JP5427647B2 - Electric actuator - Google Patents

Description

  The present invention relates to an electric actuator.

  2. Description of the Related Art Conventionally, electric actuators configured to convert a rotary motion of an electric motor into a linear motion of a rod and cause the rod to reciprocate linearly have been widely used as means for conveying a workpiece or the like. As such an electric actuator, for example, the one described in Patent Document 1 is known.

  The actuator of Patent Document 1 includes a hollow base, and a motor case is attached to one end of the base. A servo motor is accommodated in the motor case. The servo motor includes a stator fixed to the inner surface of the motor case, and a rotor that is rotatably disposed on the inner peripheral side of the stator. A rotating shaft is provided on the inner peripheral side of the rotor so as to be able to rotate integrally with the rotor, and a ball screw is connected to the rotating shaft so as to be integrally rotatable.

  A cylindrical rod is supported in the base so as to be movable in the axial direction of the base. A ball screw is inserted into the rod, and a ball nut is screwed into the ball screw. Further, the ball nut and the rod are connected via a rod / nut coupling member.

  Rotation restricting members are provided at four orthogonal positions (positions of 90 degrees when viewed from the cross-sectional direction) on the outer peripheral surface of the rod / nut coupling member. The rotation restricting member includes an elongated plate-like rotation restricting member main body, and notches are formed at both ends of the rotation restricting member main body. Urethane rubber is press-fitted into each notch. When the urethane rubber is press-fitted into the notch, the notch is slightly expanded. Each rotation restricting member is engaged with a groove formed on the inner peripheral surface of the base.

  And when the servomotor is driven and the ball screw rotates along with the rotation of the rotating shaft, the ball nut and the rod try to rotate, but since the rotation restricting member is engaged with the groove, the rod / nut coupling member The rotation of the ball nut and the rod is restricted through the rod, and the rod is linearly moved in the base in the axial direction. Further, in a state where the rotation restricting member is engaged with the groove, urethane rubber is press-fitted and the notch is expanded, so that both end sides of the rotation restricting member main body are in contact with the inner side surface of the groove without any gap. Therefore, generation of vibration and noise is suppressed.

JP 2002-130419 A

  However, in the actuator of Patent Document 1, when the ball nut moves linearly, the ball nut may be eccentric with respect to the axial direction. In this case, when an uneven load is applied to the rotation restricting member, the outer peripheral surface of the rotation restricting member is unevenly worn, and a gap is formed between the outer peripheral surface of the rotation restricting member main body and the inner surface of the groove. . As a result, when rotation is transmitted to the rod / nut coupling member, the outer peripheral surface of the rotation restricting member collides with the inner surface of the groove, and vibration and noise are generated.

  The present invention has been made paying attention to such problems existing in the prior art, and its purpose is to suppress uneven wear of the rotation restricting member and to suppress vibration and noise. An object of the present invention is to provide an electric actuator that can be used.

In order to achieve the above object, an invention according to claim 1 is based on a moving body that is housed in a body and linearly moves in the body based on a rotational motion of a motor, and a linear motion of the moving body. And a rotation restricting member that is attached to the moving body and engages with a groove formed in the body to restrict the rotational movement of the moving body. an actuator, wherein between the mobile body and the inner peripheral surface of said body, the enlarged diameter can wear rings themselves with having a slit is provided in a portion, the wear ring is separated in the Waring the entire outer peripheral surface of the wear ring by provided between the one end and the other end is with the mobile forcibly in diameter state to approach the inner peripheral surface of said body of said body Is a state of being pressed against the surface, the rotation by holding the state in which the movable body is the entire outer peripheral surface of the wear ring and enlarged when eccentric moving is pressed against the inner peripheral surface of said body The gist is to suppress the application of an offset load to the regulating member .

  The invention according to claim 2 is the gist of the invention according to claim 1, wherein an urging member for expanding the diameter of the wear ring is further provided on the inner peripheral side of the wear ring. To do.

The gist of the invention described in claim 3 is that, in the invention described in claim 1 or claim 2, a plurality of notches are provided on the outer peripheral surface of the wear ring .

  According to the present invention, uneven wear of the rotation restricting member can be suppressed, and vibration and noise can be suppressed.

