Actuator

Abstract

To provide an actuator that enables reduction of the entire length.SOLUTION: An actuator 1 comprises: a housing; a hollow rotational shaft 20; an output screw shaft 30; a screw nut 40; and a motor part 50. The screw nut 40 is arranged in a hole of the hollow rotational shaft 20 and is screwed with the output screw shaft 30. The motor part 50 includes: a stator core 51 that is supported on the housing; an insulation 52 installed at the stator core 51; a winding 53 wound on the insulation 52; and a rotor magnet 54 that faces the stator core 51, and is installed at the hollow rotational shaft 20. At least a part of the screw nut 40 is arranged at a position that overlaps with a projection part 53a of the winding 53 projecting to one side (-Y side) of the stator core 51 in a radial direction D2 orthogonal to an axial direction D1 of the hollow rotational shaft 20.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to an actuator. [Background technology]

[0002] Patent Document 1 discloses an actuator in which a small diameter part of a hollow rotating shaft is installed in a motor part, and a screw nut is installed in a large diameter part of the hollow rotating shaft. In the actuator of Patent Document 1, the motor part rotates the hollow rotating shaft, thereby moving the output screw shaft back and forth. The screw nut is pinned in a direction perpendicular to the axial direction of the hollow rotating shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-154378 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the device disclosed in Patent Document 1, the motor section and the threaded nut section are arranged in series without overlapping in a direction perpendicular to the axial direction of the hollow rotating shaft. Therefore, in the device disclosed in Patent Document 1, a dead space is formed between the winding section protruding to one side of the stator core and the hollow rotating shaft in a radial direction perpendicular to the axial direction of the hollow rotating shaft. In addition, in order to pin the threaded nut to the hollow rotating shaft, the size of the pinning section must also be taken into consideration. Therefore, in the device disclosed in Patent Document 1, it is difficult to further shorten the overall length.

[0005] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide an actuator capable of realizing a reduction in the overall length. [Means for solving the problem]

[0006] In order to achieve the above object, the actuator according to the present invention comprises: Housing and a hollow rotating shaft having a hole opening in an axial direction and configured to be hollow; an output screw shaft arranged coaxially with the hollow rotating shaft; A screw nut is disposed in the hole of the hollow rotating shaft and is screwed onto the output screw shaft. a motor section including a stator core supported by the housing, an insulator installed on the stator core, a winding wound around the insulator, and a rotor magnet facing the stator core and installed on the hollow rotating shaft, At least a portion of the screw nut is disposed at a position overlapping the winding protruding to one side of the stator core in a radial direction perpendicular to the axial direction of the hollow rotating shaft.

[0007] A male thread is formed on the outer periphery of the screw nut, and a female thread is formed on the hollow rotating shaft, The threaded nut may be fixed to the hollow rotating shaft by screwing the male thread into the female thread.

[0008] The hollow rotating shaft has a stepped structure, and thus has a maximum diameter portion having a larger outer diameter in the radial direction than other portions, The maximum diameter portion of the hollow rotating shaft may be formed at a position overlapping in the radial direction with the winding protruding from one side of the stator core.

[0009] The threaded nut may be disposed at the maximum diameter portion of the hollow rotating shaft.

[0010] a first bearing that is installed in the housing and rotatably supports the hollow rotating shaft; The first bearing may be positioned and disposed on one end face of the maximum diameter portion of the hollow rotating shaft in the axial direction.

[0011] The first bearing may be disposed so as to overlap the lead screw nut in the radial direction.

[0012] The rotor magnet may be positioned and disposed on an end face on the other side in the axial direction of the maximum diameter portion of the hollow rotating shaft.

[0013] The motor unit may have a stator substrate disposed at an end of the insulator protruding from the stator core to the other side in the axial direction of the hollow rotating shaft.

[0014] The stator substrate has a through hole through which the hollow rotating shaft is inserted, The hollow rotating shaft inserted into the through hole may have an extension portion extending further to the other side from the point where the stator substrate is installed, and may be rotatably supported at the extension portion by a second bearing.

[0015] a bearing holder fixed to the housing and holding the second bearing; An encoder board on which a detection unit for detecting rotation of the hollow rotating shaft is mounted may be installed in the bearing holder.

