Actuator

Abstract

To provide an actuator whose shaft has higher propulsive force and whose motor has higher reverse actuation.SOLUTION: An actuator includes a first motor having a first stator and a first rotor, a second motor that is spaced apart from the first motor in the axial direction of the central axis and includes a second stator and a second rotor, a shaft member that axially passes through the first rotor and the second rotor and has a first portion, a second portion, and a third portion, a spline outer cylinder, a nut member, and a mounting member that is attached to the outer circumferential side of the second portion via a bearing and that blocks transmission of rotational force of the second portion.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to actuators. [Background technology]

[0002] An actuator having a ball screw and a ball spline is known (see, for example, Patent Document 1). The actuator described in Patent Document 1 includes a ball screw nut, a ball spline outer cylinder, one motor, a compound shaft having both a ball screw groove and a ball spline groove formed on its outer periphery, and an attachment member fixed to an end of the compound shaft. With this configuration, the ball screw nut rotates when driven by the motor, and the compound shaft and the attachment member fixed to the compound shaft perform linear motion in the axial direction along the ball spline groove. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-300106 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for an actuator that has a higher thrust when the compound shaft moves linearly and a higher reverse action of the motor when the compound shaft is subjected to an external force.

[0005] The present disclosure has been made in consideration of the above, and has an object to provide an actuator having a higher thrust force of a shaft and a higher reverse action capability of a motor. [Means for solving the problem]

[0006] An actuator according to one aspect of the present disclosure includes a first motor having a first stator and a first rotor rotatable in a direction around a central axis relative to the first stator; a second motor arranged at a distance in the axial direction of the central axis relative to the first motor, and having a second stator and a second rotor rotatable relative to the second stator and arranged coaxially with the central axis of the first rotor; a first portion penetrating the first rotor and the second rotor in the axial direction, protruding from the first rotor toward an opposite side of the second rotor in the axial direction and having a spline groove portion on an outer periphery thereof, the spline groove portion extending in the axial direction, a second portion being arranged on one side of the first portion in the axial direction and extending in the axial direction, and a second portion extending forward from the second rotor. the second rotor includes a shaft member having a third portion protruding toward the other side in the axial direction toward the opposite side of the first rotor and having a male threaded portion on its outer periphery; a spline outer cylinder that guides the shaft member in the axial direction along the spline groove portion of the first portion of the shaft member and rotates together with the first rotor to rotate the shaft member in an axial direction around the central axis; a nut member that has a female threaded portion that meshes with the male threaded portion of the third portion of the shaft member via a plurality of balls and that rotates together with the second rotor to move the shaft member in the axial direction; a bearing; and an attachment member that is attached to the outer periphery of the second portion via the bearing, and the transmission of rotational force of the second portion is blocked by the bearing.

[0007] The actuator of Patent Document 1 described above has only one motor, and the driving force when the compound shaft moves linearly also comes from the driving force of the single motor. In contrast, the actuator of the present disclosure has two motors, a first motor and a second motor. Therefore, by driving and rotating both the first motor and the second motor, the axial driving force of the shaft member can be increased.

[0008] In addition, in the actuator of Patent Document 1, it is also conceivable to arrange two motors side by side in order to obtain a high propulsive force. However, when two motors are arranged side by side and subjected to reverse operation, the torque generated by the back electromotive force in the two motors becomes larger than the torque generated by the back electromotive force in one motor of the actuator of Patent Document 1. Therefore, when two motors are arranged in Patent Document 1, the reverse operation of the motors is low. In contrast, in the present disclosure, as described above, when an external force in the axial direction is input to the mounting member, only the second motor is rotated, and the first motor does not output a torque due to the back electromotive force. Therefore, the actuator according to one aspect of the present disclosure has a higher reverse operation of the motor.

[0009] In addition, since the transmission of rotational force from the second portion to the mounting member is blocked, the mounting member is capable of responding to a free movement mode independent of the second portion.

[0010] In a preferred embodiment, the central axis of the bearing is coaxial with the central axis of the first rotor, thereby suppressing radial vibration of the mounting member caused by rotation when the mounting member is rotated relative to the second portion.

[0011] In a preferred embodiment, the motor housing includes a cylindrical motor housing that extends in a circumferential direction around the central axis and that houses the first motor and the second motor. In this manner, the motor housing is cylindrical and has high rigidity. Therefore, even if an external force that vibrates in the radial direction is applied to the motor housing via an attachment member, the motor housing can support the external force.