The longitudinal cross-sectional view of the electric actuator in embodiment. FIG. 2 is a sectional view taken along line AA in FIG. 1. The longitudinal cross-sectional view which expands and shows the peripheral part of a piston. The perspective view which shows a 1st wear ring. The longitudinal cross-sectional view which expands and shows the peripheral part of a rod cover. The top view which shows the 1st wear ring in another embodiment. The top view which shows the 1st wear ring in another embodiment. The top view which shows the 1st wear ring in another embodiment. The longitudinal cross-sectional view which expands and shows the peripheral part of the rod cover in another embodiment.

  Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS. In the following description, the front-rear direction of the electric actuator 10 is the direction of the arrow Y1 shown in FIG.

  As shown in FIG. 1, the electric actuator 10 includes a cylindrical body 11. A circular hole-like accommodation hole 12 is formed in the body 11 so as to extend along the longitudinal direction of the body 11. An annular rod cover 13 as a contact member is provided on the front end side (one end side) in the accommodation hole 12, and the front end side of the accommodation hole 12 is closed by the rod cover 13. Further, a connecting block body 14 is joined to the rear end portion (the other end portion) of the body 11, and an insertion hole 14 a is formed in the connecting block body 14.

  A motor case 21 is attached to the rear end portion of the body 11 via a connecting block body 14. The motor case 21 accommodates a motor 22 that can rotate forward and backward. The motor 22 includes a stator 22a fixed to the inner surface of the motor case 21, and a rotor 22b that is rotatably arranged on the inner peripheral side of the stator 22a. A rotating shaft 23 is provided on the inner peripheral side of the rotor 22b so as to be rotatable integrally with the rotor 22b. The rotating shaft 23 is provided so as to extend through the front end face of the motor case 21 until the front end side reaches the insertion hole 14 a of the connection block body 14.

  A ball screw 31 is rotatably supported on the body 11 via a bearing 32 disposed on the rear end side of the body 11. The rear end side of the ball screw 31 is inserted into a coupling 33 disposed in the insertion hole 14 a of the connection block body 14, and the ball screw 31 can be rotated integrally with the rotary shaft 23 through the coupling 33. It is connected to.

  A ball nut 34 constituting a part of the moving body is screwed onto the ball screw 31, and an annular piston 35 is fitted on the outer peripheral surface of the ball nut 34. The piston 35 has a large-diameter portion 35a, a medium-diameter portion 35b whose outer diameter is smaller than that of the large-diameter portion 35a, and a small-diameter portion 35c whose outer diameter is smaller than that of the medium-diameter portion 35b. A large-diameter portion 35a, a medium-diameter portion 35b, and a small-diameter portion 35c are provided in this order from the front end to the rear end of the piston 35.

  A cylindrical rod 36 is inserted into the accommodation hole 12. The rod 36 is supported so as to be linearly movable via a rod bearing 13 b as a bearing disposed in the rod cover 13. Female threads are formed on the inner peripheral surfaces of both ends of the rod 36. A male screw formed on the outer peripheral surface of the connecting member 39 is screwed to the female screw on the front end side of the rod 36. For example, a work is attached to the connecting member 39. Further, a male screw formed on the outer peripheral surface of the front end side of the ball nut 34 is screwed to the female screw on the rear end side of the rod 36, and the rod 36 and the ball nut 34 are coupled to be movable together.

  In the ball screw 31, a magnet holder 37 is screwed in front of the bearing 32. The magnet holder 37 has a cylindrical main body portion 37a and a flange portion 37b protruding outward from the main body portion 37a. In a state where the magnet holder 37 is screwed into the ball screw 31, the main body portion 37a enters the rear end side of the piston 35, and the front end surface of the flange portion 37b contacts the rear end surface of the piston 35 (small diameter portion 35c). ing. The flange portion 37b protrudes in the radial direction from the outer peripheral surface of the small diameter portion 35c. A magnet 37c for detecting the position of the piston 35 is held between the rear end surface of the medium diameter portion 35b and the front end surface of the flange portion 37b.

  As shown in FIG. 2, a rotation restricting member 38 is attached to the outer peripheral surface of the medium diameter portion 35 b of the piston 35. The rotation restricting member 38 is formed by injection molding from a low-sliding material such as a fluororesin, and protrudes in a radial direction from the annular main body 38a and the outer peripheral surface of the main body 38a. And four projecting portions 38b extending over the entire axial direction. The four protrusions 38b are arranged at equal intervals along the circumferential direction of the main body 38a.

