Actuator

Abstract

To provide an actuator capable of suppressing degradation of waterproof performance.SOLUTION: An actuator comprises: a shaft member SF in which a spline groove portion 633 and a male screw part 533 are formed; a spline outer cylinder portion 61 which guides the shaft member SF along the spline groove 633, and causes the shaft member SF to rotate in a rotational direction around a center axis AX; an arm attachment member 70 which is fixed to an end portion of the shaft member SF on a side of the spline groove portion 633; a spline outer cylinder housing 43 which covers the spline outer cylinder portion 61 and the shaft member SF; a cylinder portion 72 which extends from a connection portion 71 of the arm attachment member 70 toward a side where the shaft member SF is placed along an axial direction, is separated from the spline outer cylinder housing 43, and covers the spline outer cylinder housing 43; a sliding seal 77 which is arranged on an inner peripheral surface of the cylinder portion 72 and comes into contact with the spline outer cylinder housing 43; and an auxiliary sealing member 78 which is arranged on the inner peripheral surface of the tubular portion 72 and closer to the connection portion 71 than the sliding seal 77.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an actuator.

Background Art

[0002] As an actuator that performs rotational motion and linear motion, for example, the actuators described in Patent Document 1 and Patent Document 2 are known. The actuators described in Patent Documents 1 and 2 have a ball screw and a ball spline, and a shaft member in which the screw shaft of the ball screw and the shaft of the ball spline are connected is used. In this configuration, when the nut of the ball screw rotates, the shaft member performs linear motion, and when the spline outer cylinder of the ball spline rotates, the shaft member performs rotational motion.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Actuators may be used in environments where they are exposed to liquids such as water or oil, depending on the environment in which they are installed. For example, when an actuator is installed in a machine tool, it may be used in an environment where cutting fluid applied to the cutting part during workpiece cutting may come into contact with the actuator. A waterproof structure for actuators used in such liquid-exposed environments is described in Patent Documents 1 and 2, which involves placing a sealing member that moves together with the moving member that moves the arm that transports the workpiece in the actuator, and sealing the gap between the two, in the space between the moving member and the fixed member. However, when waterproof performance is ensured by sealing the gap between the moving member and the fixed member with a sealing member, the sealing member may wear down as it moves while rubbing against the fixed member when the moving member moves relative to the fixed member, which may reduce the waterproof performance.

[0005] This disclosure has been made in view of the above, and aims to provide an actuator that can suppress the deterioration of waterproof performance. [Means for solving the problem]

[0006] The actuator of this disclosure includes a shaft member having a spline groove portion extending along the axial direction and a male thread portion formed in a helical shape around a central axis; a spline outer cylinder that engages with the spline groove portion of the shaft member to guide the shaft member along the spline groove portion in the axial direction and rotate the shaft member in the direction around the central axis; an arm mounting member fixed to the end of the shaft member on the spline groove portion side and the end on the male thread portion side of the shaft member; and the end portion of the spline outer cylinder and the shaft member on the side of the spline outer cylinder to which the arm mounting member is fixed. The system comprises: a spline outer cylinder housing that covers the spline outer cylinder; a cylindrical portion formed in a cylindrical shape with an inner diameter larger than the outer diameter of the spline outer cylinder housing, extending along the axial direction from the connecting portion which is the part of the arm mounting member that is connected to the shaft member, toward the side where the shaft member is located, and covering the spline outer cylinder housing at a distance from the spline outer cylinder housing; a sliding seal disposed on the inner circumferential surface of the cylindrical portion and in contact with the spline outer cylinder housing; and an auxiliary sealing member formed in a cylindrical shape with an inner diameter smaller than the inner diameter of the cylindrical portion, and disposed on the inner circumferential surface of the cylindrical portion closer to the connecting portion than the sliding seal.

[0007] With this configuration, by positioning the auxiliary sealing member on the inner circumferential surface of the cylindrical part covering the spline outer cylinder housing, closer to the connection portion of the arm mounting member than the sliding seal, it is possible to suppress the entry of liquid into the actuator through the gap between the spline outer cylinder housing and the cylindrical part when the sliding seal wears out. This ensures waterproof performance when the sliding seal wears out and suppresses a decrease in waterproof performance.

[0008] In a desirable configuration, multiple auxiliary sealing members are arranged spaced apart in the axial direction.

[0009] With this configuration, when liquid enters the area where the auxiliary sealing members are located in the gap between the spline outer cylinder housing and the cylindrical part, the width of the liquid flow path can be significantly varied between the area where the auxiliary sealing members are located and the area between the auxiliary sealing members. This disrupts the liquid flow, increasing the resistance to the liquid flow and more reliably preventing the liquid from entering the actuator through the gap between the spline outer cylinder housing and the cylindrical part. Therefore, a decrease in waterproofing performance can be more reliably suppressed.

[0010] In a desirable configuration, the auxiliary sealing member has an intermediate groove extending in the circumferential direction formed on its inner circumferential surface.

[0011] With this configuration, when liquid enters the area where the auxiliary sealing member is located in the gap between the spline outer cylinder housing and the cylindrical part, the width of the liquid flow path can be significantly varied between the area where the intermediate groove is formed and the area without the intermediate groove. This disrupts the liquid flow, increasing the resistance to liquid flow and more reliably preventing liquid from entering the actuator through the gap between the spline outer cylinder housing and the cylindrical part. Therefore, a decrease in waterproofing performance can be more reliably suppressed.

[0012] In a desirable configuration, the auxiliary sealing member is positioned such that, when the shaft member moves along the axial direction in a direction away from the spline outer cylinder housing, and the distance between the connecting portion connected to the shaft member and the spline outer cylinder housing is maximized, the end of the auxiliary sealing member on the connecting portion side in the axial direction is closer to the sliding seal than the end of the spline outer cylinder housing on the connecting portion side in the axial direction.

[0013] With this configuration, when the distance between the connecting portion and the spline outer cylinder housing is at its maximum, the end of the auxiliary sealing member on the connecting portion side is positioned closer to the sliding seal than the end of the spline outer cylinder housing on the connecting portion side. Therefore, regardless of the movement state of the shaft member, the waterproof performance between the cylindrical portion and the spline outer cylinder housing can be ensured by the auxiliary sealing member. This makes it possible to more reliably suppress the deterioration of waterproof performance.

[0014] A preferred configuration includes a first motor having a first rotor, a second motor having a second rotor arranged coaxially with the first rotor, and a nut member having a female thread that engages with the male thread of the shaft member, wherein the shaft member is arranged coaxially with respect to the first and second rotors by penetrating them in the axial direction, the spline outer cylinder is connected to the first rotor and rotates with the first rotor to rotate the shaft member in the direction of the central axis, and the nut member is positioned with its female thread engaging with the male thread of the shaft member and is connected to the second rotor and rotates with the second rotor to move the shaft member in the axial direction.

[0015] In this configuration, the shaft member passes through a first rotor that rotates the shaft member around the central axis and a second rotor that moves the shaft member in the axial direction of the central axis. Therefore, the actuator that causes rotation around the axis and movement in the axial direction of the shaft member can be made compact. This allows for space savings in the actuator. [Effects of the Invention]

[0016] The actuator relating to this disclosure has the effect of suppressing the deterioration of waterproof performance. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a cross-sectional view of the actuator according to the first embodiment. [Figure 2] Figure 2 is an enlarged cross-sectional view near the upper end of the actuator shown in Figure 1. [Figure 3] Figure 3 is a detailed view around the arm attachment member shown in Figure 2. [Figure 4] Figure 4 is an enlarged cross-sectional view near the lower end of the actuator shown in Figure 1. [Figure 5] Figure 5 is an explanatory diagram showing the state where the shaft member shown in Figure 1 has risen. [Figure 6] Figure 6 is a schematic diagram around the sliding seal when the sliding seal is worn. [Figure 7] Figure 16 is an enlarged cross-sectional view near the upper end of the actuator when the shaft member has risen. [Figure 8] Figure 8 is a cross-sectional view of the main part of the actuator of the second embodiment and is a schematic diagram around the sliding seal. [Figure 9] Figure 9 is a cross-sectional view of the main part of the actuator of the third embodiment and is a schematic diagram around the sliding seal. [Figure 10] Figure 10 is a cross-sectional view of the actuator according to the fourth embodiment. [Figure 11] Figure 11 is a detailed view of the two-axis integrated motor shown in Figure 10. [Figure 12] Figure 12 is a cross-sectional view of the two-axis integrated motor by a plane perpendicular to the rotating shaft. [Figure 13] Figure 13 is an enlarged cross-sectional view near the upper end of the actuator according to the fourth embodiment shown in Figure 10. [Figure 14] Figure 14 is an explanatory diagram showing the state where the shaft member of the actuator 1A according to the fourth embodiment shown in Figure 10 has risen.

Mode for Carrying Out the Invention

[0018] It should be noted that in the original text, there is no Figure 16 in the content you provided. I translated it according to the text you gave. You may need to check and correct it if there is a mistake in the original text.Embodiments for carrying out the invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments described below. Furthermore, the components described below include those that can be easily imagined by those skilled in the art, and those that are substantially the same. Moreover, the components described below can be combined as appropriate.

[0019] [First Embodiment] Figure 1 is a cross-sectional view of the actuator 1 according to the first embodiment. The cross-section in Figure 1 is a plane cross-section that includes the central axis AX of the first rotor and the second rotor, which will be described later.

[0020] As shown in Figure 1, the actuator 1 is used, for example, as a pick-and-place device. The actuator 1 comprises an arm portion 80, a first motor M1, a second motor M2, a shaft member SF, a spline outer cylinder 61, and a nut member 51.

[0021] In the following description, the direction parallel to the Z-direction, with the direction from the first motor M1 toward the arm portion 80 being defined as upward and the direction from the arm portion 80 toward the first motor M1 being defined as downward. Furthermore, the axial direction of the central axis AX of the arm portion 80 is the same as the Z-direction.

[0022] The arm portion 80 is, for example, a cantilever arm having only a single arm. The actuator 1 is fixed to a mounting base ST with, for example, the central axis AX of the arm portion 80 facing in the Z direction. The arm portion 80 is fixed on an arm mounting member 70. The arm mounting member 70 is fixed to the upper end of a shaft 63, which will be described later, via a bolt. The actuator 1 moves the arm portion 80 up and down in the Z direction (linear direction, axial direction of the central axis AX), and rotates the arm portion 80 in a plane perpendicular to the Z direction in the direction of the central axis AX. A workpiece (not shown) is mounted on the arm portion 80, and the workpiece is transported to a desired position.

[0023] The first motor M1 includes a first stator 10, a first rotor 20, a first motor housing 40, and a first rotation detection unit 101.

[0024] A first stator holder 11 is positioned radially inward of the first stator 10. The first stator 10 is fixed to the first stator holder 11. The first rotor 20 is positioned on the outer circumference 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 fixed radially inward of the first rotor bracket 21 and having permanent magnets. The first rotor bracket 21 is formed in a cylindrical shape with the central axis AX as its center. The first rotor bracket 21 also has an outer ring retainer 21a that supports the outer ring of the first bearing 31.

[0025] The first stator 10 and the first rotor 20 are arranged coaxially with respect to a central axis AX. The first rotor 20 is positioned radially outward from 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 bolts. The first stator 10 is cylindrical in shape around the central axis AX.