[0012] In a preferred embodiment, the shaft member is divided into a first shaft including the first portion and a second shaft including the second portion, and the first shaft and the second shaft are connected by screw fastening. With this, when wear or the like occurs in the first shaft or the second shaft, only the member where wear or the like occurs needs to be replaced, and therefore, it is possible to reduce parts costs.

[0013] In a preferred embodiment, the first motor and the second motor are direct drive motors. A direct drive motor transmits the generated driving force directly to an object without a reduction mechanism. That is, the shaft member can be rotated by directly rotating the spline outer cylinder with the driving force of the first motor. Also, the shaft member can be linearly moved by directly rotating the nut member with the driving force of the second motor. Effect of the Invention

[0014] According to the present invention, it is possible to provide an actuator having a higher shaft thrust and a higher motor reverse action capability. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a cross-sectional view of an actuator according to an embodiment. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of a portion of FIG. [Diagram 3] FIG. 3 is a cross-sectional view of the actuator according to the embodiment, showing a state in which the stroke of the shaft member is at the upper limit. [Figure 4] FIG. 4 is an enlarged cross-sectional view of a portion of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The following describes in detail the form (embodiment) for carrying out the invention with reference to the drawings. The present invention is not limited to the contents described in the following embodiment. The components described below include those that a person skilled in the art can easily imagine and those that are substantially the same. Furthermore, the components described below can be appropriately combined.

[0017] Fig. 1 is a cross-sectional view of an actuator according to an embodiment. Fig. 2 is a cross-sectional view of an enlarged portion of Fig. 1. Fig. 3 is a cross-sectional view of the actuator according to an embodiment, showing a state in which the stroke of a shaft member is at the upper limit. Fig. 4 is a cross-sectional view of an enlarged portion of Fig. 3.

[0018] As shown in Fig. 1, the actuator 1 is used, for example, as a pick-and-place device. The actuator 1 includes a first motor M1, a second motor M2, a shaft member SF, a spline outer cylinder 61, a nut member 51, a mounting member 70, a first motor housing 40, and a second motor housing 40A. Hereinafter, the central axis of the first motor M1 and the second motor M2 is referred to as a central axis AX, and the axial direction of the central axis AX is referred to as a Z direction. One side in the axial direction (Z direction) is referred to as a Z1 side, and the other side in the axial direction (Z direction) is referred to as a Z2 side.

[0019] The first motor M1 includes a first stator 10, a first rotor 20, and a first rotation detection unit 101.

[0020] A first stator holder 11 is disposed radially inside the first stator 10. The first stator 10 is fixed to the first stator holder 11. The first rotor 20 is disposed on the outer peripheral side of the first stator 10. The first rotor 20 rotates about a central axis AX. The first rotor 20 has a first rotor bracket 21 and a first rotor core 22. The first rotor core 22 is fixed radially inside the first rotor bracket 21. The first rotor core 22 has a permanent magnet. The first rotor bracket 21 has a cylindrical shape centered on the central axis AX. The first rotor bracket 21 also has an outer ring holder 21a that supports an outer ring of the first bearing 31.

[0021] The first stator 10 and the first rotor 20 are arranged coaxially around the central axis AX. The first rotor 20 is arranged radially outward of the first stator 10 and the first stator holder 11 and rotates relative to the first stator 10. In other words, the first rotor 20 is rotatably supported by the first stator 10 and the first stator holder 11 via a first bearing 31. The first stator holder 11 is fixed to the first motor housing 40 via a bolt. The first stator 10 is provided in a cylindrical shape around the central axis AX.

[0022] The first motor housing 40 is formed, for example, in a cylindrical shape and accommodates the first motor M1. The upper end of the first motor housing 40 is open, and the opening is covered by the spline outer cylinder housing 43. The spline outer cylinder housing 43 includes a housing main body portion 43a and a tubular portion 43b. The tubular portion 43b is provided in a cylindrical shape along the axial direction of the central axis AX. The spline outer cylinder 61 is disposed inside the tubular portion 43b. The housing main body portion 43a is attached to the upper bottom portion 40a of the first motor housing 40 via a bolt. A first cover member 111 is provided on the Z2 side of the housing main body portion 43a. The first cover member 111 is fixed to the outer ring holder 21a of the first rotor bracket 21 via a bolt. A through hole is provided in the radial center of the first cover member 111, and the spline outer cylinder 61 passes through the through hole. The underside of first cover member 111 is provided with a recess 112 that is recessed upward.