  Moreover, the groove | channel 12a which can engage each protrusion part 38b is formed in four places in the internal peripheral surface of the accommodation hole 12 (body 11). The four grooves 12 a are formed at equal intervals along the circumferential direction of the accommodation hole 12. Each groove 12 a is formed so as to extend linearly along the longitudinal direction of the body 11 over the entire movement range of the rotation restricting member 38. In a state where the rotation restricting member 38 is accommodated in the accommodation hole 12, each protrusion 38b is engaged with each groove 12a. A slight clearance is provided between the side surface of the protruding portion 38b and the inner surface of the groove 12a facing the side surface.

  When the motor 22 is driven and the rotor 22 b rotates, the rotating shaft 23 rotates and the ball screw 31 rotates as the rotating shaft 23 rotates. When the ball screw 31 rotates, the ball nut 34 tries to rotate, and the rotation is transmitted to the rotation restricting member 38. However, since the protrusion 38b of the rotation restricting member 38 is engaged with the groove 12a, the rotation restricting member 38 is rotated. And the rotation of the ball nut 34 are restricted. The ball nut 34 linearly moves along the axial direction of the ball screw 31 as the ball screw 31 rotates, and the piston 35, the rod 36, and the magnet holder 37 are integrated with the ball nut 34 in the housing hole 12 (body 11). It is designed to move in a straight line. Therefore, the piston 35 and the magnet holder 37 constitute a moving body that moves linearly within the body 11. Further, when the ball nut 34 moves in the protruding direction of the rod 36 and the front end surface of the ball nut 34 contacts the rear end surface of the rod cover 13, the movement of the rod 36 in the protruding direction is restricted. Yes.

  As shown in FIG. 3, a mounting recess 41 is formed on the outer peripheral surface of the large-diameter portion 35 a of the piston 35. A wear ring 43 is attached.

  The outer diameter of the first O-ring 42 is formed larger than the inner diameter of the first wear ring 43 when it is shaped into an annular shape. The first O-ring 42 is disposed on the bottom 41 a side of the first wear ring 43 in the mounting recess 41, and the outer peripheral surface of the first O-ring 42 is the first wear ring 43. It is in contact with the inner surface. Further, the first O-ring 42 urges the first wear ring 43 in the direction away from its central axis along the radial direction by its elastic restoring force.

  As shown in FIG. 4, the first wear ring 43 is formed of a highly slidable material such as polyacetal resin, and a slit 43a is formed in a part thereof to form an incomplete ring shape. By forming the slits 43a, the first wear ring 43 expands its diameter by itself. In addition, the first wear ring 43 is formed such that one end and the other end are separated from each other and the one end side and the other end side do not overlap with each other, and a portion to be polymerized along the radial direction is not formed.

  As shown in FIG. 3, in a state where the first wear ring 43 is mounted in the mounting recess 41, the first wear ring 43 is forcibly pushed toward both ends along the inner peripheral surface of the body 11. Reduced diameter. However, the first wear ring 43 is biased by the biasing force of the first O-ring 42 in the direction of increasing the diameter from the inner peripheral side. Due to the first O-ring 42, the entire outer peripheral surface 43 b of the first wear ring 43 protrudes in the radial direction from the outer peripheral surface of the large-diameter portion 35 a of the piston 35. Further, the entire outer peripheral surface 43 b of the first wear ring 43 is pressed against the inner peripheral surface of the body 11 by the biasing force of the first O-ring 42, and the inner peripheral surface of the body 11 is moved when the piston 35 is moved. It comes to slidably contact with.

  As shown in FIG. 5, a mounting recess 51 is formed on the inner peripheral surface of the rod cover 13, and a second O-ring 52 and a second wear ring as biasing members are formed in the mounting recess 51. 53 is attached.

  The inner diameter of the second O-ring 52 is smaller than the outer diameter of the second wear ring 53 when it is shaped into an annular shape. The second O-ring 52 is disposed in the mounting recess 51 closer to the bottom 51 a than the second wear ring 53, and the inner peripheral surface of the second O-ring 52 is the second wear ring 53. It is in contact with the outer peripheral surface. Further, the second O-ring 52 urges the second wear ring 53 in the direction approaching its central axis along the radial direction by its elastic return force. The second wear ring 53 has substantially the same configuration as the first wear ring 43 already described, and thus detailed description thereof is omitted.