[0026] The first motor housing 40 is formed, for example, in a cylindrical shape and houses the first motor M1. The upper end of the first motor housing 40 is open, and a cover member 111 is provided in the opening. The cover member 111 is fixed to the outer ring retainer 21a of the first rotor bracket 21 via bolts. A through hole is provided in the radial center of the cover member 111, and the through hole is covered by a spline outer cylinder 61, which is fixed to the cover member 111 via bolts.

[0027] Furthermore, a mounting flange 40a is provided at the upper end of the first motor housing 40, extending radially outward. The mounting flange 40a is placed on the upper surface of the fixing base ST and can be fixed to the fixing base ST via bolts. A small gap is formed between the outer circumference of the cover member 111 and the inner circumference of the first motor housing 40, allowing the cover member 111 to rotate relative to the first motor housing 40.

[0028] 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 positioned above the first bearing 31.

[0029] The second motor M2 is positioned parallel to the first motor M1 in the axial direction of the central axis AX. The second motor M2 includes a second stator 10A, a second rotor 20A, a second motor housing 40A, and a second rotation detection unit 101A. The first motor M1 and the second motor M2 are cylindrical direct-drive motors. That is, the first rotor 20 of the first motor M1 and the second rotor 20A of the second motor M2 are both formed in a cylindrical shape, and when the first motor M1 and the second motor M2 are driven, the cylindrical first rotor 20 and second rotor 20A rotate around the central axis AX. The shaft member SF is positioned coaxially with respect to the first rotor 20 and the second rotor 20A by passing through the first rotor 20 and the second rotor 20A in the axial direction.

[0030] The second rotor 20A is positioned on the outer circumference of the second stator 10A. The second rotor 20A rotates about its 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 includes a second rotor bracket 21A and a second rotor core 22A fixed radially inward of the second rotor bracket 21A and having permanent magnets. The second rotor bracket 21A is formed in a cylindrical shape with the central axis AX as its center. The second stator 10A and the second rotor 20A are positioned coaxially with respect to the central axis AX.

[0031] A second stator holder 11A is positioned radially inward of the second stator 10A. The second stator 10A is fixed to the second stator holder 11A. The second rotor 20A is positioned radially outward of 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 a second bearing 32. The second stator 10A is fixed to the second stator holder 11A, which is positioned radially inward of the second stator 10A. The second stator holder 11A is fixed to the second motor housing 40A via bolts. The second stator 10A is cylindrical around a central axis AX.

[0032] Here, the shaft member SF will be described. The shaft member SF has an upper shaft 63 and a lower screw shaft 53. The shaft 63 extends from the arm mounting member 70 along the axial direction of the central axis AX to the connecting portion 100. The connecting portion 100 is located in a position adjacent to the second rotation detection unit 101A. The shaft 63 has a reduced diameter portion 63a, a large diameter portion 631, and a small diameter portion 632, and is formed as a single unit. The reduced diameter portion 63a is located on the opposite side of the end of the shaft 63 where the screw shaft 53 is located, and is formed with a diameter smaller than the diameter of the large diameter portion 631. That is, the reduced diameter portion 63a is located at the upper end of the shaft 63 and is formed in the portion of the shaft 63 to which the arm mounting member 70 is attached.

[0033] The large-diameter portion 631 extends from the arm mounting member 70 to the vicinity of the lower bottom portion 40b of the first motor housing 40 when the shaft member SF is in its lowest position. The large-diameter portion 631 has a first large-diameter portion 631a located below the reduced-diameter portion 63a, and a second large-diameter portion 631b located between the lower end of the first large-diameter portion 631a and the upper end of the small-diameter portion 632. Multiple spline grooves 633 extending along the axial direction of the central axis AX are provided on the outer circumference of the second large-diameter portion 631b at intervals in the circumferential direction. On the inner circumference side of the spline outer cylinder 61, although not shown, there is a spline portion having multiple protrusions that can engage with the spline grooves 633. The second large-diameter portion 631b is positioned inside the spline outer cylinder 61, and the spline grooves 633 formed in the second large-diameter portion 631b engage with the spline portion provided on the inner circumference side of the spline outer cylinder 61.

[0034] Thus, the shaft member SF has a first portion S1 that protrudes upward in one axial direction from the first rotor 20 toward the opposite side of the second rotor 20A, and the first portion S1 is provided with a spline groove 633 that extends along the axial direction. The spline groove 633 and the spline portion engage via a plurality of balls, so that the shaft member SF is guided along the spline portion in the axial direction, and the shaft member SF rotates together with the first rotor 20, so that the shaft member SF can rotate around the axis of the central axis. In other words, the spline outer cylinder 61 engages with the spline groove 633 of the shaft member SF to guide the shaft member SF along the spline groove 633 in the axial direction of the central axis AX, and also makes it possible to rotate the shaft member SF around the axis of the central axis AX.

[0035] Furthermore, the spline outer cylinder 61 is connected to the first rotor bracket 21 of the first rotor 20 via the cover member 111; that is, the spline outer cylinder 61 is connected to the first rotor 20 via the cover member 111. As a result, when the first motor M1 is driven, the spline outer cylinder 61 can rotate together with the first rotor 20, and by rotating together with the first rotor 20, the shaft member SF can be rotated in the direction of the axis of the central axis AX.

[0036] Furthermore, the small-diameter portion 632 of the shaft 63 extends from the lower end of the large-diameter portion 631 to the connecting portion 100. In this way, a ball spline for rolling guidance is applied to the first portion S1.

[0037] The screw shaft 53 extends from the connecting portion 100 to the stopper 55. The screw shaft 53 has an upper large-diameter portion 531 and a lower small-diameter portion 532. The tip of the large-diameter portion 531 of the screw shaft 53 (the upper end in Figure 1) is provided with a thin-diameter portion 531a that protrudes upward. A male thread is provided on the outer circumference of the thin-diameter portion 531a. A recess 632a is provided at the lower end of the small-diameter portion 632 of the shaft 63. A female thread is provided on the inner circumference of the recess 632a that engages with the male thread of the thin-diameter portion 531a. The female thread on the inner circumference of the recess 632a engages with the male thread of the thin-diameter portion 531a. As a result, the small-diameter portion 632 of the shaft 63 and the large-diameter portion 531 of the screw shaft 53 are integrally connected. That is, the shaft 63 and the screw shaft 53 are connected by screw fastening. Furthermore, a male threaded portion 533 is formed on the outer circumference of the large-diameter portion 531. That is, the shaft member SF has a second portion S2 that protrudes downward, which is the other axial direction from the second rotor 20A toward the opposite side of the first rotor 20, and the second portion S2 is provided with a male threaded portion 533 that is formed in a spiral shape around the central axis AX. Furthermore, no male threaded portion is provided on the outer circumference of the small-diameter portion 532. Also, the diameter D1 of the spline groove portion 633 in the shaft member SF is larger than the diameter D2 of the male threaded portion 533. The diameter D1 of the spline groove portion 633 is the larger diameter of the large and small diameters. The diameter D2 of the male threaded portion 533 is the outer diameter of the inner diameter (root diameter) of the outer diameter.

[0038] The second motor housing 40A is formed, for example, in a cylindrical shape and houses the second motor M2. The upper end of the second motor housing 40A is open, and a shaft member SF is provided passing through this opening. An upper bottom portion 40Aa is provided on the outer circumference of the opening, extending in an annular manner around the axis of 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 bolts. The lower bottom portion 40Ab of the second motor housing 40A is also open, and a nut housing 42 is attached to this opening.

[0039] The nut housing 42 has an upper flange 42a and a cylindrical portion 42b that extends downward from the inner circumference of the upper flange 42a. The upper flange 42a is fixed to the lower bottom portion 40Ab of the second motor housing 40A via bolts.

[0040] A stopper 55 is attached to the lower end of the small-diameter portion 532 by a nut 56. Inside the nut housing 42 are the nut member 51 and the second connecting bracket 45.

[0041] A female thread is provided on the inner circumference of the nut member 51. The female thread engages with the male thread 533 of the second part S2 of the shaft member SF via multiple balls. Therefore, the nut member 51 is positioned so that its inner female thread engages with the male thread 533 of the shaft member SF. A second connecting bracket 45 is positioned radially outward and slightly above the nut member 51, and the nut member 51 is fixed to the second connecting bracket 45 via bolts. A flange 45a that extends radially outward is provided at the upper end of the second connecting bracket 45, and the flange 45a is fixed to the first connecting bracket 46 via bolts. In this way, a ball screw for rolling guide is applied to the second part S2.

[0042] The first connecting bracket 46 is fixed to the second rotor bracket 21A via bolts. In this way, the nut member 51, the second connecting bracket 45, the first connecting bracket 46, and the second rotor bracket 21A are rotatable as a single unit. 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 stator 10A and the second stator holder 11A via the second bearing 32. The nut member 51 is thus connected to the second rotor bracket 21A via the second connecting bracket 45 and the first connecting bracket 46, that is, it is connected to the second rotor 20A. Therefore, when the second motor M2 is driven, the nut member 51 can rotate together with the second rotor 20A as a single unit.

[0043] Furthermore, the nut member 51 is positioned so that its inner female threaded portion engages with the male threaded portion 533 of the shaft member SF. Therefore, when the nut member 51 rotates around the axis of the central axis AX, the nut member 51 is able to move the shaft member SF in the axial direction of the central axis AX. Consequently, when the second motor M2 is driven, the nut member 51 rotates together with the second rotor 20A, thereby moving the shaft member SF in the axial direction of the central axis AX.

[0044] 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 positioned in the axial direction, aligned with the connecting portion 100.

[0045] Figure 2 is an enlarged cross-sectional view of the area near the upper end of the actuator 1 shown in Figure 1. A spline outer cylinder housing 43 is fixed to the upper end of the first motor housing 40 via bolts. The spline outer cylinder housing 43 has a first cylindrical portion 431 and a second cylindrical portion 432. Inside the spline outer cylinder housing 43 are the first portion S1 of the shaft member SF, i.e., the first large diameter portion 631a and the second large diameter portion 631b of the shaft 63, and the spline outer cylinder 61 through which the second large diameter portion 631b passes. In other words, the spline outer cylinder housing 43 covers the spline outer cylinder 61 and the portion of the shaft member SF that is on the end side of the spline outer cylinder 61 where the arm mounting member 70 is fixed. More specifically, the first cylindrical portion 431 of the spline outer cylinder housing 43 covers the spline outer cylinder 61, and the second cylindrical portion 432 of the spline outer cylinder housing 43 covers the portion of the shaft member SF that is exposed from the spline outer cylinder 61 at the end side where the arm mounting member 70 is fixed.

[0046] Furthermore, a cover member 111 is fixed to the upper end of the first rotor bracket 21 (see Figure 1) via bolts. The flange 62 of the spline outer cylinder 61 is fixed to the upper end of the cover member 111 via bolts.

[0047] The first cylindrical portion 431 of the spline outer cylinder housing 43 has a first cylindrical portion 431b located on the upper side in the vertical direction, a stepped portion 431d located below the first cylindrical portion 431b, and a second cylindrical portion 431e located below the stepped portion 431d.

[0048] The first cylindrical portion 431b has a receiving portion 431a extending radially inward in an annular shape along its circumference. The upper surface of the receiving portion 431a has a recess that is indented downward, and an O-ring 74 is housed in the recess. With the lower end surface of the second cylindrical portion 432 pressing against the O-ring 74, the lower end of the second cylindrical portion 432 is fixed to the receiving portion 431a of the first cylindrical portion 431 via a bolt. A recess is formed on the side surface of the lower end portion 431c of the second cylindrical portion 431e, and an O-ring 75 is housed in the recess.

