Electric actuator

Abstract

To provide an electric actuator that can be miniaturized while ensuring insulation. [Solution] One embodiment of the electric actuator of the present invention comprises a motor unit having a rotor rotatable about a central axis extending in the axial direction and a stator located radially outward from the rotor; a reduction mechanism having a movable part connected to one axial side of the rotor and rotating in conjunction with the rotation of the rotor; and a case housing the motor unit and the reduction mechanism. The stator has a stator core in which a plurality of stator teeth and slots are alternately arranged in the circumferential direction around a central axis, and a winding section mounted on the stator teeth. An insulating partition member is provided between the winding section and the movable part in the axial direction.

Description

Technical Field

[0001] The present invention relates to an electric actuator.

Background Art

[0002] An electric actuator is known to have a structure in which a motor unit having a rotor and a stator, and a speed reducer are housed in a case. For example, Patent Document 1 discloses a configuration in which the movable portion of the speed reducer is arranged to face the coil of the stator.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0004] In order to ensure insulation properties, it is necessary to increase the axial length between the movable portion of the speed reducer and the coil, which gives rise to the problem that the electric actuator increases in size.

[0005] The present invention has been made in consideration of the above points, and an object thereof is to provide an electric actuator that can be reduced in size while ensuring insulation properties.

Means for Solving the Problems

[0006] One embodiment of the electric actuator of the present invention comprises a motor unit having a rotor rotatable about a central axis extending in the axial direction, and a stator located radially outward from the rotor; a reduction mechanism having a movable part connected to one axial side of the rotor and rotating in conjunction with the rotation of the rotor; and a case housing the motor unit and the reduction mechanism, wherein the stator has a stator core in which a plurality of stator teeth and slots are alternately arranged in the circumferential direction about the central axis, and a winding portion mounted on the stator teeth, and an insulating partition member is provided between the winding portion and the movable part in the axial direction. [Effects of the Invention]

[0007] According to one aspect of the present invention, it is possible to provide an electric actuator that can be miniaturized while ensuring insulation. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a cross-sectional view showing an electric actuator of the first embodiment. [Figure 2] Figure 2 is a cross-sectional view showing an electric actuator of the first embodiment, and is a cross-sectional view taken along line II-II in Figure 1. [Figure 3] Figure 3 is an exploded perspective view showing a portion of the electric actuator of the first embodiment. [Figure 4] Figure 4 is a partial cross-sectional view showing an electric actuator of the second embodiment. [Figure 5] Figure 5 is a plan view of the motor section of the electric actuator of the third embodiment, viewed from above. [Figure 6] Figure 6 is a partial cross-sectional view showing an electric actuator of the third embodiment, and is a cross-sectional view AA in Figure 5. [Modes for carrying out the invention]

[0009] The following description of an electric actuator according to an embodiment of the present invention will be made with reference to the drawings. Note that the scope of the present invention is not limited to the following embodiments, and can be arbitrarily modified within the scope of the technical idea of ​​the present invention. Furthermore, in the following drawings, the scale and number of components in each structure may differ from the actual structure in order to make the components easier to understand.

[0010] In each figure, the Z-axis direction is the vertical direction, with the positive side being the upper side and the negative side being the lower side. The axial direction of the central axis J1, as shown in each figure, is parallel to the Z-axis direction, i.e., the vertical direction. In the following explanation, unless otherwise specified, the direction parallel to the axial direction of the central axis J1 will simply be called the "axial direction." Also, unless otherwise specified, the radial direction centered on the central axis J1 will simply be called the "radial direction," and the circumferential direction centered on the central axis J1 will simply be called the "circumferential direction."

[0011] In this embodiment, the lower side corresponds to one axial side, and the upper side corresponds to the other axial side. Note that "upper side" and "lower side" are merely names used to describe the relative positional relationship of each part, and the actual arrangement may differ from those indicated by these names.

[0012] [First embodiment of an electric actuator] The electric actuator 1 of the first embodiment shown in Figures 1 to 3 is, for example, an electric actuator mounted on a vehicle. As shown in Figures 1 and 3, the electric actuator 1 comprises a case 10, a partition member 15, a lid member 80, a motor unit 20 having a motor shaft 21 that rotates about a central axis J1, a first bearing 53, a second bearing 51, a third bearing (shaft bearing) 52, a reduction mechanism 30, an output shaft 41, a magnetic sensor 63, a circuit board 70, a busbar holder 140, and a busbar 150.

[0013] As shown in Figure 1, the case 10 houses the partition member 15, the motor unit 20, the motor shaft 21, the reduction mechanism 30, the output shaft 41, the magnetic sensor 63, the circuit board 70, the busbar holder 140, and the busbar 150. The case 10 has an opening that opens upwards.