[0016] A controller board on which circuit components for controlling the driving of the motor unit are mounted is installed on one side of the housing, The controller board includes a rotation control board that controls the rotation of the motor unit, and a driver board that supplies driving power to the motor unit; The rotation control board and the driver board may be installed in parallel on one side of the housing, stacked together.

[0017] The controller board may be installed across the housing and the bearing holder.

[0018] A controller cover is provided to cover the controller board. An input / output unit is disposed on one side of the controller cover, through which power or signals are input / output to / from the controller board; The input / output portion may be oriented in the radial direction perpendicular to the axial direction without protruding from one end of the housing.

[0019] The input / output unit may be provided rotatably around the axial direction relative to the controller cover. Effect of the Invention

[0020] In the actuator according to the present invention, at least a portion of the lead screw nut is disposed in a position radially overlapping with the winding protruding from one side of the stator core, thereby making it possible to reduce the overall length of the actuator according to the present invention. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a perspective view of an actuator according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a front view of the actuator according to the present embodiment. [Diagram 3] 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 1 is an exploded perspective view (part 1) of an actuator according to the present embodiment. [Diagram 5] FIG. 2 is an exploded perspective view (part 2) of the actuator according to the present embodiment. [Figure 6] FIG. 3 is an exploded perspective view (part 3) of the actuator according to the present embodiment. [Figure 7] FIG. 2 is a perspective view of a motor unit according to the present embodiment. [Figure 8] FIG. 2 is an exploded perspective view of a motor unit according to the present embodiment. [Figure 9] FIG. 2 is an exploded cross-sectional view of the actuator according to the present embodiment. [Figure 10]1A is a perspective view of a hollow rotating shaft, an output screw shaft, and a lead screw nut according to the present embodiment, and FIG. 1B is a cross-sectional view of the hollow rotating shaft, the output screw shaft, and the lead screw nut according to the present embodiment. [Figure 11] 2 is a cross-sectional view of a hollow rotating shaft, an output screw shaft, a screw nut, and a motor unit according to the present embodiment. FIG. [Figure 12] 1A is a front view (part 1) for explaining the operation of the input / output unit according to the present embodiment, and FIG. 1B is a front view (part 2) for explaining the operation of the input / output unit according to the present embodiment. [Figure 13] 1A is a cross-sectional view (part 1) for explaining the operation of the actuator according to the present embodiment, and FIG. 1B is a cross-sectional view (part 2) for explaining the operation of the actuator according to the present embodiment. [Figure 14] FIG. 11 is a cross-sectional view of an actuator according to a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The actuator 1 according to the embodiment of the present invention will be described below. Note that the Y-axis direction in the figure is the same as the axial direction D1 in which the tip fitting T moves as shown in FIG. 1, and the X-axis direction and the Z-axis direction are directions perpendicular to the axial direction D1. The XY plane in the figure is a horizontal plane parallel to the surface on which the actuator 1 is installed. However, this is not limited to this, and the object on which the actuator 1 is installed is not limited to a flat surface. The actuator 1 may be installed in a location other than a flat surface.

[0023] As shown in Figures 2 and 3, the actuator 1 includes, in addition to the end fitting T, a housing 10, a hollow rotating shaft 20, an output screw shaft 30, a screw nut 40, a motor unit 50, a first bearing 60, a bearing holder H, a second bearing 70, an encoder board 80, a controller board 90, a controller cover 95, and an input / output unit 96.

[0024] As shown in Figs. 3 and 4, the housing 10 houses the hollow rotating shaft 20, the output screw shaft 30, and the screw nut 40 to protect these components. The housing 10 also has a front cover 11 that houses the hollow rotating shaft 20, the output screw shaft 30, and the screw nut 40 and is attached from the front on the -Y side. As shown in Figs. 5 and 6, the housing 10 is formed in a rectangular tubular shape having a top surface 10a on the +Z side, a side surface on the +X side, a side surface on the -X side, and a bottom surface on the -Z side. In the housing 10, a controller cover 95 is disposed on the top surface 10a of the rectangular tubular shape.