[0049] The inner circumferential surface of the upper end of the first motor housing 40 is pressing against the O-ring 75. In this state, the lower end of the first cylindrical portion 431 is fixed to the upper end of the first motor housing 40 via a bolt. Furthermore, a recess is provided on the outer circumferential surface of the upper end of the first motor housing 40 that is recessed radially inward, and the O-ring 76 is housed in the recess. With the inner circumferential surface of the mounting base ST pressing against the O-ring 76, the mounting flange 40a of the first motor housing 40 is fixed to the upper surface of the mounting base ST via a bolt.

[0050] An annular connecting bracket 34 is positioned on the upper part of the flange 62 of the spline outer cylinder 61, surrounding the spline outer cylinder 61. The connecting bracket 34 is positioned such that its position in the axial direction of the central axis AX coincides with the second cylindrical portion 431e of the first cylindrical portion 431, and a third bearing 33 is held between the second cylindrical portion 431e of the first cylindrical portion 431 and the connecting bracket 34. The connecting bracket 34 is fixed to the flange 62 of the spline outer cylinder 61. Thus, the third bearing 33 rotatably supports the spline outer cylinder 61 and the connecting bracket 34. The third bearing 33 is, for example, a rolling bearing. The third bearing 33 is supported by the stepped portion 431d of the first cylindrical portion 431 via a wave washer 39a and a retaining member 39b. The third bearing 33 is positioned in the axial direction of the central axis AX by a wave washer 39a and a retaining member 39b. The third bearing 33 is also supported radially by the first cylindrical portion 431, the first motor housing 40, and the fixed base ST.

[0051] Figure 3 is a detailed view of the arm mounting member 70 shown in Figure 2. The arm mounting member 70, which is fixed to the upper end of the shaft 63, has a connecting portion 71, a cylindrical portion 72, and a cover portion 73. The connecting portion 71 is connected to the reduced diameter portion 63a located on the opposite side of the end of the shaft 63 where the screw shaft 53 is located. Therefore, the arm mounting member 70 is fixed to the end of the shaft member SF on the spline groove portion 633 side and the end on the male screw portion 533 side.

[0052] The cylindrical portion 72 of the arm mounting member 70 is formed in a cylindrical shape and is provided extending downward from the connecting portion 71, which is the part of the arm mounting member 70 that is connected to the shaft member SF. The cylindrical portion 72 is positioned outside the second cylindrical portion 432 of the spline outer cylinder housing 43 and accommodates the upper part 432a of the second cylindrical portion 432. In other words, the cylindrical portion 72 is formed in a cylindrical shape with an inner diameter larger than the outer diameter of the upper part 432a of the second cylindrical portion 432 of the spline outer cylinder housing 43, and extends axially from the connecting portion 71 of the arm mounting member 70 toward the side where the shaft member SF is located. As a result, the cylindrical portion 72 covers the second cylindrical portion 432 of the spline outer cylinder housing 43 at a distance from the spline outer cylinder housing 43.

[0053] A recess 72a is provided at the lower end of the cylindrical portion 72. The recess 72a is formed by widening the diameter of the lower end of the inner circumferential surface of the cylindrical portion 72. A sliding seal 77 is placed in the recess 72a. The sliding seal 77 is positioned on the inner circumferential surface of the cylindrical portion 72 and contacts the spline outer cylinder housing 43. More specifically, the sliding seal 77 contacts the upper part 432a of the second cylindrical portion 432 of the spline outer cylinder housing 43. As a result, the sliding seal 77 seals the gap formed between the cylindrical portion 72 of the arm mounting member 70 and the upper part 432a of the second cylindrical portion 432 of the spline outer cylinder housing 43.

[0054] In other words, the inner diameter of the cylindrical portion 72 of the arm mounting member 70 is slightly larger than the outer diameter of the upper part 432a of the second cylindrical portion 432, and a gap is formed between the cylindrical portion 72 and the second cylindrical portion 432. As a result, the cylindrical portion 72 of the arm mounting member 70 is positioned to move relative to the upper part 432a of the second cylindrical portion 432 of the spline outer cylinder housing 43 in the axial direction of the central axis AX and in the rotational direction around the axis. The sliding seal 77, which is positioned on the inner circumferential surface side of the cylindrical portion 72, can seal the gap formed between the cylindrical portion 72 of the arm mounting member 70 and the upper part 432a of the second cylindrical portion 432 by contacting the upper part 432a of the second cylindrical portion 432.

[0055] Examples of the sliding seal 77 include a structure in which a U-shaped or U-shaped member in cross-section is formed into a ring shape. The sliding seal 77 is formed using, for example, an elastically deformable material. The sliding seal 77 is positioned in a state of elastic deformation, in contact with both the inner circumferential surface of the recess 72a and the outer circumferential surface of the second cylindrical portion 432. The sliding seal 77 protects the shaft 63 from the outside. A projection 72b that protrudes inward is formed at the lower end of the recess 72a. This projection 72b prevents the sliding seal 77 from falling out.

[0056] Furthermore, an auxiliary sealing member 78 is positioned on the inner circumferential surface of the cylindrical portion 72. The auxiliary sealing member 78 is formed in a cylindrical shape with an inner diameter smaller than the inner diameter of the cylindrical portion 72, and is positioned closer to the connecting portion 71 than the sliding seal 77 on the inner circumferential surface of the cylindrical portion 72. Specifically, on the inner circumferential surface of the cylindrical portion 72, a notch 72c is formed adjacent to the recess 72a, on the upper side of the recess 72a where the sliding seal 77 is positioned, that is, on the opposite side of the recess 72a from the side where the projection 72b is formed. The notch 72c has a smaller diameter than the diameter of the recess 72a and is formed by expanding the diameter of the inner circumferential surface of the cylindrical portion 72. The auxiliary sealing member 78 is positioned in the notch 72c formed in this way on the inner circumferential surface of the cylindrical portion 72.

[0057] The auxiliary sealing member 78, which is formed in a cylindrical shape and positioned in the notch 72c, has an outer diameter that is approximately the same as the diameter of the notch 72c. Furthermore, the inner diameter of the auxiliary sealing member 78 is smaller than the portion of the inner circumferential surface of the cylindrical portion 72 above the notch 72c, and larger than the outer diameter of the upper part 432a of the second cylindrical portion 432 of the spline outer cylinder housing 43. In other words, the inner diameter of the cylindrical auxiliary sealing member 78 is between the inner diameter of the portion of the inner circumferential surface of the cylindrical portion 72 above the notch 72c and the outer diameter of the upper part 432a of the second cylindrical portion 432. In addition, the length of the auxiliary sealing member 78 in the axial direction of the central axis AX is approximately the same as the length of the notch 72c in the same direction. As a result, the auxiliary sealing member 78 is positioned in a state where it fits into the notch 72c formed by the expansion of the inner circumferential surface of the cylindrical portion 72.

[0058] Furthermore, the auxiliary seal member 78 is positioned such that the end 78a of the auxiliary seal member 78 on the connecting portion 71 side, which is the part of the arm mounting member 70 that connects to the shaft member SF, is located closer to the sliding seal 77 than the end 43b of the spline outer cylinder housing 43 on the connecting portion 71 side, in the axial direction of the central axis AX. In other words, the shaft member SF is movable in the axial direction of the central axis AX, and the arm mounting member 70 attached to the shaft member SF is also movable in the axial direction together with the shaft member SF. Thus, the auxiliary seal member 78, which is positioned on the cylindrical portion 72 of the axially movable arm mounting member 70, is formed such that, regardless of the movement state of the cylindrical portion 72, the end 78a of the auxiliary seal member 78 on the connecting portion 71 side is located closer to the sliding seal 77 than the end 43b of the spline outer cylinder housing 43 on the connecting portion 71 side.

[0059] The auxiliary sealing member 78 is formed from a relatively soft metal material such as brass or copper, and is positioned in the notch 72c by being press-fitted into the notch 72c. Alternatively, the auxiliary sealing member 78 is formed from a harder resin material and is positioned in the notch 72c by being press-fitted into the notch 72c.

[0060] Furthermore, the recess 72a is formed in a groove-like shape between the notch 72c and the projection 72b, as the notch 72c adjacent to the recess 72a is formed with a smaller diameter than the recess 72a. The sliding seal 77 is positioned by fitting into the groove-shaped recess 72a.

[0061] The cover portion 73 is attached to the cover mounting surface 71d of the connecting portion 71 by bolts. The cover portion 73 protects the reduced diameter portion 63a of the shaft 63 from the outside.

[0062] Figure 4 is an enlarged cross-sectional view of the area near the lower end of the actuator 1 shown in Figure 1. A clamping mechanism 130 is located below the nut housing 42 of the actuator 1. The clamping mechanism 130 includes a small-diameter portion 532 of a screw shaft 53, a collet 132, and a cylinder 134. The collet 132 comprises a radially deformable gripping portion 132A and a substantially cylindrical flange portion 132B. Four slots are formed in the Z direction of the gripping portion 132A. The cross-sectional view shown in Figure 4 shows a cross-section cut along these slots. The slots are formed at positions that are 90 degrees apart in the circumferential direction. This allows the gripping portion 132A to be elastically deformable in the radial direction. The number, shape, and position of the slots are not particularly limited. The slots only need to be formed so that the gripping portion 132A can be elastically deformed in the radial direction.

[0063] The small-diameter portion 532 of the screw shaft 53 is inserted into the collet 132. The collet 132 comprises a first tapered surface 132a, a second tapered surface 132b, a recess 132c, and an inner circumferential surface 132d. The first tapered surface 132a is the outer circumferential surface of the gripping portion 132A. The first tapered surface 132a is an inclined surface whose outer diameter decreases as it is directed downward in the Z direction. In other words, the first tapered surface 132a has a substantially conical shape.

[0064] The second tapered surface 132b is the outer peripheral surface of the flange portion 132B on the upper side in the Z direction. The second tapered surface 132b is an inclined surface whose outer diameter decreases as it moves upward in the Z direction. In other words, the second tapered surface 132b has a substantially conical shape. The recess 132c is a groove formed on the outer peripheral surface of the flange portion 132B. The recess 132c is formed between the first tapered surface 132a and the second tapered surface 132b in the Z direction. The inner peripheral surface 132d is the surface facing the clamped portion 53b of the screw shaft 53. The collet 132 is positioned so that the inner peripheral surface 132d faces the clamped portion 53b of the screw shaft 53 even when the screw shaft 53 moves to its maximum extent in the axial direction.

[0065] The cylinder 134 comprises a piston 136, a cylinder tube 138, a first seal member 160, and a second seal member 162. The cylinder 134 also comprises a gas supply section 163, a fixing member 144, a stopper section 146, a screw shaft housing 150, and a spring 156.

[0066] The small-diameter portion 532 of the screw shaft 53 is inserted into the piston 136. The piston 136 includes an inclined surface 136a, a first outer surface 136b, a second outer surface 136c, a groove 136d, a bottom surface 136e, a recess 136f, and an upper surface 136g.