[0014] The case 10 is cylindrical in shape, extending axially around a central axis J1. The case 10 has a substrate housing section 13a, a case cylindrical section 13b, an output section housing section 13c, and a bearing holding section 13d. The substrate housing section 13a is the part that houses the circuit board 70 and the busbar holder 140. The substrate housing section 13a opens upward. The substrate housing section 13a is located radially inward of the upper part of the case 10. The bottom surface of the substrate housing section 13a is a second support surface 12 that supports and fixes the circuit board 70 and the busbar holder 140. The second support surface 12 faces upward.

[0015] The case cylinder portion 13b surrounds the radially outer side of the motor portion 20. The output portion housing portion 13c is the part that houses the output portion 46, which will be described later. The bearing holding portion 13d holds the second bearing 51. The bearing holding portion 13d extends upward from the lower end of the case 10 with the central axis J1 as its center.

[0016] The lid member 80 covers the opening of the case 10 and is fixed to the case 10. The lid member 80 is a container-shaped member having a recess 16a that opens downwards. The lid member 80 and the case 10 are fastened together by a plurality of bolts 201 (see Figure 3) that penetrate the lid member 80 axially. In this embodiment, the lid member 80 corresponds to a lid that covers the opening of the case 10 from above. The lid member 80 has a bearing retaining portion 16b. The bearing retaining portion 16b holds the first bearing 53. The bearing retaining portion 16b extends downwards with respect to the central axis J1.

[0017] The central axis of the motor unit 20 is the central axis J1. As shown in Figure 1, the motor unit 20 has a rotor 22 and a stator 23. The rotor 22 has a motor shaft 21, a rotor core 22a, and a magnet 40.

[0018] The motor shaft 21 includes a first shaft portion 21a, a second shaft portion 21b, and a through hole 25. The first shaft portion 21a extends in the axial direction and is located on the upper side of the motor shaft 21. The second shaft portion 21b extends in the axial direction and is located on the lower side of the motor shaft 21. The diameter of the second shaft portion 21b is larger than the diameter of the first shaft portion 21a. More specifically, the outer diameter of the second shaft portion 21b is larger than the outer diameter of the first shaft portion 21a. The second shaft portion 21b is an eccentric shaft portion centered on an eccentric axis J2 that is eccentric with respect to the central axis J1. The eccentric axis J2 is parallel to the central axis J1. The through hole 25 extends around the central axis J1. Accordingly, the first shaft portion 21a has a cylindrical shape extending around the central axis J1. The second shaft portion 21b has an axial recessed portion 26 on the lower side. The recessed portion 26 extends around the eccentric axis J2. Accordingly, the second shaft portion 21b has a cylindrical shape extending around the eccentric axis J2. The upper side of the recessed portion 26 is connected to the lower side of the through hole 25. In the motor shaft 21, the second shaft portion 21b is supported by a third bearing 52 so as to be rotatable around the eccentric axis J2.

[0019] Rotation of the motor shaft 21 is transmitted to the output shaft 41 via the speed reduction mechanism 30. The output shaft 41 has a shaft portion 41a and a coupling portion 42. The shaft portion 41a is located on the upper side, and the coupling portion 42 is located on the lower side. The shaft portion 41a has a columnar shape extending around the central axis J1. The upper side of the shaft portion 41a is passed through the through hole 25 of the motor shaft 21. The upper end portion of the shaft portion 41a protrudes to the upper side of the motor shaft 21. The upper end portion of the shaft portion 41a protruding to the upper side of the motor shaft 21 is supported by a first bearing 53 so as to be rotatable around the central axis J1. The upper end portion of the motor shaft 21 is supported by a cover member 80 via the first bearing 53.

[0020] The lower end portion of the connecting portion 42 protrudes to the lower side of the motor shaft 21. The lower end portion of the connecting portion 42 protruding to the lower side of the motor shaft 21 is supported by the second bearing 51 so as to be rotatable around the central axis J1. The lower end portion of the motor shaft 21 is supported by the case 10 via the second bearing 51. The axial end portion of the output shaft 41 is supported by the first bearing 53 and the second bearing 51 so as to be rotatable around the central axis J1. Accordingly, the motor shaft 21 having the shaft portion 41a of the output shaft 41 passed through the through hole 25 is supported by the shaft portion 41a so as to be rotatable around the central axis J1.

[0021] The first bearing 53, the second bearing 51, and the third bearing 52 are rolling bearings each having an inner ring and an outer ring positioned radially outward of the inner ring. In the present embodiment, the first bearing 53, the second bearing 51, and the third bearing 52 are, for example, ball bearings in which the inner ring and the outer ring are connected via a plurality of balls.

[0022] The upper side of the connecting portion 42 is inserted into the recessed portion 26 of the motor shaft 21. Since the upper side of the connecting portion 42 is inserted into the recessed portion 26 of the motor shaft 21, the axial length of the output shaft 41 can be shortened. Accordingly, the axial length of the electric actuator 1 can be shortened to achieve downsizing.