[0025] The motor section 50 is, for example, a servo motor. The motor section 50 includes a stator core 51, an insulator 52, a winding 53, a rotor magnet 54, and a stator substrate 55, as shown in FIGS.

[0026] The stator core 51 is supported by the housing 10. The stator core 51 is configured, for example, by laminating a plurality of disk-shaped plates made of a magnetic material. The disk-shaped plates constituting the stator core 51 are formed, for example, by punching a metal plate made of a magnetic material with a press.

[0027] 7 and 8, the insulators 52 are made of an insulating material and are installed in the stator core 51. A plurality of the insulators 52 are arranged at equal intervals along a circumference centered on the central axis A1 of the laminated disc-shaped stator core 51. The insulators 52 protrude in the +Y direction and are formed with conductive terminals 52a.

[0028] The windings 53 are made of a conductive material and are wound around each of the insulators 52. The windings 53 form a coil by being wound around the insulators 52. The windings 53 are electrically connected to terminals 52a protruding in the +Y direction of the insulators 52. The windings 53, the stator core 51, and the insulators 52 form a stator of the motor unit 50.

[0029] 9, the rotor magnet 54 rotates when power is supplied to the motor unit 50. The rotor magnet 54 is made of a magnetic material. The rotational motion of the rotor magnet 54 is output to the hollow rotating shaft 20. This causes the hollow rotating shaft 20 to rotate.

[0030] As shown in FIG. 8, the stator board 55 is a circuit board electrically connected to the windings 53 wound around the insulator 52. Specifically, a conductor pattern and through holes are formed on the stator board 55. The conductor pattern is provided on the surface of the stator board 55. The terminals 52a of the insulator 52 are inserted into the through holes to be electrically connected. While the terminals 52a are inserted into the through holes, the stator board 55 is placed on the end 52b (end on the +Y side) of the insulator 52 protruding from the stator core 51 to the +Y side in the axial direction D1 (Y-axis direction). The terminals 52a are inserted into the through holes formed in the stator board 55 to electrically connect the conductor pattern of the stator board 55 to the windings 53.

[0031] As shown in Figures 3 and 9, the hollow rotating shaft 20 is rotatably supported relative to the housing 10 by a first bearing 60. Also, as shown in Figure 10, the hollow rotating shaft 20 has a stepped structure formed on its outer circumferential surface. Furthermore, the hollow rotating shaft 20 is configured to be hollow by forming a hole 21 penetrating in the axial direction D1. The hole 21 of the hollow rotating shaft 20 has a female thread 20a formed on a part of its inner circumferential surface.

[0032] The hollow rotating shaft 20 also has a maximum diameter portion 22 and an extension portion 23 .

[0033] Maximum diameter portion 22 is a portion of hollow rotating shaft 20 whose outer diameter is larger in radial direction D2 than other portions. As shown in Fig. 11, maximum diameter portion 22 is formed so that at least a portion of it overlaps in radial direction D2 with protruding portion 53a of winding 53 protruding from one side (-Y side) of stator core 51. Maximum diameter portion 22 is formed in a shape having end face 22a on one side (-Y side) in axial direction D1 and end face 22b on the other side (+Y side) in axial direction D1.

[0034] The rotor magnet 54 is in contact with the end face 22b on the other side (+Y side) of the maximum diameter portion 22. As a result, the rotor magnet 54 is positioned at the end face 22b on the other side (+Y side) of the maximum diameter portion 22.

[0035] 10, the extension portion 23 extends further to the other side (+Y side) on the hollow rotating shaft 20 from a position P3 where the stator substrate 55 is installed. The extension portion 23 is inserted into a through hole 55a formed in the stator substrate 55.

[0036] The output screw shaft 30 is disposed coaxially with the hollow rotating shaft 20. The output screw shaft 30 has an outer circumferential surface formed with a threaded surface 30a.