[0067] The inclined surface 136a is the inner circumferential surface of the piston 136 on the upper side in the Z direction. The inclined surface 136a is inclined such that its diameter increases as it moves upward in the Z direction. The inclined surface 136a overlaps with the first tapered surface 132a of the collet 132 in the Z direction. With this configuration, the inclined surface 136a can contact the first tapered surface 132a when the piston 136 moves upward in the Z direction. When the inclined surface 136a contacts the first tapered surface 132a, it can press the first tapered surface 132a radially inward. In other words, the inclined surface 136a is a chuck portion that can press the gripping portion 132A radially inward. The inclined surface 136a faces the first tapered surface 132a. That is, the inclined surface 136a and the first tapered surface 132a have approximately the same inclination. The inclined surface 136a is positioned to overlap with the first tapered surface 132a in the radial direction. This reduces the axial dimension of the space occupied by the piston 136 and collet 132.

[0068] The first outer surface 136b and the second outer surface 136c are the outer surfaces of the piston 136. The first outer surface 136b is located above the second outer surface 136c in the Z direction. The second outer surface 136c, located below the first outer surface 136b in the Z direction, has a larger diameter than the first outer surface 136b. The first outer surface 136b and the second outer surface 136c are arranged to overlap the first tapered surface 132a in the radial direction. The groove 136d is a rectangular groove formed on the first outer surface 136b. The groove 136d is formed along the circumferential direction of the first outer surface 136b. The bottom surface 136e is the lower surface of the piston 136 in the Z direction. A recess 136f is formed on the bottom surface 136e, recessed upward in the Z direction. The top surface 136g is the upper surface of the piston 136 in the Z direction.

[0069] The cylinder tube 138 is a substantially cylindrical member that houses the piston 136. The cylinder tube 138 comprises a cylindrical portion 138a, an outer diameter flange portion 138b, an inner diameter flange portion 138c, a groove portion 138d, a first inner surface 138e, a second inner surface 138f, and a gas supply passage 138g. The cylindrical portion 138a is a cylindrical member. The outer diameter flange portion 138b and the inner diameter flange portion 138c are connected to the upper end of the cylindrical portion 138a in the Z direction. The outer diameter flange portion 138b is an annular flange surface. The outer diameter flange portion 138b is fixed to the lower end of the cylindrical portion 42b of the nut housing 42 by a fixing member 140 such as a bolt. The inner diameter flange portion 138c is formed in an annular shape and is positioned radially inward from the outer diameter flange portion 138b. A stepped surface 142 is formed on the inner diameter flange portion 138c. The stepped surface 142 is formed at the upper end in the Z direction on the inner circumferential surface side of the inner diameter flange portion 138c. When viewed from above in the Z direction, the stepped surface 142 has an annular shape.

[0070] The first inner surface 138e is the radially inward side surface of the inner diameter side flange portion 138c. The first inner surface 138e faces the first outer surface 136b of the piston 136. The second inner surface 138f is the radially inward side surface of the cylindrical portion 138a. The diameter of the second inner surface 138f is larger than the diameter of the first inner surface 138e. The second inner surface 138f faces the second outer surface 136c of the piston 136. The first inner surface 138e and the second inner surface 138f are arranged to overlap the first tapered surface 132a of the collet 132 in the radial direction. The groove portion 138d is a rectangular groove formed on the second inner surface 138f. The groove portion 138d is formed along the circumferential direction of the second inner surface 138f.

[0071] The gas supply passage 138g is an opening that penetrates from the outside of the cylinder tube 138 to the inside of the cylinder tube 138. The gas supply pipe 158 is connected to the gas supply passage 138g. The gas supply passage 138g and the gas supply pipe 158 are fixed together with screws, for example, via sealing tape.

[0072] The first sealing member 160 is an O-ring. The first sealing member 160 is positioned in a groove 136d formed on the first outer surface 136b of the piston 136. The first sealing member 160 fills the gap between the first outer surface 136b of the piston 136 and the first inner surface 138e of the cylinder tube 138. This seals the gap between the first outer surface 136b of the piston 136 and the first inner surface 138e of the cylinder tube 138.

[0073] The second sealing member 162 is an O-ring. The second sealing member 162 is positioned in a groove 138d formed on the second inner surface 138f of the cylinder tube 138. The second sealing member 162 fills the gap between the second outer surface 136c of the piston 136 and the second inner surface 138f of the cylinder tube 138. As a result, the gap between the second outer surface 136c of the piston 136 and the second inner surface 138f of the cylinder tube 138 is sealed. With this configuration, a pressure chamber 139 is formed in the clamp mechanism 130, surrounded by the gas supply pipe 158, the gas supply passage 138g, the first outer surface 136b, the second outer surface 136c, the first inner surface 138e, the second inner surface 138f, the first sealing member 160, and the second sealing member 162.

[0074] The gas supply unit 163 is a compressor that supplies compressed air. The gas supply unit 163 is connected to the gas supply piping 158. Note that the gas supplied by the gas supply unit 163 is not limited to compressed air. For example, the gas supply unit 163 may supply compressed nitrogen.

[0075] The fixing member 144 is an annular plate member. The fixing member 144 is positioned so that its radially outer lower surface contacts the stepped surface 142 formed on the inner diameter side flange portion 138c of the cylinder tube 138. The radially inner end of the fixing member 144 is inserted into the recess 132c formed in the collet 132.

[0076] The stopper portion 146 is an annular-shaped member. The small-diameter portion 532 of the screw shaft 53 is inserted into the stopper portion 146. The stopper portion 146 has an inclined surface 146a that faces the second tapered surface 132b of the collet 132. This allows the stopper portion 146 to restrict the upward movement of the collet 132 in the Z direction. The stopper portion 146 is fixed to the inner diameter side flange portion 138c of the cylinder tube 138 by a fixing member 148 such as a bolt, with the fixing member 144 sandwiched between the cylinder tube 138 and the stepped surface 142 of the cylinder tube 138. Therefore, the stopper portion 146 fixes the position of the fixing member 144 in the Z direction. The inner diameter side end of the fixing member 144 is inserted into the recess 132c of the collet 132. As a result, the fixing member 144 can restrict the downward movement of the collet 132 in the Z direction. This configuration determines the position of the collet 132 in the Z direction.

[0077] The screw shaft housing 150 is fixed to the mounting base ST via the cylinder tube 138, the nut housing 42, the second motor housing 40A, and the first motor housing 40. The screw shaft housing 150 has a flange portion 150a, a flange surface 150b, a cylindrical portion 150c, a recess 150d, and a cover member 150e. The flange portion 150a is formed in an annular shape and is fixed to the lower end of the cylindrical portion 138a of the cylinder tube 138 by a fixing member 152 such as a bolt. The flange surface 150b is the upper surface of the flange portion 150a in the Z direction.

[0078] The flange surface 150b faces the lower surface 136e of the piston 136. The cylindrical portion 150c extends downward from the inner circumference of the flange portion 150a. As shown in Figure 4, the cylindrical portion 150c accommodates the lower end of the screw shaft 53. The recess 150d is a recess that is recessed downward in the Z direction from the flange surface 150b. The cover member 150e is a member that closes the lower side of the cylindrical portion 150c in the Z direction. The cover member 150e is fixed to the lower end face of the cylindrical portion 150c in the Z direction by bolts. This prevents foreign matter from entering the inside of the screw shaft housing 150 from the lower side in the Z direction.

[0079] The spring 156 is a compression coil spring. One end of the spring 156 contacts the bottom surface of a recess 136f formed in the lower surface 136e of the piston 136. The other end of the spring 156 contacts the bottom surface of a recess 150d formed in the flange surface 150b of the screw shaft housing 150. Therefore, the spring 156 is compressed by the bottom surface of the recess 136f of the piston 136 and the bottom surface of the recess 150d of the screw shaft housing 150. Since the screw shaft housing 150 is fixed to the fixed base ST, the bottom surface of the recess 150d does not move downward in the Z-axis direction. Therefore, the spring 156 presses the piston 136 upward in the Z-direction. Although the spring 156 is described as a compression coil spring, it is not limited to this. The spring 156 can be any elastic member that biases the piston 136 in the direction that the piston 136 approaches the gripping portion 132A of the collet 132. The spring 156 may be, for example, a square spring or a conical spring. In addition, multiple springs 156 may be arranged.

[0080] A stopper 55 is attached to the lower end of the screw shaft 53 by a nut 56. The stopper 55 is an annular-shaped member. The stopper 55 is inserted into the screw shaft 53. An annular-shaped cushioning member 55a is positioned above the stopper 55 in the Z direction. The cushioning member 55a is, for example, an elastic urethane rubber. The outer diameter r2 of the cushioning member 55a and the stopper 55 is larger than the inner diameter r1 of the flange portion 150a of the screw shaft housing 150. Therefore, when the screw shaft 53 rises by a predetermined length, the stopper 55 comes into contact with the flange portion 150a via the cushioning member 55a. In this way, the stopper 55 can restrict the screw shaft 53 from rising beyond a predetermined length.

[0081] Next, the movement of actuator 1 will be explained. Figure 5 is an explanatory diagram showing the state in which the shaft member SF shown in Figure 1 is raised. First, the mode in which the shaft member SF moves up and down (linear motion) will be explained. In this mode, only the second motor M2 operates, and the first motor M1 does not operate.

[0082] When the second motor M2 is activated, the second rotor 20A rotates around the central axis AX. Specifically, the second rotor 20A rotates 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.

[0083] The nut member 51 is integrated with the second rotor 20A by being connected to the second rotor bracket 21A via the second connecting bracket 45 and the first connecting bracket 46. Therefore, the nut member 51 also rotates integrally with the second rotor 20A in the direction of the axis of the central axis AX. The female thread formed on the inner circumference of the nut member 51 engages with the male thread 533 formed on the second portion S2 of the shaft member SF, so that the rotation of the nut member 51 causes the shaft member SF to move linearly along the axis. For example, as shown in Figure 2, the rotation of the nut member 51 causes the shaft member SF to rise along the axis. When the shaft member SF rises along the axis, the stopper 55 contacts the flange portion 150a of the screw shaft housing 150 via the buffer member 55a, thereby restricting the upward movement of the shaft member SF.

[0084] Next, the modes in which the shaft member SF pivots (rotates) will be described. In this mode, depending on how the shaft member SF moves in the Z direction, there are a first mode, a second mode, and a third mode.

[0085] In the first embodiment, the first motor M1 operates, and the second motor M2 does not operate. As described above, the spline groove 633 formed on the shaft 63 of the shaft member SF engages with the spline portion formed on the inner circumference side of the spline outer cylinder 61. As a result, the shaft member SF is guided axially along the spline portion of the spline outer cylinder 61. The spline outer cylinder 61 is also connected to the first rotor 20 of the first motor M1 via the cover member 111. Therefore, when the first motor M1 operates, the shaft member SF rotates together with the first rotor 20 via the spline outer cylinder 61, thereby becoming rotatable around the axis of the central axis AX.

[0086] Furthermore, in the first embodiment, since the second motor M2 does not operate, the nut member 51 also does not rotate. Therefore, when the shaft member SF rotates in conjunction with the rotation of the spline outer cylinder 61, the shaft member SF moves relative to the nut member 51 along the axial direction. Thus, in the first embodiment, the shaft member SF rotates integrally with the spline outer cylinder 61 and moves linearly in the Z direction by rotating relative to the stationary nut member 51.