[0023] Although not shown, a spline portion is provided on the inner circumference of the spline outer cylinder 61. The spline portion meshes with a spline groove portion 633 provided on the outer circumference of the shaft member SF described later via a plurality of balls. The spline portion has a plurality of protrusions that protrude toward the inner circumference and extend in the axial direction (Z direction). The plurality of protrusions are disposed at equal intervals in the circumferential direction on the inner circumference of the spline outer cylinder 61. A flange 62 that extends radially outward is provided on the lower end of the spline outer cylinder 61. The flange 62 is inserted into the recess 112. The flange 62 is fixed to the first cover member 111 via a bolt.

[0024] The first rotation detection unit 101 is, for example, a resolver. The first rotation detection unit 101 detects the rotation state of the first motor M1. The first rotation detection unit 101 is disposed above the first bearing 31.

[0025] The second motor M2 is located on the Z2 side relative to the first motor M1. The second motor M2 is arranged next to the first motor M1 in the axial direction of the central axis AX. The second motor M2 has a second stator 10A, a second rotor 20A, and a second rotation detector 101A. The first motor M1 and the second motor M2 are cylindrical direct drive motors.

[0026] The second rotor 20A is disposed on the outer periphery of the second stator 10A. The second rotor 20A rotates about a central axis AX. That is, the central axis of the second rotor 20A is coaxial with the central axis AX of the first rotor 20. The second rotor 20A has a second rotor bracket 21A and a second rotor core 22A. The second rotor core 22A is fixed to the radially inner side of the second rotor bracket 21A. The second rotor core 22A has a permanent magnet. The second rotor bracket 21A is formed in a cylindrical shape centered on the central axis AX. The second stator 10A and the second rotor 20A are disposed coaxially centered on the central axis AX.

[0027] The second rotor 20A is disposed radially outside the second stator 10A and the second stator holder 11A, and rotates relative to the second stator 10A and the second stator holder 11A. In other words, the second rotor 20A is rotatably supported by the second stator 10A and the second stator holder 11A via the second bearing 32. The second stator 10A is fixed to the second stator holder 11A. The second stator holder 11A is disposed radially inside the second stator 10A. The second stator holder 11A is fixed to the second motor housing 40A via a bolt. The second stator 10A is provided in a cylindrical shape around the central axis AX.

[0028] Here, the shaft member SF will be described. The shaft member SF is disposed coaxially with the central axis AX. The shaft member SF extends in the axial direction of the central axis AX. The shaft member SF has a first shaft 63 and a second shaft 53.

[0029] The first shaft 63 extends from the connecting portion 100 to the small diameter portion 635. The connecting portion 100 is provided at a position aligned with the second rotation detection portion 101A in the Z direction. The first shaft 63 includes a small diameter portion 632, a large diameter portion (first portion S1) 631, a medium diameter portion 634, and a small diameter portion 635. The small diameter portion 632, the large diameter portion 631, the medium diameter portion 634, and the small diameter portion (second portion S2) 635 are arranged in this order from the Z2 side toward the Z1 side.

[0030] The second motor M2 is disposed on the outer periphery of the small diameter portion 632. The first motor M1 is disposed on the outer periphery of the large diameter portion 631. The end of the large diameter portion 631 on the Z2 side is aligned with the lower bottom portion 40b of the first motor housing 40 in the Z direction. The large diameter portion 631 is also referred to as the first portion S1. A spline groove portion 633 is provided on the outer periphery of the large diameter portion 631. The spline groove portion 633 has a diameter D1. The diameter D1 of the spline groove portion 633 is the larger of the large diameter and the small diameter. That is, the diameter D1 of the spline groove portion 633 is larger than the outer diameter of the small diameter portion 632, the outer diameter of the medium diameter portion 634, and the outer diameter of the thin diameter portion 635. The spline groove portion 633 extends in the Z direction (axial direction). A plurality of spline groove portions 633 are provided on the outer periphery of the large diameter portion 631 at equal intervals in the circumferential direction. As described above, the spline groove portion 633 meshes with the spline portion provided on the inner peripheral side of the spline outer cylinder 61 via multiple balls. Therefore, the shaft member SF is movable in the Z direction (axial direction) relative to the spline outer cylinder 61 but is unable to rotate in the circumferential direction around the central axis AX.