  In a state where the second wear ring 53 is mounted in the mounting recess 51, the diameter of the second wear ring 53 is reduced by the urging force of the second O-ring 52. When the diameter of the second wear ring 53 is reduced by the urging force of the second O-ring 52, the entire inner peripheral surface 53 b of the second wear ring 53 is more radial than the inner peripheral surface of the rod cover 13. Protruding. Further, the entire inner peripheral surface 53 b of the second wear ring 53 is pressed against the outer peripheral surface of the rod 36 by the urging force of the second O-ring 52, and the rod 36 moves to the outer peripheral surface of the rod 36 when moving. It comes in sliding contact.

  In the electric actuator 10 having the above configuration, when the piston 35 and the rod 36 move linearly within the body 11, the piston 35 and the rod 36 may be eccentric with respect to the axial direction. In this case, the first wear ring 43 is pressed toward the bottom 41 a side of the mounting recess 41. Then, the first O-ring 42 closer to the bottom 41a than the first wear ring 43 is crushed and deformed, and due to this deformation, the first O-ring 42 is elastically restored to return to its original shape. Power is generated. Then, the first wear ring 43 is urged in the radial direction by the elastic restoring force, and the urging force resists the eccentric load generated by the eccentricity of the piston 35 and the rod 36 and the first wear. The diameter of the ring 43 is increased, and the entire outer peripheral surface 43 b of the first wear ring 43 is in pressure contact with the inner peripheral surface of the body 11.

  Further, when the second wear ring 53 is pressed toward the bottom 51a side of the mounting recess 51, the second O-ring 52 closer to the bottom 51a than the second wear ring 53 is crushed and deformed. Thus, the second O-ring 52 generates an elastic return force that attempts to return to the original shape. Then, the second wear ring 53 is urged in the radial direction by the elastic restoring force, and this urging force resists the eccentric load generated by the eccentricity of the piston 35 and the rod 36, and the second wear ring 53. The diameter of the ring 53 is reduced, and the entire inner peripheral surface 53 b of the second wear ring 53 is in pressure contact with the outer peripheral surface of the rod 36.

In the above embodiment, the following effects can be obtained.
(1) The piston 35 is provided with a first wear ring 43, and the first wear ring 43 itself is configured to expand in diameter. The entire circumferential direction on the outer peripheral surface 43 b of the first wear ring 43 is pressed against the inner peripheral surface of the body 11. Therefore, even if the piston 35 tries to be eccentric while moving, the eccentricity of the piston 35 can be suppressed by the pressure contact of the first wear ring 43. As a result, it is possible to suppress an unbalanced load from being applied to the rotation restricting member 38, and it is difficult for the engagement portion between the protrusion 38b and the groove 12a in the rotation restricting member 38 to be worn. Uneven wear can be suppressed. Since uneven wear of the rotation restricting member 38 can be suppressed, it is difficult to form a gap between the protrusion 38b and the groove 12a, and vibration and noise generated by the protrusion 38b coming into contact with the groove 12a are prevented. Can be suppressed.

  (2) In order for the rotation restricting member 38 to move linearly within the body 11, a slight clearance is provided between the side surface of the protrusion 38b and the inner surface of the groove 12a facing this side surface. However, since the entire outer peripheral surface 43b of the first wear ring 43 is pressed against the inner peripheral surface of the body 11, the rotation restricting member 38 is prevented from rotating vigorously, and the side surface of the protruding portion 38b is formed on the groove 12a. The generation of noise associated with the collision with the inner surface can be suppressed.

  (3) The first O-ring 42 is provided on the inner peripheral side of the first wear ring 43, and the first wear ring 43 is urged so as to be expanded in diameter by the first O-ring 42. . Therefore, as compared with the case where the first wear ring 43 is not urged by the first O-ring 42, the diameter of the first wear ring 43 is expanded more reliably, and the outer peripheral surface of the first wear ring 43. 43b can be reliably brought into pressure contact with the inner peripheral surface of the body 11.

  (4) A second wear ring 53 is attached to the inner peripheral surface of the rod cover 13. The entire circumferential direction on the inner circumferential surface 53 b of the second wear ring 53 is pressed against the outer circumferential surface of the rod 36. Therefore, the eccentricity of the rod 36 is suppressed by the rod bearing 13b, but the eccentricity of the rod 36 can be further suppressed by providing the second wear ring 53 in the vicinity of the rod bearing 13b.