[0037] The threaded nut 40 is screwed onto the threaded surface 30a of the output screw shaft 30. The threaded nut 40 is disposed in the hole 21 of the hollow rotating shaft 20 and is fixed to the hollow rotating shaft 20 so as to rotate together with the hollow rotating shaft 20. In this embodiment, the threaded nut 40 has a male thread 40a formed on its outer periphery. The threaded nut 40 is fixed to the hollow rotating shaft 20 by screwing the male thread 40a into the female thread 20a formed on the hollow rotating shaft 20. The threaded nut 40 is used to convert the rotational motion of the hollow rotating shaft 20 into the linear motion of the output screw shaft 30. Specifically, the threaded nut 40 rotates together with the hollow rotating shaft 20 to move the output screw shaft 30 in both the -Y direction and the +Y direction.

[0038] The threaded nut 40 is disposed on the maximum diameter portion 22 of the hollow rotating shaft 20. Specifically, the threaded nut 40 is disposed so that at least a portion of the threaded nut 40 overlaps with the inner side of the maximum diameter portion 22 of the hollow rotating shaft 20 in the radial direction D2.

[0039] 11, a part of the screw nut 40 is disposed at a position overlapping in the radial direction D2 with a protruding portion 53a of the winding 53 protruding to one side (-Y side) of the stator core 51.

[0040] As shown in FIG. 9, the first bearing 60 is installed in the housing 10 and rotatably supports the hollow rotating shaft 20. The first bearing 60 is, for example, a ball bearing. However, the present invention is not limited to this. The first bearing 60 may be a plain bearing. The first bearing 60 is positioned in the axial direction D1 by contacting an end face 22a on one side (-Y side) of the maximum diameter portion 22 of the hollow rotating shaft 20 in the axial direction D1. The first bearing 60 is arranged so as to overlap with the threaded nut 40 in the radial direction D2. That is, the threaded nut 40 is arranged so as to straddle the maximum diameter portion 22 of the hollow rotating shaft 20 and the first bearing 60. The first bearing 60 is fitted inside the housing 10 and is covered with the front cover 11 together with a ring-shaped seal material 12 (see FIG. 6) made of microfiber. As shown in Figures 6 and 10(A), the sealing material 12 is used to prevent dust and other particles adhering to the output screw shaft 30 from entering the threaded portion between the output screw shaft 30 and the screw nut 40.

[0041] 6, the outer ring of the first bearing 60 is fixed between the housing 10 and the front cover 11. Also, the inner ring of the first bearing 60 is fixed between the end face 22a of the maximum diameter portion 22 of the hollow rotating shaft 20 (see FIG. 6) and a bearing holding nut 61.

[0042] The bearing holder H is fixed to the housing 10 as shown in Figures 6 and 9. In this embodiment, the bearing holder H is fixed to the housing 10 from the +Y side with fasteners B1 made of bolts or screws. The bearing holder H also has a holder cover H1. The bearing holder H houses the encoder board 80 and is covered by the holder cover H1. The holder cover H1 is fixed to the bearing holder H with fasteners B2 made of bolts or screws.

[0043] The second bearing 70 is held by a bearing holder H. This second bearing 70 rotatably supports the extension portion 23 of the hollow rotating shaft 20. The second bearing 70 is, for example, a ball bearing. However, the present invention is not limited to this. The second bearing 70 may be a plain bearing.

[0044] As shown in FIG. 9, the outer ring of the second bearing 70 is fitted into the hole of the bearing holder H from the +Y side and is held by a step Ha on the +Y side of the hole of the bearing holder H. Also, in the second bearing 70, the inner ring is held by a step 23a between the extension 23 of the hollow rotating shaft 20 and a stator board arrangement part having a larger diameter than the extension 23. Also, as shown in FIG. 6, the second bearing 70 is sandwiched between the bearing holder H and the step 23a of the hollow rotating shaft 20 together with a spring member 71 formed of a wave-type compression spring and a shim ring 72. The spring member 71 is used to press the second bearing 70 to the bearing holder H based on the spring force of the spring member 71. The spring member 71 may be something other than a wave-type compression spring as long as it has the function of pressing the second bearing 70 to the bearing holder H. The shim ring 72 is used to adjust the gap between the bearing holder H and the step portion 23a of the hollow rotating shaft 20. The shim ring 72 may also be in a shape other than a ring, so long as it can adjust the gap between the bearing holder H and the step portion 23a of the hollow rotating shaft 20.