[0087] In the second embodiment, the nut member 51 is rotated so that the position of the shank member SF in the Z direction does not change, while the shank member SF is rotated integrally with the spline outer cylinder 61. Therefore, in the second embodiment, both the first motor M1 and the second motor M2 are operated. That is, the operation caused by the operation of the first motor M1 is the same as in the first embodiment, and when the first motor M1 is operated, the shank member SF rotates in the direction of the axis of the central axis AX by rotating together with the first rotor 20 via the spline outer cylinder 61. The second motor M2 was not operated in the first embodiment, but in the second embodiment, by operating the second motor M2, the nut member 51 is rotated in the opposite direction to the direction in which the shank member SF moves linearly due to the rotation of the shank member SF caused by the operation of the first motor M1. Thus, in the second embodiment, the shank member SF rotates integrally with the spline outer cylinder 61 without changing the position of the shank member SF in the Z direction.

[0088] In the third embodiment, the linear motion speed (movement speed in the Z direction) of the shaft member SF is varied by appropriately adjusting the rotational speed of the nut member 51 while the shaft member SF is rotated integrally with the spline outer cylinder 61. Therefore, in the third 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 in the direction of the axis of the central axis AX by rotating together with the first rotor 20 via the spline outer cylinder 61. At that time, the rotational speed of the second motor M2 is set to match the desired linear motion speed of the shaft member SF. Thus, in the third embodiment, the shaft member SF rotates integrally with the spline outer cylinder 61 while appropriately adjusting the movement speed of the shaft member SF in the Z direction.

[0089] The actuator 1 operates the first motor M1 and the second motor M2 in this manner, causing the shaft member SF to rotate around the axis of the central axis AX or to move linearly along the axis of the central axis AX. This moves the arm mounting member 70 attached to the shaft member SF, and the arm portion 80 attached to the arm mounting member 70 moves the workpiece to the desired position.

[0090] The actuator 1 is fixed to the fixed base ST by a mounting flange 40a of the first motor housing 40. However, the upper surface of the fixed base ST, which is the side where the workpiece is located relative to the fixed base ST, may be exposed to liquids such as water or oil during operation. For example, when machining such as cutting is performed on a workpiece, cutting fluid may be applied to the workpiece during the operation, and therefore, liquids such as cutting fluid may also come into contact with the actuator 1.

[0091] On the other hand, in the actuator 1, the spline outer cylinder 61 is covered by the spline outer cylinder housing 43, and the upper part 432a of the second cylindrical portion 432 of the spline outer cylinder housing 43 is covered by the cylindrical portion 72 of the arm mounting member 70. As a result, the opening at the upper end of the upper part 432a of the second cylindrical portion 432, which is the part of the spline outer cylinder housing 43 to which the shaft member SF extends upward from the inside, opens into the cylindrical portion 72 of the arm mounting member 70, and does not open directly to the outside. This prevents liquid from entering the spline outer cylinder housing 43 even when the actuator 1 is used in an environment where liquid comes into contact with the actuator 1.

[0092] Furthermore, the arm mounting member 70 is attached to the shaft member SF, and the spline outer cylinder housing 43 is attached to the first motor housing 40. Therefore, when the shaft member SF moves linearly or rotates, the cylindrical portion 72 of the arm mounting member 70 moves relative to the spline outer cylinder housing 43 in accordance with the movement of the shaft member SF. At that time, the cylindrical portion 72 of the arm mounting member 70 moves relative to the spline outer cylinder housing 43 while the sliding seal 77, which is located on the inner circumferential surface side of the cylindrical portion 72, slides against the outer circumferential surface of the upper part 432a of the second cylindrical portion 432 of the spline outer cylinder housing 43.

[0093] In other words, a gap is formed between the inner circumferential surface of the cylindrical portion 72 of the arm mounting member 70 and the outer circumferential surface of the second cylindrical portion 432 of the spline outer cylinder housing 43. However, the sliding seal 77 slides against the outer circumferential surface of the second cylindrical portion 432, maintaining a sealed state of this gap. As a result, the cylindrical portion 72 of the arm mounting member 70 moves relative to the spline outer cylinder housing 43 while maintaining the seal of the gap between it and the second cylindrical portion 432 of the spline outer cylinder housing 43. Therefore, even if liquid is applied to the actuator 1, the sliding seal 77 prevents the liquid from entering the gap between the cylindrical portion 72 of the arm mounting member 70 and the second cylindrical portion 432 of the spline outer cylinder housing 43. Consequently, the liquid applied to the actuator 1 is prevented from passing through the gap between the cylindrical portion 72 and the second cylindrical portion 432 and entering the inside of the second cylindrical portion 432.

[0094] Here, when the cylindrical portion 72 of the arm mounting member 70 moves relative to the spline outer cylinder housing 43, the sliding seal 77 slides against the second cylindrical portion 432 of the spline outer cylinder housing 43. Therefore, if the sliding seal 77 is repeatedly slid, it may wear out.

[0095] Figure 6 is a schematic diagram of the area around the sliding seal 77 when the sliding seal 77 is worn. Figure 6 is an explanatory diagram illustrating the role of the auxiliary sealing member 78 when the sliding seal 77 is worn. For this reason, the recess 72a in the cylindrical portion 72 where the sliding seal 77 is located, and the notch 72c where the auxiliary sealing member 78 is located are not shown. The same applies to Figures 8 and 9, which will be described later.

[0096] If the sliding seal 77 wears down, a gap h may form between the sliding seal 77 and the second cylindrical portion 432. In this case, it is conceivable that the liquid that comes into contact with the actuator 1 could pass through the gap h between the sliding seal 77 and the second cylindrical portion 432 and enter the gap g between the cylindrical portion 72 and the second cylindrical portion 432.

[0097] In the actuator 1 according to the first embodiment, an auxiliary sealing member 78 is positioned on the inner circumferential surface of the cylindrical portion 72, closer to the connecting portion 71 of the arm mounting member 70 than to the sliding seal 77. Since the auxiliary sealing member 78 is formed in a cylindrical shape with an inner diameter smaller than the inner diameter of the cylindrical portion 72, the gap s between the auxiliary sealing member 78 and the second cylindrical portion 432 is smaller than the gap g between the cylindrical portion 72 and the second cylindrical portion 432.

[0098] Therefore, when the liquid applied to the actuator 1 passes through the gap h between the sliding seal 77 and the second cylindrical portion 432, the liquid L that passes through will pass through the gap s between the auxiliary sealing member 78 and the second cylindrical portion 432 over the length t of the auxiliary sealing member 78 in the axial direction of the central axis AX. As a result, the dynamic pressure Pv of the liquid L passing through the gap s between the auxiliary sealing member 78 and the second cylindrical portion 432 will be reduced due to the resistance caused by passing through a narrow flow path.

[0099] On the other hand, an internal pressure Pi equal to the pressure of the atmosphere inside the second cylindrical portion 432 acts on the atmosphere in the gap g between the cylindrical portion 72 and the second cylindrical portion 432. As a result, the liquid L, whose dynamic pressure Pv has decreased by passing through the gap s between the auxiliary sealing member 78 and the second cylindrical portion 432, has its flow obstructed by the internal pressure Pi acting in the gap g between the cylindrical portion 72 and the second cylindrical portion 432, making it difficult for it to flow into the gap g between the cylindrical portion 72 and the second cylindrical portion 432. Consequently, the liquid L that has flowed in from the gap h between the sliding seal 77 and the second cylindrical portion 432 has difficulty flowing through the gap g between the cylindrical portion 72 and the second cylindrical portion 432 to the upper end of the upper part 432a of the second cylindrical portion 432, making it difficult for the liquid L to enter the inside of the second cylindrical portion 432.

[0100] Therefore, waterproof performance can be ensured even when the sliding seal 77, which is positioned between the inner circumferential surface of the cylindrical portion 72 of the arm mounting member 70 and the outer circumferential surface of the second cylindrical portion 432 of the spline outer cylinder housing 43, wears down. As a result, a decrease in waterproof performance can be suppressed.

[0101] Figure 7 is an enlarged cross-sectional view of the area near the upper end of the actuator 1 when the shaft member SF is raised. When the actuator 1 moves the arm portion 80 in the Z direction, it moves the shaft member SF in the axial direction of the central axis AX. When the shaft member SF moves in the axial direction of the central axis AX, the cylindrical portion 72 of the arm mounting member 70 also moves in the axial direction together with the shaft member SF. Therefore, when the shaft member SF moves in the axial direction of the central axis AX, the cylindrical portion 72 of the arm mounting member 70 moves relative to the spline outer cylinder housing 43.

[0102] In this case, the auxiliary sealing member 78 positioned on the inner circumferential surface of the cylindrical portion 72 is positioned such that, regardless of the movement state of the cylindrical portion 72, the end 78a of the auxiliary sealing member 78 on the connecting portion 71 side of the arm mounting member 70 is located closer to the sliding seal 77 than the end 43b of the spline outer cylinder housing 43 on the connecting portion 71 side. Therefore, even when the distance between the connecting portion 71 and the spline outer cylinder housing 43 is at its maximum when the connecting portion 71 connected to the shaft member SF moves away from the spline outer cylinder housing 43, the end 78a of the auxiliary sealing member 78 on the connecting portion 71 side is located closer to the sliding seal 77 than the end 43b of the spline outer cylinder housing 43 on the connecting portion 71 side.

[0103] As a result, even when the sliding seal 77 is worn, the auxiliary sealing member 78 can ensure waterproofing performance between the inner circumferential surface of the cylindrical portion 72 of the arm mounting member 70 and the outer circumferential surface of the second cylindrical portion 432 of the spline outer cylinder housing 43, regardless of the movement state of the shaft member SF in the axial direction. This makes it possible to more reliably suppress the deterioration of waterproofing performance.

[0104] Furthermore, in the actuator 1 according to the first embodiment, the shaft member SF passes through a first rotor 20 that rotates the shaft member SF around the axis of the central axis AX via a spline outer cylinder 61, and a second rotor 20A that moves the shaft member SF in the axial direction of the central axis AX via a nut member 51. This allows the actuator 1, which causes rotation around the axis and movement in the axial direction of the shaft member SF, to be constructed compactly. As a result, the actuator 1 can be made more space-efficient.

[0105] [Second Embodiment] Next, the actuator 1 according to the second embodiment will be described. Components identical to those in the first embodiment are denoted by the same reference numerals and their descriptions are omitted. The following description will focus on the differences from the first embodiment.

[0106] Figure 8 is a cross-sectional view of the main part of the actuator 1 of the second embodiment, and is a schematic diagram of the area around the sliding seal 77. Note that Figure 8 is a schematic diagram of the sliding seal 77 in a worn state.

[0107] In the second embodiment as well, an auxiliary sealing member 78 is arranged on the inner circumferential surface of the cylindrical portion 72 of the arm mounting member 70. In the second embodiment, unlike the first embodiment, multiple auxiliary sealing members 78 are arranged spaced apart in the axial direction of the central axis AX. In the second embodiment, two auxiliary sealing members 78 are arranged: a first auxiliary sealing member 78b and a second auxiliary sealing member 78c. The first auxiliary sealing member 78b is located closer to the connecting portion of the arm mounting member 70 in the axial direction of the central axis AX, and the second auxiliary sealing member 78c is located closer to the sliding seal 77. The first auxiliary sealing member 78b and the second auxiliary sealing member 78c are arranged spaced apart in the axial direction.