  (5) The second O-ring 52 is provided on the outer peripheral side of the second wear ring 53, and the second wear ring 53 is urged so as to reduce the diameter by the second O-ring 52. Therefore, compared with the case where the second wear ring 53 is not biased by the second O-ring 52, the diameter of the second wear ring 53 is further reduced, and the inner peripheral surface 53 b of the second wear ring 53. Can be reliably brought into pressure contact with the outer peripheral surface of the rod 36.

  (6) In the electric actuator 10 of the present embodiment, the first O-ring 42 is provided in order to expand the diameter of the first wear ring 43. Therefore, the elastic restoring force of the first O-ring 42 acts on the first wear ring 43 as an urging force, and the entire outer peripheral surface 43b of the first wear ring 43 is pressed against the inner peripheral surface of the body 11 so that the body 11 follow the inner peripheral surface. Therefore, even if there is a dimensional tolerance in the inner diameter of the body 11, the first wear ring 43 can be sufficiently pressed against the inner peripheral surface of the body 11 to follow.

  (7) The elastic restoring force of the first O-ring 42 acts on the first wear ring 43 as an urging force, and the entire outer peripheral surface 43 b of the first wear ring 43 is pressed against the inner peripheral surface of the body 11. Therefore, the first wear ring 43 can serve as a centering bearing for the piston 35. Therefore, the backlash of the piston 35 can be absorbed, and even if an eccentric load is applied to the piston 35, the piston 35 can be made difficult to be eccentric. As a result, the rod 36 can be prevented from dripping when the rod 36 protrudes from the body 11.

  (8) The entire outer peripheral surface 43 b of the first wear ring 43 is pressed against the inner peripheral surface of the body 11 by the radial biasing force of the first O-ring 42. Therefore, the inner peripheral surface of the body 11 and the outer peripheral surface of the piston 35 are not in direct contact with each other, so that no galling occurs between the body 11 and the piston 35. Therefore, the operability of the electric actuator 10 can be improved.

In addition, you may change embodiment as follows.
In the embodiment, as shown in FIG. 6, a plurality of notches 61 may be formed on the outer peripheral surface 43 b of the first wear ring 43 at equal intervals along the circumferential direction of the first wear ring 43. . Each notch 61 intersects the outer peripheral surface 43b of the first wear ring 43 and extends in a straight line from the outer peripheral surface 43b of the first wear ring 43 so as to approach each other radially inward. It consists of a side surface 61a and a second inner side surface 61b. The radially inner ends of the first inner side surface 61a and the second inner side surface 61b intersect each other, and the notch 61 has a V shape in plan view. According to this, the lubricating oil applied between the inner peripheral surface of the body 11 and the outer peripheral surface 43 b of the first wear ring 43 is easily stirred by the notch 61, and the outer peripheral surface of the first wear ring 43. The lubricity between the inner peripheral surface of the body 11 and the outer peripheral surface 43b of the first wear ring 43 can be improved as compared with the case where the notch 61 is not formed in 43b.

  In the embodiment, as shown in FIG. 7, a plurality of notches 71 may be formed on the outer circumferential surface 43 b of the first wear ring 43 at equal intervals along the circumferential direction of the first wear ring 43. . Each notch 71 intersects with the outer peripheral surface 43b of the first wear ring 43 and extends linearly from the outer peripheral surface 43b of the first wear ring 43 in parallel to each other in the radial direction. 71a and a second inner side surface 71b, and a bottom surface 71c connecting the first inner side surface 71a and the second inner side surface 71b. The bottom surface 71c extends linearly in a direction orthogonal to the first inner side surface 71a and the second inner side surface 71b.

  In the embodiment, as shown in FIG. 8, a plurality of notches 81 may be formed on the outer peripheral surface 43 b of the first wear ring 43 at equal intervals along the circumferential direction of the first wear ring 43. . Each notch 81 intersects with the outer peripheral surface 43b of the first wear ring 43, and extends linearly from the outer peripheral surface 43b of the first wear ring 43 toward the inner side in the radial direction. 81a and a second inner side surface 81b, and a bottom surface 81c connecting the first inner side surface 81a and the second inner side surface 81b. The bottom surface 81c extends so as to draw an arc from the radially inner ends of the first inner surface 61a and the second inner surface 61b.