[0031] The medium diameter portion 634 protrudes from the Z1 side end of the large diameter portion 631 toward the Z1 side. The outer diameter of the medium diameter portion 634 is larger than the outer diameter of the small diameter portion 632. The thin diameter portion 635 protrudes from the Z1 side end of the medium diameter portion 634 toward the Z1 side. The thin diameter portion 635 is also referred to as a second portion S2. The outer diameter of the thin diameter portion 635 is smaller than the outer diameter of the small diameter portion 632, the outer diameter of the large diameter portion 631, and the outer diameter of the medium diameter portion 634.

[0032] The second shaft 53 extends from the connecting portion 100 to the stopper 55. The second shaft 53 has a large diameter portion (third portion S3) 531, a small diameter portion 532, and a thin diameter portion 531a. The thin diameter portion 531a, the large diameter portion 531, and the small diameter portion 532 are arranged in order from the Z1 side to the Z2 side. A male thread is provided on the outer periphery of the thin diameter portion 531a. A recess 632a is provided at the end of the small diameter portion 632 of the first shaft 63. A female thread is provided on the inner periphery of the recess 632a to mesh with the male thread of the thin diameter portion 531a. The female thread on the inner periphery of the recess 632a meshes with the male thread of the thin diameter portion 531a. As a result, the small diameter portion 632 of the first shaft 63 and the large diameter portion 531 of the second shaft 53 are integrally connected. That is, the first shaft 63 and the second shaft 53 are connected by screw fastening to form a connecting portion 100 .

[0033] A male thread portion 533 is formed on the outer periphery of the large diameter portion 531. The large diameter portion 531 is also referred to as a third portion S3. A diameter D1 of the spline groove portion 633 in the shaft member SF is larger than a diameter D2 of the male thread portion 533. The diameter D1 of the spline groove portion 633 is the larger diameter of the large diameter and the small diameter. The diameter D2 of the male thread portion 533 is the outer diameter of the outer diameter and the inner diameter (root diameter).

[0034] Further, a small diameter portion 532 is provided on the Z2 side of the large diameter portion 531. The outer diameter of the small diameter portion 532 is smaller than the diameter D2 of the large diameter portion 531. A stopper 55 is attached to the Z2 side end of the small diameter portion 532 by a nut 56. The stopper 55 is an annular member. A buffer member 55a having a circular shape is provided on the Z1 side of the stopper 55. The buffer member 55a is, for example, an elastic urethane rubber. When the shaft member SF rises, the stopper 55 hits the bottom portion 42c of the nut housing 42 via the buffer member 55a, thereby restricting the rise of the shaft member SF.

[0035] The second motor housing 40A is formed, for example, in a cylindrical shape and houses the second motor M2. The end of the second motor housing 40A on the Z1 side is open, and the shaft member SF is provided to pass through the opening. An upper bottom portion 40Aa is provided on the outer periphery of the opening, extending in an annular shape in the axial direction around the central axis AX. The upper bottom portion 40Aa abuts against the lower bottom portion 40b of the first motor housing 40 and is fixed to the lower bottom portion 40b via a bolt. The lower bottom portion 40Ab of the second motor housing 40A is also open, and the opening is covered by the nut housing 42 and the stopper cover 44. In this way, the first motor housing 40 and the second motor housing 40A have a cylindrical shape extending in the circumferential direction around the central axis AX.

[0036] The nut housing 42 has an upper end flange 42a, a cylindrical portion 42b formed in a cylindrical shape extending downward from the inner peripheral end of the upper end flange 42a, and a bottom portion 42c extending from the lower end of the cylindrical portion 42b to the inner peripheral side. The upper end flange 42a is fixed to the lower bottom portion 40Ab of the second motor housing 40A via a bolt. The stopper cover 44 is fixed to the bottom portion 42c of the nut housing 42 via a bolt. A recessed groove 42d recessed toward the Z2 side is provided on the Z1 side surface of the bottom portion 42c. The diameter of the recessed groove 42d is larger than the outer diameter of the large diameter portion 531 of the second shaft 53. Therefore, the Z2 side end of the large diameter portion 531 fits into the recessed groove 42d. In addition, a through hole is provided in the recessed groove 42d, and the small diameter portion 532 of the second shaft 53 is provided to pass through the through hole.

[0037] The stopper cover 44 has an upper end flange 44a, a cylindrical portion 44b, and a bottom portion 44c. The upper end flange 44a is fixed to the bottom portion 44c via a bolt. The cylindrical portion 44b has a cylindrical shape extending from the upper end flange 44a toward the Z2 side. The bottom portion 44c seals the Z2 side opening of the cylindrical portion 44b. A mounting portion 57 protruding toward the Z2 side is attached to the bottom portion 44c. A through hole 57a is provided in the mounting portion 57. The through hole 57a is, for example, circular. The mounting portion 57 is fixed to, for example, a mechanical device to which the actuator 1 is attached. That is, for example, a protruding portion of the mechanical device is inserted into the through hole 57a and fixed to the mechanical device.