[0023] The connecting portion 42 has a cylindrical tube portion 44 extending around the central axis J1. A connecting recess 45 is provided on the inner diameter of the tube portion 44. The connecting recess 45 is recessed upward from the lower end portion of the output shaft 41. The connecting recess 45 has a substantially circular shape centered on the central axis J1 when viewed along the axial direction. A plurality of spline grooves are provided on the inner peripheral surface of the connecting recess 45 along the circumferential direction. Another member to which the driving force of the electric actuator 1 is output is inserted and connected to the connecting recess 45. The other member is, for example, a manual shaft in a vehicle. The electric actuator 1 drives the manual shaft based on a driver's shift operation to switch the gear of the vehicle.

[0024] The connecting portion 42 has a connecting recess 45 that is recessed upward, which allows the axial length of the output shaft 41 to be shortened compared to the case where the connecting portion 42 is shaft-shaped and protrudes downward. Therefore, the axial length of the electric actuator 1 can be shortened and it can be made smaller. The first bearing 53 is held in a bearing holding portion 16b provided on the case 10, and the second bearing 51 is held in a bearing holding portion 13d provided on the case 10, which improves the coaxiality of the output shaft 41 with respect to the central axis J1. The first bearing 53 is held in a bearing holding portion 16b provided on the case 10, and the second bearing 51 is held in a bearing holding portion 13d provided on the case 10, which eliminates the need to provide separate holders for the first bearing 53 and the second bearing 51, which contributes to cost reduction and miniaturization of the electric actuator 1.

[0025] The rotor core 22a is fixed to the outer circumferential surface of the motor shaft 21. More specifically, the rotor core 22a is fixed to the outer circumferential surface of the first shaft portion 21a. The magnets 40 are fixed to the radially outer side of the rotor core 22a. Multiple magnets 40 are arranged at intervals in the circumferential direction.

[0026] The stator 23 is located radially outward of the rotor 22. The stator 23 has a stator core 23a, a plurality of winding sections 23b, and an insulator 29. The stator core 23a is an annular shape that surrounds the radially outward side of the rotor 22. The outer circumferential surface 24a of the stator core 23a is fixed to the inner surface 14 of the case cylindrical section 13b. In other words, the inner surface 14 of the case 10 surrounds the stator 23 from the radially outward side.

[0027] As shown in Figure 2, the stator core 23a has stator teeth 23t and slots 23s. The stator teeth 23t and slots 23s are arranged alternately in the circumferential direction. Multiple winding sections 23b are mounted on the stator teeth 23t of the stator core 23a via insulators 29.

[0028] The stator 23 has an outer circumferential surface 24b that is radially inward from the core outer circumferential surface 24a. The outer circumferential surface 24b is the surface facing radially outward from the insulator 29. The outer circumferential surfaces 24b are arranged for each magnetic pole. Viewed in the axial direction, the outer circumferential surfaces 24b are perpendicular to the circumferential magnetic pole centers. The outer circumferential surface 24b of the stator 23 is provided with grooves 27 that are recessed radially inward. The grooves 27 extend continuously in the axial direction. The grooves 27 are located on the upper and lower sides of the core outer circumferential surface 24a of the stator core 23a, respectively. The grooves 27 extend along the axial direction and open to the other side in the axial direction. Multiple grooves 27 are arranged at intervals in the circumferential direction.

[0029] As shown in Figure 1, the peripheral edge of the stator core 23a is supported from below by the outer edge 15b of the partition member 15, which will be described later. The peripheral edge of the stator core 23a is in contact with the outer edge 15b of the partition member 15 from one axial side.

[0030] The partition member 15 is positioned on one axial side of the motor section 20. The partition member 15 is positioned between the stator 23 and the reduction mechanism 30 in the axial direction. The partition member 15 is positioned between the winding section 23b and the movable section 30A of the reduction mechanism 30 (details will be described later) in the axial direction. The partition member 15 is made of an insulating resin material. Since the partition member 15, positioned between the winding section 23b and the movable section 30A in the axial direction, is made of an insulating resin material, it is no longer necessary to increase the axial length between the winding section 23b and the movable section 30A in order to ensure insulation. Therefore, the electric actuator 1 can be miniaturized while ensuring insulation.

[0031] The partition member 15 is an annular plate shape. The partition member 15 has a main body portion 15a and an outer edge portion 15b. The main body portion 15a surrounds the central axis J1 and extends radially around the central axis J1. The outer edge portion 15b extends upward from the outer peripheral edge portion 17a (see Figure 3) of the main body portion 15a on the other axial side. The outer edge portion 15b contacts the first support surface 11 of the case 10 from above. The first support surface 11 is located below the inner surface 14. The first support surface 11 faces upward.