  In the embodiment, the mounting recess 51 is formed on the inner peripheral surface of the rod cover 13, and the second O-ring 52 and the second wear ring 53 are mounted in the mounting recess 51, but this is not a limitation. For example, as shown in FIG. 9, in the rod cover 13, the mounting recess 91 is formed inside the rod bearing 13 b, and the second O-ring 52 is mounted in the mounting recess 91. The rod bearing 13b may be biased in the direction approaching its own central axis along the radial direction by the elastic restoring force. In this case, a slit needs to be formed in a part of the rod bearing 13b so that the rod bearing 13b itself can be reduced in diameter. According to this, since the whole inner peripheral surface of the rod bearing 13b is pressed against the outer peripheral surface of the rod 36, the eccentricity of the rod 36 with respect to the axial direction can be suppressed without providing the second wear ring 53. Can do.

  In the embodiment, the first O-ring 42 and the second O-ring 52 having an annular shape are used as the urging members. However, the present invention is not limited to this, and a rubber member having an incomplete annular shape having a slit in part. Or a plurality of rubber pieces or springs provided in the mounting recesses 41 and 51.

  In the embodiment, since the first wear ring 43 and the second wear ring 53 themselves have a function of increasing or decreasing the diameter, the first O-ring 42 or the second O-ring is provided in the mounting recesses 41 and 51. 52 may not be provided.

  In the embodiment, the first wear ring 43 is provided on the piston 35. However, the present invention is not limited thereto. For example, a mounting recess is formed in the ball nut 34, and the first wear ring 43 is provided in the mounting recess. Also good. Furthermore, a first O-ring 42 may be provided on the inner peripheral side of the first wear ring 43 in the mounting recess.

  In the embodiment, the first wear ring 43 is provided on the piston 35. However, the present invention is not limited thereto. For example, the flange portion 37b of the magnet holder 37 is extended to the inner peripheral surface of the body 11, and the mounting recess is mounted on the flange portion 37b. The first wear ring 43 may be provided in the mounting recess. Furthermore, a first O-ring 42 may be provided on the inner peripheral side of the first wear ring 43 in the mounting recess.

In the embodiment, the second O-ring 52 and the second wear ring 53 provided on the inner peripheral surface of the rod cover 13 may be deleted.
In the embodiment, a slide nut may be used instead of the ball nut 34.

The technical idea conceivable from the above embodiment and other examples will be described below.
(A) A slit is formed in a part of the bearing, the bearing can be reduced in diameter by itself, and an urging member for reducing the diameter of the bearing is provided on the outer peripheral side of the bearing. The electric actuator according to claim 4 or 5, wherein the electric actuator is provided.

  DESCRIPTION OF SYMBOLS 10 ... Electric actuator, 11 ... Body, 13 ... Rod cover as contact member, 13b ... Rod bearing, 22 ... Motor, 34 ... Ball nut which comprises a part of moving body, 35 ... A part of moving body , Piston, 36 ... rod, 37 ... magnet holder constituting a part of the moving body, 38 ... rotation restricting member, 42 ... first O-ring as urging member, 43 ... first wear ring, 43a ... slit 43b ... outer peripheral surface, 52 ... second O-ring as a biasing member, 53 ... second wear ring, 53b ... inner peripheral surface, 61, 71, 81 ... notches.

Claims (3)

A moving body that is housed in the body and linearly moves in the body based on the rotational movement of the motor;
A rod that is projected and retracted with respect to the body based on a linear motion of the moving body;
A rotation restricting member that is attached to the moving body and engages with a groove formed in the body to restrict the rotational movement of the moving body ,
Wherein between the mobile and the inner circumferential surface of the body, the enlarged diameter can wear rings are provided itself with a slit in a part,
The wear ring is provided between the movable body and the inner peripheral surface of the body in a state in which the diameter is forcibly reduced so that one end and the other end that are separated in the wear ring approach each other . The entire outer peripheral surface is pressed against the inner peripheral surface of the body, and the diameter of the wear ring is increased when the movable body is eccentric while moving, and the entire outer peripheral surface of the wear ring is pressed against the inner peripheral surface of the body. An electric actuator characterized in that an unbalanced load is suppressed from being applied to the rotation restricting member by holding the state .   2. The electric actuator according to claim 1, wherein a biasing member for expanding the diameter of the wear ring is further provided on an inner peripheral side of the wear ring.   The electric actuator according to claim 1, wherein a plurality of notches are provided on an outer peripheral surface of the wear ring.

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