[0108] In the second embodiment as well, the auxiliary sealing member 78 is formed such that, regardless of the movement state of the cylindrical portion 72 of the arm mounting member 70, the end 78a of the auxiliary sealing member 78 on the connecting portion 71 side is located closer to the sliding seal 77 than the end 43b of the spline outer cylinder housing 43 on the connecting portion 71 side. That is, even when the distance between the connecting portion 71 of the arm mounting member 70 and the spline outer cylinder housing 43 is at its maximum, the end 78a of the first auxiliary sealing member 78b on the connecting portion 71 side is located closer to the sliding seal 77 than the end of the spline outer cylinder housing 43 on the connecting portion 71 side.

[0109] In the second embodiment as well, when the sliding seal 77 wears down, a gap h is created between the sliding seal 77 and the second cylindrical portion 432, and the liquid that has come into contact with the actuator 1 may enter the gap h between the sliding seal 77 and the second cylindrical portion 432 and flow into the side where the auxiliary sealing member 78 is located. The liquid L that has flowed into the side where the auxiliary sealing member 78 is located flows into the gap s between the auxiliary sealing member 78 and the second cylindrical portion 432.

[0110] In this configuration, the auxiliary sealing member 78 comprises a first auxiliary sealing member 78b and a second auxiliary sealing member 78c, and the first auxiliary sealing member 78b and the second auxiliary sealing member 78c are spaced apart in the axial direction of the central axis AX. Therefore, in the portion between the first auxiliary sealing member 78b and the second auxiliary sealing member 78c, the liquid L flows through the gap between the cylindrical portion 72 and the second cylindrical portion 432, but the gap between the cylindrical portion 72 and the second cylindrical portion 432 is larger than the gap s between the auxiliary sealing member 78 and the second cylindrical portion 432.

[0111] As a result, when liquid L enters the area where the auxiliary sealing member 78 is located, the width of the liquid L's flow path changes significantly between the area where the auxiliary sealing member 78 is located and the area between the first auxiliary sealing member 78b and the second auxiliary sealing member 78c, thus disrupting the flow of liquid L. Therefore, the resistance to the flow of liquid L can be increased, and it is possible to more reliably suppress the liquid L that has entered between the cylindrical portion 72 and the second cylindrical portion 432 from flowing up to the upper end of the upper part 432a of the second cylindrical portion 432 and entering the inside of the second cylindrical portion 432. As a result, the deterioration of waterproof performance can be more reliably suppressed.

[0112] [Third Embodiment] Next, the actuator 1 according to the third embodiment will be described. Components identical to those in the first embodiment are given the same reference numerals and their descriptions are omitted. The following description will focus on the differences from the first embodiment.

[0113] Figure 9 is a cross-sectional view of the main part of the actuator 1 of the third embodiment, and is a schematic diagram of the area around the sliding seal 77. Note that Figure 9 is a schematic diagram of the sliding seal 77 in a worn state.

[0114] In the third embodiment as well, an auxiliary sealing member 78 is arranged on the inner circumferential surface of the cylindrical portion 72 of the arm mounting member 70. In the third embodiment, unlike the first embodiment, an intermediate groove portion 78e extending in the circumferential direction is formed on the inner circumferential surface 78d of the auxiliary sealing member 78. The intermediate groove portion 78e is located near the center in the longitudinal direction of the auxiliary sealing member 78, and is formed as a groove that extends around the circumference with a depth from the inner circumferential surface 78d of the auxiliary sealing member 78 that is shallower than the thickness of the cylindrical auxiliary sealing member 78.

[0115] In the third embodiment as well, the auxiliary sealing member 78 is formed such that, when the distance between the connecting portion 71 of the arm mounting member 70 and the spline outer cylinder housing 43 is at its maximum, the end portion 78a on the connecting portion 71 side is positioned closer to the sliding seal 77 than the end portion of the spline outer cylinder housing 43 on the connecting portion 71 side.

[0116] In the third embodiment as well, when the sliding seal 77 wears down, a gap h is created between the sliding seal 77 and the second cylindrical portion 432, and the liquid that has come into contact with the actuator 1 may enter the gap h between the sliding seal 77 and the second cylindrical portion 432 and flow into the side where the auxiliary sealing member 78 is located. The liquid L that has flowed into the side where the auxiliary sealing member 78 is located flows into the gap s between the auxiliary sealing member 78 and the second cylindrical portion 432.

[0117] In this case, since the auxiliary sealing member 78 has an intermediate groove 78e formed on its inner circumferential surface 78d, the liquid L flows into the area of ​​the intermediate groove 78e, but the distance between the intermediate groove 78e and the second cylindrical portion 432 is greater than the gap s between the auxiliary sealing member 78 and the second cylindrical portion 432 in areas other than the intermediate groove 78e.

[0118] As a result, when liquid L enters the area where the auxiliary sealing member 78 is located, the width of the liquid L's flow path changes significantly between the area where the intermediate groove 78e is formed and the area outside the intermediate groove 78e, thus disrupting the flow of liquid L. Therefore, the resistance to the flow of liquid L can be increased, and liquid L that has entered between the cylindrical portion 72 and the second cylindrical portion 432 can be more reliably prevented from flowing to the upper end of the upper part 432a of the second cylindrical portion 432 and entering the inside of the second cylindrical portion 432. As a result, a decrease in waterproof performance can be more reliably suppressed.

[0119] [Fourth Embodiment] Next, the actuator 1 according to the fourth embodiment will be described. Components identical to those in the first embodiment are denoted by the same reference numerals and their descriptions are omitted. The following description will focus on the differences from the first embodiment.

[0120] Figure 10 is a cross-sectional view of actuator 1A according to the fourth embodiment. Figure 11 is a detailed view of the twin-axis integrated motor MP shown in Figure 10. Figure 12 is a cross-sectional view of the twin-axis integrated motor MP with respect to a plane perpendicular to the central axis AX. Unlike actuator 1 according to the first embodiment, actuator 1A according to the fourth embodiment uses a twin-axis integrated motor MP as its power source. The twin-axis integrated motor MP is composed of a first motor M1 and a second motor M2 integrated together, and one twin-axis integrated motor MP has an output shaft for the first motor MP1 and an output shaft for the second motor MP2.

[0121] The dual-axis integrated motor MP comprises a stator 210, a first rotor 220, a second rotor 230, a housing 240, a first rotation detection unit 301, and a second rotation detection unit 302. The first rotor 220 is the output shaft of the first motor MP1 in the dual-axis integrated motor MP, and the second rotor 230 is the output shaft of the second motor MP2 in the dual-axis integrated motor MP. The stator 210, the first rotor 220, and the second rotor 230 are arranged coaxially with respect to a central axis AX. The stator 210 is positioned between the first rotor 220 and the second rotor 230. For example, the first rotor 220 is positioned radially outward from the stator 210 and rotates relative to the stator 210. The second rotor 230 is positioned radially inward from the stator 210 and rotates relative to the stator 210.

[0122] The stator 210 includes a stator core 211, a first excitation coil 212, and a second excitation coil 213. As shown in Figure 12, the stator 210 is cylindrically arranged around a central axis AX. The stator core 211 includes a cylindrical back yoke 215, a plurality of first teeth 214 arranged radially outward from the back yoke 215, and a plurality of second teeth 216 arranged radially inward from the back yoke 215. The first excitation coil 212, the first teeth 214, and the first rotor 220 constitute the first motor MP1, and the second excitation coil 213, the second teeth 216, and the second rotor 230 constitute the second motor MP2.

[0123] Multiple first teeth 214 are arranged along the outer circumference of the back yoke 215. Multiple first teeth 214 are connected to the back yoke 215. A first excitation coil 212 is wound around the first teeth 214. The first excitation coil 212 is electrically connected to a first driver 321. The first driver 321 drives the first rotor 220 by supplying a first drive current I1 to the first excitation coil 212.

[0124] The rotating magnetic field obtained by exciting the first excitation coil 212 is, for example, three-phase. The first excitation coil 212 includes excitation coils for the U-phase, V-phase, and W-phase, each with a 120° phase difference in the drive signal.

[0125] Multiple second teeth 216 are aligned along the inner circumference of the back yoke 215. Multiple second teeth 216 are connected to the back yoke 215. A second excitation coil 213 is wound around the second teeth 216. The second excitation coil 213 is electrically connected to a second driver 322. The second driver 322 drives the second rotor 230 by supplying a second drive current I2 to the second excitation coil 213.

[0126] The rotating magnetic field obtained by exciting the second excitation coil 213 is, for example, three-phase. The second excitation coil 213 includes excitation coils for the U-phase, V-phase, and W-phase, each with a 120° phase difference in the drive signal.

[0127] The first driver 321 and the second driver 322 are electrically connected to the controller 320. The controller 320 independently controls the first driver 321 and the second driver 322. The controller 320 independently controls the amount of the first drive current I1 and the amount of the second drive current I2. The rotation angle of the first rotor 220 is controlled by the amount of the first drive current I1. The rotation angle of the second rotor 230 is controlled by the amount of the second drive current I2. The controller 320 independently controls the rotation angle of the first rotor 220 and the rotation angle of the second rotor 230.

[0128] The first rotor 220 comprises a first rotor bracket 221 and a first rotor core 222 composed of permanent magnets. The first rotor bracket 221 is positioned on the outer circumference of the first rotor core 222. As shown in Figure 12, the first rotor bracket 221 is cylindrically provided around the central axis AX and serves as the outer diameter cylindrical output shaft in the twin-axis integrated motor MP. The first rotor core 222 has a north pole magnet portion and a south pole magnet portion. The north pole magnet portion and the south pole magnet portion are arranged alternately at equal intervals in the rotational direction. The first rotor core 222 rotates in response to the rotating magnetic field excited by the first excitation coil 212 on the first teeth 214. The first rotor core 222 may be attached to the inner circumferential surface of the first rotor bracket 221 or embedded inside the first rotor bracket 221.

[0129] The second rotor 230 includes a second rotor bracket 231, a second rotor core 232 made of permanent magnets, and connecting brackets 233 and 234 connected to a nut member 251, which will be described later. As shown in Figure 12, the second rotor bracket 231 is cylindrically arranged around the central axis AX and serves as the inner diameter cylindrical output shaft in the twin-axis integrated motor MP. The inner diameter of the second rotor 230 is smaller than the outer diameter of the nut member 251 and the spline outer cylinder 261, which will be described later.

[0130] The second rotor core 232 has a north pole magnet section and a south pole magnet section. The north pole magnet section and the south pole magnet section are arranged alternately at equal intervals in the direction of rotation. The second rotor core 232 rotates in response to the rotating magnetic field excited by the second excitation coil 213 on the second teeth 216. The second rotor core 232 may be attached to the outer surface of the second rotor bracket 231, or it may be embedded inside the second rotor core 232.

[0131] The connecting bracket 233 is formed in a cylindrical shape and is positioned on the inner circumference side of the second rotor bracket 231. In the fourth embodiment, the connecting bracket 233 is fixed to the upper end of the second rotor bracket 231 and extends downward along the inner circumference of the second rotor bracket 231. The connecting bracket 234 is fixed to the lower end of the connecting bracket 233 and extends downward from the connecting bracket 233.

[0132] The first bearing 225 is positioned so as not to overlap with the first teeth 214 and the first excitation coil 212 in the Z direction. The first bearing 225 is located between the back yoke 215 and the first rotor bracket 221 and rotatably supports the first rotor 220. The first bearing 225 is a combination bearing having bearings 225a and 225b.