[0032] The busbar holder 140 is positioned above the rotor 22. The busbar holder 140 is positioned on the other axial side of the motor section 20. The busbar holder 140 is an annular plate shape. The busbar holder 140 has a holder body 148 and a collar member 143. The holder body 148 is made of an insulating resin material. The holder body 148 of the busbar holder 140 has a flange portion 140f that extends radially outward from the cylindrical portion 141, which will be described later. The flange portion 140f of the busbar holder 140 contacts the second support surface 12 of the case 10 from the other axial side. The second support surface 12 is located on the other axial side of the inner surface 14. The second support surface 12 faces the other axial side.

[0033] The collar member 143 is cylindrical in shape and extends in the axial direction. The collar member 143 is embedded in the flange portion 140f of the holder body 148 in an orientation along the axial direction. The collar member 143 protrudes above the busbar holder 140. The other axial end face 143f of the collar member 143 is in contact with the underside of the circuit board 70. The one axial end face 143g of the collar member 143 is in contact with the second support surface 12. As a result, the busbar holder 140 is sandwiched between the circuit board 70 and the second support surface 12 in the axial direction.

[0034] Screws 144 are inserted into the collar member 143 to fasten the circuit board 70 to the second support surface 12. The busbar holder 140 and the circuit board 70 are screwed to the second support surface 12 of the case 10 by screws 144 that pass through the circuit board 70 and the collar member 143 from above. For example, four screws 144 are provided. The busbar holder 140 and the circuit board 70 are screwed to each other by screws 144 from above at a position that overlaps with the collar member 143 when viewed in the axial direction. The circuit board 70 is fastened to the second support surface 12 in the axial direction by screws 144. The screwed-together circuit board 70 is positioned above the busbar holder 140 with a gap. The dimension of the gap between the circuit board 70 and the busbar holder 140 is the dimension by which the collar member 143 protrudes above the busbar holder 140.

[0035] The busbar holder 140 has a cylindrical portion 141 that extends downward. The cylindrical portion 141 is located radially outward from the outer circumferential surface 24b of the stator 23. The cylindrical portion 141 surrounds the outer circumferential surface 24b of the stator 23. The cylindrical portion 141 is located radially inward from the outer circumferential surface 24a of the core of the stator 23. The lower end of the cylindrical portion 141 contacts the upper side of the stator 23 when the busbar holder 140 is screwed to the second support surface 12.

[0036] When the busbar holder 140 is screwed to the second support surface 12 of the case 10, the lower end of the cylindrical portion 141 comes into contact with the upper side of the stator 23, so that the stator 23 is sandwiched between the busbar holder 140 and the first support surface 11 in the axial direction. Supported from below by the partition member 15, the stator 23 is positioned and fixed in the case 10 in the axial direction.

[0037] As shown in Figure 2, the cylindrical portion 141 of the busbar holder 140 has a protruding portion 142. The protruding portion 142 projects radially inward on the inner circumferential surface of the cylindrical portion 141. The protruding portion 142 extends in the axial direction. The circumferential position of the protruding portion 142 is the same as the circumferential position of the groove 27 of the stator 23. The protruding portion 142 faces the groove 27 in the radial direction. The protruding portion 142, which projects radially inward from the cylindrical portion 141, is inserted into the groove 27 above the outer circumferential surface 24a of the core. With the protruding portion 142 inserted into the groove 27, the busbar holder 140 is positioned circumferentially relative to the stator 23. When the busbar holder 140 is housed in the substrate housing portion 13a while inserting the protruding portion 142 from above into the recessed groove 27 that opens upward, the busbar holder 140 can be positioned circumferentially with respect to the stator 23 and the case 10. Therefore, when the busbar holder 140 is screwed to the second support surface 12 of the case 10, the busbar holder 140, the stator 23, and the case 10 can be positioned relative to each other in the circumferential and axial directions.

[0038] The holder body 148 holds the magnetic sensor 63, the conductive wire 64, and the multiple busbars 150. In this embodiment, the holder body 148, the magnetic sensor 63, the conductive wire 64, the color member 143, and the multiple busbars 150 are a molded body that is integrated by resin molding. More specifically, the busbar holder 140 is made by insert molding, with the magnetic sensor 63, the conductive wire 64, the color member 143, and the busbars 150 as insert members.

[0039] The magnetic sensor 63 is capable of detecting the magnetic field of the magnet 40. The magnetic sensor 63 is, for example, a Hall element. The magnetic sensor 63 is held in the magnetic sensor holding portion 145 of the busbar holder 140. The magnetic sensor holding portion 145 is provided on the lower surface of the busbar holder 140. The magnetic sensor holding portion 145 is recessed in the other axial direction from the lower surface of the busbar holder 140. The magnetic sensor 63 is fixed to the busbar holder 140 by being inserted into the magnetic sensor holding portion 145.