[0038] A nut member 51 and a second connecting bracket 45 are housed inside the nut housing .

[0039] A female threaded portion is provided on the inner peripheral side of the nut member 51. The female threaded portion meshes with a male threaded portion 533 of a large diameter portion 531 of the shaft member SF via a plurality of balls. A second connecting bracket 45 is disposed on the radially outer side of the nut member 51. A flange portion 51a extending radially outward is formed on the Z2 side end of the nut member 51. The flange portion 51a is fixed to the second connecting bracket 45 via a bolt. A flange 45a extending radially outward is provided on the Z1 side end of the second connecting bracket 45, and the flange 45a is fixed to the first connecting bracket 46 via a bolt.

[0040] The first connecting bracket 46 is fixed to the second rotor bracket 21A via a bolt. In this manner, the nut member 51, the second connecting bracket 45, the first connecting bracket 46, and the second rotor bracket 21A are rotatable together. In detail, the nut member 51, the second connecting bracket 45, the first connecting bracket 46, and the second rotor bracket 21A are rotatably supported by the second bearing 32 relative to the second stator 10A and the second stator holder 11A.

[0041] The second rotation detection unit 101A is, for example, a resolver. The second rotation detection unit 101A detects the rotation state of the second motor M2. The second rotation detection unit 101A is disposed at a position aligned with the coupling unit 100 in the axial direction.

[0042] Next, the mounting member 70 will be described. As shown in FIG. 2, the mounting member 70 has a housing 71, a bearing 72, a cover 73, and a mounting portion 75. The mounting member 70 and the thin-diameter portion 635 of the shaft member SF are relatively rotatable in the circumferential direction around the central axis AX. In other words, the mounting member 70 is mounted on the outer periphery of the thin-diameter portion 635 (second portion S2) via a bearing 72, and the bearing 72 blocks the transmission of the rotational force of the thin-diameter portion 635 to the mounting member 70. The thin-diameter portion 635 and the bearing 72 are housed inside the housing 71. The bearing 72 is provided between the housing 71 and the thin-diameter portion 635. The bearing 72 has an inner ring 72a, an outer ring 72b, and a rolling element 72c. The inner ring 72a is sandwiched between the bearing pressing member 74B and the medium-diameter portion 634 in the Z direction and is mounted to the thin-diameter portion 635. The bearing pressing member 74B extends in the circumferential direction around the central axis AX. The bearing pressing member 74B includes a fixed portion 74Ba and a pressing portion 74Bb. The bearing pressing member 74B has a U-shape in a cross section including the central axis AX. The pressing portion 74Bb is provided on the outer circumferential side of the fixed portion 74Ba. The Z-direction thickness of the pressing portion 74Bb is greater than the Z-direction thickness of the fixed portion 74Ba. The fixed portion 74Ba is fixed to the end face on the Z1 side of the small diameter portion 635 via bolts BL1 and BL2. The pressing portion 74Bb presses the inner ring 72a.

[0043] The bearing pressing member 74A extends in the circumferential direction around the central axis AX. The bearing pressing member 74A includes a fixed portion 74Aa and a pressing portion 74Ab. The bearing pressing member 74A has an L-shape in a cross section including the central axis AX. The pressing portion 74Ab is provided on the inner peripheral side of the fixed portion 74Aa. The Z-direction thickness of the pressing portion 74Ab is thicker than the Z-direction thickness of the fixed portion 74Aa. The fixed portion 74Aa is fixed to the bottom surface of the recess 71b of the housing 71 via bolts BL3 and BL4. The pressing portion 74Ab presses the outer ring 72b. That is, the outer ring 72b is attached to the housing 71 by being sandwiched in the Z direction between the bearing pressing member 74A and the bottom portion 71a of the housing 71.

[0044] On the Z1 side of the housing 71, an annular portion 71c protrudes toward the Z1 side along the circumferential direction around the central axis AX. A recess 71b is disposed on the radially inner side of the annular portion 71c. The Z1 side opening of the housing 71 is sealed by a lid 73. The lid 73 is fixed to the Z1 side end face 71d of the annular portion 71c via bolts BL5 and BL6. An attachment portion 75 protrudes toward the Z1 side from the Z1 side end face of the lid 73. A through hole 75a is provided in the attachment portion 75. The through hole 75a is, for example, circular. For example, an arm or the like is attached to the attachment portion 75, and a workpiece is attached to the arm. For example, a protruding portion of the arm is inserted into the through hole 75a, and the arm is fixed to the attachment portion 75.