[0045] The encoder board 80 is installed on the bearing holder H as shown in FIG. 3 and FIG. 6. The encoder board 80 is fixed to the bearing holder H from the +Y side by a fastener B3 made of a bolt or a screw. A part of the encoder board 80 protrudes from the bearing holder H to the outside. The encoder board 80 is equipped with a detection unit that detects the rotation of the encoder magnet 81 (see FIG. 3 and FIG. 10(B)) installed on the extension part 23 of the hollow rotating shaft 20. The encoder magnet 81 is positioned on the step part 23b formed on the +Y axis side of the step part 23a. The encoder board 80 is concentrated at the rear end part (end part on the +Y side) of the actuator 1 together with the stator board 55, so that the controller board 90 described later can also be disposed at the rear end part (end part on the +Y side) of the actuator 1.

[0046] The controller board 90 is installed on the upper surface 10a of the housing 10, as shown in Figs. 3 and 4. Circuit components for controlling the driving of the motor unit 50 are mounted on the controller board 90. Specifically, the controller having the controller board 90 is configured to include, for example, a CPU (Central Processing Unit), a main memory unit, an auxiliary memory unit, a display unit, an input unit, and an interface unit. The CPU, the main memory unit, and the like are mounted on the controller board 90. The controller board 90 is also installed so as to straddle the housing 10 and the bearing holder H. The controller board 90 has a rotation control board 91 and a driver board 92. In the actuator 1, the controller board 90 is disposed on the rear end side (+Y side) of the actuator 1, so that it can be disposed at a position away from the tip fitting T driven by the front end (-Y end) of the actuator 1.

[0047] The rotation control board 91 controls the rotation of the rotor magnet 54 of the motor unit 50. The rotation control board 91 is disposed parallel to the upper surface 10a of the housing 10.

[0048] The driver board 92 supplies driving power to the motor unit 50. The driver board 92 is disposed parallel to the upper surface 10a of the housing 10, and is also disposed parallel to the rotation control board 91. The driver board 92 is also disposed so as to overlap the rotation control board 91.

[0049] The controller cover 95 is disposed on the upper surface 10a of the housing 10 and covers the controller board 90. In this embodiment, the controller cover 95 is composed of two parts, an upper part 95-1 and a lower part 95-2. The rotation control board 91 and the driver board 92 are fixed to the upper surface 10a by fasteners 90a composed of bolts and screws, and the lower part 95-2 covers the periphery of the rotation control board 91 and the driver board 92. The upper part 95-1 is fixed to the housing 10 together with the lower part 95-2 by fasteners 95-3 composed of bolts and screws. An input / output unit 96 is disposed on one side (-Y side) of the controller cover 95.

[0050] As shown in FIG. 1 and FIG. 2, the input / output unit 96 has an actuator cable 97 drawn out. The input / output unit 96 is for inputting and outputting power or a signal to and from the controller board 90. As shown in FIG. 3, the input / output unit 96 is provided so that the direction D3 in which the actuator cable 97 is drawn out faces the radial direction D2 perpendicular to the axial direction D1 of the hollow rotating shaft 20 without protruding in the -Y direction from the end 10b on one side (-Y side) of the housing 10. Since the input / output unit 96 does not protrude from the end 10b on one side (-Y side) of the housing 10, the actuator 1 suppresses the actuator cable 97 from interfering with the tip fitting T and the output screw shaft 30 that move linearly in the axial direction D1. In addition, the input / output unit 96 is provided so as to be rotatable about the axial direction D1 with respect to the controller cover 95, as shown in FIG. 2 and FIG. 12. Since the input / output unit 96 rotates, the actuator cable 97 can be installed in a desired direction. Specifically, the input / output unit 96 is provided so that the direction D3 of the input / output unit 96 faces three directions: the -X direction shown in Fig. 2, the +Z direction shown in Fig. 12(A), and the +X direction shown in Fig. 12(B). However, the directions in which the direction D3 of the input / output unit 96 faces are not limited to three directions. The directions in which the direction D3 of the input / output unit 96 faces may be two or less directions, or the directions in which the direction D3 of the input / output unit 96 faces may be four or more directions.

[0051] The operation of the actuator 1 configured as above will be described with reference to the drawings.