[0040] The magnetic sensors 63 are positioned opposite the magnet on the upper side, with a gap in between. As shown in Figure 2, three magnetic sensors 63 are arranged with circumferential spacing between them. The circumferential spacing between the magnetic sensors 63 is the same as the circumferential spacing between the magnetic poles. The magnetic sensors 63 detect the rotational position of the magnet 40 by detecting the magnetic field of the magnet 40, thereby detecting the rotation of the motor shaft 21.

[0041] As shown in Figure 1, one end of the conductive wire 64 is electrically connected to the magnetic sensor 63. The conductive wire 64 may be a terminal extending from the magnetic sensor 63, or it may be a busbar with one end connected to the magnetic sensor 63. The conductive wire 64 passes through the busbar holder 140 from inside the busbar holder 140, and the other end is electrically connected to the circuit board 70 by a connection method such as soldering, welding, or press-fitting.

[0042] One end of the busbar 150 is electrically connected to the stator 23. The other end of the busbar 150 is electrically connected to the circuit board 70.

[0043] The circuit board 70 is located on the other axial side of the busbar holder 140. The circuit board 70 is plate-shaped and extends in a plane perpendicular to the axial direction. The circuit board 70 is housed in the case 10. More specifically, the circuit board 70 is housed in the board housing section 13a. The circuit board 70 is a board that is electrically connected to the motor section 20. The circuit board 70 controls, for example, the current supplied to the motor section 20. That is, the circuit board 70 is equipped with, for example, an inverter circuit. The circuit board 70 is electrically connected to the motor section 20 via the busbar 150.

[0044] The reduction mechanism 30 is connected to the rotor 22 on one axial side of the motor unit 20. The reduction mechanism 30 reduces the power of the rotor 22. The reduction mechanism 30 is positioned radially outward of the second shaft portion 21b on the motor shaft 21 and radially outward of the connecting portion 42 on the output shaft 41. The reduction mechanism 30 is positioned below the motor unit 20. The reduction mechanism 30 includes an external gear 31, an internal gear 32, an output portion 46, and a plurality of protrusions 43.

[0045] The external gear 31 is an annular plate shape that extends radially around the eccentric axis J2 of the second shaft portion 21b. A gear portion is provided on the radially outer surface of the external gear 31. The gear portion of the external gear 31 has multiple teeth arranged along the outer circumference of the external gear 31.

[0046] The external gear 31 is connected to the motor shaft 21. More specifically, the external gear 31 is connected to the second shaft portion 21b of the motor shaft 21 via a third bearing 52. This connects the motor shaft 21 to the reduction mechanism 30. The external gear 31 is fitted radially outward to the outer ring of the third bearing 52. The second shaft portion 21b is fitted radially outward to the inner ring of the third bearing 52. This connects the motor shaft 21 and the external gear 31 so that they can rotate relative to each other around the eccentric axis J2.

[0047] In this embodiment, the external gear 31 has a plurality of holes 31a. In this embodiment, the holes 31a penetrate the external gear 31 in the axial direction. The plurality of holes 31a are arranged along the circumferential direction. More specifically, the plurality of holes 31a are arranged at equal intervals along the circumferential direction around the eccentric axis J2. The holes 31a are circular in shape when viewed in the axial direction. The inner diameter of the holes 31a is larger than the outer diameter of the protrusion 43. Note that the holes 31a may have a bottom.

[0048] The internal gear 32 is located radially outside the external gear 31 and is annular in shape, surrounding the external gear 31. In this embodiment, the internal gear 32 is annular in shape, centered on the central axis J1. The radial outer edge of the internal gear 32 is positioned and fixed to a stepped portion 13e that is recessed radially inward on the inner circumferential surface of the case cylinder portion 13b. This holds the reduction mechanism 30 in the case 10. The internal gear 32 meshes with the external gear 31. A gear portion is provided on the radial inner surface of the internal gear 32. The gear portion of the internal gear 32 has multiple teeth arranged along the inner circumference of the internal gear 32. In this embodiment, the gear portion of the internal gear 32 meshes with the gear portion of the external gear 31 in only a portion of the circumferential direction.

[0049] The output section 46 is an annular plate shape that expands radially around the central axis J1. The output section 46 is located below the external gear 31. The output section 46 is fixed to the outer circumferential surface of the output shaft 41. More specifically, the output section 46 is fixed to the outer circumferential surface of the connecting section 42 of the output shaft 41.

[0050] Multiple protrusions 43 are fixed to the output section 46, for example, by welding. Multiple protrusions 43 project upward from the output section 46. That is, multiple protrusions 43 project from the output section 46 toward the external gear 31. The protrusions 43 are cylindrical. Multiple protrusions 43 are arranged along the circumferential direction. More specifically, multiple protrusions 43 are arranged at equal intervals along the circumferential direction around the central axis J1. The number of protrusions 43 is, for example, eight.