[0045] Next, the movement of the actuator 1 will be described.

[0046] (First aspect) First, a first mode in which the shaft member SF moves up and down (linearly) will be described. In the first mode, only the second motor M2 operates, and the first motor M1 does not operate.

[0047] 1, when the second motor M2 is operated, the second rotor 20A rotates in a direction around the central axis AX. In detail, the second rotor 20A rotates in a direction around the central axis AX relative to the second stator 10A and the second stator holder 11A via the second bearing 32. The first rotor 20 does not rotate.

[0048] The nut member 51 is integral with the second rotor 20A. Therefore, the nut member 51 also rotates in the axial direction around the central axis AX together with the second rotor 20A. Since the female thread of the nut member 51 is engaged with the male thread 533 of the shaft member SF, the shaft member SF moves linearly along the axial direction due to the rotation of the nut member 51. In detail, as shown in FIG. 3, the shaft member SF rises along the axial direction. As the shaft member SF rises, the stopper 55 hits the bottom 42c of the nut housing 42 via the buffer member 55a, thereby restricting the rise of the shaft member SF. Here, as described above, the mounting member 70 is mounted on the outer periphery side of the thin diameter portion 635 (second portion S2) via the bearing 72, and the transmission of the rotational force of the thin diameter portion 635 is interrupted. Therefore, as shown in FIG. 3 and FIG. 4, the mounting member 70 does not rotate and rises together with the thin diameter portion 635. It is also possible to rotate only the mounting member 70, so the mounting member 70 may be rotated while being raised.

[0049] Next, a manner in which the shaft member SF rotates will be described. This manner includes a second manner, a third manner, and a fourth manner, depending on how the shaft member SF moves in the Z direction.

[0050] (Second aspect) In the second mode, the first motor M1 operates and the second motor M2 does not operate. As described above, the spline groove portion 633 and the spline portion mesh with each other. As a result, the shaft member SF is guided in the axial direction along the spline portion of the spline outer cylinder 61. In addition, the shaft member SF rotates together with the first rotor 20 via the spline outer cylinder 61, so that the shaft member SF can rotate in the axial direction around the central axis AX. Furthermore, since the second motor M2 does not operate, the nut member 51 does not rotate either. Therefore, as shown in Figs. 3 and 4, when the shaft member SF rotates by the spline outer cylinder 61, the shaft member SF rises in the axial direction by the nut member 51. As described above, in the second mode, the shaft member SF rises (linearly moves) by rotating relative to the stationary nut member 51 while rotating integrally with the spline outer cylinder 61. The mounting member 70 can rise together with the thin-diameter portion 635 without rotating. However, it is also possible to rotate the mounting member 70.

[0051] (Third aspect) In the third mode, the shaft member SF rotates integrally with the spline outer cylinder 61, while rotating the nut member 51 so that the position of the shaft member SF in the Z direction does not change. Therefore, in the third mode, both the first motor M1 and the second motor M2 are operated. That is, the rotation by the first motor M1 is the same as in the first mode, and the shaft member SF rotates together with the first rotor 20 via the spline outer cylinder 61, so that the shaft member SF can rotate in the axial direction around the central axis AX. The second motor M2 was not operated in the second mode, but rotates the nut member 51 in the direction opposite to the direction in which the shaft member SF moves linearly. As described above, in the third mode, the shaft member SF rotates integrally with the spline outer cylinder 61 while the position of the shaft member SF in the Z direction does not change. The mounting member 70 does not rotate or rise. However, it is also possible to rotate only the mounting member 70.

[0052] (Fourth aspect) In the fourth embodiment, the shaft member SF rotates integrally with the spline outer cylinder 61, and the rotation speed of the nut member 51 is appropriately adjusted to vary the speed at which the shaft member SF moves linearly (the moving speed in the Z direction). Therefore, in the fourth embodiment, both the first motor M1 and the second motor M2 are operated. That is, the rotation by the first motor M1 is the same as in the first and second embodiments, and the shaft member SF rotates together with the first rotor 20 via the spline outer cylinder 61, so that the shaft member SF can rotate in the axial direction around the central axis AX. The second motor M2 sets the motor rotation speed in accordance with the desired linear moving speed of the shaft member SF. As described above, in the fourth embodiment, the shaft member SF rotates integrally with the spline outer cylinder 61, while the moving speed in the Z direction of the shaft member SF is appropriately adjusted. The mounting member 70 can be moved linearly together with the thin-diameter portion 635 without rotating. However, it is also possible to rotate the mounting member 70.