[0052] 2 and 13, when power is supplied to the motor unit 50, the hollow rotating shaft 20 rotates together with the screw nut 40 due to electromagnetic interaction between the stator and the rotor magnet 54. Then, since the output screw shaft 30 is screwed into the screw nut 40, the rotational motion of the screw nut 40 is converted into linear motion of the output screw shaft 30. This causes the output screw shaft 30 to move linearly in the axial direction D1. As a result, the tip fitting T fixed to the -Y side of the output screw shaft 30 moves linearly in the axial direction D1.

[0053] 11, in the actuator 1 according to this embodiment, a part of the threaded nut 40 is disposed at a position overlapping in the radial direction D2 with the protruding portion 53a of the winding 53 protruding to one side (-Y side) of the stator core 51. Therefore, in the actuator 1, it is possible to reduce the overall length L (length in the Y-axis direction).

[0054] 14, in actuator 1A according to the comparative example, a part of threaded nut 40 is disposed at a position that does not overlap in radial direction D2 with protruding portion 53a of winding 53 protruding to one side (-Y side) of stator core 51. For this reason, there is a risk that actuator 1A will have a long overall length L (length in the Y-axis direction).

[0055] 11, unlike the comparative example, a part of the threaded nut 40 is disposed at a position overlapping in the radial direction D2 with the protruding portion 53a of the winding 53. Therefore, the actuator 1 can achieve a shorter overall length L (length in the Y-axis direction) than the actuator 1A according to the comparative example.

[0056] Furthermore, in actuator 1 according to this embodiment, maximum diameter portion 22 is formed so as to overlap, at least in part, in radial direction D2 with protruding portion 53a of winding 53 protruding from one side (-Y side) of stator core 51. For this reason, in actuator 1, it is possible to achieve a reduction in overall length L (length in the Y-axis direction).

[0057] Furthermore, in the actuator 1 according to the embodiment, the maximum diameter portion 22 is provided on the -Y side where the stator substrate 55 is not installed. This allows the size of the maximum diameter portion 22 in the radial direction D2 to be large without interfering with the stator substrate 55. This allows the main components, such as the screw nut 40 and the rotor magnet 54, to be concentrated in the vicinity of the maximum diameter portion 22 of the hollow rotating shaft 20. As a result, the actuator 1 can achieve a reduction in overall length L (length in the Y-axis direction).

[0058] 14, in the actuator 1A according to the comparative example, in the radial direction D2 perpendicular to the axial direction D1 of the hollow rotating shaft 20, a dead space S is formed between the protruding portion 53a of the winding 53 protruding toward the -Y side of the stator core 51 and the hollow rotating shaft 20. Therefore, in the actuator 1A, it is difficult to further shorten the overall length L2.

[0059] 11, in actuator 1, maximum diameter portion 22 is formed so that at least a portion of it overlaps in radial direction D2 with protruding portion 53a of winding 53 protruding from one side (-Y side) of stator core 51. Therefore, unlike the comparative example, actuator 1 can suppress the formation of dead space S. Therefore, actuator 1 can achieve a shorter overall length L (length in the Y-axis direction) than actuator 1A according to the comparative example.

[0060] 10, in the actuator 1 according to this embodiment, the threaded nut 40 is disposed so that at least a portion of it overlaps with the inside of the maximum diameter portion 22 of the hollow rotating shaft 20 in the radial direction D2. Therefore, in the actuator 1, it is possible to reduce the overall length L (length in the Y-axis direction).

[0061] In the actuator 1 according to this embodiment, the threaded nut 40 is fixed to the hollow rotating shaft 20 by screwing its male thread 40a into the female thread 20a formed on the hollow rotating shaft 20. This eliminates the need for a threaded nut locking member from a direction different from the rotating shaft. In addition, in the actuator 1, the threaded nut 40 can be easily assembled to the hollow rotating shaft 20.

[0062] 14, in the actuator 1A according to the comparative example, the lead screw nut 40 is pinned to the hollow rotating shaft 20 in the radial direction D2 by a pin 41. The provision of this pin 41 makes it difficult to arrange the lead screw nut 40 so as to overlap the inside of the maximum diameter part 22 of the hollow rotating shaft 20 in the radial direction D2.