[0133] The second bearing 235 is positioned so as not to overlap with the second teeth 216 and the second excitation coil 213 in the Z direction. The second bearing 235 is located between the back yoke 215 and the second rotor bracket 231 and rotatably supports the second rotor 230. The second bearing 235 is a combination bearing having bearings 235a and 235b.

[0134] The first rotation detection unit 301 is located in a position that does not overlap with the first bearing 225 in the Z direction. The first rotation detection unit 301 detects the rotation angle of the first rotor bracket 221 relative to the housing 240 and supplies it to the controller 320 (see Figure 12).

[0135] The first rotation detection unit 301 is, for example, a resolver. The first rotation detection unit 301 includes a resolver rotor 301a and a resolver stator 301b. The resolver rotor 301a is fixed to the inner circumferential surface of the first rotor bracket 221. The resolver rotor 301a is positioned radially opposite to the resolver stator 301b. The controller 320 adjusts the amount of the first drive current I1 based on the detection result of the first rotation detection unit 301 so that a desired rotation angle can be obtained in the first rotor 220.

[0136] A second rotation detection unit 302 is provided at a position that does not overlap with the second bearing 235 in the Z direction. The second rotation detection unit 302 detects the rotation angle of the second rotor bracket 231 relative to the housing 240 and supplies it to the controller 320 (see Figure 12).

[0137] The second rotation detection unit 302 is, for example, a resolver. The second rotation detection unit 302 includes a resolver stator 302a and a resolver rotor 302b. The resolver rotor 302b is fixed to the outer circumferential surface of the second rotor bracket 231. The resolver stator 302a is positioned opposite the resolver rotor 302b in the radial direction. The controller 320 adjusts the amount of the second drive current I2 based on the detection result of the second rotation detection unit 302 so that a desired rotation angle can be obtained in the second rotor 230.

[0138] The first rotation detection unit 301 and the second rotation detection unit 302 are covered by an annular plate-shaped cover 299, which prevents foreign matter from entering the area around the first rotation detection unit 301 and the second rotation detection unit 302.

[0139] The shaft member SF, like the actuator 1 according to the first embodiment, has a shaft 262 and a screw shaft 252. The shaft 262 is provided with a plurality of spline grooves 262a arranged in the circumferential direction, extending along the axial direction. The screw shaft 252 has a male screw portion 252a formed in a helical shape with a central axis AX as the center. These shafts 262 and screw shafts 252 are arranged coaxially and integrally connected in a configuration in which the shaft 262 is located on the upper side and the screw shaft 252 is located on the lower side in the operating configuration of the actuator 1A. In the fourth embodiment, the screw shaft 252 and the shaft 262 are press-fitted at a connecting portion 256, and together they constitute the shaft member SF. The connecting portion 256 is provided with a hole 256a for releasing air when the screw shaft 252 and the shaft 262 are press-fitted.

[0140] The shaft member SF is positioned coaxially with respect to the first rotor 220 and the second rotor 230 by passing through them in the axial direction. Specifically, the shaft member SF is positioned to pass through the inside of the second rotor bracket 231, which is the inner diameter cylindrical output shaft in the two-shaft integrated motor MP, in the axial direction.

[0141] Below the second rotor bracket 231, a nut member 251 is positioned, which has a female threaded portion on its inner circumference. The nut member 251 is positioned coaxially with the second rotor 230 and rotates with the rotation of the second rotor 230. The nut member 251 has a flange portion 251a. The flange portion 251a is fixed to the connecting bracket 234 by a fixing member 251b. The nut member 251 is connected to the second rotor bracket 231 via the connecting bracket 234 and the connecting bracket 233. For example, the second rotor bracket 231 and the connecting bracket 233 are fixed together by a fixing member 236. Also, the connecting bracket 233 and the connecting bracket 234 are fixed together by a fixing member 237. For example, bolts can be used as fixing members 236 and 237. The nut member 251 is provided integrally with the second rotor bracket 231 by the connecting brackets 233 and 234. Therefore, when the second rotor 230 rotates, the nut member 251 rotates together with the second rotor 230 in the direction of the central axis AX.

[0142] The screw shaft 252 of the shaft member SF protrudes downward from the second rotor 230. The screw shaft 252 is inserted into the inner diameter side of the nut member 251 and passes through the nut member 251. The screw shaft 252 and the nut member 251 are engaged by a male threaded portion 252a formed on the screw shaft 252 and a female threaded portion formed on the inner circumference side of the nut member 251 via a plurality of balls. As a result, the screw shaft 252 is configured to move axially (in the Z direction) in accordance with the rotation of the nut member 251.

[0143] Below the nut member 251, a negative-acting electromagnetic brake 253 is positioned. The negative-acting electromagnetic brake 253 includes a field 253a, a side plate 253b, an armature 253c, a brake disc 253d, and an electromagnetic coil 253e. A coil spring (not shown) is positioned within the field 253a. The coil spring presses the armature 253c toward the brake disc 253d. When the electromagnetic coil 253e is energized, the armature 253c is attracted toward the field 253a by a force stronger than the elastic force of the coil spring, and the brake disc 253d is released. When the electromagnetic coil 253e is not energized, the attractive force from the electromagnetic coil 253e ceases to act, and the armature 253c is rapidly pressed toward the brake disc 253d by the elastic force of the coil spring. The brake disc 253d is connected to the lower end 234a of the connecting bracket 234, and is connected to the nut member 251 via the connecting bracket 234. When the brake disc 253d is released, the nut member 251 becomes rotatable. Also, when the armature 253c is pressed against the brake disc 253d, the rotation of the brake disc 253d is restricted, and this restricts the rotation of the nut member 251. Therefore, when the electromagnetic coil 253e is not energized, the screw shaft 252 is prevented from falling. Note that the configuration of the negative-acting electromagnetic brake 253 is not limited to the above configuration and may be other configurations.

[0144] A stopper 254 is attached to the lower end of the screw shaft 252. The stopper 254 restricts the upward movement of the screw shaft 252.

[0145] The shaft 262 of the shaft member SF is positioned to pass through the inside of the spline outer cylinder 261. The spline outer cylinder 261 is positioned above the first rotor bracket 221. In other words, the spline outer cylinder 261 is positioned axially above and outside the second rotor 230. The spline outer cylinder 261 is positioned coaxially with the first rotor 220 and rotates with the rotation of the first rotor 220. The spline outer cylinder 261 is connected to the first rotor bracket 221 via a connecting bracket 223. For example, the first rotor bracket 221 and the connecting bracket 223 are fixed together by a fixing member 226. For example, a bolt can be used as the fixing member 226. The spline outer cylinder 261 is provided integrally with the first rotor bracket 221 by the connecting bracket 223. Therefore, when the first rotor 220 rotates, the spline outer cylinder 261 rotates together with the first rotor 220 in the direction of the central axis AX.

[0146] A connecting bracket 224 is positioned at the upper end of the spline outer cylinder 261. The connecting bracket 224 is fixed to the connecting bracket 223 by a fixing member 227. For example, a bolt can be used as the fixing member 227.

[0147] The shaft 262 protrudes upward from the second rotor 230. As a result, the shaft 262 is inserted into the inner diameter side of the spline outer cylinder 261 and passes through the spline outer cylinder 261. The inner circumferential surface of the spline outer cylinder 261 is provided with a spline portion having a plurality of protrusions that can engage with the spline groove portion 262a. The shaft 262 that passes through the spline outer cylinder 261 has its spline groove portion 262a engaged with the spline portion of the spline outer cylinder 261 via a plurality of balls. As a result, when the spline outer cylinder 261 rotates, the shaft 262 moves axially (Z direction) in accordance with the rotation. Also, when the screw shaft 252 moves in the axial direction of the central axis AX due to the rotation of the nut member 251 while the spline outer cylinder 261 is not rotating, the shaft 262 moves axially together with the screw shaft 252.

[0148] The housing 240 includes a motor housing 241, a nut housing 242, and a spline outer cylinder housing 243. The motor housing 241 is formed, for example, in a cylindrical shape and houses a twin-axis integrated motor MP.

[0149] The nut housing 242 has a flange portion 242a and a cylindrical portion 242b. The flange portion 242a is formed in an annular shape and is fixed to the lower end of the motor housing 241 by a fixing member 244. A fixing member 245 for fixing the stator core fixing housing 217 is attached to the flange portion 242a. The stator core 211 is fixed to the housing 240 by the fixing member 245. The cylindrical portion 242b extends downward from the inner circumference of the flange portion 242a. The cylindrical portion 242b houses the nut member 251. A negative-acting electromagnetic brake 253 is fixed to the lower end of the cylindrical portion 242b.

[0150] Furthermore, the nut housing 242 holds the fourth bearing 238 between itself and the connecting bracket 234. The fourth bearing 238 rotatably supports the nut member 251. The fourth bearing 238 is, for example, a rolling bearing. The fourth bearing 238 is supported on the flange portion 242a via a wave washer 239a and a retaining member 239b. The fourth bearing 238 is pressed against the cylindrical portion 242b by the wave washer 239a and the retaining member 239b.

[0151] The spline outer cylinder housing 243 has a flange portion 243a, a first cylindrical portion 243b, and a second cylindrical portion 243c. The flange portion 243a is formed in an annular shape and is fixed to the upper end of the motor housing 241 by a fixing member 246. The flange portion 243a is also fixed to the fixing base ST by a fixing member 247. The actuator 1 is fixed to the fixing base ST by fixing the flange portion 243a to the fixing base ST.

[0152] Figure 13 is an enlarged cross-sectional view of the area near the upper end of the actuator 1A according to the fourth embodiment shown in Figure 10. The first cylindrical portion 243b is formed in a cylindrical shape, extends upward from the inner circumference of the flange portion 243a, and houses the spline outer cylinder 261 inside. The first cylindrical portion 243b is connected to the second cylindrical portion 243c via the first stepped portion 243d and the second stepped portion 243e.

[0153] The first cylindrical portion 243b holds the third bearing 228 between itself and the connecting bracket 224 at the first stepped portion 243d. The third bearing 228 is supported by the second stepped portion 243e via a wave washer 229a and a retaining member 229b. The third bearing 228 is pressed against the connecting bracket 224 by the wave washer 229a and the retaining member 229b, and rotatably supports the spline outer cylinder 261 via the connecting bracket 224.

[0154] The second stage section 243e is provided with an air supply section 243f that connects the outside with the space formed between the second cylindrical section 243c and the shaft 262. An air fitting for air purging can be attached to the air supply section 243f. A detachable closing bolt 243g is provided on the air supply section 243f to prevent foreign matter such as dust from entering the air supply section 243f.

[0155] The second cylindrical portion 243c is formed in a cylindrical shape with a smaller diameter than the first cylindrical portion 243b and extends upward from the upper end of the first cylindrical portion 243b. The second cylindrical portion 243c is positioned to cover a portion of the outer circumferential surface of the shaft 262.

[0156] A reduced-diameter portion 262b is formed at the end of the shaft member SF on the spline groove portion 262a side, i.e., at the tip of the shaft 262, and an arm mounting member 270 is connected to the tip of the shaft 262. The arm mounting member 270 has a connecting portion 271 and a cylindrical portion 272. The connecting portion 271 is connected to the reduced-diameter portion 262b of the shaft 262. An arm portion 280 for transporting the workpiece to a desired position is attached to the connecting portion 271.