[0053] Next, the thrust of the shaft member SF and the reverse operation of the motor will be described.

[0054] (Thrust of shaft member SF) In order to obtain a small propulsive force, for example, only one of the two motors M1 and M2 may be driven, specifically, in the first or second manner described above.

[0055] In order to obtain a large propulsive force, for example, both of the two motors M1 and M2 may be driven, specifically, in the above-mentioned third or fourth mode.

[0056] (Motor reverse operation) For example, when an external force toward the Z2 side is input to the mounting member 70, that is, when the motor is subjected to reverse operation, a counter electromotive voltage is generated in the motor, and a torque is output in a direction against the reverse operation. In this embodiment, when an external force on the Z2 side is input to the mounting member 70 and the shaft member SF is pushed toward the Z2 side, only the second motor M2 is rotated, and the first motor M1 does not output a torque due to the counter electromotive voltage. Therefore, compared to a case where both the first motor M1 and the second motor M2 output a torque in a direction against the reverse operation, this embodiment has a higher reverse operation property of the motor.

[0057] A brief description will now be given of the procedure for transmitting force when an external force directed toward the Z2 side is input to the mounting member 70. As shown in Fig. 2, first, the end face 71d of the annular portion 71c is pressed toward the Z2 side from the mounting portion 75 via the cover 73. Next, the bearing pressing member 74A presses the outer ring 72b of the bearing 72, and the inner ring 72a of the bearing 72 presses the medium diameter portion 634 toward the Z2 side. As a result, the shaft member SF is pressed toward the Z2 side, generating a counter electromotive force in the second motor M2.

[0058] As described above, the actuator 1 includes a first motor M1 having a first stator 10 and a first rotor 20, a second motor M2 arranged spaced apart from the first motor M1 in the axial direction of the central axis AX and having a second stator and a second rotor 20A, a shaft member SF axially penetrating the first rotor 20 and the second rotor 20A and having a first portion S1, a second portion S2 and a third portion S3, a spline outer tube 61, a nut member 51, and a mounting member 70 attached to the outer periphery of the second portion S2 via a bearing 72 and blocking the transmission of rotational force of the second portion S2.

[0059] The actuator of Patent Document 1 described above has only one motor, and the driving force when the compound shaft moves linearly also comes from the driving force of the single motor. In contrast, the present embodiment has two motors, a first motor M1 and a second motor M2. Therefore, by driving and rotating both the first motor M1 and the second motor M2, the axial driving force of the shaft member SF can be increased.

[0060] Furthermore, in the actuator of Patent Document 1, if two motors are arranged side by side to obtain a high propulsive force, when the motors are subjected to reverse operation, a back electromotive voltage is generated in the two motors, and a high torque is output in a direction against the reverse operation. Therefore, when two motors are arranged as in Patent Document 1, the reverse operation of the motors is low. In contrast, in this embodiment, as described above, when an external force on the Z2 side is input to the mounting member 70, only the second motor M2 is rotated, and the first motor M1 does not output a torque due to the back electromotive voltage. Therefore, the reverse operation of the motors is higher in this embodiment.

[0061] Furthermore, since the transmission of the rotational force of the second portion S2 to the mounting member 70 is blocked, the mounting member 70 can move freely independent of the second portion S2. Note that, in the initial stage of rotation of the second portion S2, it is possible that a small amount of rotational force due to static friction is transmitted to the mounting member 70, but the "blocking" of the present invention also includes the transmission of this small amount of rotational force in the initial stage.

[0062] The central axis of rotation of the bearing 72 is coaxial with the central axis AX of the first rotor 20. This suppresses radial vibration of the mounting member 70 due to rotation when the mounting member 70 is rotated relative to the small diameter portion 635 (second portion S2).

[0063] The motor housing includes a cylindrical first motor housing 40 and a cylindrical second motor housing 40A (motor housing) that extend in the circumferential direction around the central axis AX and accommodate the first motor M1 and the second motor M2. As described above, the motor housing is cylindrical and has high rigidity. Therefore, even if an external force that vibrates in the radial direction is applied to the motor housing via the mounting member 70, the motor housing can support the external force.