[0063] 10, the screw nut 40 is fixed to the hollow rotating shaft 20 by screwing its male thread 40a into the female thread 20a formed on the hollow rotating shaft 20. Therefore, unlike the comparative example, the actuator 1 does not require the pin 41. Therefore, the actuator 1 can achieve a shorter overall length L (length in the Y-axis direction) than the actuator 1A according to the comparative example.

[0064] 9, in the actuator 1 according to this embodiment, the first bearing 60 is positioned in the axial direction D1 by contacting the end face 22a on one side (-Y side) of the maximum diameter portion 22 of the hollow rotating shaft 20 in the axial direction D1. This makes it possible to easily assemble the hollow rotating shaft 20 and the first bearing 60 in the actuator 1. Furthermore, the hollow rotating shaft 20 and the first bearing 60 can be assembled while eliminating a gap between the maximum diameter portion 22 and the first bearing 60. This makes it possible to reduce the overall length L (length in the Y-axis direction) of the actuator 1.

[0065] Moreover, in the actuator 1 according to this embodiment, the first bearing 60 is disposed so as to overlap the lead nut 40 in the radial direction D2. Therefore, in the actuator 1, the lead nut 40 can be easily assembled to the hollow rotating shaft 20.

[0066] Furthermore, in the actuator 1 according to this embodiment, the rotor magnet 54 is positioned on the end face 22b on the other side (+Y side) of the maximum diameter portion 22 of the hollow rotating shaft 20. This allows the hollow rotating shaft 20 and the motor unit 50 to be easily assembled together in the actuator 1. Furthermore, the hollow rotating shaft 20 and the motor unit 50 can be assembled together while eliminating any gap between the maximum diameter portion 22 and the rotor magnet 54. This allows the actuator 1 to achieve a reduction in overall length L (length in the Y-axis direction).

[0067] Moreover, in the actuator 1 according to this embodiment, the first bearing 60 is disposed so as to overlap the lead screw nut 40 in the radial direction D2. That is, the lead screw nut 40 is disposed so as to straddle the maximum diameter portion 22 of the hollow rotating shaft 20 and the first bearing 60. This makes it possible to reduce the overall length L (length in the Y-axis direction) of the actuator 1. Moreover, the actuator 1 can stably hold the lead screw nut 40 on the hollow rotating shaft 20, ensure the strength of the installation portion of the lead screw nut 40, and can stably rotate the lead screw nut 40 together with the hollow rotating shaft 20.

[0068] Furthermore, in the actuator 1 of this embodiment, as shown in Figures 3 and 4, the controller board 90 is made up of two boards, a rotation control board 91 and a driver board 92, and is installed parallel to the upper surface 10a of the housing 10, thereby shortening the length of the actuator 1 in the Y-axis direction.

[0069] Furthermore, in the actuator 1 according to this embodiment, the input / output portion 96 does not protrude from the -Y side end 10b of the housing 10, so the feature of the actuator 1 that the length in the Y axis direction is shortened is not lost.

[0070] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

[0071] For example, as shown in Fig. 1, the actuator 1 according to this embodiment has a housing 10 formed in a square tube shape, and a tip fitting T moves in an axial direction D1. However, the type of the actuator 1 is not limited to this. The actuator 1 may be one other than that exemplified in the embodiment.

[0072] In the actuator 1 according to this embodiment, the hole 21 of the hollow rotating shaft 20 is formed to penetrate in the axial direction D1 as shown in Fig. 3. However, this is not limited thereto. The hole 21 of the hollow rotating shaft 20 may be a non-through hole that does not penetrate in the axial direction D1.

