 ... Front wall part, 13a ... Front shaft insertion hole, 14 ... Back wall part, 14a ... Rear shaft insertion hole , 16 ... front bearing (bearing portion), 17 ... rear bearing, 20 ... rotor, 20a ... axis of rotor, 21 ... rotor shaft, 21a ... large diameter portion, 21b ... shaft main body portion, 21c ... small diameter portion, 21d ... Flange, 21e ... nut member housing space, 21f ... inner surface surrounding nut member housing space on rotor shaft, 22 ... magnet, 23 ... N pole rotor core, 23a ... core small teeth, 23b ... through hole, 23c ... large diameter portion, 23d ... small diameter part, 24 ... S pole rotor core, 24a ... core small teeth, 24b ... through hole, 24c ... large diameter part, 24d ... small diameter part, 25 ... nut member, 25a ... axis of nut member, 25b ... 25c ... a through hole, 25d ... a part of the through hole, 25e ... another part of the through hole, 26 ... a rotation receiving part, 26a ... a boss, 26b ... a plane of the rotation receiving part, 27 DESCRIPTION OF SYMBOLS ... Oscillating part, 28 ... Connection part, 29 ... Female thread part, 29a ... Center of female screw part, 30, 30A ... Stator, 31, 31A ... Stator core, 32, 32A ... Stator core body part, 32a ... Opposing surface, 32A1 ... Inner circumferential surface, 32b, 32c, 32d ... plane, 33 ... phase A stator teeth, 33a ... shaft portion, 33b ... tip, 33c ... stator small teeth, 34 ... phase B stator teeth, 34a ... shaft portion, 34b ... tip part, 34c ... stator small teeth, 35 ... A phase winding, 36 ... B phase winding, 40 ... screw shaft, 40a ... axis of screw shaft, 41 ... shaft body, 41a ... male screw part, 45 ... head Part, 45b... Head part groove, 6 ... disc part, 47 ... hemispherical part, 48 ... connection part, 49 ... female screw part, T ... connected body, Ta ... center line, Te ... head part accommodation space, Tf ... head part accommodation space in the connection object. Surrounding inner surface, D ... diameter of rotor, L ... axial length of rotor, P ... axial direction of rotor, Q ... circumferential direction of rotor, X ... width direction, Y ... length direction, Z ... height direction.

Claims (6)

A stator,
A cylindrical rotor rotated around an axis by a magnetic action with the stator;
A nut member that is arranged coaxially with the axis of the rotor and that rotates as the rotor rotates;
A screw shaft threadedly engaged with the nut member and advanced or retracted by rotation of the nut member,
A head portion is provided at the front end portion of the screw shaft so as to swingably connect the body to be connected.
The linear actuator according to claim 1, wherein the nut member has a female thread portion into which the screw shaft is screwed and a rocking portion capable of rocking in a direction intersecting with the axis of the rotor. The nut member is formed in a spherical shape and provided with a groove extending in the rotational direction at a position shifted backward from the center of the spherical shape,
A portion of the nut member closer to the front than the groove constitutes the swinging portion,
The linear motion actuator according to claim 1, wherein a nut member housing space surrounded by a spherical inner surface with which the spherical surface of the swinging portion is slidably contacted is provided in the rotor. The portion of the nut member closer to the rear than the groove constitutes a rotation receiving portion in which the rotational movement around the axis of the rotor is restricted with respect to the rotor. Linear actuator. The linear actuator according to any one of claims 1 to 3, wherein the nut member is disposed at a front end portion of the rotor. The nut member is disposed inside the rotor;
The linear motion actuator according to any one of claims 1 to 4, further comprising a bearing portion that rotatably supports a portion of the rotor where the nut member is disposed. 2. The head portion groove formed in a spherical shape and provided with a head portion groove extending in the rotational direction of the rotor at a position shifted forward from the center of the spherical shape. The linear motion actuator according to claim 5.

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