[0051] Multiple protrusions 43 are inserted into multiple holes 31a. The outer circumferential surfaces of the protrusions 43 are in tangent to the inner circumferential surfaces of the holes 31a. As a result, the multiple protrusions 43 support the external gear 31 so that it can swing around the central axis J1 via the inner surfaces of the holes 31a. Therefore, the external gear 31, the output section 46, and the multiple protrusions 43 constitute the movable section 30A. In other words, the reduction mechanism 30 has a movable section 30A.

[0052] In this embodiment, the hole 31a and the projection 43 overlap with the third bearing 52 and the second shaft portion 21b when viewed along the radial direction. In other words, the hole 31a, the projection 43, the third bearing 52, and the second shaft portion 21b each have portions that are located at the same position relative to each other in the axial direction.

[0053] When the motor shaft 21 rotates around the central axis J1, the eccentric second shaft portion 21b revolves circumferentially around the central axis J1. The revolution of the second shaft portion 21b is transmitted to the external gear 31 via the third bearing 52, causing the external gear 31 to oscillate while the in-contact position between the inner surface of the hole portion 31a and the outer surface of the projection portion 43 changes. As a result, the meshing position between the gear portion of the external gear 31 and the gear portion of the internal gear 32 changes circumferentially. Therefore, the rotational force of the motor shaft 21 is transmitted to the internal gear 32 via the external gear 31.

[0054] In this embodiment, the internal gear 32 is fixed and therefore does not rotate. As a result, the external gear 31 rotates around the eccentric axis J2 due to the reaction force of the rotational force transmitted to the internal gear 32. At this time, the direction of rotation of the external gear 31 is opposite to the direction of rotation of the motor shaft 21. The rotation of the external gear 31 around the eccentric axis J2 is transmitted to the output unit 46 via the hole 31a and the projection 43. This causes the output shaft 41 to rotate around the central axis J1. In this way, the rotation of the motor shaft 21 is transmitted to the output shaft 41 via the reduction mechanism 30.

[0055] The rotation of the output shaft 41 is reduced relative to the rotation of the motor shaft 21 by the reduction mechanism 30. Specifically, in the configuration of the reduction mechanism 30 of this embodiment, the reduction ratio R of the rotation of the output shaft 41 relative to the rotation of the motor shaft 21 is expressed as R = -(N2-N1) / N2. The negative sign at the beginning of the equation representing the reduction ratio R indicates that the direction of rotation of the reduced output shaft 41 is opposite to the direction of rotation of the motor shaft 21. N1 is the number of teeth of the external gear 31, and N2 is the number of teeth of the internal gear 32. For example, if the number of teeth N1 of the external gear 31 is 59 and the number of teeth N2 of the internal gear 32 is 60, the reduction ratio R is -1 / 60.

[0056] Thus, according to the electric actuator 1 of this embodiment, since the partition member 15 positioned between the winding section 23b and the movable section 30A in the axial direction is insulating, the insulation distance between the winding section 23b and the movable section 30A can be increased. Therefore, the axial length between the winding section 23b and the movable section 30A can be shortened, and the electric actuator 1 can be miniaturized while ensuring insulation.

[0057] [Second embodiment of an electric actuator] Next, a second embodiment of the electric actuator 1 will be described with reference to Figure 4. In this figure, elements identical to those in the first embodiment shown in Figures 1 to 3 are denoted by the same reference numerals, and their descriptions may be omitted. Figure 4 schematically illustrates the motor unit 20.

[0058] As shown in Figure 4, the electric actuator 1 of this embodiment has an inner edge portion 15c on the partition member 15. The inner edge portion 15c extends from the inner peripheral edge portion 17b of the main body portion 15a to the other axial direction. The inner edge portion 15c is arranged around the circumference. The outer peripheral edge portion 17a of the partition member 15 is located radially outward from the winding portion 23b. The inner peripheral edge portion 17b of the partition member 15 is located inward from the radial center of the winding portion 23b. Viewed in the axial direction, the area of ​​the slot 23s is wider radially outward than radially inward. Therefore, the winding portion 23b may have more windings on the radially outward side than on the radially inward side. By having the outer peripheral edge portion 17a of the partition member 15 located radially outward from the winding portion 23b, the insulation between the winding portion 23b and the movable part 30A of the reduction mechanism 30 can be improved. Furthermore, since the partition member 15 has an inner edge portion 15c extending from the inner peripheral edge portion 17b to the other axial direction, the creepage distance between the winding portion 23b and the movable portion 30A can be further increased.

[0059] According to the electric actuator 1 of this embodiment, in addition to obtaining the same operation and effects as in the first embodiment described above, the creepage distance between the winding portion 23b and the movable portion 30A is increased by the inner edge portion 15c, and insulation can be further improved.

[0060] [Third embodiment of an electric actuator] Next, a third embodiment of the electric actuator 1 will be described with reference to Figures 5 and 6. In these figures, elements identical to those in the second embodiment shown in Figure 4 are denoted by the same reference numerals, and their descriptions may be omitted.