[0073] The present invention allows various embodiments and modifications without departing from the broad spirit and scope of the present invention. The above-described embodiments are for the purpose of explaining the present invention and do not limit the scope of the present invention. [Explanation of symbols]

[0074] 1, 1A: Actuator 10: Housing 10a:Top surface 10b: End 11: Front cover 12: Sealing material 20: Hollow rotating shaft 20a: Female thread 21: Hole 22: Maximum diameter part 22a: (One side) end face 22b: (other side) end face 23: Stretching part 23a: Stepped section 23b: Stepped section 30: Output screw shaft 30a: Thread surface 40: Screw nut 40a: Male thread 41: Pin 50: Motor section 51: Stator core 52: Insulator 52a: Terminal 52b: End 53: Winding 53a:Protruding part 54: Rotor magnet 55: Stator board 55a: Through hole 60: First bearing 61: Bearing retaining nut 70: Second bearing 71: Spring material 72: Shim ring 80: Encoder board 81: Encoder magnet 90: Controller board 90a: Fastener 91: Rotation control board 92: Driver board 95: Controller cover 95-1: Upper part 95-2: Lower parts 95-3: Fastener 96: Input / output section 97: Actuator cable H: Bearing holder Ha:Dan section H1: Holder cover T: Tip fitting B1, B2, B3: Fasteners D1: Axial direction D2: Radial direction D3: Direction L, L2: Total length S: Dead Space A1: Central axis P3:Position

Claims

1. Housing and a hollow rotating shaft having a hole opening in an axial direction and configured to be hollow; an output screw shaft arranged coaxially with the hollow rotating shaft; A screw nut is disposed in the hole of the hollow rotating shaft and is screwed onto the output screw shaft. a motor section including a stator core supported by the housing, an insulator installed on the stator core, a winding wound around the insulator, and a rotor magnet facing the stator core and installed on the hollow rotating shaft, an actuator, wherein at least a portion of the screw nut is arranged in a position overlapping with the winding protruding to one side of the stator core in a radial direction perpendicular to the axial direction of the hollow rotating shaft.

2. A male thread is formed on the outer periphery of the screw nut, and a female thread is formed on the hollow rotating shaft, The actuator according to claim 1 , wherein the threaded nut is fixed to the hollow rotating shaft by screwing the male thread into the female thread.

3. The hollow rotating shaft has a stepped structure, and thus has a maximum diameter portion having a larger outer diameter in the radial direction than other portions, 2 . The actuator according to claim 1 , wherein the maximum diameter portion of the hollow rotating shaft is formed at a position radially overlapping the winding protruding from one side of the stator core.

4. The actuator according to claim 3 , wherein the threaded nut is disposed at the maximum diameter portion of the hollow rotating shaft.

5. a first bearing that is installed in the housing and rotatably supports the hollow rotating shaft; The actuator according to claim 3 , wherein the first bearing is positioned and disposed on an end face on one side in the axial direction of the maximum diameter portion of the hollow rotating shaft.

6. The actuator according to claim 5 , wherein the first bearing is disposed so as to overlap the lead screw nut in the radial direction.

7. The actuator according to claim 3 , wherein the rotor magnet is positioned and disposed on an end face on the other side in the axial direction of the maximum diameter portion of the hollow rotating shaft.

8. The actuator according to claim 1 , wherein the motor portion has a stator substrate disposed at an end of the insulator that protrudes from the stator core to the other side in the axial direction of the hollow rotating shaft.

9. The stator substrate has a through hole through which the hollow rotating shaft is inserted, 9. The actuator according to claim 8, wherein the hollow rotating shaft inserted into the through hole has an extension portion extending further to the other side from the point where the stator substrate is installed, and the extension portion is rotatably supported by a second bearing.

10. a bearing holder fixed to the housing and holding the second bearing; The actuator according to claim 9 , wherein an encoder board having a detection unit mounted thereon for detecting rotation of the hollow rotating shaft is disposed in the bearing holder.

11. A controller board on which circuit components for controlling the driving of the motor unit are mounted is installed on one side of the housing, The controller board includes a rotation control board that controls the rotation of the motor unit, and a driver board that supplies driving power to the motor unit; The actuator according to claim 10 , wherein the rotation control board and the driver board are arranged in parallel and stacked on one side of the housing.

12. The actuator according to claim 11 , wherein the controller board is installed across the housing and the bearing holder.

13. A controller cover is provided to cover the controller board. An input / output unit is disposed on one side of the controller cover, through which power or signals are input / output to / from the controller board; The actuator according to claim 11 , wherein the input / output portion faces the radial direction perpendicular to the axial direction without protruding from one end of the housing.

14. The actuator according to claim 13 , wherein the input / output unit is provided rotatably about the axial direction with respect to the controller cover.

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