[0157] The cylindrical portion 272 is formed in a cylindrical shape, similar to the first embodiment, and is provided extending downward from the connecting portion 271. The cylindrical portion 272 is positioned outside the second cylindrical portion 243c of the spline outer cylinder housing 243 and accommodates the upper part 243ca of the second cylindrical portion 243c. In other words, the cylindrical portion 272 is formed in a cylindrical shape with an inner diameter larger than the outer diameter of the upper part 243ca of the second cylindrical portion 243c of the spline outer cylinder housing 243, and extends axially from the connecting portion 271 of the arm mounting member 270 toward the side where the shaft member SF is located. As a result, the cylindrical portion 272 covers the second cylindrical portion 243c of the spline outer cylinder housing 243, at a distance from the spline outer cylinder housing 243.

[0158] Similar to the first embodiment, a recess 272a is formed at the lower end of the cylindrical portion 272, and a sliding seal 277 is positioned in the recess 272a. The sliding seal 277 is positioned on the inner circumferential surface of the cylindrical portion 272 and contacts the upper part 243ca of the second cylindrical portion 243c of the spline outer cylinder housing 243. As a result, the sliding seal 277 seals the gap formed between the cylindrical portion 272 of the arm mounting member 270 and the upper part 243ca of the second cylindrical portion 243c of the spline outer cylinder housing 243. A projection 272b protruding inward is formed at the lower end of the recess 272a, and the projection 272b prevents the sliding seal 277 from falling. Furthermore, when the power supply is cut off, the sealing resistance of the sliding seal 277 suppresses the rotation of the shaft 262, i.e., the rotation of the shaft member SF.

[0159] Furthermore, an auxiliary sealing member 278 is positioned on the inner circumferential surface of the cylindrical portion 272 at a location closer to the connecting portion 271 than the sliding seal 277, and is formed in a cylindrical shape with an inner diameter smaller than the inner diameter of the cylindrical portion 272. The auxiliary sealing member 278 is formed in a cylindrical shape with an inner diameter smaller than the inner diameter of the cylindrical portion 272 and is positioned closer to the connecting portion 271 than the sliding seal 277 on the inner circumferential surface of the cylindrical portion 272. That is, similar to the first embodiment, a notch 272c is formed above the recess 272a on the inner circumferential surface of the cylindrical portion 272 by expanding the inner circumferential surface of the cylindrical portion 272 with a diameter smaller than the diameter of the recess 272a, and the auxiliary sealing member 278 is positioned in this notch 272c.

[0160] The auxiliary sealing member 278 has an inner diameter that is between the inner diameter of the portion of the cylindrical portion 272 above the notch 272c on the inner circumferential surface and the outer diameter of the upper part 243ca of the second cylindrical portion 243c. Furthermore, regardless of the movement of the cylindrical portion 272 due to the movement of the shaft member SF in the axial direction of the central axis AX, the auxiliary sealing member 278 is formed such that the end portion 278a of the auxiliary sealing member 278 on the connecting portion 271 side of the arm mounting member 270 is positioned closer to the sliding seal 277 than the end portion 243h of the spline outer cylinder housing 243 on the connecting portion 271 side.

[0161] Figure 14 is an explanatory diagram showing the state in which the shaft member SF of the actuator 1A according to the fourth embodiment shown in Figure 10 is raised. In the actuator 1A according to the fourth embodiment, the spline outer cylinder 261, which rotates integrally with the first rotor 220, is rotated by rotating the first rotor 220. As a result, the shaft 262 can be rotated in the direction of the axis of the central axis AX along with the rotation of the spline outer cylinder 261. In addition, the nut member 251, which rotates integrally with the second rotor 230, is rotated by rotating the second rotor 230. As a result, the nut member 251 can be rotated relative to the screw shaft 252 without moving the nut member 251 in the Z direction, and the screw shaft 252 can be moved in the Z direction as the nut member 251 rotates.

[0162] The actuator 1A can rotate the shaft 262 around the axis of the central axis AX or move the screw shaft 252 in the Z direction by rotating the first rotor 220 and the second rotor 230 as described above. In other words, by controlling the rotation of the first rotor 220 and the second rotor 230, the shaft member SF can be rotated around the axis of the central axis AX or moved in the Z direction. Therefore, the arm portion 280 attached to the shaft member SF via the arm mounting member 270 can be rotated around the axis of the central axis AX or moved in the Z direction, and the arm portion 280 can be made to perform a desired operation.

[0163] When moving the shaft member SF upward, as shown in Figure 14, the stopper 254 at the lower end of the screw shaft 252 abuts against the lower end of the connecting bracket 234, restricting the upward movement of the shaft member SF. When moving the shaft member SF downward, as shown in Figures 10 and 13, the connecting portion 271 abuts against the upper end of the second cylindrical portion 243c of the spline outer cylinder housing 243, restricting the downward movement of the shaft member SF.

[0164] In the actuator 1A according to the fourth embodiment, the spline outer cylinder 261 is covered by the spline outer cylinder housing 243, and the upper part 243ca of the second cylindrical portion 243c of the spline outer cylinder housing 243 is covered by the cylindrical portion 272 of the arm mounting member 70. Furthermore, a sliding seal 277 is arranged on the inner circumferential surface side of the cylindrical portion 272 of the arm mounting member 270, which contacts the outer circumferential surface of the upper part 243ca of the second cylindrical portion 243c of the spline outer cylinder housing 243. As a result, even when the actuator 1A is used in an environment where liquid comes into contact with the actuator 1A, it is suppressed that the liquid that comes into contact with the actuator 1A enters the spline outer cylinder housing 243.

[0165] Furthermore, when the shaft member SF moves linearly in the Z direction or rotates around the axis of the central axis AX, the cylindrical portion 272 of the arm mounting member 270 moves relative to the spline outer cylinder housing 243 in accordance with the movement of the shaft member SF. At that time, the sliding seal 277, which is located on the inner circumferential surface side of the cylindrical portion 272 of the arm mounting member 270, slides against the second cylindrical portion 243c of the spline outer cylinder housing 243. As a result of this sliding, the sliding seal 277 may wear down, but an auxiliary sealing member 278 is located on the inner circumferential surface of the cylindrical portion 272. This ensures that even if the gap between the sliding seal 277 and the outer circumferential surface of the second cylindrical portion 243c becomes larger due to wear of the sliding seal 277, the auxiliary sealing member 278 can prevent liquid from entering the area between the cylindrical portion 272 and the second cylindrical portion 243c.

[0166] Therefore, even when a two-axis integrated motor MP is used as the power source for actuator 1A, waterproof performance can be ensured when the sliding seal 277, which is positioned between the cylindrical portion 272 of the arm mounting member 270 and the second cylindrical portion 243c of the spline outer cylinder housing 243, wears out. As a result, a decrease in waterproof performance can be suppressed.

[0167] Although preferred embodiments of the present invention have been described above, the present invention is not limited to those described in the above embodiments. For example, in the second embodiment, there may be three or more auxiliary sealing members 78, and in the third embodiment, there may be two or more intermediate grooves 78e formed in the auxiliary sealing member 78. Furthermore, the first to fourth embodiments may be combined as appropriate. [Explanation of symbols]

[0168] 1. 1A Actuator 10 First Status 10A Second Stator 20, 220 1st Rotor 20A, 230 Second Rotor 22,222 First rotor core 22A, 232 Second rotor core 40 First motor housing 40A Second Motor Housing 42,242 Nut housing 43, 243 Spline Outer Cylinder Housing 51, 251 Nut component 53,252 Screw shaft 61,261 Splined outer casing 63,262 shafts 70, 270 Arm mounting components 71, 271 connection part 72, 272 Cylindrical part 72a, 272a recess 72c, 272c notch 77,277 Sliding seals 78, 278 Auxiliary sealing member 78a, 278a end 78b First auxiliary sealing member 78c Second auxiliary sealing member 78d Inner surface 78e Intermediate groove 80, 280 Arm section 130 Clamping Mechanism 150 Screw shaft housing 432, 243c Second cylindrical part 432a, 243ca upper part 533, 252a Male threaded portion 633, 262a Spline groove 240 Housing 241 Motor housing 253 Negative-acting electromagnetic brake

Claims

1. A shaft member having a spline groove portion extending along the axial direction and a male screw portion formed in a spiral shape around the central axis, A spline outer cylinder engages with the spline groove of the shaft member to guide the shaft member along the spline groove in the axial direction and rotates the shaft member in the direction around the central axis, Of the two ends of the shaft member, the end on the spline groove side and the end on the male thread side, an arm mounting member is fixed to the end on the spline groove side, A spline outer cylinder housing that covers the portion of the spline outer cylinder and the shaft member that is on the end side of the spline outer cylinder where the arm mounting member is fixed, A cylindrical portion is formed with an inner diameter larger than the outer diameter of the spline outer cylinder housing, extending along the axial direction from the connecting portion which is the part of the arm mounting member that is connected to the shaft member, toward the side where the shaft member is located, and covering the spline outer cylinder housing at a distance from the spline outer cylinder housing, A sliding seal is disposed on the inner circumferential surface of the cylindrical portion and contacts the spline outer cylinder housing, An auxiliary sealing member is formed in a cylindrical shape with an inner diameter smaller than the inner diameter of the cylindrical portion and larger than the outer diameter of the spline outer cylinder housing, having a gap between its inner circumferential surface and the outer circumferential surface of the spline outer cylinder housing, and is positioned closer to the connecting portion than the sliding seal on the inner circumferential surface of the cylindrical portion, Equipped with, The auxiliary sealing member has an intermediate groove extending in the circumferential direction formed on its inner circumferential surface. The intermediate groove is located near the center of the auxiliary sealing member in the axial direction, and its width in the axial direction is narrower than the width of the inner circumferential surface of the auxiliary sealing member in the portions located on both sides of the intermediate groove in the axial direction. The inner circumferential surface of the cylindrical portion is provided with a recess formed by the expansion of the inner circumferential surface, and a notch formed adjacent to the recess by the expansion of the inner circumferential surface with a diameter smaller than the diameter of the recess. The sliding seal is positioned in the recess, The actuator is characterized in that the auxiliary sealing member is arranged in the notch.

2. Multiple auxiliary sealing members are arranged spaced apart in the axial direction. The actuator according to claim 1.

3. The auxiliary sealing member is provided in a state where the distance between the connecting portion and the spline outer cylinder housing is maximum when the shaft member moves along the axial direction in a direction that moves the connecting portion connected to the shaft member away from the spline outer cylinder housing. The end of the auxiliary sealing member on the connecting portion side in the axial direction is located closer to the sliding seal than the end of the spline outer cylinder housing on the connecting portion side in the axial direction. The actuator according to claim 1 or 2.

4. A first motor having a first rotor, A second motor having a second rotor arranged coaxially with the first rotor, A nut member having a female threaded portion that engages with the male threaded portion of the shaft member, Equipped with, The shaft member is arranged coaxially with respect to the first rotor and the second rotor by penetrating the first rotor and the second rotor in the axial direction. The spline outer cylinder is connected to the first rotor and rotates together with the first rotor, thereby rotating the shaft member in the direction of the axis of the central shaft. The nut member is positioned so that its female threaded portion engages with the male threaded portion of the shaft member, and is connected to the second rotor. By rotating together with the second rotor, the nut member moves the shaft member in the axial direction. The actuator according to any one of claims 1 to 3.

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