[0064] The shaft member SF is divided into a first shaft 63 including a first portion S1 and a second shaft 53 including a second portion S2, and the first shaft 63 and the second shaft 53 are connected by screw fastening. With this, when wear or the like occurs in the first shaft 63 or the second shaft 53, it is only necessary to replace the member where wear or the like occurs, and therefore it is possible to reduce the cost of parts.

[0065] The first motor M1 and the second motor M2 are direct drive motors. A direct drive motor transmits the generated driving force directly to an object without a speed reducing mechanism. That is, the shaft member SF can be rotated by directly rotating the spline outer cylinder 61 with the driving force of the first motor M1. Also, the shaft member SF can be linearly moved by directly rotating the nut member 51 with the driving force of the second motor M2.

[0066] The first motor housing 40, the second motor housing 40A, the second connecting bracket 45, the nut member 51, the spline outer cylinder 61, the first motor M1, the second motor M2, etc. are each separate. Therefore, when assembling each of them in order, the positional relationship between a given part and other parts can be accurately determined, and highly accurate centering of the motor can be easily performed. [Explanation of symbols]

[0067] 1 Actuator 10 First stator 10A Second Stator 11 First stator holder 11A Second stator holder 20 First Rotor 20A Second Rotor 21 No. 1 rotor bracket 21a Outer ring holder 21A Second rotor bracket 22 First rotor core 22A Second rotor core 31 No. 1 bearing 32 No. 2 bearing 40 First motor housing (motor housing) 40a top bottom 40b bottom bottom 40A Second motor housing (motor housing) 40Aa top bottom 40Ab lower bottom 42 Nut housing 42a Upper flange 42b Cylindrical part 42c bottom 42d groove 43 Spline outer cylinder housing 43a Housing body 43b Cylinder part 44 Stopper cover 44a Upper flange 44b Cylindrical part 44c bottom 45 Second connecting bracket 46 First connecting bracket 51 Nut material 51a Flange part 53 Second Shaft 55 Stopper 55a Cushioning material 56 Nut 57 Mounting part 57a Through hole 61 Spline outer cylinder 62 Flange 63 First Shaft 70 Mounting material 71 Case 71a bottom 71b Recess 71c Circular section 71d End face 72 Bearings 72a Inner circle 72b Outer ring 72c rolling element 73 Lid 74A Bearing holder 74B Bearing holder 75 Mounting part 75a through hole 100 Connection part 101 First rotation detector 101A Second rotation detector 111 First cover member 112 Recess 531 Large diameter section 531a Narrow diameter part 532 Small diameter section 533 Male thread 631 Large diameter section 632 Small diameter section 632a Recess 633 Spline groove 634 Medium diameter section 635 Thin section D1 diameter D2 diameter M1 First motor M2 Second motor S1 Part 1 S2 2nd part S3 3rd part SF shaft member

Claims

1. A first motor having a first stator and a first rotor rotatable about an axis of a central axis with respect to the first stator; A second motor disposed axially spaced apart from the first motor with respect to the central axis, and having a second stator and a second rotor rotatable with respect to the second stator and coaxially disposed with the central axis of the first rotor; The first rotor and the second rotor penetrate in the axial direction; A first portion provided with a spline groove portion protruding to one side in the axial direction from the first rotor toward the opposite side of the second rotor and extending in the axial direction on an outer periphery; a second portion provided on one side in the axial direction with respect to the first portion and extending in the axial direction; and a third portion protruding to the other side in the axial direction from the second rotor toward the opposite side of the first rotor and provided with a male thread portion on an outer periphery; an axial member having; A spline outer cylinder that guides the axial member in the axial direction along the spline groove portion of the first portion of the axial member and rotates together with the first rotor to be rotatable about the axis of the central axis; A nut member provided with a female thread portion that meshes with the male thread portion of the third portion of the axial member and rotates together with the second rotor to be movable in the axial direction; A bearing; An attachment member attached to the outer peripheral side of the second portion via the bearing, and the transmission of the rotational force of the second portion is blocked by the bearing; Comprising; An actuator.

2. The rotation center axis of the bearing is coaxial with the central axis of the first rotor, The actuator according to claim 1.

3. Comprising a cylindrical motor housing that extends along the circumferential direction around the axis of the central axis and houses the first motor and the second motor, The actuator according to claim 1 or 2.

4. The axial member is divided into a first shaft including the first portion and a second shaft including the second portion, and the first shaft and the second shaft are connected by screw fastening, The actuator according to claim 1 or 2.

5. The first motor and the second motor are direct drive motors, The actuator according to claim 1 or 2.

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