[0061] As shown in Figures 5 and 6, in this embodiment, the electric actuator 1 has an inner edge portion 15c provided on the partition member 15 that extends in one axial direction. That is, the inner edge portion 15c in this embodiment protrudes from the main body portion 15a in one axial direction. By the inner edge portion 15c protruding from the main body portion 15a in one axial direction, it is possible to suppress the diffusion of grease from the movable part 30A to the winding portion 23b. Furthermore, the radial position of the inner edge portion 15c in this embodiment is such that it overlaps with at least a part of the third bearing 52 in the axial direction. The inner edge portion 15c overlaps with the outer ring of the third bearing 52 in the axial direction. By the inner edge portion 15c overlapping with the outer ring of the third bearing 52 in the axial direction, it is possible to suppress the diffusion of grease from the third bearing 52 to the winding portion 23b.

[0062] Furthermore, the partition member 15 has a radially extending rib 15d. The rib 15d protrudes from the main body portion 15a to the other axial direction. As shown in Figure 5, the rib 15d is positioned so as to overlap with the slot 23s when viewed in the axial direction. By providing the rib 15d that protrudes from the main body portion 15a to the other axial direction and extends radially, radial deformation of the partition member 15 can be suppressed. By positioning the rib 15d so as to overlap with the slot 23s when viewed in the axial direction, the rib 15d can be positioned without interfering with the winding portion 23b. The radial end of the rib 15d may be connected to at least one of the outer edge portion 15b and the inner edge portion 15c. By connecting the rib 15d to the outer edge portion 15b and the inner edge portion 15c at its radial end, deformation of the partition member 15 can be further suppressed.

[0063] The partition member 15 has a recess 15e with a bottom on the surface facing the movable part 30A. By providing a recess 15e with a bottom on the surface facing the movable part 30A, deformation of the partition member 15 can be further suppressed. The recess 15e overlaps with the rib 15d when viewed in the axial direction. If the thickness of the main body 15a is thin, providing a recess 15e with a bottom may make it impossible to secure the thickness between the upper surface of the main body 15a and the bottom of the recess 15e. Since the recess 15e overlaps with the rib 15d when viewed in the axial direction, the rib 15d is located above the bottom of the recess 15e, so the thickness can be secured.

[0064] It is preferable that a lubricant G is provided in the recess 15e. The lubricant G is, for example, grease. If the lubricant G in the movable part 30A decreases and dirt accumulates, the insulating properties may decrease due to wear particles generated in the movable part 30A. By providing a lubricant G in the recess 15e, the generation of wear particles can be suppressed, preventing a decrease in insulating properties, and the frequency of replenishing the lubricant G in the movable part 30A can be reduced, thereby reducing maintenance work.

[0065] According to the electric actuator 1 of this embodiment, in addition to obtaining the same operation and effects as in the first embodiment described above, the inner edge portion 15c protrudes from the main body portion 15a in one axial direction, thereby suppressing the diffusion of grease from the movable portion 30A to the winding portion 23b. Furthermore, according to the electric actuator 1 of this embodiment, the inner edge portion 15c is positioned to overlap with at least a part of the third bearing 52 in the axial direction, thereby suppressing the diffusion of grease from the third bearing 52 to the winding portion 23b.

[0066] Furthermore, according to the electric actuator 1 of this embodiment, a rib 15d is provided that protrudes from the main body 15a to the other axial side and extends radially, thereby suppressing radial deformation of the partition member 15. Moreover, according to the electric actuator 1 of this embodiment, the rib 15d is positioned so that it overlaps with the slot 23s when viewed in the axial direction, making it possible to position the rib 15d without interfering with the winding portion 23b.

[0067] In this embodiment, the electric actuator 1 is provided with a recess 15e having a bottom on the surface facing the movable part 30A, which further suppresses deformation of the partition member 15. Furthermore, in this embodiment, the electric actuator 1 is provided with a recess 15e that overlaps with the rib 15d when viewed in the axial direction, which ensures the thickness of the upper part of the bottom of the recess 15e. Moreover, in this embodiment, the electric actuator 1 is provided with a lubricant G in the recess 15e, which suppresses the generation of wear particles and the diffusion of wear particles in the grease, thereby suppressing a decrease in insulation performance, and also reduces the frequency of replenishing the lubricant G to the movable part 30A, thereby reducing maintenance work.

[0068] Preferred embodiments of the present invention have been described above with reference to the attached drawings, but it goes without saying that the present invention is not limited to these examples. The shapes and combinations of the constituent members shown in the above examples are merely examples, and can be modified in various ways based on design requirements, etc., without departing from the spirit of the present invention.

[0069] For example, the electric actuator may be an electric pump comprising a pump section driven by a motor section. The application of the electric actuator is not particularly limited. The electric actuator may be mounted in a shift-by-wire actuator system driven based on the driver's shift operation. Furthermore, the electric actuator may be mounted in equipment other than a vehicle. The configurations described herein can be combined as appropriate, within the bounds of what is not inconsistent with each other.

[0070] Furthermore, this technology can be configured as follows: (1) A motor unit having a rotor that can rotate about a central axis extending in the axial direction, and a stator located radially outward from the rotor, A reduction mechanism having a movable part connected to one axial side of the rotor and rotating in conjunction with the rotation of the rotor, A case housing the motor section and the reduction mechanism, Equipped with, The stator is, A stator core in which multiple stator teeth and slots are arranged alternately in the circumferential direction around the aforementioned central axis, The winding portion attached to the stator teeth, It has, An electric actuator in which an insulating partition member is provided between the winding portion and the movable portion in the axial direction. (2) The aforementioned partition member is A main body portion that surrounds the central axis and extends radially around the central axis, An outer edge portion extending from the outer peripheral edge of the main body portion to the other side in the axial direction, An inner edge portion extending axially from the inner peripheral edge portion of the main body portion, Having, (1) The electric actuator described above. (3) The outer peripheral edge is located radially outward from the winding portion, The inner peripheral edge is located inward from the radial center of the winding portion. (2) The electric actuator described above. (4) The inner edge portion extends from the inner peripheral edge portion in the other axial direction, The electric actuator described in (2) or (3). (5) The inner edge portion extends from the inner peripheral edge portion in one axial direction, An electric actuator as described in any one of (2) through (4). (6) The movable part has a bearing that rotatably supports it, The inner edge portion overlaps with at least a part of the bearing in the axial direction. (5) The electric actuator described above. (7) The partition member has a rib that extends radially and protrudes radially from the main body to the other side in the axial direction, at a position that overlaps with the slot when viewed in the axial direction. An electric actuator as described in any one of (2) through (6). (8) The rib is connected to the outer edge, (7) The electric actuator described above. (9) The partition member is provided with a recess having a bottom on the surface facing the movable part. The electric actuator described in (7) or (8). (10) The recessed portion overlaps with the rib when viewed in the axial direction. (9) The electric actuator described above. (11) A lubricant is provided in the aforementioned recess. The electric actuator described in (9) or (10). [Explanation of Symbols]

[0071] 1…Electric actuator, 10…Case, 15…Partition member, 15a…Main body, 15b…Outer edge, 15c…Inner edge, 15d…Rib, 15e…Recess, 17a…Outer peripheral edge, 17b…Inner peripheral edge, 20…Motor section, 22…Rotor, 23…Stator, 23a…Stator core, 23b…Winding section, 23s…Slot, 23t…Stator teeth, 30…Reduction mechanism, 30A…Movable part, 52…Third bearing (shaft bearing), J1…Central shaft

Claims

1. A motor unit having a rotor that can rotate about a central axis extending in the axial direction, and a stator located radially outward from the rotor, A reduction mechanism having a movable part connected to one axial side of the rotor and rotating in conjunction with the rotation of the rotor, A case housing the motor section and the reduction mechanism, Equipped with, The stator is, A stator core in which multiple stator teeth and slots are arranged alternately in the circumferential direction around the aforementioned central axis, The winding portion attached to the stator teeth, It has, An electric actuator in which an insulating partition member is provided between the winding portion and the movable portion in the axial direction.

2. The aforementioned partition member is A main body portion that surrounds the central axis and extends radially around the central axis, An outer edge portion extending from the outer peripheral edge of the main body portion to the other side in the axial direction, An inner edge portion extending axially from the inner peripheral edge portion of the main body portion, Having, The electric actuator according to claim 1.

3. The outer peripheral edge is located radially outward from the winding portion, The inner peripheral edge is located inward from the radial center of the winding portion. The electric actuator according to claim 2.

4. The inner edge portion extends from the inner peripheral edge portion in the other axial direction, The electric actuator according to claim 2 or 3.

5. The inner edge portion extends from the inner peripheral edge portion in one axial direction, The electric actuator according to claim 2 or 3.

6. The movable part has a bearing that rotatably supports it, The inner edge portion overlaps with at least a part of the bearing in the axial direction. The electric actuator according to claim 5.

7. The partition member has a rib that extends radially and protrudes radially from the main body to the other side in the axial direction, at a position that overlaps with the slot when viewed in the axial direction. The electric actuator according to claim 2 or 3.

8. The rib is connected to the outer edge, The electric actuator according to claim 7.

9. The partition member is provided with a recess having a bottom on the surface facing the movable part. The electric actuator according to claim 7.

10. The recessed portion overlaps with the rib when viewed in the axial direction. The electric actuator according to claim 9.

11. A lubricant is provided in the aforementioned recess. The electric actuator according to claim 9 or 10.

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